MECHANICAL PROCESSES 
 
AN ELEMENTARY OUTLINE OF 
 
 MECHANICAL PROCESSES 
 
 GIVING A BRIEF ACCOUNT OF 
 
 THE MATERIALS USED IN ENGINEERING CONSTRUCTION AND OF THE 
 
 ESSENTIAL FEATURES IN THE METHODS OF PRODUCING THEM, 
 
 ALSO DESCRIBING SHOP PROCESSES AND EQUIPMENT 
 
 FOR THE SHAPING OF METALS INTO FORMS 
 
 FOR ENGINEERING AND GENERAL USES 
 
 ARRANGED FOR THE INSTRUCTION OF MIDSHIPMEN AT THE U, S. NAVAL ACADEMY 
 AMD FOR STUDENTS IN GENERAL 
 
 BY 
 
 G. W. DANFORTH, U. S. NAVY 
 
 Instructor in the Department of Marine Engineering and Naval Construction 
 U. S. Naval Academy, Annapolis, Maryland 
 
 ANNAPOLIS, MARYLAND 
 THE UNITED STATES NAVAL INSTITUTE 
 
 1912 
 
COPYRIGHT, 1912 
 BY 
 
 PHILIP R. ALGER 
 
 Secretary and Treasurer 
 U.S. Naval Institute 
 
 Q0<*ftttrtore ( 
 
 BALTIMORE, MD., U. S. A. 
 
PREFACE 
 
 This book is intended as an elementary account of the several 
 classes of processes employed in shaping materials of construction 
 for various mechanical uses. A brief account of the properties of 
 these materials and of the methods of producing them is also given. 
 
 Effort has been made to present the subject matter in brief and 
 elementary form, with sufficient detail to outline methods and 
 principles clearly. It is intended to show completely, though 
 briefly, the steps of metal manufacture from the ore to the finished 
 product, so that the student may be enabled to classify all branches 
 of metal manufacture, and may pursue intelligently such study as 
 will give fuller information than is possible to include herein. 
 
 Most of the subject matter is from notes taken by the writer 
 when on engineering instruction, on shipyard inspection and other 
 engineering duty and during recent visits to manufacturing plants 
 where processes were observed through the courtesy of officials of 
 those plants, and where valuable information was obtained which 
 could not be obtained otherwise. These notes were in several in- 
 stances checked and supplemented by information from various 
 technical books and papers, particularly by reference to their re- 
 ports of original investigations. A list of the books of great assist- 
 ance in this work is as follows: 
 
 Iron (The Metallurgy of) Turner. 
 
 Steel (The Metallurgy of) Harbord and Hall. 
 
 The Metallurgy of Iron and Steel Stoughton. 
 
 Chemistry of Materials of Engineering Sexton. 
 
 Elementary Text Book of Metallurgy Sexton. 
 
 Materials of Engineering Thurston. 
 
 The Materials of Construction Johnson. 
 
 Calcareous Cements Redgrave and Spackman. 
 
 Hawkins Mechanical Dictionary. 
 
 Cyclopaedia of Mechanical Engineering. 
 
 Journal of the American Society of Naval Engineers. 
 
 302099 
 
4 PREFACE 
 
 The shops of the following named industrial companies were re- 
 cently visited : 
 
 Acme Steel & Malleable Iron Works, Buffalo, N. Y. 
 
 American Iron and Steel Mfg. Co., Beading, Pa. 
 
 American Sheet and Tin Plate Co., Pittsburgh, Pa. 
 
 American Steel and Wire Co., Springfield, Mass. 
 
 American Welding Co., Carbondale, Pa. 
 
 Babcock and Wilcox Boiler Co., Bayonne, N. J. 
 
 Benedict and Burnham Mfg. Co., Waterbury, Conn. 
 
 Best Mfg. Co., Pittsburgh, Pa. 
 
 Bethlehem Steel Co., South Bethlehem, Pa. 
 
 Billings and Spencer Co., Hartford, Conn. 
 
 E. W. Bliss Co., Brooklyn, N. Y. 
 
 Brown & Sharpe Mfg. Co., Providence, R. I. 
 
 The Carborundum Co., Niagara Falls, N. Y. 
 
 The Coe Brass Mfg. Co., Ansonia, Conn. 
 
 Cramp & Sons Ship and Engine Bldg. Co., Philadelphia. 
 
 The Crosby Co., Buffalo, N. Y. 
 
 Fore Eiver Ship and Engine Bldg. Co., Quincy, Mass. 
 
 Glasgow Iron Works, Pottstown, Pa. 
 
 C. G. Hussey & Co., Pittsburgh, Pa. 
 
 Midvale Steel Co., Wayne Junction, Pa. 
 
 National Tube Co/s Works at 
 
 Christy Park, Pa. 
 
 McKeesport, Pa. 
 
 Elwood City, Pa. 
 
 New York Shipbuilding Co., Camden, N. J. 
 Nicholson File Co., Providence, R. I. 
 Niles-Benent-Pond Co., Philadelphia, Pa. 
 and branches 
 
 Pond Machine Tool Co., Plainfield, N. J. 
 
 Pratt & Whitney Co., Hartford, Conn. 
 Eeading Steel Castings Co., Reading, Pa. 
 Schutte and Koerting Co., Philadelphia, Pa. 
 Seneca Iron and Steel Co., Buffalo, N. Y. 
 Worth Bros. Iron Works, Coatesville, Pa. 
 IT. S. Navy Yard, New York, N. Y. 
 U. S. Navy Yard, Boston, Mass. 
 
PREFACE 5 
 
 In addition, the following named companies have contributed 
 useful information : 
 
 Harbison Walker Eefractories Co., Pittsburgh, Pa. 
 
 Illinois Steel Co., South Chicago, 111. 
 
 C. W. Leavitt & Co., New York, N. Y. 
 
 Manning, Maxwell and Moore, New York, N. Y. 
 
 Oliver Machinery Co., Grand Eapids, Mich. 
 
 Eockwell Furnace Co., New York, N. Y. 
 
 United Engineering and Foundry Co., Pittsburgh, Pa. 
 
 The manuscript was read by Captain F. W. Bartlett, IT. S. Navy, 
 Head of the Department of Marine Engineering and Naval Con- 
 struction at the Naval Academy, and many valuable suggestions made 
 by him are embodied in the text. 
 
 G. W. DANFORTH, U. S. Navy. 
 
 U. S. NAVAL ACADEMY, September, 1911. 
 
TABLE OF CONTENTS 
 
 CHAPTER I. 
 
 INTRODUCTORY. ENGINEERING MATERIALS. 
 
 1. Scope of Mechanical Processes. 2. Study of Processes. 3. General 
 Classification of Materials. 4. Materials Most Used. 5. Proper- 
 ties of Materials. 6. Influences Which Change Properties of 
 Materials. 7. Fatigue of Metals. 8. Classification of Forces. 
 9. Alloys. 10. Peculiarities of Alloys. 11. Designation of Weil- 
 Known Alloys. 12. Brass. 13. The Bronzes. 14. Other Useful 
 Alloys. 15. Copper. Its Uses. 16. Properties of Copper. 17. 
 Uses of Zinc. 18. Properties of Zinc. 19. Uses of Tin. 20. 
 Properties of Tin. 21. Uses of Lead. 22. Properties of Lead. 
 23. Uses of Nickel. 24. Properties of Nickel. 25. Uses of 
 Aluminum. 26. Properties of Aluminum. 27. Use and Proper- 
 ties of Antimony. 28. Portland Cement and Concrete. General 
 Characteristics. 29. Varieties of Lime and Cement. 30. True 
 Cements. 31. Requisites in Selecting Raw Materials, 32. Com- 
 position of Cement. 33. Manufacture of Portland Cement. 
 34. Uses of Portland Cement. 35. Cement Mixtures. 36. Method 
 of Using Concrete. 37. Causes of Settling and Strengthening of 
 Cement. 38. Wood. Use as Parts of Machinery. 39. Lumber 
 and Timbers. 40. Lumber Grading. 41. Hard and Soft Wood 
 Lumber. 42. Heart and Sap Wood. 43. Lumber Inspection 
 Rules. 44. Standard Defects. 45. Rough and Dressed Lumber. 
 46. Lumber Measurement. 47. Durability of Wood 13 
 
 CHAPTER II. 
 
 A GENERAL OUTLINE OF METAL-PRODUCING PROCESSES. 
 48. Ores. 49. Elimination of Gangue. 50. Calcination. 51. Break- 
 ing up the Ore Compound. 52. Smelting Furnaces. 53. The 
 Blast Furnace. 54. Blast Furnace Modifications. 55. Acid and 
 Basic Ores. 56. Fluxes. 57. Blast Furnace Operation. 58. 
 The Blast Stove. 59. Reverberatory Furnaces. 60. Atmosphere 
 of Reverberatory Furnaces. 61. Refractory Materials. 62 
 Sources of Copper. 63. Producing Copper from its Sulphides. 
 64. The Poling Process. 65. Electrolytic Refining of Copper. 66. 
 Zinc. 67. Tin. 68. Lead. 69. Nickel. 70. Aluminum. 71. 
 Electricity in Metallurgy 35 
 
 CHAPTER III. 
 
 FUELS. 
 
 72. Uses. 73. Combustion. 74. Components of Fuels. 75. Classes 
 of Fuel. 76. Wood and Charcoal. 77. Coal. 78. Coke. 79. Coke 
 Making. 80. Powdered Coal. 81. Screenings. Briquettes. 82. 
 Liq\iid Fuels. 83. Gas Fuels. 84. Natural Gas. 85. Producer 
 Gas. 86. Water Gas. 87. Illuminating Gas 58 
 
TABLE OF CONTENTS 
 
 CHAPTER IV. 
 
 IRON AND STEEL. 
 
 88. Iron Ores. 89. Preliminary Preparation of Iron Ores. 90. Cal- 
 cination. 91. Reduction. 92. Pig Iron. 93. Disposition of Iron 
 from the Blast Furnace. 94. Grades of Pig Iron. 95. The 
 Three General Classes. 96. Carbon in Iron. 97. Silicon in Iron. 
 98. Sulphur in Iron. 99. Phosphorus in Iron. 100. Manganese 
 in Iron. 101. Properties of Cast Iron. 102. Properties of 
 Wrought Iron. 103. Properties of Steel. 104. History of 
 Wrought Iron. 105. Methods of Production. 106. The Indirect 
 Process of Wrought-Iron Making. 107. The Puddling Furnace. 
 108. Puddling-Furnace Operation. 109. Treatment of Puddle 
 Balls. 110. Re-heating and Welding Muck Bar into Wrougnt 
 Iron. 111. Rolls for Shaping Wrought Iron. 112. History of 
 Steel. 113. The Cementation Process. 114. Present Processes of 
 Steel Making. 115. The Bessemer Process. 116. Operation of 
 the Converter. 117. Pouring the Steel into Moulds. 118. 
 Features of the Bessemer Process. 119. The Open-Hearth Pro- 
 cess. 120. The Open-Hearth Furnace. 121. Charging the Open- 
 Hearth Furnace. 122. Operation of the Open-Hearth Furnace. 
 123. Tapping Out. 124. Pouring the Moulds. 125. The Tal- 
 bot Process. 126. The Duplex Process. 127. Uses of Open- 
 Hearth Steel. 128. The Crucible Process. 129. Materials used 
 in Crucible Steel. 130. Crucibles. 131. The Crucible Furnace. 
 132. Charging a Crucible. 133. Operation of the Crucible 
 Furnace. 134. Properties of Crucible Steel. 135. Special Steels. 
 136. Ingot Moulds. Stripping Ingots. 137. Impurities in 
 Steel. Segregation. 138. Defects in Steel Ingots. 139. Fluid 
 Compressed Steel. 140. Compressing Steel. 141. The Electric 
 Refining Furnace 68 
 
 CHAPTER V. 
 
 MECHANICAL TREATMENT OF METALS. HEAT TREATMENT 
 
 OF METALS. 
 
 142. Forms of Newly Produced Metals. 143. Primary Outline of 
 the Shaping of Metals. 144. Reducing an Ingot to Marketable 
 Forms. 145. Re-heating of Ingots. The Soaking Pit. 146. 
 Rolling an Ingot. 147. Mill Scale. 148. Structural Steel Shapes. 
 149. Types of Rolling Mills. 150. The Cogging Mill. 151. The 
 Structural Mill. 152. The Billet Mill. 153. The Rail Mill. 
 154. The Sheet-Bar Mill. 155. Plate Mills. 156. Names of Roll- 
 ing-Mill Parts. 157. Re-heating of Blooms, Slabs and Billets. 
 158. Re-heating Furnace for Large Blooms. 159. Precautions 
 in Re-heating High-Grade Steel. 160. Points for the Inspection 
 of Rolled Material. 161. Effect of Mechanical Treatment of 
 Metals. 162. Cold-Rolled Steel. 163. Large Forgings. 164. 
 The Hydraulic Forging Press. 165. Handling Large Ingots for 
 Forging. 166. The Heat Treatment of Metals. 167. Changes in 
 Steel Due to Heating. 168. Annealing of Metals. 169. The 
 Hardening of Steel. 170. Oil Tempering of Steel. 171. Rolling 
 Sheet Copper. The Sheet Mill. 172. Rolling of Sheet Brass. 
 173. Extruded Brass. 174. Extruded Shapes 123 
 
TABLE OF CONTENTS 9 
 
 CHAPTER VI. 
 
 THE RE-MANUFACTURE OF METALS. 
 
 175. Scope of Metal Re-Manufacturing. 176. Tool Making. 177. 
 Special Methods of Heating and Hardening Steel Articles. 178. 
 Sheet Iron. 179. The Manufacture of Sheet Iron. 180. Galvan- 
 izing. 181. Tinning. 182. The Manufacture of Tin Plate 
 183. Terne Plates. 184. Russia Iron. 185. Wire Drawing. 186. 
 Gaging the Sizes of Wire. 187. Coating Wire for Protection 
 from Corrosion. 188. Hard Wire. Spring Material. 189. Pipes 
 and Tubes. 190. The Manufacture of Welded Pipe. 191. Defects 
 in Welded Pipe. 192. Iron Pipe. 193. Seamless Tubes. 194. 
 Piercing Billets for Seamless Tubes. 195. Rolling Pierced 
 Blanks. 196. Cross Rolling. 197. Sizing. 198. Straightening 
 and Cutting to Length. 199. Cold-Drawn Tubes. 200. Brass 
 and Copper Tubing. 201. Tubes of Thin Walls and Small Di- 
 ameters 202. Defects in Seamless Tubes. 203. Hot-Drawn 
 Seamless Tubes. 204. Steel Cylinders for Storage of Gases. 
 205. Cold Pressing of Metals. 206. Steps in Shaping Articles from 
 Sheet Metals. 207. Drop Forgings. 208. The Drop Hammer. 
 209. Drop-Forging Dies. Making a Drop Forging. 210. Bolts, 
 Nuts and Rivets. 211. Screw-Cutting Machines. 212. Examples 
 of Work from the Screw Machine 158 
 
 CHAPTER VII. 
 
 SHOPS OF MACHINERY BUILDING AND REPAIRING PLANTS. 
 DRAWINGS FOR SHOP USE. 
 
 213. Distinctive Features of Building and Repairing Plants. 214. 
 Shops Composing a Building and Repairing Plant. 215. The 
 Drawing Room. 216. Drawing-Room Methods. 217. Shop Draw- 
 ings. 218. Methods of Representing Articles on Drawings. 
 219. Consecutive Order of Shop Work 199 
 
 CHAPTER VIII. 
 
 THE PATTERN SHOP. 
 
 220. Work of the Pattern Shop. 221. Pattern-Shop Equipment. 
 222. Power Tools. 223. The Circular Saw. 224. The Speed Lathe. 
 225. Turning Tools. 226. The Wood Lathe. 227. The Face 
 Lathe. 228. The Band Saw. 229. The Hand Planer. 230. 
 The Surface Planer. 231. The Boring Machine. 232. The Mor- 
 tise Machine. 233. Hand Tools. 234. Materials used for Pat- 
 terns. 235. Joints and Cuts in Woodworking. 236. Essential 
 Features of Patterns. 237. Shrinkage Allowance. 238. Draw- 
 ing a Pattern from the Mould. 239. Core Prints and Core Boxes. 
 240. Fillets. 241. The Prevention of Warping. 242. Marking 
 and Preserving Patterns. 243. Pattern-Shop Accessories and 
 Methods. 244. The Laying-Down Board. 245. The Marking- 
 Off Table. 246. Varieties of Patterns. 247. Skeleton Patterns. 
 248. Sweeps 205 
 
10 TABLE OF CONTENTS 
 
 CHAPTER IX. 
 
 THE FOUNDRY. 
 
 249. The Work of the Foundry. 250. Iron, Brass and Steel Found- 
 ries. 251. Classes of Moulds. 252. Example of an Open Sand 
 Mould. 253. Example of a Green Sand Mould. 254. Essential 
 Features of a Mould. 255. Foundry Equipment. 256. Moulding 
 Sand. 257. Other Materials Used in Moulding. 258. Flasks for 
 Green and Dry Sand Moulds. 259. Tools Used in Moulding. 
 260. Example of Making a Small Mould. 261. Moulding Ma- 
 chines. 262. Cores. 263. Chaplets. 264. Chill Moulds. 265. 
 Example of a Loam Mould. 266. Building a Loam Mould. 267. 
 The Cupola, 268. Operation of the Cupola. 269. Ladles. 270. 
 Foundry Iron. 271. Brass Furnaces. 272. Defects in Castings. 
 273. Remedies for Defective Castings. 274. Steel Castings. 
 275. Steel and Iron Foundries Compared. 276. Moulds for 
 Steel Castings. 277. Particular Requirements for Steel Moulds. 
 278. Surfaces of Steel Moulds. 279. Means of Avoiding 
 Shrinkage Cracks. 280. Avoiding Surface or Interior Cavities. 
 281. Steel for Castings. 282. The Tropenas Converter. 283. 
 Temperature of Steel for Pouring. 284. Annealing Steel Cast- 
 ings. 285. Defects in Steel Castings 228 
 
 CHAPTER X. 
 
 THE BLACKSMITH SHOP. 
 
 286. The Blacksmith and Forge Shop. 287. Materials for Forgings. 
 288. Shop Equipment for Hand Forging. 289. The Forge. 
 290. The Anvil. 291. Smiths' Hammers. 292. Tongs and Anvil 
 Tools. 293. Fuel for Use in Forges. 294. Heating in a Forge. 
 295. Terms Commonly Used in Forging. 296. Measuring Stock 
 for Forging. 297. Welding. 298. Hardening and Tempering at 
 the Forge. 299. Color Table for Judging Hardness. 300. Hard- 
 ening of Alloy-Steel Tools. 301. Influence of the Cooling Me- 
 dium in Hardening. 302. Annealing in the Blacksmith Shop. 
 303. Equipment of the Forge Shop. 304. The Steam Hammer. 
 305. Appliances Used with the Steam Hammer. 306. Heating 
 Furnaces. 307. Notes on Steam Hammer Forging 260 
 
 CHAPTER XI. 
 
 THE MACHINE SHOP. 
 
 308. Scope of Machine-Shop Work. 309. Machine-Shop Practice. 
 310. Machine-Shop Equipment. 311. Marking Work to be Ma- 
 chined. 312. The Marking-Off Table. 313. Tools and Appli- 
 ances for the Marking-Off Table. 314. Refined Measuring in 
 Machine Work. 315. Tools for Measuring. 316. The Micrometer 
 Caliper. 317. Machine Tools. 318. The Lathe. 319. Varieties of 
 the Lathe. 320. Lathe Tools. 321. Lathe Attachments. 322. 
 The Lathe Chuck. 323. Lathe Mandrels. 324. The Boring Bar. 
 325. The Steady Rest. 326. Centering Work for the Lathe. 
 327. Cutting of Screw Threads. 328. Forms of Threads. Defi- 
 nitions. 329. Standard Threads. 330. Drilling Machines. 331. 
 The Vertical Drill. 332. The Radical Drill. 333. Drills and At- 
 tachments for Drilling Machines. 334. The Planer. 335. Types 
 of the Planer. 336. Planer Tools. 337. The Planer Chuck and 
 
TABLE OF CONTENTS 11 
 
 Planer Jack. 338. The Planing of Propeller Blades. 339. The 
 Shaper. 340. The Milling Machine. 341. Description of the 
 Milling Machine. 342. The Universal Milling Machine. 343. 
 Milling-Machine Cutters and Arbors. 344. Milling-Machine At- 
 tachments. 345. The Boring Machine. 346. The Horizontal 
 Boring and Drilling Machine. 347. The Vertical Boring and 
 Turning Mill. 348. The Slotting Machine. 349. Tools for the 
 Slotting Machine. 350. Pipe Cutting and Threading Machines. 
 351. Tool-Sharpening Machines. 352. Metal-Cutting Saws. 
 353. Forcing Presses. 354. Machine-Shop Notes. 355. Bench 
 Work in the Machine Shop. 356. Cold Chisels. 357. Files. 
 358. Taps and Dies. 359. Wrenches. 360. Scrapers. 361. Sur- 
 face Plates. 362. Abrasive Materials. 363. Portable Tools. 
 364. Pipe Fitting. 365. Fittings. 366. Tools Used in Pipe Fit- 
 ting. 367. Bolts, Nuts and Machine Screws 275 
 
 CHAPTER XII. 
 
 THE BOILER SHOP. 
 
 368. Work of the Boiler Shop. 369. Types of Boilers. Their Man- 
 ufacture. 370. Boiler Material. 371. Preliminary Diagram 
 for Laying Out Work. 372. Diagram for Laying Out Shell 
 Plates. 373. Preparation of Plates for Laying Out. 374. Opera- 
 tions for Shaping Plates. 375. Planing Plate Edges. 376. 
 Plate-Bending Rolls. 377. Marking a Flange. 378. Methods 
 of Flanging. 379. Equipment for Flanging by Hand. 380. The 
 Hydraulic Flanging Press. 381. The Hydraulic Accumulator. 
 382. Flange-Heating Furnace. 383. Straightening and An- 
 nealing of Flanged Plates. 384. Drilling Holes in Boiler Plates. 
 385. Assembling the Parts of a Boiler. 386. Riveting. 387. 
 Rivet-Heating Furnace. 388. Methods of Holding Boiler Tubes 
 in Place. 389. Chipping and Caulking. 390. Corrugated Fur- 
 naces. 391. Other Equipment for the Boiler Shop. 392. Power 
 Shears and Punch. 393. Hand Shears and Punch. 394. Shapes 
 of Rivets 338 
 
 CHAPTER XIII. 
 
 OTHER SHOPS SPECIAL PROCESSES. 
 
 395. Sheet Metal Work. 396. The Copper Shop. Materials Used. 
 397. Copper Shop Equipment. 398. Cutting, Bending and 
 Riveting Tools. 399. Coppersmith Hammers. 400. Brazing. 
 401. Heat for Brazing. 402. Annealing. 403. Soldering. 404. 
 Method of Soldering. 405. Copper Pipe. 406. Joining Lengths 
 of Copper Pipe. 407. Brazing a Branch in a Copper Pipe. 
 408. The Plate and Angle Shop. 409. The Bending Slab. 410. 
 Special Processes. 411. Malleableizing. 412. Case Hardening. 
 413. Pipe Bending. 414. Joining Metals. 415. Electric Weld- 
 ing. 416. The Resistance System. 417. The Arc System. 418. 
 The Thermit Process. 419. Making a Thermit Weld. 420. Blow 
 Pipe Welding. 421. Method of Making a Blow Pipe Weld. 422. 
 Application of Blow Pipe Welding. 423. Blow Pipe Cutting of 
 Metals. 424. Burning On. 425. Puddling. 426. Classification 
 of Welding. Methods. 427. Grinding. 428. Grinding Machines. 
 429. Grinding Wheels. 430. Lapping. 431. Armor-Plate 
 Making 363 
 
12 TABLE OF CONTENTS 
 
 APPENDIX. 
 
 432. Table of Brasses and Bronzes. 433. Degrees of Hardness of 
 Steel Tools. 434. File Making. 435. Wire Gage Table. 436 
 Wire Dies. 437. Dimensions of Standard Iron Pipes. 438! 
 Methods of Threading Bolts. 439. Illustration of Automatic 
 Screw Machine Work. 440. Shop Location and Equipment. 
 441. Allowance for Forcing and Shrinkage Fits. 442. U. S. 
 Standard Screw Threads. 443. Hydraulic Data 395 
 
 INDEX . 407 
 
CHAPTEE I. 
 INTRODUCTORY. ENGINEERING MATERIALS. 
 
 1. Scope of Mechanical Processes. Mechanical processes prop- 
 erly include every manual and machine process, and the mechanical 
 part of every chemical process, used in the extensive field of the 
 mechanical arts. This broad field includes every branch of manu- 
 facturing and construction. It would be obviously impracticable 
 to attempt to cover this field in one book, hence it is intended to 
 include here a brief account of (1) the more important materials 
 of construction and the essential steps in producing them; and (2) 
 the methods of shaping metals for use, particularly the shop proc- 
 esses much used in mechanical and marine engineering construction. 
 
 To give a full account of all that investigators have brought to 
 light of the properties of the commonly used engineering materials, 
 and of all the methods devised for shaping them into useful forms, 
 would require the space of many volumes, and then the subject 
 would not be exhausted, as doubtless many facts and methods are 
 yet undeveloped. Attempt is made herein to give the student an 
 elementary understanding of the materials and methods employed 
 in machine building, for use of those who enter or must come into 
 intelligent contact with modern engineering. 
 
 2. Study of Processes. Every process involves time, labor, and 
 expense, and is employed in whole or in part only because it accom- 
 plishes a definite and necessary purpose. Its use must be justified 
 as a necessary step toward a definite result, else there would be no 
 reason for employing it. A process may not be perfect, although it 
 may bring excellent results, and improvements in processes are 
 being made constantly, despite the remarkable degree of skill at 
 present existing in the production and shaping of metals for a great 
 variety of uses. 
 
 From a superficial knowledge of the properties of metals, many 
 remarkable processes of shaping them hot or cold have been gradu- 
 
14 MECHANICAL PROCESSES 
 
 ally evolved or improved upon by patient and persistent experi- 
 ments, and methods for shaping metals are now in vogue which 
 were deemed impossible a decade ago. Success along these lines 
 comes only from testing the properties of a material beyond the 
 known range, studying the causes of failure, and bringing to one's 
 aid improved apparatus for holding, pressing, cutting, heating, etc., 
 as necessity may require. 
 
 The details of many processes vary because of difference in the 
 skill of workmen, or difference in equipment or quality of materials 
 with which they work. 
 
 3. General Classification of Materials. The materials used in all 
 branches of construction are commonly called engineering materials 
 or materials of construction. The most important of these, as iron, 
 steel, brass, wood, stone, etc., are well known. There are many 
 other materials less extensively used, and more or less widely known. 
 
 Another class of materials necessary to the various processes in- 
 clude those employed to assist the processes, though not intended 
 to enter into the finished product, as fuel, flux in smelting and in 
 welding, emery in grinding, sand in moulding, etc. 
 
 4. Materials Most Used. The material most extensively used in 
 engineering construction is iron in its several forms, included under 
 three divisions, viz., wrought iron, steel and cast iron. The materials 
 of these three divisions are made the subjects of a subsequent 
 chapter. Other materials, of varying degrees of importance, are: 
 
 Alloys, Nickel, 
 
 Copper, Aluminum, 
 
 Zinc, Antimony, 
 
 Tin, Portland cement. 
 
 Lead, Wood. 
 
 5. Properties of Materials. All materials have certain physical 
 properties which determine their fitness for specific purposes. Of 
 first consideration in materials of construction is strength, or 
 tenacity, which is the attraction between molecules of a material 
 giving them the power to resist tearing apart. Next in considera- 
 tion is the property of a material which allows a change of relative 
 position of its molecules (which is change of shape), without de- 
 stroying or seriously affecting tenacity. 
 
INTRODUCTORY. ENGINEERING MATERIALS 15 
 
 Specific properties of materials are : 
 
 (1) Hardness, the property of resisting change of shape tinder 
 pressure and separation into parts. 
 
 (2) Brittleness, associated with hardness,, the property of resist- 
 ing a change of the relative position of molecules, or liability to 
 fracture without change of shape. 
 
 (3) Density, the weight of a unit volume usually compared with 
 unit volume of water. 
 
 (4) Elasticity, the power of returning to the original shape 
 upon removal of the force which has caused change of shape. 
 
 (5) Ductility, the property of metals allowing them to be drawn 
 out, as in wire-making, without breaking. 
 
 (6) Malleability, similar to ductility, the property of metals 
 allowing them to bend or be permanently distorted without rupture. 
 Examples of this are rolling a metal into sheets or changing its 
 form by hammering. Opposed to brittleness. 
 
 (7) Fusibility, the property of being liquefied by heat. 
 
 (8) Conductivity, the power to transmit molecular vibrations 
 caused by heat or electricity. 
 
 (9) Contraction and expansion, the change of volume due to 
 change of temperature. 
 
 6. Influences Which Change Properties of Materials. Heat has 
 more or less influence in changing these properties in a given ma- 
 terial. 
 
 Hardness and strength are increased by hammering or rolling a 
 metal, and these properties are changed, often in a marked degree, 
 by a slight amount of another substance in the metal. 
 
 Conductivity is usually increased or decreased by heat, and elec- 
 tric conductivity is greatly reduced by impurity in metals. 
 
 Some metals and alloys expand upon cooling, due to certain 
 ingredients. 
 
 Heating and cooling suddenly, will render steel hard and brittle, 
 and annealing., which is a different process for different metals, 
 brings a metal or an alloy back to its natural or normal state of 
 softness after having been hardened by hammering, rolling, or 
 otherwise. 
 
 7. Fatigue of Metals. It has been found that metals give way in 
 some cases under smaller loads than they could originally carry. 
 
16 MECHANICAL PROCESSES 
 
 This is called fatigue, and is caused by a very great number of 
 reversals or repetitions of load, as when a metal receives constant 
 shocks or impacts in use. It is a popular but erroneous idea that 
 the particles of metal change to a weakened crystalline form. 
 Later investigations show that the loss of strength is due to the 
 crystals of metal being so shaken that the small planes of. cleavage 
 between them join in one continuous plane of rupture, which, when 
 sufficiently extended, leaves the remaining sound metal unable to 
 resist the shock brought upon it. Cases of fatigue are unusual. 
 
 8. Classification of Forces. Forces acting upon materials are 
 classified according to their direction of action. 
 
 A force acting on a material is called a stress, and the deforma- 
 tion caused by this action is the consequent strain. 
 
 If, upon removal of the force, the material returns to its original 
 shape, the strain has been within the elastic limit of the material, 
 
 FIG. 1. 
 
 but if upon removing the force, the material fails to resume its 
 original shape, it has been strained beyond its elastic limit, and is 
 said to have a permanent set. If the force continues to be increased 
 beyond that causing permanent set, a rupture of the material will 
 finally result. 
 
 Tension is the action of forces tending to pull apart the particles 
 of a material, and tensile strength of a material, expressed in 
 pounds per square inch of cross section of the material pulled, is a 
 measure of the force required to disrupt the material. The amount 
 which a metal stretches in pulling apart is called the elongation. 
 This is expressed as a per cent of the original length of the metal 
 specimen subjected to tension. 
 
 Compression is the crushing action of forces. 
 
 Torsion is the twisting action of forces. 
 
 Shearing is the action of forces tending to cause adjacent parts 
 of a material to move in opposite directions parallel to a plane of 
 cleavage. 
 
INTRODUCTORY. ENGINEERING MATERIALS 17 
 
 To illustrate the result of bending, consider that a piece of ma- 
 terial is bent as shown in Fig. 1. Its fibres or particles along AB, 
 and for a distance thereunder, are in tension and are slightly elon- 
 gated, while fibres or particles along FGr, and for a distance above, 
 are in compression, and are slightly shortened. 
 
 There is a portion of the piece along CD which is neither under 
 tension nor compression and remains of unchanged length. This is 
 called the neutral axis. 
 
 9. Alloys. An alloy is a combination formed by stirring together 
 two or more metals (occasionally with other substances introduced) 
 in a state of fusion. Investigators state that some alloys are chem- 
 ical combinations, some are mechanical mixtures and others are 
 apparently solutions of one metal in another. 
 
 10. Peculiarities of Alloys. Alloys have peculiarities demanding 
 special and extensive study to understand them, and no laws have 
 yet been found by which the properties of an alloy may be deter- 
 mined from the properties of its constituents. The properties of 
 an alloy are not an average of like properties in its constituents, 
 and very unexpected results may be obtained by varying the propor- 
 tions of constituents of an alloy, or by introducing the slightest 
 amount of some other ingredient. 
 
 The following items give the important peculiarities of alloys: 
 
 (1) The strength of some alloys, particularly when hammered, 
 rolled or drawn into wire, is much greater than that of any of the 
 composing metals. This is true of the useful brasses and bronzes. 
 
 (2) Varying the proportions of the same metals in an alloy 
 throughout a wide range will give very different products in 
 strength, hardness, malleability, ductility, density, fusion point, and 
 color. These changes will not come in a line of regularity. Some 
 of the products will differ widely from the rest. 
 
 (3) The fusing point of an alloy is usually lower than the aver- 
 age of the fusing points of the constituents, and sometimes lower 
 than the fusing point of any constituent. Some alloys, composed 
 of about 50% of bismuth, melt below the temperature of boiling 
 water. 
 
 (4) The introduction of a slight amount of some metals, metal- 
 loids or impurities in a given alloy may bring great changes to one 
 
18 MECHANICAL PROCESSES 
 
 or more of its properties, sometimes improving the alloy, but more 
 frequently rendering it worthless. 
 
 (5) The order of melting and mixing the several metals of an 
 alloy influences the quality of the alloy, because some metals oxidize 
 more readily than others in the fused state. This oxidation should 
 be reduced to a minimum because it wastes the metal and the oxide 
 weakens the alloy. 
 
 In making alloys, it is needless to attempt to get good results by 
 using any but the purest of commercial metals, and scrap alloys 
 may be used only when their composition is known and when it i& 
 suitable to the correct proportioning of the mixture to be made. 
 
 The principal requirements in melting metals for alloys are 
 (1) melt the metal of highest fusion point, and, when melted, drop 
 in the other metal broken up in chunks; (2) have the molten sur- 
 face of metal covered with salt or other flux, or with charcoal, to 
 prevent oxidation from atmospheric oxygen; (3) stir the metals 
 well with an iron rod before pouring from the crucible. 
 
 If the metals in an alloy are not thoroughly mixed, they may not 
 form a homogeneous mass upon cooling. The separating out of any 
 masses of one of the metals is called liquation. This condition will 
 not likely show on the surface of the alloy when cold, but will affect 
 strength and other qualities. 
 
 11. Designations of Weil-Known Alloys. The most extensively 
 used of all alloys are those consisting mainly of copper. Their 
 ornamental appearance and non-corrosive quality make them de- 
 sirable, and their strength, with varying degrees of hardness, elas- 
 ticity, ductility and malleability, supplies the requirements for 
 materials of a wide range of use. 
 
 In general, copper-zinc alloys are called brass, although some 
 brass may contain also a small amount of lead or tin; copper-tin 
 alloys are the main constituents of bronze; and copper-tin-zinc 
 alloys are known as composition. These terms, as will be learned, 
 are loosely used in practice and not confined to the designations 
 here given. 
 
 12. Brass. This is one of the most important of the alloys. 
 While its usual constituents, copper and zinc, combine in any pro- 
 portion, the range of useful proportions varies from about 60 to 
 
INTRODUCTORY. ENGINEERING MATERIALS 19 
 
 89% of copper. A widely used formula for brass is about % cop- 
 per and 1/3 zinc. 
 
 The range of composition of brass offers a material suitable for 
 a great number of particular uses. Zinc gives brass its hardness, 
 and tin in small quantities increases this. Experiment shows that 
 the tensile strength of cast brass is greatest (about 50,000 Ibs. per 
 sq. in.) when the composition is about 62% copper and 38% zinc; 
 and that ductility and malleability are greatest for about 70% 
 copper and 30% zinc. These properties, however, are improved by 
 adding a small amount of tin for hardness, or lead for ductility. 
 
 Brass may be considerably hardened by rolling or hammering, 
 hot or cold, or by drawing it into wire. Its strength and rigidity 
 are by these means increased, and brass thus treated is used for 
 springs, but these effects may be removed by annealing, which con- 
 sists of heating to a cherry-red and cooling slowly, or rapidly, if its 
 composition will not cause cracking. Thoroughly annealed brass 
 has no springiness and may be bent like lead. 
 
 13. The Bronzes. Phosphor, manganese and aluminum bronzes 
 are among the best bronzes known, and are the most extensively used. 
 Bronzes are used when a strong and fairly ductile non-corrosive alloy 
 is necessary in ship and machinery parts. They are the strongest 
 and about the most expensive alloys in engineering use. Phosphorus 
 and manganese are used in the bronzes designated by these names 
 merely to assist in purging the molten mixtures of metallic oxides, 
 thus producing alloys of greater metallic purity and consequently 
 of greater strength. 
 
 Aluminum and copper seem to form a chemical union of remark- 
 able strength and ductility, having properties resembling those of 
 mild steel. The alloy can be forged at a red heat, it makes excellent 
 castings, its strength is greatly increased by hammering or rolling, 
 and it resists the corrosive action of air and salt water. 
 
 Generally, the bronzes can be considerably strengthened by ham- 
 mering or rolling, can be forged hot, (but not welded in a black- 
 smith forge), and their hardness increases as the per cent of copper 
 is lessened, while ductility increases as the copper is increased. The 
 less ductile mixtures should be rolled or worked hot. A peculiarity 
 of the copper-tin alloys is that quick cooling in water tends to re- 
 
20 MECHANICAL PROCESSES 
 
 move brittleness and to increase ductility and softness, while slow 
 cooling from a red heat restores the original hardness. 
 
 The bronzes are less ductile than brass, and those to be rolled 
 into sheets or drawn into wire must not contain as much tin as 
 those to be cast. Their hardness makes them excellent for ma- 
 chinery bearings. Propellers and many ship fittings are made of 
 bronze because of its strength and resistance to salt water corrosion. 
 
 14. Other Useful Alloys in engineering work are : 
 Anti-Friction Metal, used to line bearings for shafts; composed 
 
 of 
 
 Best refined copper 3.7 per cent 
 
 Banca tin 88.8 " " 
 
 Eegulus of antimony 7.5 " " 
 
 These must be well fluxed with borax and rosin in mixing. 
 Monel Metal, for blades of steam turbines. 
 Nickel, not less than 60 per cent; 
 Copper, remainder to make up 100 per cent. 
 A monel metal consisting of nickel, copper, and iron is refined 
 from a deposit of natural alloy of these metals. It is much cheaper 
 than the made-up alloy and is well adapted to practical use, al- 
 though its proportions are not likely to be always the same. 
 Another alloy recently brought into use consists of 
 
 Aluminum 90 per cent 
 
 Magnesium 10 " " 
 
 This alloy is lighter and stronger than aluminum, and will 
 doubtless find extensive use in airship construction, and possibly 
 for castings for submarine and other naval uses, where lightness 
 and strength are requisite features. 
 
 15. Copper. Its Uses. Copper is next in importance to iron aa 
 a metal of the useful arts, though it is used mostly in alloys. Its 
 principal uses are: 
 
 (1) As the main constituent of most of the useful alloys. 
 
 (2) For pipes and tubes to convey steam and liquids. A coating 
 of tin is frequently given copper pipes and tubes used to convey 
 liquids to aid in resisting corrosion. 
 
INTRODUCTORY. ENGINEERING MATERIALS 21 
 
 (3) As wire for resisting corrosion and particularly for electric 
 conductors because of its high degree of conductivity when pure. 
 
 (4) For sheathing and fastenings of wooden ships. 
 
 16. Properties of Copper. The color of copper is dull red. In 
 malleability and ductility, either hot or cold, it ranks very high. 
 Its tensile strength is about 30,000 Ibs., although rolling, ham- 
 mering or drawing it into wire nearly doubles its strength. It fuses 
 at about 1985 F. The most striking properties of copper are, 
 (1) the adverse way in which the smallest amount of impurity 
 affects it, and (2) its superior conductivity for heat and electricity 
 when pure (99.9%). 
 
 It is easily forged or rolled hot or cold and when worked cold it 
 becomes hard, as in wire drawing, but it may be again softened, or 
 annealed, by heating to red heat and plunging into cold water, 
 which also causes a loss of the tensile strength gained by working. 
 
 Commercial copper is often very impure, containing arsenic, 
 antimony, copper oxide, iron, and lead, according to the ores from 
 which extracted. This must be refined, and should then be 99.8% 
 pure for high grade uses. Refineries supply copper for market in 
 (1) "pigs" for melting and making alloys, (2) slabs for rolling 
 into sheets for various uses, and (3) ingots for wire or tube- 
 drawing. 
 
 17. Uses of Zinc. The principal uses for this metal are as fol- 
 lows: 
 
 (1) The most important use is for alloying with copper in mak- 
 ing brass or composition. 
 
 (2) When zinc is exposed to air or water, a durable and im- 
 permeable coating of zinc carbonate is formed on the surface of the 
 metal. This makes it useful for galvanizing iron to protect against 
 rusting. Zinc sheets may be used for sheathing or roofing. 
 
 (3) Zinc is the most electro-positive of the common metals. 
 This makes it particularly useful as a protection against galvanic 
 corrosion in steam boilers, and on the hulls of steel ships. Copper, 
 brass and bronze may also be protected by its use. Rolled zinc slabs 
 are bolted in scraped metallic contact with the part to be protected, 
 and the electrolytic action of impure water in which the metals are 
 immersed gradually corrodes the zinc, leaving the protected metal 
 intact. However, when the zinc becomes much corroded and its 
 
22 MECHANICAL PROCESSES 
 
 metallic surface is no longer exposed, the zinc compound resulting 
 from the corrosion acts electro-negative to the protected metal and 
 this metal is itself destroyed. The protection of iron by galvaniz- 
 ing, as mentioned in item (2), is due not only to a coating of zino 
 but to the fact that when a part of the zinc coating is broken and 
 the iron is exposed, dampness sets up an electric current which con- 
 sumes the zinc instead of the iron. 
 
 (4) Zinc plates are used extensively in electric batteries. 
 
 (5) Oxide and sulphide of zinc are used to make a superior grade 
 of white paint. 
 
 18. Properties of Zinc. Zine has a bluish-white color. Its malle- 
 ability and ductility are confined to certain narrow limits of tem- 
 perature, and it must be maintained at a temperature of about 
 240 F. when it is being rolled into sheets. It melts at about 
 800 F., and boils at about 1900 F. It is hard, brittle and highly 
 crystalline in fracture, and if the fracture shows dull specks, an 
 excess of iron is present. Boiled zinc is more dense than the cast 
 metal, and can be bent to a moderate degree. 
 
 Commercial zinc is known as spelter, and its impurities are 
 mostly lead and iron. 
 
 19. Uses of Tin. (1) The most important engineering use of 
 this metal is in alloys. 
 
 (2) It is used extensively for coating sheets of iron to prevent 
 corrosion, and these sheets are widely known as " tin " ; also it is 
 used to coat copper, brass and iron wire, pipes, and tubes, by dipping 
 them into melted tin. 
 
 (3) It is used as an ingredient of solder and brazing metal. 
 
 20. Properties of Tin. Tin has nearly the whiteness of silver. 
 It is very malleable and flexible, but not elastic. Its tensile strength 
 is too low for it to be drawn into wire. Air will not tarnish it 
 readily, but some acids and strong alkaline solutions attack it 
 noticeably, particularly when hot, 
 
 It is a poor conductor of heat and electricity. When pure, a bar 
 or sheet of tin makes a crackling sound when bent, called the " cry 
 of tin," and as this sound is destroyed by lead as an impurity, this 
 fact is often made use of in testing tin. It melts at about 445 F. 
 
 Tin is marketed in small ingots, and is known as '' Straits," 
 "Banca," "Malacca," "Australian," etc., according to its source. 
 
INTRODUCTORY. ENGINEERING MATERIALS 23 
 
 Its usual impurities are lead, iron, copper, and antimony. Good 
 tin should be 99.75% pure. 
 
 21. TJses of Lead. This metal has several minor uses in engi- 
 neering. Of these the principal uses are : 
 
 ( 1 ) As sheet lead for lining tanks and basins because of its power 
 to resist corrosion from air and from many dilute acids. 
 
 (2) As pipes in plumbing work due to its flexibility, ease of 
 soldering, and qualities mentioned in item (1), although it cannot 
 stand high heat or high pressure. 
 
 (3) As wire for gaging tightness of large engine bearings, and 
 for electric fuses. 
 
 (4) As pigments for well-known paints in the form of " red 
 lead" (oxide of lead), and of "white lead" (lead carbonate). 
 
 (5) Occasionally for alloying in small quantities with other 
 metals to increase ductility and malleability. 
 
 22 Properties of Lead. Lead has a blue-gray color. It is the 
 softest and heaviest of the common metals. It is very malleable 
 and ductile, but has no elastic strength, and its tensile strength is 
 so low that it cannot be drawn readily into fine wires. It is a 
 poor conductor of heat and electricity. On account of its softness 
 it can be readily squeezed through a press and thus shaped into 
 rods or pipes. It melts at about 600 F. 
 
 The best grade of commercial lead should be 99.5% pure. 
 
 23. Uses of Nickel. (1) A very important engineering use for 
 this metal is in alloy with steel. Its addition to mild steel gives a 
 product of great elastic and tensile strength and fair ductility. Its 
 presence in steel lessens corrosion. 
 
 (2) Another alloy of nickel of importance is monel metal. 
 
 (3) The use of nickel for plating metal articles is well known. 
 
 (4) In commercial alloys, principally German silver, nickel is 
 extensively used; also an alloyed nickel is used for small coins. 
 
 24. Properties of Nickel. Xickel is white with a bluish tinge. 
 It is malleable and ductile It has about the same hardness and 
 fusion point as iron, and is heavier than iron, to which it is closely 
 related, having magnetic properties. 
 
 25. TJses of Aluminum. The principal uses of aluminum are in 
 making aluminum bronze, and as pressed sheet or cast aluminum 
 
24 MECHANICAL PROCESSES 
 
 for various utensils and fittings where extreme lightness and fair 
 strength are required. 
 
 26. Properties of Aluminum. This metal presents a remarkable 
 combination of qualities. It is the lightest of the useful metals 
 (excepting magnesium., which has only limited uses as a metal), 
 has many exceptional uses, is more abundant in nature than any 
 other known metal, and is extracted by a process quite apart from 
 general metal extraction methods. 
 
 Its physical qualities are as follows : 
 
 Color, silvery white. 
 
 Malleability and ductility, slightly less than that of copper. 
 
 Tensile strength, varying from about 16,000 Ibs. for cast metal 
 to about 25,000 Ibs. for rolled metal. Annealing slightly decreases 
 the strength of rolled metal. 
 
 Fusing point, about 1200 F. 
 
 Specific gravity, about 2.6, or about % the weight of iron. 
 
 It is an excellent conductor of heat and electricity, does not cor- 
 rode in air or in water to a noticeable degree, but it can be soldered 
 only with much difficulty due to the fact that the pure metallic sur- 
 face quickly unites with oxygen, forming a film on which the solder 
 will not hold. 
 
 Aluminum is not so soft as copper, and when hammered assumes 
 the hardness of hard brass, although annealing (heating to a red 
 heat and cooling slowly) again renders it pliable. 
 
 In melting it for castings, an ordinary crucible should be used, 
 but flux should not be used because of the chemical combination 
 likely to result. It shrinks much on cooling. 
 
 27. Use and Properties of Antimony. In engineering uses this 
 metal serves as a hardening constituent for anti-friction alloys. It 
 also causes these alloys to expand after they are poured into place, 
 making them fill completely, when cold, the space intended for 
 them. It is grayish white, extremely brittle, has a peculiar odor, 
 and melts at about 850 F. 
 
 Its usual commercial form, the regulus of antimony, is a some- 
 what impure metal extracted from its compound with sulphur. 
 
 28. Portland Cement. General Characteristics. This material 
 having been perfected within recent years, has many important 
 uses. It is supplied commercially in a very finely ground state, 
 
INTRODUCTORY. ENGINEERING MATERIALS 25 
 
 and, when mixed with, water alone, or when mixed with water and 
 definite proportions of sand, gravel, or broken stone, it can be 
 moulded to any form desired and will gradually harden in air or 
 under water in the form to which it is moulded. When used in 
 this way it is popularly known as concrete or beton. 
 
 29. Varieties of Lime and Cement. The many forms of lime and 
 building cement consist mostly of calcium oxide (CaO), which is 
 formed from calcium Carbonate (CaC0 3 ) by calcination. These 
 forms merge one into another according to the kinds and amounts 
 of other substances mixed with the lime', and their variety is infinite. 
 
 30. True Cements. When limestone (CaC0 3 ) contains clay, the 
 process of calcination produces a compound which, due to the silica 
 in the clay, gives the product the power of solidifying or " setting " 
 when wet, either under water or in the open air. The degree of 
 heat employed in the calcining process, and the relative proportions 
 of clay and limestone,, determine whether the product is hydraulic 
 lime, quick-setting cement, or Portland cement. These cements 
 were calcined formerly from deposits of the constituent materials 
 just as they were found mixed in the earth, and the varieties 
 of these mixtures were such that the resulting cements were not 
 uniform, but the application of chemistry within recent years for 
 the purpose of securing exactly the amount of each material re- 
 quired, and of avoiding deleterious materials, has brought about 
 the extensive manufacture of a high grade of Portland cement. 
 This has for most uses displaced other kinds of building cement, 
 but has not displaced the use of lime for mortar, and there are 
 cases in which a quicker setting cement may be more advantageously 
 used than Portland cement. The name " Portland cement " comes 
 from the supposed resemblance of the dry cement to Portland stone, 
 in England, and was given it by its discoverer, in 1824. 
 
 31. Requisites in Selecting Raw Materials. In any natural 
 materials chosen for the manufacture of this cement, there must be 
 ascertained : 
 
 (1) The proportions of the required ingredients contained. 
 
 (2) The kinds and quantities of other ingredients, which may 
 be harmful in quantity or because of their chemical action. 
 
 32. Composition of Cement. It is now established that the essen- 
 tial raw ingredients of Portland cement are limestone, 75 to 
 
26 MECHANICAL PROCESSES 
 
 and alumina (A1 2 3 ) and silica (Si0 2 ) 20 to 25%. The alumina 
 and silica are commonly found combined as * clay, which is a silicate 
 of aluminum (Al 2 3 2Si0 2 ) + 2H 2 0. All cements contain other 
 ingredients due to the essential materials not being pure in nature 
 and from contact with fuel in calcination. Some of these acci- 
 dental ingredients may improve the cement., others are inert and 
 harmless except that they exist in such quantity as to displace 
 essential ingredients, and others are positively harmful,, if present 
 in quantity, because of the chemical action they produce. There 
 are accidental ingredients usually amounting to about 5%, but 
 these must not include over 1.75% anhydrous sulphuric acid (S0 3 ), 
 nor over 3% of magnesia (MgO). 
 
 Excess of clay causes a cement to " set " quickly, while excess of 
 lime causes it to " set " slowly or imperfectly. Iron oxide gives 
 cement its color. Portland cement is improved in dry storage, as 
 any excess of lime particles are air slaked. 
 
 33. Manufacture of Portland Cement. A cement manufacturing 
 plant is usually located at or near a natural deposit of the materials 
 composing cement. These materials may or may not be a natural 
 mixture, but in either case chemical analyses must be made to de- 
 termine, (1) the per cent of lime, (2) the per cent of clay, and (3) 
 the per cent and kind of other ingredients. This analysis deter- 
 mines the fitness of the deposit for cement manufacture. With a 
 cement plant established, the essential steps in manufacture are : 
 
 (1) Chemical analysis in the laboratory to determine the correct 
 proportion of lime and of clay for making up a kiln charge. 
 
 (2) Grinding the properly proportioned ingredients to a very 
 fine state, which also accomplishes their thorough mixture. These 
 may be coarsely ground before mixing, but must be ground after 
 mixing sufficient to pass through a sieve of about 900 meshes to the 
 square inch. Lack of proper grinding may cause the cement to be 
 worthless. 
 
 (3) Burning the ground materials to a state of incipient fusion, 
 to change their chemical composition. This is done in a long, 
 cylindrical kiln, built of iron plate, lined with refractory brick and 
 
 * The relative proportions of silica and alumina, as compared with the 
 limestone in cement, are found by Messrs. Newberry from the formula 
 Wt. of limestone 2. 8 Xwt. of silica+l.lXwt. of alumina. 
 
INTRODUCTORY. ENGINEERING MATERIALS 27 
 
 mounted to revolve on its axis at a slight inclination to the horizon- 
 tal. The ground mixture is introduced wet or dry at the higher 
 end, and the fuel oil, gas, or powdered coal, is blown in at the lower 
 end v/here it ignites in a flame maintained by the continuous intro- 
 duction of fuel. The finely divided cement material is gradually 
 dehydrated and deprived of its carbon dioxide as it is tumbled by 
 the slowly revolving kiln, presenting every part of the mass to the 
 heat, and is finally vitrified at a white heat into small clinkers vary- 
 ing in size from that of a pea to that of a walnut. These clinkers 
 are kept from fusing by being tumbled from the lower end of the 
 kiln at the proper time. Their continuous falling from the kiln is 
 due to the kiln's inclination and slow revolution. 
 
 (4) Grinding the clinker to a fine powder. This is done in two 
 operations. The first grinding is done between millstones, or in a 
 revolving cylinder containing steel balls about 6" in diameter. The 
 pulverizing is then accomplished by machines for the purpose, in 
 one form of which the cement is fed into one end of a revolving 
 cylinder partly filled with flint stones about as large as walnuts. 
 The pulverized cement issues from the other end of the cylinder. 
 It must be ground so fine that not more than 8% of its weight 
 will fail to pass through a sieve of no. 100 mesh (100 x 100 meshes 
 per square inch). 
 
 34. Uses of Portland Cement. Cement mixed with water is vir- 
 tually a plastic stone, and it can be used for many purposes in place 
 of stone with economy in shaping to the form required, and advan- 
 tage in securing a hard, fire-proof material. It may be used for 
 shop floors, buildings, foundations for heavy machinery, bridge 
 piers, walks, waterworks dams, reservoirs, walls, dry-docks, culverts, 
 etc. A concrete casing will protect iron or timber structures from 
 corrosion in air or in water, and will protect exposed iron work of 
 structures from effects of conflagration. 
 
 Strengthened with iron bars, or meshed wire, placed in it when 
 it is being moulded to shape, it is known as re-enforced concrete, 
 and will thus form bridge floors, bridge spans, and the upper floors 
 of buildings which must support great weight. 
 
 In marine use, concrete is limited because of its weight. It may 
 be used as permanent ballast in the bilges of steel ships, and is an 
 effective protection from corrosion when applied to absolutely clean 
 
MECHANICAL PROCESSES 
 
 iron or to iron surfaces covered with closely adhering red rust. 
 When so used, cement may be mixed with water and applied with 
 a brush, or it may be mixed in the proportion of about two parts 
 sand and one part cement and applied wet, with a trowel, in a 
 layer varying from % i ncn to any thickness desired. In this way 
 ships' tanks, bunkers, and bilges are protected, as the mixture 
 forms a close bond with the iron. In no case will this bond form if 
 the iron is oil coated. 
 
 35. Cement Mixtures. Cement and water alone are known as 
 " neat " cement, and are seldom so employed except where economy 
 is not considered, or for purposes of maximum strength. 
 
 For most purposes a mixture of sand, broken stone, and cement 
 gives ample strength, and is far more economical than the use of 
 cement alone. 
 
 The following table of parts by volume, gives various concrete 
 mixtures : 
 
 No. 
 
 Portland 
 Cement. 
 
 Sharp 
 Sand. 
 
 Broken 
 Stone. 
 
 Uses. 
 
 1 
 
 1 
 
 2 
 
 4 
 
 Highest grade of miscellaneous work. 
 
 2 
 
 J 
 
 3 
 
 6 
 
 For largest building foundations. 
 
 3 
 
 1 
 
 4 
 
 8 
 
 For ordinary construction. 
 
 4 
 
 1 
 
 4 
 
 10 
 
 For economical construction. 
 
 In these mixtures, the broken stone merely fills space, and if not 
 available, the proportions of cement and sand should remain as 
 given. 
 
 The sand also fills space, saving cement, and for strength it is 
 essential that enough cement be used to surround entirely each 
 grain of sand and thus form a perfect bond between cement par- 
 ticles. Broken stone and sharp sand present corners and angles 
 for the better attachment of cement, as claimed by some users, but 
 beach sand, the grains of which have been washed round by the 
 sea, and rounded pebbles, are also frequently used with cement, 
 
 36. Method of Using Concrete. For shaping concrete to a form 
 required, the usual practice is to make a form of planks or timbers, 
 well braced, enclosing the space which the concrete is to occupy. 
 The mixture is carefully made in a mixing machine or by men with 
 
INTRODUCTORY. ENGINEERING MATERIALS 29 
 
 shovels, wet with clean water to a mushy consistency, deposited and 
 tamped in place. Sea water has not an adverse effect on Portland 
 cement of good quality. When once wet, the mixture must be 
 promptly placed in the form, as it will " set " in an hour or less. 
 After setting, the mass is at first very weak and may be crumbled 
 by pressure of the hand, but if left undisturbed it gradually hardens 
 to the consistency of stone, requiring months or years for reaching 
 final limit of hardness. In setting and for a few hours afterward, 
 the mixture must be kept wet. In extensive work, where a form 
 cannot be filled in one day, the upper surface is left rough at the 
 end of each day's work to give a suitable surface for the close 
 bonding of the mixture deposited the following day. 
 
 When concrete is dumped into a form submerged in water, it is 
 essential that the mixture be subjected to as little wash as possible 
 for the fine particles of the different materials composing the ce- 
 ment must be thoroughly mixed, and these must form unbroken 
 contact throughout the interstices of the sand and stone in order 
 to insure a solid, well bonded mass after setting. 
 
 Concrete work is practically impervious to water, but not abso- 
 lutely so in all cases. 
 
 37. Causes of Setting and Strengthening of Cement. It is 
 thought that the setting of cement is due to the crystallizing of the 
 silicate and aluminate of lime, which, in their dry and anhydrous 
 form after burning, are soluble in water, but which pass into the 
 hydrated state when sufficiently wet, in which state they are insolu- 
 ble. 
 
 The hardening after setting is due to a continued crystallization 
 of salts from solution, accompanied by other chemical and physical 
 changes which occur very slowly and which are not well understood. 
 
 38. Wood. Use as Parts of Machinery. Very little wood is now 
 used as engine or machinery parts. Metal has displaced wood 
 almost entirely in moving and stationary parts of machines, and in 
 many general uses for which wood was once exclusively employed. 
 The present highly developed industry of pressing sheet metal to 
 many forms more or less intricate has made it possible to substitute 
 metal for wood in furniture, house and ship trimmings, automobile 
 body fittings, utensils and many other articles. 
 
 3 
 
30 
 
 MECHANICAL PROCESSES 
 
 However, wood remains a very useful structural material, and is 
 particularly of value in engineering needs as a material for making 
 patterns of objects to be cast in metal, as will be seen in Chapter 
 VIII. 
 
 Wood is used for decks and sheathing of ships, and for many 
 parts in ship equipment. About the only important use remaining 
 for it in marine machinery is as bearings for propeller shafting. 
 These bearings support that part of the shafting between the pro- 
 peller and the body of the ship. They cannot be given care or atten- 
 tion except when the vessel is in dry dock, and are lubricated en- 
 tirely by the water in which the vessel floats. Lignum vitae, a 
 tropical wood, is used for this purpose. 
 
 39. Lumber and Timbers. Wood for general uses is handled com- 
 mercially in the form of lumber or timbers. Trees are felled, and 
 
 FIG. 2. 
 
 FIG. 3. 
 
 that part of the lower trunk free of large limbs is sawed into logs 
 usually a few inches longer than an even number of feet. These 
 logs are hauled to the sawmill and sawed into widths and thick- 
 nesses as required. 
 
 The log end in Fig. 2 is numbered to show the consecutive cuts 
 in the usual method of sawing. Most of these are tangential cuts, 
 i. e., more nearly perpendicular than parallel to the radius of the 
 log end. Pieces 20 and 21 are known as quarter-sawed pieces, as 
 their width is cut along the radius of the log end. Tangential cuts 
 are cheaper because of less handling on the saw carriage and less 
 
INTRODUCTORY. ENGINEERING MATERIALS 31 
 
 waste of the log material, but lumber from these cuts warps more, 
 is less durable, and does not show the fineness f grain when com- 
 pared with quarter-sawed lumber. The upper half of Fig. 3 shows 
 a method of getting more quarter-sawed cuts from a log than are 
 obtained in Fig. 2 without greatly increasing the cost of cutting. 
 The log is quartered and each quarter is sawed into pieces as con- 
 secutively numbered, quadrant A giving two quarter-sawed pieces, 
 1 and 2, and two pieces, 3 and 9, which are nearly quarter sawed. 
 Quadrant B shows another method of sawing, giving pieces 3 and 
 11, quarter sawed, and but one piece, No. 10, corresponding to 
 pieces N"os. 3 and 9 of quadrant A. True quarter sawing is shown 
 in quadrant D, and approximate quarter sawing, with less waste, 
 is shown in quadrant C ? of Fig. 3. 
 
 40. Lumber Grading, The several pieces sawed from a log are 
 not of the same quality, but vary more or less in grade. The slabs, 
 covered on one side with bark, and the culls or very unsound pieces, 
 are of no value as lumber. The ungraded lumber from a log is 
 known as log run. In large mills, log run is graded as to quality 
 after it is finally sent from the saw on roller conveyors and the sev- 
 eral grades are stacked separately in such a way as to allow ready 
 access of air for seasoning and to shed rain. After drying, and 
 when removing it from the stacks for shipping, the lumber is further 
 subject to an adopted form of inspection, in which each piece is 
 graded for the purchaser's acceptance. 
 
 41. Hard and Soft Wood Lumber. Hard woods are those cut 
 from the broad-leaf trees (as oak, hickory, poplar), and soft woods 
 are those from the conifers, or needle-leaf trees (as pine, cedar, fir 
 and redwood). 
 
 42. Heart and Sap Wood. The wood surrounding the center of 
 a tree is heart wood and outside of this is the sap wood, usually 
 lighter in color than the heart. Sap wood, except in certain trees, 
 as ash and hickory, is less hard and durable than heart wood. 
 However when the heart wood at the center of the tree is exposed 
 in the surface of a board, it tends to split away from the board. 
 The amount of sap or heart wood in a piece of sawed timber may 
 be seen by the difference in color of the sawed surface, also end 
 inspection will show from which part of the tree the piece is taken. 
 
32 MECHANICAL PROCESSES 
 
 In Fig. 4 the large radii of curvature of the rings show these as 
 sap pieces, the points A being nearest the bark. Fig. 5 shows 
 
 FIG. 4. 
 
 FIG. 5. 
 
 heart pieces, indicated by the curvature of the rings. The heart of 
 the tree is at B. 
 
 43. Lumber Inspection Rules. For uniformity in lumber sizes 
 and qualities, certain general rules are adopted by lumber pro- 
 ducers, who adopt, also, specific rules for the inspection of each 
 kind of wood according to its uses. Lumber rules are subject to 
 changes particularly because of the increasing scarcity of wood. 
 
 (1) Standard lumber lengths are 6, 8, 10, 12, 14, and 16 feet, 
 though 6- and 8-foot lengths are for special uses. Boards measur- 
 ing an odd number of feet are classed with the next lower even 
 lengths, unless specified otherwise. 
 
 (2) Standard thicknesses are %, %, %, %, 1, 1*4, 1V 2 , 2, 2%, 
 3, and 4 inches. Pieces larger than 4x4 inches are called timbers. 
 
 (3) The standard qualities or grades for hardwoods are, usually, 
 firsts, seconds, and one or more grades of common. Soft woods are 
 graded according to their uses. An inspector determines the grade 
 to which any piece of lumber belongs by its width, amount of heart 
 or sap, and defects affecting its strength and appearance. 
 
INTRODUCTORY. ENGINEERING MATERIALS 33 
 
 (4) Inspection is usually made of the worst side of the board, 
 and warps are always considered as defects. 
 
 It is not uncommon for purchasers of large amounts of lumber 
 to have their own specifications for the general inspection of lumber. 
 
 44. Standard Defects. An example of the standardization of 
 lumber defects is given by the following copy of Navy Department 
 General Lumber Specifications. Each one of the following items 
 constitutes a standard defect : 
 
 (a) One sound knot, 114 inches in diameter, called a standard 
 knot. 
 
 (&) Two knots not exceeding in extent or damage one standard 
 knot. 
 
 (c) Wormholes, grub holes, or rafting-pin holes not exceeding 
 in extent or damage one standard knot. 
 
 (d) Heart centers, shakes, rot, or dote not exceeding in extent 
 or damage one standard knot. 
 
 (e) Splits which do not exceed 12 inches in length in firsts, nor 
 one-sixth the length of the piece in seconds. Not more than 25 per 
 cent of the whole number of pieces in each grade may be so split. 
 
 NOTE. Wide pieces of lumber that would take two or three 
 standard knots may have, if properly located, one large knot, equal 
 to two or three standard knots, if there are no other defects. 
 
 Shakes are splits in the end of a board due to seasoning, generally 
 occurring before the board is cut from the log. 
 
 Checks are cracks showing in the surface of a board, due to sea- 
 soning, and are sometimes large enough to be defects. 
 
 Dote is unsoundness due to decay. 
 
 Wane is the beveled or bark-covered edge of a board. 
 
 45. Rough and Dressed Lumber. All lumber direct from the 
 saw is rough lumber. After seasoning, the better grades may be 
 re-sawed into smaller pieces and are frequently planed smooth, on 
 one or both faces and one or both edges, by machinery, before mar- 
 keting. Lumber thus planed is said to be dressed, and is sold at 
 the width and thickness it had when rough. Examples of designa- 
 tions of dressed lumber are as follows: SIS means surfaced (or 
 dressed) on one side; S1S1E means surfaced on one side and one 
 edge; S2S2E means surfaced on both sides and both edges. 
 
34 MECHANICAL PROCESSES 
 
 46. Lumber Measurement. Lumber and timbers are measured 
 and sold by board feet. A board foot has a surface 12 x 12 inches 
 and a thickness of one inch. Boards less than an inch in thick- 
 ness are regarded as an inch thick in selling, but those of any frac- 
 tion over an inch are sold for what they actually contain. 
 
 A specimen bill of lumber is as follows: 
 
 (1) 40 p. 2 x 6x16 
 
 (2) 12 p. Jx 8x12 
 
 (3) 80 p. IJx 6x16 
 
 (4) 30 p. 1 X 12x14 
 
 Written in full, the first item, for example, reads 40 pieces 2 
 
 inches thick, 6 inches wide, 16 feet long. 
 
 The board feet in the 2d and 3d items are as follows : 
 
 fn item (2), each piece is regarded as having a thickness of one 
 
 inch. The surface of one piece in square feet is T 8 2- X 12 ; hence the 
 
 item has a total of 12_xlx8x 12 = 96 board ft. 
 
 1/& 
 
 In item (3), the surface of each piece is -f-% x 16 sq. ft., hence the 
 item has a total of 80 X f X A X 16 = 960 board ft. 
 
 47. Durability of Wood. Wood may be preserved indefinitely if 
 kept dry or submerged in still water, and free from attacks of in- 
 sects. Wood exposed to the atmosphere absorbs more or less moist- 
 ure. Alternate wetting and drying, very common with posts or 
 poles where they enter the ground, is an active means of decay. 
 The best preserved wood is that buried in wet or damp earth, ex- 
 cluded from air and insects. Timbers preserved in this way have 
 remained sound for centuries. 
 
CHAPTEE II. 
 A GENERAL OUTLINE OF METAL-PRODUCING PROCESSES. 
 
 48. Ores. The common metals, excepting copper, do not occur 
 free in nature, but are produced from their ores which generally 
 require chemical treatment at high heat in furnaces. Uncomhined 
 copper, known as " native " copper, mixed with more or less earthy 
 material, is found in some parts of the world, notably in the Lake 
 Superior region, but the main source of all engineering metals is 
 their ores, which are more or less abundantly distributed over the 
 earth. 
 
 An ore is a natural substance composed of a metal chemically 
 combined with one or more non-metallic substances. Ores of differ- 
 ent metals are sometimes found incorporated in the same mass, 
 and almost all ores are found mixed with impurities of a non- 
 metallic nature, as rock, sand, clay, etc., known in mining as 
 gangue. Many ore deposits within range of easy transportation can- 
 not be profitably worked either because of excessive gangue or 
 because of chemical composition of ore or gangue which renders 
 smelting unprofitable. 
 
 49. Elimination of Gangue. As an ore comes from the mine it is 
 desirable to eliminate at once the gangue. This may be done more 
 or less successfully with some ores by simple hand-picking methods, 
 while other ores must be crushed in a stone breaker or stamp mill, 
 and the gangue eliminated from the finely crushed mass by dress- 
 ing, which consists of passing running water over the mass in a 
 succession of boxes so that the current will carry the lighter par- 
 ticles to the lower boxes while the heavier particles settle in the 
 upper boxes. There are ores from which the gangue cannot be re- 
 moved except in furnace processes, and some ores have too little 
 gangue to need preliminary separation. 
 
 Some ores are subjected to weathering. They are heaped in the 
 open air and left exposed to sun and rain for weeks or months. 
 
36 MECHANICAL PROCESSES 
 
 This disintegrates the lumps and washes away soluble salts and 
 much powdered gangue. 
 
 50. Calcination. Another method of reducing the quantity of 
 impurity before the ore is transported from the mine is by calcina- 
 tion, which consists of heating the ores to a point short of fusion. 
 This drives away moisture and some combined sulphur, and breaks 
 up carbonates, changing them to oxides by driving off C0 2 . Calcina- 
 tion is done crudely by making alternate layers of fuel and ore on 
 the ground and lighting the fuel, but more effective methods are 
 to confine the ore and fuel by walls, or still better by kilns, in 
 which the heat is more intense and more uniformly distributed. 
 
 After calcining, the ore is ready for transportation to the smelter, 
 which is usually located away from the mines for the convenience 
 of obtaining fuel and labor. 
 
 51. Breaking up the Ore Compound. The actual metallurgical 
 operation of breaking up the chemical combination of metal with 
 oxygen and with other elements in ores is done by heat in furnaces 
 and is called the dry process; or is done by making a solution of the 
 metallic compounds and breaking up these by chemical re-agents, 
 known as the wet process or leaching. 
 
 Smelting, as used in the dry process, is the operation of fusing 
 ores by heat in suitable furnaces. This is an essential step of metal 
 extracting, and its meaning is usually broadened to include all 
 steps of the process of heat extraction of metals. 
 
 Reduction is the separation of a metal from its oxide, though 
 usually applied to the separation of a metal from any ore, whether 
 oxide or not. 
 
 Roasting is the heating with free access of air in order to change 
 the ore partly or entirely to an oxide for reduction later on. 
 
 The processes of extracting most of the common metals from 
 their ores are complicated because of the several chemical changes 
 necessary to extract the metal in a sufficiently pure state for use. 
 The different chemical compositions of ores, their various grades 
 due to the relative per cents of metal and of other ingredients con- 
 tained, and the existence frequently of two or more metals in the 
 same ore mixture, make the treatment of most ores very varied and 
 
GENERAL OUTLINE OF METAL-PRODUCING PROCESSES 37 
 
 complex. By far the greater quantity of metals is produced by the 
 dry process, and iron is very easily produced because its oxide ores 
 are abundant and are smelted by the single process of reduction. 
 
 The treatment of ores of copper, zinc, lead, tin, nickel and anti- 
 mony is more difficult. The object of each step in the processes 
 of extracting a metal from its ores is to simplify the ore com- 
 pound. This is done, as has been outlined in part, by (1) sep- 
 arating the ore from the gangue (par. 49), (2) driving away cer- 
 tain ingredients by a heat short of fusion (par. 50), and (3) 
 fusing the ore one or more times in the presence of certain re-agents 
 called fluxes which combine with the non-metallic substances and 
 allow the liberated metal to separate and settle in an impure state. 
 A metal thus obtained in the impure state must be refined before it 
 is used. 
 
 52. Smelting Furnaces. The step of the process named in item 
 (3) of the preceding paragraph is that of smelting, and is usually 
 carried on in furnaces built of common silica brick for the outer 
 layers, and high grade refractory brick for the inner layers. This 
 brick work is either incased in a shell of iron plates, or is held to- 
 gether by iron bands and rods, which are wholly on the outside of 
 the furnace and do not enter the fire space. There are several 
 modifications of furnaces for smelting ores of different metals, but 
 all smelting furnaces are included in the two general types of this 
 class, namely, the blast furnace and the reverberatory furnace. 
 These must be strongly built on permanent foundations, and must 
 be able to stand the intense heat of the operation. 
 
 53. The Blast Furnace. Fig. 6 shows the essential parts of a 
 blast furnace for smelting iron. It is given the name of blast 
 furnace because combustion is maintained by forcing a blast of air 
 through the mass of fuel, ore and flux which completely fills the 
 furnace. This type of furnace is vertical so that gravity may assist 
 in disposing of the fused products. The main point of difference 
 from the reverberatory furnace is that ore and fuel are mixed in 
 the blast furnace and are kept separate in the reverberatory furnace. 
 
38 
 
 MECHANICAL PROCESSES 
 
 Figs. 6a and 6b are two views of the outside of a blast furnace. 
 They are lettered to agree with the description given for Fig. 6. 
 
 FIG. 6. Blast Furnace. 
 
 The parts of this furnace, shown in Fig. 6, are designated as 
 follows, viz. : 
 
 S. Shaft. This extends from the top down to the part of largest 
 diameter. 
 
GENERAL OUTLINE OF METAL-PRODUCING PROCESSES 39 
 
 B. Boshes. This is the tapered portion below the shaft. Built 
 in with the brick work of the boshes are many hollow wedge-shaped 
 segments of copper. These segments are placed with alternate seg- 
 ments of bricks to encircle the boshes, and many layers of this con- 
 struction make up the walls of the boshes. These copper segments 
 are known as " bosh plates." Some of them are marked P in Fig. 
 6a. Water is circulated through each bosh plate, by a system of 
 external piping, to allay the intense heat at that part of the furnace 
 and thus prevent injury to the bosh walls. The bosh plate edges 
 do not extend in quite so far as does the brick work, and are pro- 
 tected by a covering of clay. If a plate becomes clogged by sedi- 
 ment from the circulating water, or if its inner edge is melted or 
 damaged, it can be pulled out and replaced by a new plate by re- 
 ducing the blast pressure while this work is in progress. 
 
 Y. Tuyere holes. These openings conduct into the furnace the. 
 air of the blast. Fig.' 6 has eight tuyere holes. The tuyeres are metal 
 tubes leading from the blast main into the furnace through the 
 tuyere holes. Tuyeres are not shown in Fig. 6, and the horizontal 
 portion (or tuyere proper) is disconnected and removed in Fig. 6a. 
 Each tuyere is surrounded by a helix of pipe through which water 
 circulates to keep the end of the tuyere from melting in the furnace. 
 Fig. 6a shows at E an opening, covered by a mica door when the 
 furnace is in use, which enables the furnace man to see the interior 
 of the furnace through the tuyere when in blast. 
 
 M. Hot blast main. This is a pipe 3 ft. or more in diameter, 
 made of iron plates and lined inside with refractory brick. It en- 
 circles the furnace, delivering highly heated air from the blast stove 
 to the tuyeres. 
 
 //. Hearth. This is the part of the furnace below the line of 
 tuyere holes which receives molten slag and metal, and when the 
 slag, which floats on the metal, reaches the height of the cinder 
 notch C, it is drawn off. 
 
 T. Tapping hole. Metal is tapped from the hearth through this 
 hole. In tapping, an iron bar is used to dig out the clay plug stop- 
 ping the hole, and when the metal has run out, another plug is 
 forced in to stop the hole, by means of the ram U (known as the 
 " mud gun ") swung from the small crane W. 
 
40 MECHANICAL PROCESSES 
 
 G. Gas main or " down comer/' a brick-lined pipe leading 
 away the gaseous products of the blast and delivering them, through 
 the dust catcher, to the gas main, Q, which distributes them to the 
 blast stoves. 
 
 J. Shaft lining. This lining is of highest quality refractory 
 brick (fire clay) laid in a mortar of fire clay. The lining can be 
 renewed when worn out. The double hatched lining below the 
 tuyere holes in Fig. 6 is not subject to excessive wear. 
 
 D. Silica brick body, in Fig. 6. The furnace body is encased in 
 plate steel marked D in Fig. 6b. 
 
 K. Cone. This is a cone-shaped hollow cast iron ring built into 
 the top or " throat " of the furnace. 
 
 L. Bell, a cast iron cone suspended by a heavy chain from the 
 lever N. This cone closes the throat of the furnace and is opened 
 for admitting materials of the furnace charge. 
 
 R. Stand pipe. Before lowering the bell to admit a new charge 
 to the furnace, the lid of the stand pipe is raised to relieve the gas 
 pressure at the top of the furnace. This obviates the escape of gas 
 and flame from the furnace throat. 
 
 54. Blast Furnace Modifications. The principle of the blast 
 furnace as shown in Fig. 6 is applied to the smelting of copper and 
 lead ores, but the furnaces used for these ores are somewhat modi- 
 fied. Iron smelting furnaces vary from 50 to 100 ft. in height, but 
 copper and lead furnaces are much smaller and are not always circu- 
 lar in cross section. In copper and lead furnaces the boshes and 
 at least part of the shaft have merely inner and outer surfaces of 
 iron, with water circulating between them. This water jacket 
 arrangement is necessary as the oxides of these metals attack a fire 
 brick lining. The cooling effect of the water is such that the inner 
 surface of the iron jacket becomes covered with a solidified slag 
 which is replaced as fast as it wears away. 
 
 The modifications of this furnace for lead and copper smelting 
 are due to the differences of the ores of these metals from the ores 
 of iron, and to the complexity in smelting these as compared with 
 iron smelting. 
 
 55. Acid and Basic Ores. The earthy matter of ores consists 
 mostly of silica (sand), silicate of aluminum (clay), limestone, and 
 magnesia. All of these are seldom found in the same ore, but 
 
GENERAL OUTLINE OF METAL-PRODUCING PROCESSES 41 
 
 almost all ores contain (1) silica and silicate of aluminum, or (2) 
 limestone and magnesia. The ores containing a predominance of 
 the materials of group ( 1 ) are acid ores,, and those containing a pre- 
 dominance of the materials of group (2) are basic ores. Acid ores 
 are in much greater abundance than basic ores. 
 
 FIG. GA. Base of a Blast Furnace. 
 B Boshes. P Bosh plates. 
 
 E Peep hole. T Tapping hole. 
 
 H Hearth. U Mud gun. 
 
 M Blast main. V Water valves for bosh plates. 
 
 W Mud gun crane. 
 
 Y Tuyere holes. 
 
 Z Furnace supports. 
 
 56. Fluxes. The usual operations of smelting require that an ore 
 shall always be mixed with a flux. The ore is either acid or basic, 
 and the flux must be either basic or acid, opposite to the character 
 of the ore. At the temperature of the furnace, neither the acid 
 
42 MECHANICAL PROCESSES 
 
 nor the basic substance in an ore will melt, and in order to melt 
 and dispose of it, there must be introduced with the ore a certain 
 amount of flux, which combines chemically with the earthy sub- 
 stances of the ore, forming slag. At the temperature of the fur- 
 nace the slag is molten, and when slag and metal collect in the 
 hearth, the slag floats on the metal and protects it from oxidation. 
 
 The materials used as fluxes in smelting are (1) silica and sili- 
 cate of aluminum as acid fluxes, and (2) limestone and magnesite 
 (an impure magnesia) as basic fluxes. These fluxes are the same 
 materials as those found with ores which determine their acid or 
 basic character, hence it is necessary to place with an ore the flux 
 opposite in character to that which the ore is found naturally to 
 contain. 
 
 In making up a furnace charge, the chemical composition of the 
 ore must be determined in the laboratory, and a flux must be 
 chosen, in kind and quantity, which will unite completely with the 
 earthy materials of the ore. Too little flux will not take up all the 
 refuse parts of the ore, and too much will act in disintegrating the 
 fire brick lining of a furnace in spots not protected by a slag coat- 
 ing. A practical smelter can judge from the color of a broken 
 piece of cold slag whether or not the flux is in sufficient quantity, 
 and an occasional analysis of the slag is a beneficial check. Sulphur 
 and phosphorus must be avoided in fluxes, and are not desirable in 
 ores. 
 
 57. Blast Furnace Operation. This description applies particu- 
 larly to iron smelting, but it is also the essential part of blast fur- 
 nace operation for smelting other ores. The starting of a blast fur- 
 nace in operation is called " blowing in." A light fire is started in 
 the hearth and is for a while supplied only with enough fuel to 
 keep it going. Care must be taken to heat up and dry out the 
 furnace very slowly to avoid cracks in the newly built or repaired 
 parts, or in the slag coating which acts as a protection to the fur- 
 nace walls. Very gradually the quantity of fuel is increased and 
 when it is above the tuyeres, a light blast is started to increase 
 combustion. After a few weeks, with a large iron smelting furnace, 
 the shaft becomes well filled with fuel and the heat has reached a 
 maximum. 
 
 A little slag from the slag dump is now added. This melts and 
 runs down, covering the bottom of the hearth and keeping it hot, 
 
GENERAL OUTLINE OF METAL-PRODUCING PROCESSES 43 
 
 FIG. GB. Top of a Blast Furnace. 
 
 A Charging car. G Down comer. R Stand pipe. 
 
 D Furnace shaft casing. N Bell lever. 
 
44 
 
 MECHANICAL PROCESSES 
 
 The tap hole is stopped with clay. Ore and flux are added, the 
 blast pressure is increased to that desired, and the furnace soon 
 reaches a condition of maximum output. The furnace may be kept 
 in operation for months without cessation, until it must be stopped 
 for relining or repairs. When in operation, the furnace is charged 
 at intervals of a few minutes with a layer of coke and then a layer 
 of flux and ore. The material is sprayed with water, hoisted to the 
 
 FIG. 7. Blast Furnaces and their Hot Blast Stoves. 
 
 top of the furnace, and dumped into the cone. The water prevents 
 the carrying of an excessive amount of dust from the furnace into 
 the " down comer/' In Fig. 6b, the charging car A has just 
 reached the top of its track and is about to be automatically dumped 
 into the hopper over the cone. 
 
 The air blast is supplied by a centrifugal or other form of blower, 
 and is forced through coils of heated pipe for lead and copper, or 
 through a large stove (called a regenerative or hot-blast stove) for 
 
GENERAL OUTLINE or METAL-PRODUCING PROCESSES 45 
 
 iron, entering the furnace at a high heat through the hot-blast main 
 and tuyeres. The most intense heat of the furnace begins im- 
 mediately above the tuyeres and extends up as far as the oxygen 
 lasts for the complete burning of the fuel. This is called the fusion 
 zone. 
 
 The ore heated above the fusion zone disintegrates, is reduced, 
 giving up its gangue to the action of the flux, and as it sinks into 
 the zone of fusion, it gradually melts. The metal, more or less 
 impure, trickles to the hearth, and the slag also runs down, float- 
 ing on top of the metal. When the slag rises to the level of the 
 cinder-notch it runs out, and the metal is tapped out before it is 
 high enough to reach the cinder notch. Care is always taken to 
 leave a covering of slag over the metal. The slag, drawn off at 
 the rear or side of the furnace, is conveyed along a trough or trench 
 into cars with sheet steel bodies, and is hauled away and dumped 
 when cool. Slag of some compositions is now used for making Port- 
 land cement. The metal is tapped several times during each day, and 
 is conducted from the furnace along a trench in the floor. This 
 trench is lined with a mixture of sand and clay which is baked hard 
 to prevent wearing away by the erosive action of the metal. Fig. 16 
 shows metal pouring from a furnace, and Fig. 17 shows the ladles 
 on cars to receive it. 
 
 When a furnace is to be shut down, or "blown out," the ore 
 charge is gradually reduced and stopped. Flux and fuel are con- 
 tinued until all metal and slag are tapped out, and the flux is then 
 discontinued. The fuel is gradually reduced, the blast pressure is 
 lowered and finally shut off, and the fire slowly burns out. The 
 furnace must be allowed to cool gradually before being emptied. 
 
 58, The Blast Stove. In blast furnace smelting of copper and 
 lead, the gases passing from the top of the furnace do not contain 
 much gas which will burn, hence they are allowed to escape, but in 
 the iron smelting furnace not enough oxygen reaches the upper 
 part of the furnace to unite with all the incandescent carbon of the 
 fuel. As a result of this, much C0 2 is reduced to CO, which passes 
 from the furnace unburned. To let this gas escape into the atmos- 
 phere would be a considerable loss of fuel, hence it is conveyed 
 through the " down-comer " and dust catcher to a large stove called 
 the blast or regenerative stove, where it is burned to heat the 
 4 
 
46 
 
 MECHANICAL PROCESSES 
 
 brickwork of the stove. After the brickwork has become very hot, 
 the gas is shut off from this stove, and air is blown through to 
 absorb the heat on its way to the blast furnace through the tuyeres. 
 
 SE.CTION A A 
 
 FIG. 8. Hot Blast Stove (Vertical Section). 
 
 In this way the blast is supplied with air at about 1400 F., and 
 the intensity of the furnace heat is much greater in the fusion zone 
 than if cold air were blown in. 
 
 Fig. 8 shows a form of blast stove used for this purpose, known 
 
GENERAL OUTLINE OF METAL-PRODUCING PROCESSES 47 
 
 as the Calder Stove. Several other forms of stoves are used, all 
 operated on the same principle and differing only in interior ar- 
 rangement. Fig. 7 shows a group of five stoves which are con- 
 
 AiR INLET 
 
 AS INLE1 
 SECTION B-B 
 AIR INLET 
 
 CLEAN-OUT DOOR 
 
 NOTE: 
 
 MADEOF9"e.l5>,"BRICK 
 
 FIG. SA. Hot Blast Stove (Horizontal Sections). 
 
 nected to their common chimney P by an underground smoke con- 
 duit. The stoves are made of an outside casing of steel plates and 
 an interior lining of refractory brick. Brick partitions are so 
 placed as to check the passage of air and gases. 
 
48 MECHANICAL PROCESSES 
 
 The stove in Fig. 8 is operated as follows : Valves connecting the 
 interior space of the stove with the hot and cold blast mains having 
 been closed, the chimney damper is opened and gas from the dust 
 catcher is admitted to the stove through the gas inlet marked in 
 section B-B, of Fig. 8a, This gas is hot enough to burn just as soon 
 as air is admitted through the various air inlets, which are regulated 
 by dampers. Combustion takes place in the two large vertical spaces 
 in the right half of the stove, the burned gases are drawn down- 
 ward by the chimney draft through the small vertical spaces into 
 which the left hand part of the stove is divided, and, following the 
 small arrows, enter the circular conduit through openings at the 
 bottom of the stove. In passing downward, the gases give up much 
 heat to the brick partitions, and finally they escape through the 
 chimney which surmounts the stove. After about an hour of this 
 operation, the brickwork has reached its maximum heat. The gas 
 from the dust catcher is then shut off, the chimney damper is 
 closed, the valves connecting the stove to the cold and hot blast 
 mains are opened, and atmospheric air is forced by blowers through 
 the stove in a direction opposite to that taken by the gases which 
 were burned to heat the brickwork. This part of the operation con- 
 tinues for a half hour or more, during which the air is delivered 
 very hot to the hot blast main. The operation is again reversed as 
 soon as the brickwork begins to become appreciably cooled. 
 
 At least two stoves, and usually four, are installed for each blast 
 furnace, so that at least one stove may be constantly in use for each 
 part of the reverse operation just described. 
 
 59. Reverberatory Furnaces. Two types of the reverberatory 
 furnace are used in smelting. Fig. 9 shows a roasting furnace in 
 which ores are roasted to simplify them before they are placed in 
 the melting furnace shown in Fig. 10. The melting furnace is 
 much used for smelting copper and tin ores, for refining copper and 
 tin, and for melting copper and brass in large quantities in the 
 foundry for castings. 
 
 Both furnaces have several similar parts, as follows : 
 
 G. Grate for fuel. D. Fuel door. 
 
 A. Ash pit, 
 
 W. Bridge wall to separate the fuel from the ore or metal in the 
 furnace. 
 
GENERAL OUTLINE OF METAL-PRODUCING PROCESSES 49 
 
 B. Furnace arch, which reflects heat down upon the furnace 
 charge. 
 
 F. Hearth, on which the charge rests. 
 
 C. Chimney opening, controlled by a damper. 
 
 These furnace roofs are arched from side to side, and the sides 
 are "braced by iron plates connected with long rods over and under 
 the brickwork of the furnace. The melting furnace must generate 
 
 FIG. 9. Reverberatory Furnace for Roasting. 
 
 FIG. 10. Reverberatory Furnace for Melting. 
 
 a more intense heat than the other, hence its fire box is larger. 
 These furnaces have no air blast, and their draft is produced by a 
 tall chimney. The fuel is usually oil, gas, or soft coal which pro- 
 duces a long flame. 
 
 The roasting furnace has a flat hearth over which the ore, intro- 
 duced through covered hoppers H, is evenly spread. The hearth is 
 so shaped that every part of it can be reached by a rake or rabble 
 through one of the doors M (two on each side) and when roasting 
 has reached the proper degree, a plate in the hearth at the edge of 
 
50 MECHANICAL PROCESSES 
 
 each door is lifted and the charge raked into the arched space L. 
 From there it is taken to the melting furnace. 
 
 In the regular process of smelting, the slope of the bottom leads 
 the metal to the breast K (Fig. 10) from which it is tapped. This 
 opening is stopped with a clay plug which is dug out by a pointed 
 iron bar when the metal is to be drawn off. The slag is removed 
 through an opening at the back of the furnace, higher than the 
 breast opening. 
 
 After charging the furnace with ore and flux, the door H is 
 plastered around the edges with clay to exclude air. The progress 
 of the operation is watched and any stirring needed is done through 
 the small covered opening P. 
 
 Unlike the blast furnace, the melting reverberatory furnace can 
 be placed in operation and cooled down in a short time. Usually 
 only a single charge is smelted and drawn off, after which the fur- 
 nace is opened, recharged, and again put in operation without much 
 lessening of temperature. Feeding hoppers may be placed on top 
 and the furnace made to operate continuously. 
 
 60. Atmosphere of Keverberatory Furnaces. These furnaces 
 may be so fired and the air supply to the fire so regulated as to make 
 the furnace action oxidizing or reducing. Oxidation demands (1) 
 an excess of air beyond that needed for complete oxidation of every 
 combustible part of the fuel and (2) that the excess air be at the 
 required heat to combine with (burn) the material to be oxidized. 
 
 Reduction demands ( 1 ) that the supply of air be deficient for the 
 complete burning of the fuel and (2) that the unburned gases from 
 the fuel be kept at or above their igniting temperature, in which 
 case they will extract oxygen from oxides in the charge having a 
 less affinity for oxygen. An oxidizing atmosphere necessitates a 
 thin fire and a full supply of air over and under the fuel, while a 
 reducing atmosphere necessitates a thick fire with small air supply, 
 particularly above the fuel. In both operations it is imperative that 
 the fire shall burn vigorously enough to maintain the degree of heat 
 required. Eeverberatory furnaces are not economical in fuel. 
 
 61. Refractory Materials. An important feature demanding 
 particular attention in all furnaces is the interior lining, because of 
 the intense heat and the chemical action to which furnace linings 
 are subjected. A lining must (1) resist oxidation and reduction, 
 
GENERAL OUTLINE OF METAL-PRODUCING PROCESSES 51 
 
 (2) must not melt nor disintegrate from heat, (3) must reasonably 
 stand the mechanical wear of the furnace charge, and (4) must not, 
 unless so intended, enter into chemical combination with the fur- 
 nace charge. Crucibles, in which metal is melted, the linings of 
 ladles for receiving and pouring molten metals, and the linings of 
 all classes of heating furnaces must fulfill substantially the same 
 requirements. 
 
 The refractory materials commonty used in all branches of smelt- 
 ing, refining and melting of metals, including the processes of steel 
 making, and in heating furnaces, are 
 
 (1) Silica (common sand), Si0 2 . 
 
 (2) Silicate of Aluminum (clay), Al 2 3 2Si0 2 2H 2 0. 
 
 (3) Magnesite (magnesia), MgO. 
 
 (4) Chromite (chromium oxide), Cr 2 3 FeO. 
 
 (5) Dolomite (magnesian limestone). 
 
 (6) Bauxite (alumina), A1 2 3 . 
 
 All of these substances are more or less impure as found in na- 
 ture, containing iron oxide, sand and clay, and in some cases, soda, 
 potash, and organic matter. Practice has established the limit of 
 impurities not detrimental to the uses of these materials for specific 
 purposes. 
 
 Silica and clay are closely associated in use as refractory mate- 
 rials. They are used far more than the other substances named, 
 and are adapted for use in many kinds of furnaces. A mixture of 
 the two materials is known as fire day, and different proportions of 
 the mixtures are employed in different furnaces, according to re- 
 sults obtained by experience. Silica resists the action of heat and 
 alumina resists the action of metallic oxides. Silica is not plastic 
 when wet and must be mixed with enough clay to make the grains 
 stick together. Ganister is a natural rock composed of silica and 
 clay in the proportion for making high-grade fire brick. 
 
 Silica is an " acid " material and cannot be used for bottoms of 
 furnaces for basic steel making, and for linings of other furnace 
 bottoms requiring basic material. For these uses, magnesite and 
 chromite are used in brick form, and dolomite is used for patching, 
 but it is more or less objectionable because of its lime content, an 
 excessive amount of which causes disintegration at high tempera- 
 tures. Chromite is a neutral material, that is, it is neither acid, 
 
52 MECHANICAL PROCESSES 
 
 basic, oxidizing nor reducing in its chemical action, and is unex- 
 celled for use where a material is needed to resist high heat and 
 chemical action. 
 
 Bauxite is exceedingly refractory and is neutral, but has very 
 limited use because it is subject to excessive shrinkage and loses 
 plasticity when highly heated. 
 
 Refractory materials are much used in the form of fire bricks. 
 There are many standard commercial shapes of fire bricks, and 
 many grades also, according to the purity of materials, skill in 
 shaping and care in burning. The selected materials are thoroughly 
 calcined, ground, well mixed in correct proportions with water, 
 moulded to shape, dried in the open air, and slowly burned in a 
 kiln which must be heated to a white heat and gradually allowed 
 to cool. About 1 per cent of lime in silica bricks is necessary to 
 fuse the particles together when burned. All bricks should be true 
 to shape, and their surfaces must allow them to lie in close contact 
 when placed for use. Each grade of bricks must be laid in a cement 
 or mortar of like material ground fine. This cement fills spaces 
 between the bricks, uniting the whole in a compact mass. 
 
 A good fire brick when broken should not show a crumbly mass of 
 ingredients, with large grains of material loose and ready to fall 
 out, but the mass should be dense, strong and thoroughly fused 
 together. 
 
 62. Sources of Copper. The greater part of the world's supply of 
 copper is produced by smelting the sulphide ores. A very extensive 
 source of supply of native copper is the Lake Superior deposit. 
 Only a small supply of copper comes from oxides, carbonates and 
 low-grade ores. 
 
 The sulphides and other ores, including those containing as little 
 as 5 or 6% of copper, are smelted; native copper is melted down 
 to separate it from rock and other earthy substances it holds; and 
 very low-grade ores are leached by the wet process. 
 
 63. Producing Copper from its Sulphides. In the smelting proc- 
 ess, which is preceded by roasting the ores to remove some of the 
 sulphur, large lump ores not too complicated with gangue and other 
 metals, are smelted in the blast furnace, while the powdered ores 
 and those of complex composition are smelted in the reverberatory 
 furnace. 
 
GENERAL OUTLINE OF METAL- PRODUCING PROCESSES 53 
 
 The process of producing copper is not direct and simple, as is the 
 case with iron, but consists of a number of treatments under sep- 
 arate heats, or in separate furnaces and receptacles. The object of 
 the several steps of the process is to simplify the copper compounds 
 into a nearly pure sulphide by removal of other parts of the ore, 
 principally iron and an excess of sulphur, and then to break up the 
 copper sulphide and remove its sulphur by oxidation, leaving a 
 somewhat impure metallic copper which is then refined. 
 
 Roasting the ore removes some of the sulphur and incidentally 
 oxidizes some of the free copper and iron. The roasted ore is then 
 
 FIG. 11. Copper Converter. 
 
 melted in a smelting furnace to convert the earthy matter into slag 
 by use of flux, as in iron smelting, and the remaining product is a 
 nearly pure sulphide of copper in which some iron sulphide remains. 
 This product, known as " matte " or "coarse metal/' is run in a 
 molten state from the smelting furnace into a large refractory lined 
 vessel called a converter, and cold air is blown through the molten 
 mass to oxidize the sulphur and the iron. 
 
 Fig. 11 shows a cross-section of a converter. It consists of a shell 
 fc of steel plates with a lining dd of silica. The trunnion band aa 
 supports the converter and allows it to be tilted about an axis & 
 perpendicular to the plane of the page. The wind box / extends 
 
54 MECHANICAL PROCESSES 
 
 part way around the bottom. It receives air through one of the 
 trunnions, which is hollow and connected to a blower. The air is 
 forced through several openings, as at g, into the molten charge. 
 It combines with the sulphur, forming sulphur dioxide which es- 
 capes at h into the open air. The iron in the charge is also oxidized, 
 this oxide forming a slag with the silica lining of the converter. 
 The oxidation of sulphur and iron supplies heat which keeps the 
 charge molten, and the blow is continued until the flame from the 
 converter mouth shows that these are about burned out and that 
 copper is beginning to burn. The converter is then tilted in the 
 direction of the arrow to pour the charge into a ladle. The product 
 thus obtained is copper about 98 or 99% pure, known as "blister 
 copper," because of the blisters on its surfa.ce due to expelling sul- 
 phur dioxide as the metal cools. 
 
 The last stage is the refining of blister copper either by the poling 
 process or by electrolysis. The object is the same in both cases, viz., 
 to remove the remaining sulphur, iron, copper oxide, antimony, 
 arsenic and other less frequent impurities. The purpose for which 
 the copper is to be used and the kind of impurity it contains deter- 
 mine the degree of refining necessary, though not over .5% of com- 
 bined impurities should remain in any grade of refined copper. 
 
 64. The Poling Process. This consists of melting blister copper 
 in a reverberatory furnace and stirring it to bring about the chemical 
 action necessary to remove the remaining impurities. 
 
 A charge is melted under the heat of an oxidizing flame and its 
 surface is agitated by means of a heavy hoe, or rabble, to bring the 
 impurities in reach of the flame. This is called "flapping." 
 Samples of metal dipped from the furnace during this process en- 
 able the rabbler to judge its progress. 
 
 When the oxidizable impurities are burned out, the next step is 
 to remove the copper oxide. The slag produced by flapping is drawn 
 off, the furnace flame is changed from oxidizing to reducing, and 
 the metal is covered with charcoal. Wood poles are then used to 
 stir the charge. These supply carbon which assists the charcoal 
 to reduce the oxide, forming C0 2 which escapes up the chimney. 
 Green wood is best, as its moisture boils out and helps agitate the 
 molten metal to bring carbon and copper oxide in mutual contact. 
 
GENERAL OUTLINE OF METAL-PRODUCING PROCESSES 55 
 
 When the oxide is removed, the copper is tapped from the furnace 
 into a large ladle and is poured into moulds made of copper. The 
 molten metal is kept from sticking to the moulds by a wash of thin 
 clay,, and the red-hot pig or slab of metal is dumped into a trough 
 of water to soften it for working. 
 
 Poling requires much skill and experience to know when it has 
 proceeded far enough. Too much poling produces brittle copper. 
 
 65. Electrolytic Refining of Copper. The malleability of copper 
 and its efficiency as a conductor of electricity are greatly reduced by 
 even the slightest impurities in the metal. The electrolytic process 
 of refining is used because it gives a higher grade of refined metal 
 from a greater range of impure copper than is the case with the 
 poling process. 
 
 Electrolytic refining consists of dissolving plates of blister copper 
 by electrolysis and depositing the metal from solution upon a pre- 
 viously prepared sheet of pure copper. The current gradually dis- 
 solves the plate of blister copper and deposits the metal almost abso- 
 lutely pure upon the other plate. The impurities from the dissolved 
 sheet either go into solution in the liquid of the tank in which the 
 process is carried on, or fall to the bottom in the slime. 
 
 A plate of copper thus prepared is too porous for use, hence it is 
 melted and cast into cakes, ingots or wire-bars, as may be needed. 
 
 66. Zinc is obtained from the sulphide, or "blende"; and to a 
 smaller extent from the carbonate and oxide. There are several 
 complex zinc ores, and some of these, as the zinc and lead sulphides, 
 are abundant, but so far no method has been found for the profitable 
 extraction of the metals. 
 
 The essential steps in extracting zinc are: 
 
 (1) Changing the ore to an oxide, by calcining the less stable 
 ores and roasting the sulphides. Calcining is done in kilns, and 
 roasting is done in reverberatory furnaces. 
 
 (2) Eeducing the oxide. This is done by mixing the pulverized 
 oxide with carbon and heating in clay retorts. The high heat neces- 
 sary to accomplish the reduction (1900 F.) not only liberates the 
 zinc, but vaporizes it, and the vapor is condensed in suitably placed 
 iron tubes which drain the liquid zinc into ladles from which it is 
 poured into ingots. 
 
56 MECHANICAL PROCESSES 
 
 (3) Eefining the ingots. They are remelted in quantities of 
 several tons in a specially constructed reverberatory furnace. The 
 molten metal is allowed to remain quiet for a few days, when the 
 floating impurities are skimmed off. Molten lead and iron,, which 
 are almost always present, sink to the lowest part of the furnace 
 basin and are quietly tapped out, the lead running out first, fol- 
 lowed by the iron, which carries some zinc also. The remaining 
 zinc is run out and cast into slabs or ingots for marketing. These 
 are known as "spelter/' and should contain not over 1% of lead 
 and only traces of iron. 
 
 A recent refining process for zinc consists of passing the vapor 
 from the reducing retorts through a filter of coke kept hot enough 
 to prevent condensation. This is said to remove iron and lead better 
 than by the method of re-melting. 
 
 67. Tin is produced from its oxide (Sn0 2 ) known as stannite, 
 casserite, or tin-stone, which is not so abundantly distributed as are 
 ores of many other metals. The oldest mines are in England and 
 the East Indies, though ore deposits in Europe and America are 
 now worked. The best grade of commercial tin is said to be from 
 Banca, in the East Indies. 
 
 68. Lead is produced mainly from its sulphide, known as galena. 
 The smelting of this ore is complicated by the presence of arsenic, 
 copper, iron, zinc, or silver, and like the smelting of copper sul- 
 phides, the process is one of desulphurization. The blast furnace, 
 usually of rectangular cross-section, is now generally used for smelt- 
 ing lead, though if the ore is rich in sulphur, it is first roasted in a 
 reverberatory furnace to drive off sulphur and oxidize some of the 
 ore. A flux of iron oxide and limestone assist in reducing the ore, 
 and the impure metal is drawn off through an opening in the base 
 of the furnace leading outward and upward from the bottom of the 
 hearth. 
 
 69. Nickel is produced from the arsenide, known as kupfer- 
 nickel, and to a lesser extent from the sulphide. 
 
 The smelting process is somewhat complex and is accomplished 
 by roasting, reducing in presence of flux, and Bessemerizing. The 
 sulphide is then changed by roasting to oxide, which is finally re- 
 duced with charcoal. 
 
GENERAL OUTLINE OF METAL-PRODUCING PROCESSES 57 
 
 70. Aluminum never occurs free in nature, but no other metal 
 known, not excepting iron, occurs in such abundance in its com- 
 pounds, nor is any other metal so widely distributed over the earth. 
 Its combination with oxygen, silicon, alkalies and acids forms clay, 
 koalin, emery, mica, feldspar and many of the precious stones. 
 It is obtained mostly from Bauxite, an oxide known as alumina, first 
 found near Baux, in France. This is dissolved in a fused bath of 
 cryolite (a fluoride of sodium and aluminum) by the heat of an 
 electric current. This heat fuses the cryolite, which in turn dis- 
 solves the alumina, in which condition the electrolytic action of the 
 current decomposes the alumina, but does not change the cryolite. 
 The liberated metal sinks to the bottom of the vessel and is siphoned 
 off when it accumulates. The process is continuous so long as 
 alumina is supplied and the current is maintained. 
 
 71. Electricity in Metallurgy. Electrolytic action has long been 
 applied to electro-plating, and in recent years to the refining of 
 copper. The combined electrolytic and heat actions of current are 
 used in producing aluminum, and very recently the heat of the 
 electric arc has been made commercially successful in refining steel 
 from a lower quality to a higher quality. 
 
 The advantages of the higher heat of the electric furnace, and its 
 easy control, make the application of electric heat to the smelting 
 of metals highly desirable, at least to the extent of (1) assisting the 
 fuel at the point of ore fusion, (2) of making the extracted metal 
 more fluid, and (3) of improving its quality by producing a neutral 
 atmosphere due to electric heating as compared with the oxidizing 
 atmosphere of fuel heating. Also, as some impurities come from the 
 fuel used, the reduction in fuel reduces the per cent of these, par- 
 ticularly so of phosphorus. 
 
 Recent experiments in Sweden have shown that an improved 
 grade of iron can be made in a combined electric and fuel furnace, 
 but as yet this is not economical enough for commercial require- 
 ments in general. 
 
CHAPTEE III. 
 FUELS. 
 
 72. Uses. The use of fuels of different kinds is highly essential 
 in the various industries for the producing and shaping of metals. 
 Heat is indispensable (1) to bring about chemical action which 
 breaks up the ore compounds in the smelting of metals, (2) for 
 many chemical and mechanical operations as the refining of metals 
 and the making of wrought iron and steel, and (3) for softening 
 or melting metals to assist in their shaping for definite uses. 
 
 73. Combustion. The economical use of fuel requires that none 
 of it should be wasted in an unburned state, as is frequently the case 
 in the escape of unburned gases up the chimney. Combustion is the 
 chemical union of an oxidizable substance with oxygen, and when 
 this is accomplished rapidly, as in ordinary burning, an intense 
 degree of heat is generated. Flame is caused by the burning of gas. 
 The flame from solid or liquid fuel is caused by the burning of gas 
 distilled from the fuel. The presence of fuel in many metal pro- 
 ducing and metal shaping operations is objectionable (though un- 
 avoidable) for the following reasons, viz. : in the presence of high 
 heat (1) the oxygen necessary for combustion consumes more or 
 less of the metal or other material subjected to the operation, and 
 (2) the substance of the fuel, and particularly the impurities in 
 the fuel, combine with a metal in the process of smelting and in sub- 
 sequent heating or melting operations and impair its quality. 
 
 The essentials for burning fuel completely, with no visible smoke 
 and no waste of combustible substance, are (1) every particle of 
 combustible substance must be supplied with the oxygen necessary 
 for complete oxidation, and (2) the fuel and the oxygen must be 
 hot enough to combine. 
 
 Every combustible substance must be heated up to a definite 
 temperature, called the temperature of ignition, before it will burn. 
 Each burnable substance has a temperature of ignition differing 
 more or less from that of other substances. 
 
 In the confined space of a furnace, coal in small lumps or porous 
 coke present much surface to combustion and therefore burn rapidly, 
 but if coal is too fine, it masses together and leaves too little pass- 
 age for air. 
 
FUELS 
 
 59 
 
 74. Components of Fuels, The heat-producing elements, i. e. f the 
 combustible substances, of all fuels, whether solid, liquid, or gase- 
 ous, are carbon and hydrogen. Many fuels, particularly coal, con- 
 tain free sulphur, which is always more or less objectionable, some- 
 times seriously so, and although sulphur produces heat when burned, 
 its quantity is too small to be considered in summing up the heat 
 value of a fuel. 
 
 Almost all fuels contain ash, water and other matter which will 
 not burn, and these determine largely the practical and commercial 
 values of all fuels. These are of negative value in fuel, as they 
 absorb and carry away heat when the fuel is burned. 
 
 The heating or calorific value of a fuel is usually expressed in 
 British Thermal Units. One B. T. U. is that quantity of heat 
 necessary to raise the temperature of one pound of pure water 
 through 1 F., at or near 39.1 F., its point of greatest density. 
 The heat value of a fuel is stated as that quantity of B. T. U.'s 
 which one pound of the fuel will evolve when burned. 
 
 In commercial practice, fuel is usually sold by weight, but the 
 heat value of a fuel is only crudely expressed by its weight. The 
 value of a fuel for practical purposes is far better expressed by the 
 number of heat units which a given weight of it will supply when 
 burned. The desirability of coal is also determined by the sulphur 
 it contains, and by the character and quantity of the ash it makes, as 
 some coals produce a sticky clinker hard to remove from the grate 
 bars. 
 
 75. Classes of Fuel. The following classification includes all 
 fuels in general use in the arts and industries. Some of these have 
 but limited and special uses in the metal industries. 
 
 (1) Solid Fuels. 
 
 (a) Natural Fuels. 
 
 Wood. 
 
 Peat. 
 
 Coal. 
 
 (b) Prepared Fuels. 
 
 Charcoal. 
 Coke. 
 
 Powdered Coal. 
 Briquettes. 
 
 (2) Liquid Fuels. 
 
 (a) Natural Fuels. 
 
 Mineral Oils. 
 
 (b) Prepared Fuels. 
 
 Refined Mineral Oils. 
 Alcohols. 
 
 (3) Gaseous Fuels. 
 
 (a) Natural Gas. 
 
 (b) Prepared Gases. 
 
 Producer Gas. 
 Water Gas. 
 Illuminating Gas. 
 
60 MECHANICAL PROCESSES 
 
 76. Wood and Charcoal. Wood is less and less used as fuel be- 
 cause of its increasing scarcity and because coal is abundant and 
 easily handled. Charcoal, made from wood, is now used only for 
 special purposes because of its high cost. Charcoal is prepared by 
 heating wood to a high heat and thereby distilling off nearly all 
 water and volatile gases, leaving only carbon and non-combustible 
 mineral salts. The heating must be done under a covering which 
 will exclude air. 
 
 In later processes, charcoal is produced in kilns, or in closed 
 retorts in which wood is distilled for pyroligneous acid and wood al- 
 cohol, and charcoal is a by-product. 
 
 77. Coal is the most extensively used of all fuels. The different 
 varieties of coal, with many different names, merge one into an- 
 other, and the fundamental distinction between the several varieties 
 is the difference in the amount of carbon contained. The several 
 grades or qualities of each variety are due to the per cent of sul- 
 phur, ash and water contained. Coal usually contains some 
 phosphorus. 
 
 A good practical classification of the varieties of coal is : 
 
 (1) Bituminous or soft coal. 
 
 (a) Non-caking varieties, long flame and gas coals, 40 to 
 
 70% fixed carbon. 
 
 (b) Caking, or coking varieties. Short flame coals, 55 to 
 
 80% fixed carbon. 
 
 (2) Anthracite or hard coal, 80 to 95% fixed carbon. 
 
 There are many grades of each kind, beginning with lignite, a 
 brown soft coal low in carbon, and ranging gradually through the 
 bituminous to the anthracite coals which are very rich in carbon and 
 contain very little hydrogen. The flame from coal is due to the 
 gases which are distilled off by the heat of the fire and burn after 
 they are thus liberated. Fixed carbon is the solid carbon in coal 
 as distinguished from the gaseous carbon, which is that combined 
 with hydrogen. 
 
 Bituminous coals constitute most of the world's supply. They 
 are fragile, and burn with more or less flame and smoke. From 
 this variety of coal, coal gas and coke are made. Cannel coal is a 
 variety of bituminous coal. 
 
FUELS 
 
 61 
 
 Anthracite coal has a lustrous black color, is hard, and does not 
 readily pulverize in handling, hence is comparatively free from dust. 
 The best varieties give off very little gas, hence they burn as in- 
 candescent coals with very short flame. The purer varieties are used 
 in smelting furnaces occasionally, and more frequently to melt 
 metal in crucibles. 
 
 78. Coke is a product of bituminous coal, bearing the same rela- 
 tion to coal which charcoal bears to wood. The better varieties, 
 made from the softer bituminous coals, and used almost entirely 
 in the blast furnace and for melting metals in the foundry, are 
 primary products, while the poorer varieties are b}^-products from 
 the manufacture of coal gas. A good grade of coke must be porous, 
 yet not fragile, for it must not be crushed by the weight of the 
 charge in a furnace; and it must contain little sulphur or ash, 
 which requires that it be made from a good grade of coal. 
 
 79. Coke Making. Coke is made, by subjecting coking coal to a 
 high heat for about four days, without free access of air. This 
 process drives off water and the hydrocarbon gases, leaving the free 
 
 FIG. 12. Coke Oven. 
 
 carbon and ash. Coal should be selected which contains little sul- 
 phur, as all of this is not driven off in coking. Fig. 12 shows a 
 simple type of coke oven which is still used, though more elaborate 
 and more economical ovens are displacing it. This type, known 
 as the bee-hive oven, is shown here because of its simplicity. This 
 form of oven is low in cost to build and to maintain, and is a good 
 coke producer. A number of ovens are built together to economize 
 space and heat. This oven is a chamber formed of brickwork, lined 
 5 
 
62 MECHANICAL PROCESSES 
 
 with fire brick, and provided with an opening a in the top and a 
 door at the side. Two styles of doors are here shown in two of the 
 ovens. Doors are lined inside with fire brick, and are provided with 
 dampers. The lower part of the chamber is circular, about 10 ft. 
 in diameter, and is surmounted by a hemispherical dome. 
 
 A charge of coke having been removed through the door, the oven 
 is left at a dull red heat. The door is closed and luted with elay, 
 except that a few peep holes are left for watching the process and 
 for admitting air for combustion. A charge of several tons of coal 
 is dumped in at the top opening from a car which moves along rails 
 laid over the furnaces. The furnace heat soon begins to distil off 
 the gaseous parts of the coal, which are ignited by the admission 
 of air at the dampers, and this combustion supplies heat which con- 
 tinues the coking process. It requires several hours for the charge 
 to get thoroughly hot throughout, and the distillation of gases 
 gradually extends into the mass, and when a maximum amount of 
 gas is being evolved, the furnace lining and charge are at a red heat. 
 After about thirty hours the evolution of gas begins to decrease, 
 and a little air continues to be admitted until all flame ceases, when 
 air is shut off entirely. The furnace is now nearly white hot, and 
 combustion is stopped entirely, for the charge must cool down 
 before it can be withdrawn. After about twelve hours the charge 
 has cooled to a degree which will allow a limited amount of water 
 to be introduced from a hose for quicker cooling, and after a short 
 time the door can be opened wide and the charge raked out into 
 iron barrows. 
 
 In this type of furnace the products of distillation escape par- 
 tially burned through the top opening, and may be completely 
 burned elsewhere, as they are rich in combustible gases. It is 
 sought in coking to heat the mass of coal from above by burning 
 some of the distilled gases before they escape from the oven, but the 
 burning of some of the solid carbon is unavoidable, hence this fur- 
 nace is not so economical as some of the later types. 
 
 80. Powdered Coal has a limited use in metal heating furnaces. 
 It is ground to a fine dust by revolving it in a steel drum with hard 
 pebbles. It is then conveyed through tightly made sheet iron tubes 
 to the furnaces, and is blown into the flame of the furnace by air 
 pressure through a specially constructed burner for regulating both 
 air and fuel. 
 
FUELS 63 
 
 81. Screenings. Briquettes. In handling coal at the mine, a 
 considerable quantity becomes pulverized. In this form it is known 
 commercially as screenings. This is now used in mechanical stokers 
 fitted to steam boilers, and some of it is made into briquettes by 
 mixing it with tar or crude oil and pressing it into cakes by a machine 
 for that purpose. Some grades of screenings must be washed to re- 
 move mineral matter. 
 
 82. Liquid Fuels. The only practicable cheap liquid fuel is min- 
 eral oil, better known as crude petroleum, though this is confined 
 to too few localities for general displacement of coal, but in those 
 localities is usually cheaper and more desirable than coal. It comes 
 from oil wells drilled usually deep into the earth. When taken 
 from the earth, this oil is refined before it can be safely used for 
 fuel. This consists of subjecting it to two stages of distillation 
 which causes it to give off in turn highly inflammable gases, gaso- 
 lene, benzine, and naphtha; then kerosene, and gas-enriching oils, 
 leaving a dark-colored viscous liquid residue which is used as fuel. 
 Fuel oil must be strained and frequently is heated just before it is 
 burned to increase its fluidity and prevent clogging the burners. It 
 is sprayed by pressure into the furnace. 
 
 While all mineral oils consist of the same elements, carbon and 
 hydrogen, the oils from different localities vary widely in the rela- 
 tive amounts of gasolene, kerosene, lubricating oil, and the more 
 dense constituents forming the residue, due to the fact that carbon 
 and hydrogen have a great variety of chemical combinations, and 
 each of these combinations, or compounds, differs in volatility from 
 the others. This accounts for the fact that some mineral oils have 
 a large proportion of volatile oils and only a small amount of 
 residue, while others have a large proportion of residue and need 
 but little distillation to prepare them for fuel. The residue of 
 mineral oils includes the heavier lubricating oils, vaseline, paraffin, 
 and mineral pitch better known as asphalt or bitumen. Mineral 
 oils contain more or less earthy impurities, including sulphur. It 
 is not known from what sources mineral oil was produced in its 
 natural deposits. 
 
 Of the refined oils, gasolene is much used as motor fuel, and 
 kerosene has very limited use as an industrial fuel. 
 
 Alcohols are produced from fermentation and distillation of 
 
64 MECHANICAL PROCESSES 
 
 vegetable matter and make excellent fuels, but they are little used 
 at present except in small quantity for special needs. They are 
 considered superior to petroleum fuels for motors, but their pro- 
 duction and development for this use is limited because of the ex- 
 tensive use gained by gasoline while it was very cheap. 
 
 83. Gas Fuels. The great convenience of natural and producer 
 gas as fuel in reverberatory, steel-making, and metal-heating fur- 
 naces has caused extensive use of gas fuel in all metal industries. 
 
 For furnace use a more concentrated and more intense heat can 
 be obtained from gas than from coal, as a less volume of air enters 
 the furnace with the gas, thus necessitating the heating of less 
 inert nitrogen which enters with the air. The heat from gas can be 
 regulated and directed better than that from coal, and gas leaves 
 no ash nor clinker. 
 
 84. Natural Gas, like mineral oil, is obtained from cavities in 
 which it is confined in the earth. It is abundant in a few localities 
 only, but the great desirability of gas has given rise to the artificial 
 production of fuel gas from coal, and to a less degree from oil. 
 Natural gas is composed of about 93% CH 4 , with very little free 
 hydrogen, CO, and nitrogen. 
 
 85. Producer Gas is made as follows, referring to the gas pro- 
 ducer in Fig. 13. A shell of steel plates, lined with fire-bricks, 
 rests on a cast-iron ring A, which in turn is supported by lugs rest- 
 ing on the edge of a basin B. This basin, which is a depression in 
 the concrete floor, is kept filled with water. The interior of the 
 producer contains fuel in various stages of burning, varying from 
 water-soaked ashes in the basin at the bottom to a continuously sup- 
 plied layer of fresh fuel at the top. 
 
 By means of a central tuyere with a mushroom head G, steam 
 from the pipe and nozzle marked C, and air drawn through the 
 damper D, are blown into and distributed through the fuel, en- 
 tering the hot ashes at G, and rising through the zone of in- 
 candescent fuel. When the air and vapor become sufficiently heated, 
 the oxygen of the air combines with the carbon of the fuel. The 
 tendency of this combustion is to form C0 2 , but the relatively small 
 quantity of oxygen carried in by the air in presence of a large 
 amount of incandescent carbon soon reduces the C0 2 to CO. The 
 heat produced by combustion is intense enough to decompose the 
 
FUELS 
 
 65 
 
 water vapor, the oxygen combining with the carbon of the fuel and 
 the hydrogen rising uncombined. The gases resulting from this 
 partial combustion of fuel and the hydrogen resulting from the 
 decomposing of steam rise into the space above the fuel and pass 
 away through the outlet K into " scrubbers " or cleaning compart- 
 ments, thence into the storage tanks ready for use. 
 
 mmm^zm^M^^&^m^i^. 
 
 FIG. 13. Gas Producer. 
 
 The central opening at the top is the seating for an automatic 
 feeder (not shown in the sketch) regulated to drop fuel into the 
 producer continuously at the rate needed. Fig. 14 shows a row of 
 these feeders, surmounted by coal hoppers, along a working floor 
 over the producers. The brick-work forming the body of the fur- 
 nace, as shown in Fig. 13, is closed at the top by a cast-iron pan P, 
 which holds water for keeping the top cool. This water is received 
 
66 
 
 MECHANICAL PROCESSES 
 
 from a small pipe and flows from the pan into the ash basin 
 through a small pipe R in the quantity needed to keep the basin B 
 about full. It serves also as a water seal both in pan and basin to 
 prevent the escape of gas from the producer. The fuel is poked 
 through the holes // on the side and through the water-sealed holes 
 M on top if it becomes clogged. The small covers for the water- 
 
 FIG. 14. Automatic Feeders for Gas Producers. 
 
 sealed holes on the top are shown at the floor level in Fig. 14. Ashes 
 are removed from the basin at the bottom of the producer. 
 
 The gas product passing out at K consists essentially of (1) CO, 
 from partial combustion of the fuel, (2) hydrogen from the decom- 
 posed steam, (3) and a small quantity of hydrocarbon gas distilled 
 from the coal as it heats up before beginning to burn ; these are the 
 combustible gases and should be about 50% of the whole volume of 
 gas produced for maximum efficiency of a producer. The remain- 
 
FUELS 67 
 
 der of the mixture consists of (4) a slight amount of C0 2 from 
 complete burning of the fuel, and (5) considerable nitrogen un- 
 avoidably entering as a constituent of air. 
 
 The relative amounts of air and steam blown in must be care- 
 fully regulated. With no steam, the combustion would need much 
 more air, resulting in larger proportions of nitrogen and C0 2 ,, as 
 well as in too intense a heat in the producer. Steam is advanta- 
 geous because it (1) displaces nitrogen; (2) absorbs heat in its de- 
 composition, thereby keeping down the temperature of the pro- 
 ducer; (3) supplies oxygen for combustion, and (4) hydrogen for 
 enriching the gas product. Too much steam checks combustion by 
 displacing air and by lowering the temperature of the furnace be- 
 low that required for burning the fuel. 
 
 Producer fuel for metallurgical work usually consists of the ordi- 
 nary grades of bituminous coal, including lignite. Usually the 
 cheapest grade of coal in the locality where the producer is installed 
 is suitable provided (1) it does not contain an excessive amount of 
 sulphur nor (2) a large per cent of ash which forms pasty clinkers. 
 The richest gas is made from gas coals because of the volatile hy- 
 drocarbons they give to the producer product. The fuel for a pro- 
 ducer should be in small lumps, because coal which is wholly 
 " slack " or very fine will resist the passage of air and steam. There 
 are several varieties of gas producers but all embody the same 
 principle. 
 
 86. Water Gas is produced by forcing steam through a network 
 of very hot fire bricks, on the principle of the blast stove, and im- 
 mediately, while at a high temperature, through a bed of incan- 
 descent fuel. The hot fuel decomposes the steam, consuming the 
 oxygen, liberating hydrogen and giving off CO. In this way no 
 nitrogen is introduced. The blowing of steam through the fire is 
 intermittent as it soon cools the fire and must be shut off to allow 
 the fire to regain heat by ordinary combustion. Water gas produces 
 a more intense heat than does producer gas, but is used only for 
 special needs as its cost is greater than that of producer gas. 
 
 87. Illuminating Gas is made in closed retorts from coals rich in 
 gas, and is too expensive for extensive use as fuel in mechanical 
 industries. 
 
CHAPTEK IV. 
 IRON AND STEEL. 
 
 
 
 I. Iron Ores and Their Reduction. Pig Iron. 
 
 88. Iron Ores. These ores are very widely distributed and very 
 abundant in nature, but many deposits cannot be worked profitably. 
 According to chemical composition, ores available for smelting may 
 be classified as follows: 
 
 I. Magnetic Iron Ores, or Magnetite (Fe 3 4 ). 
 II. Ferric Oxides or Hematites (Fe 2 3 ). 
 
 III. Ferrous Carbonate or Spathic Ores (FeC0 3 ). 
 
 IV. Iron Pyrites (FeS 2 , iron sulphide or fools' gold) is a very 
 
 abundant ore, but cannot be cheaply smelted because of the 
 difficulty of eliminating the sulphur. However when the 
 sulphur from this ore is extracted in the manufacture of 
 sulphuric acid, the remaining product is profitably smelted, 
 though the iron obtained by this means is but a very small 
 per cent of that smelted. 
 
 The magnetic ores, the. most valuable of all iron ores, are black, 
 very dense, not so widely distributed as the other ores, have mag- 
 netic properties and contain about 72% of iron when pure. The 
 largest known deposits are in the Lake Superior region of the 
 United States. 
 
 The hematites are usually red or brown in color, according to the 
 gangue, are widely distributed, and usually free from excessive 
 sulphur and phosphorus. They are employed more in smelting 
 than are other ores because of their abundance. 
 
 89. Preliminary Preparation of Iron Ores. Upon taking iron 
 ore from the mine, which is usually a simple process of excavating 
 after surface earth is removed, it is desirable to remove the gangue, 
 if this exists in large quantity, to avoid the labor and expense of 
 its further handling. Magnetic ore may be lifted away from gangue 
 by electro-magnets, a process known as magnetic concentration. 
 Other methods of removing gangue have been mentioned. 
 
IRON AND STEEL 
 
 69 
 
 90. Calcination. The main results of calcination, and the conse- 
 quent advantages in smelting are, for iron ores : 
 
 (1) Driving off water and thus avoiding interference with the 
 regularity of the smelter fire. 
 
 (2) Elimination of C0 2 and a consequent saving of fuel in 
 smelting as the C0 2 takes up much carbon from the fuel in the 
 upper part of the blast furnace. This changes the carbonate ores to 
 oxides. 
 
 FIG. 15. Bridge crane for handling ore. The unloading hoists on the 
 left take ore from vessels lying under them, and pass it to the bridge 
 crane in transfer cars. This crane carries it to its proper pile, accord- 
 ing to composition, and also carries ore to the charging cars of the 
 furnaces on the right. 
 
 (3) Elimination of sulphur in some ores, thus preventing its 
 combination with the metal as it melts and runs down to the hearth 
 of the furnace. 
 
 There is no advantage in calcining the magnetites and red hema- 
 tites unless they contain pyrites. Ore deposits of the world which 
 can be sent direct to the smelter without sorting or calcination are 
 yet fairly abundant. 
 
 Fig. 15 shows the ore yard of a large smelting plant where ore 
 is received for smelting. 
 
70 MECHANICAL PEOCESSES 
 
 91. Reduction. Iron ores are always reduced in the blast fur- 
 nace, the parts and operation of which have been described (Pars. 
 53 and 57. The process of smelting iron is very simple, as the 
 ores used are oxides, uncombined with other metal?, and merely 
 mixed with gangue, which is removed by combining with the flux 
 in the charge. The simplicity of the process consists in the fact 
 that all of the chemical changes take place in one operation. 
 
 The important changes are as follows: The highly heated air 
 .forced in at the tuyeres at once spreads through the charge which 
 fills the furnace. Coming in contact with the incandescent fuel, 
 the oxygen of the blast and the carbon of the fuel unite, forming 
 COo. The C0 2 meets more carbon as it rises and gives up part of its 
 oxygen, forming CO. This is a powerful reducing agent and, with 
 some complexity of reaction, it reduces the ore, and at the same time 
 the flux combines with the gangue. Metallic iron and slag are thus 
 formed, and as they sink into the fusion zone, both melt and run 
 down. 
 
 In the intense heat of the fusion zone, some of the compounds of 
 silicon, sulphur and manganese, and usually all the phosphorus 
 compounds are decomposed, and these elements enter the molten 
 iron. At the high heat of the modern blast furnace molten iron 
 also dissolves some carbon, hence when the iron settles on the fur- 
 nace hearth it has carried down with it small amounts of silicon, 
 phosphorus, sulphur, manganese and carbon, which are always pres- 
 ent in ore, flux, or fuel, but which have a great affinity for iron and 
 remain with it when tapped from the furnace. 
 
 92. Pig Iron. The product of the blast furnace is pig iron. 
 From this all other forms of iron and steel are now made. Some 
 grades of pig iron are selected, and without further change are 
 merely re-melted in the foundry for making castings, hence it has 
 become common for the designations " pig iron " and " cast iron " 
 to be interchanged. 
 
 All pig iron contains an aggregate of about 7 per cent or less of 
 the five substances, carbon, sulphur, phosphorus, silicon and man- 
 ganese, and the grade or quality of pig iron for various uses is de- 
 termined by the amounts of each of these ingredients contained 
 
IRON AND STEEL 71 
 
 Iron occasionally takes up other substances in smelting, but these 
 are usually negligible. 
 
 For high-grade uses demanding an iron of superior ductility and 
 chemical purity, a limited quantity of " charcoal iron " is at pres- 
 ent smelted. Ores of exceptional purity are selected (particularly 
 free from sulphur and phosphorus) and are smelted with charcoal 
 fuel. A cold blast of air causes the iron to dissolve less carbon than 
 it dissolves in the higher temperature of the hot blast, also a lower 
 smelting temperature lessens the introduction of other ingredients 
 into the iron, hence the superiority of " cold blast iron. 7 " 
 
 The name " pig iron " comes from the former way of running 
 iron from the blast furnace along channels and branch channels, in 
 herring-bone shape, in the level sand bed adjacent to the furnace. 
 The iron along the main channel was called the sow, and that in 
 the branch channels was called the pigs. 
 
 93. Disposition of Iron from the Blast Furnace. When iron is 
 tapped from the furnace, it is the practice at present to convey it 
 by means of a trough or trench into a large ladle, even if it is to be 
 cast into pigs. Fig. 16 shows iron flowing along a trench from the 
 furnace, on its way to the ladles, and Fig. 17 shows the metal flow- 
 ing into ladles. Large ladles hold about 50 tons, and are either 
 supported on a car and hauled by a small locomotive, or are lifted 
 and transported by a traveling crane. The ladle contents may be 
 disposed of in any of the ways below stated, depending upon the 
 purpose for which the smelter product of a particular composition 
 may be suited. 
 
 ( 1 ) Poured into a large reservoir called a " mixer " which main- 
 
 tains a supply of molten metal (designated as "hot" or 
 "direct" metal) for: 
 
 (a) Making steel by the open hearth process. 
 
 (b) Making steel by the Bessemer process. 
 
 (2) Poured into pig moulds made of heavy iron to be re-melted 
 
 later for: 
 
 (c) Making iron castings in the foundry. 
 
 (d) Making wrought iron in the puddling furnace. 
 
 (e) Uses stated in items (a) and (b). 
 
MECHANICAL PROCESSES 
 
 FIG. 16. Base of a Blast Furnace showing iron flowing from the 
 furnace along trenches conveying it to ladles. The stream is directed 
 along the trenches by the gates G. When the flow of iron from the 
 furnace is to be stopped, the " mud gun " H is swung around on its 
 crane R in front of the tapping hole. It operates a piston rod by 
 hydraulic power and forces a cone of clay into the tapping hole 
 
 FIG. 17. Ladles Receiving Molten Pig Iron from Blast Furnace 
 
 Troughs. 
 
IRON AND STEEL 73 
 
 94. Grades of Pig Iron.- The grade of iron which a furnace is 
 producing is governed within certain limits by the chemical make- 
 up of ore, fuel, and flux, but the composition of these elements of 
 the charge is not always uniform, nor are heat conditions in the 
 furnace always the same. These variations give rise to iron of 
 various compositions, within certain limits, and when iron is cast 
 into pigs, a sample from each heat is analyzed chemically, to deter- 
 mine the per cent of each of the five ingredients named, and the 
 iron is graded from this analysis. 
 
 In the old way of casting iron into pigs in the sand bed, the cast 
 had to be broken up to be removed. This gave opportunity to in- 
 spect the fracture and judge approximately the quality of the iron 
 from its carbon. These fractures showed either grey, mottled, or 
 white color, in the order of the uncombined carbon which the iron 
 contained, and by these colors the iron could be graded for its suit- 
 ability for different uses. The grey iron is soft and used mostly 
 in the foundry, as it makes excellent castings and can be easily 
 machined. The white iron, on the other extreme, is hard and 
 brittle, difficult to cut, and is best adapted for steel or wrought iron 
 making. 
 
 Various grades of pig iron are named from the locality or com- 
 pany which produces them, particularly in England. 
 
 Buyers of pig iron now purchase their iron according to its 
 chemical composition, and not according to its trade name, nor 
 according to inspection of fracture. The American Society for 
 Testing Materials has recommended that in each car load of pig 
 iron, one pig in each four tons shall be selected for sampling and 
 analysis. 
 
 II. The Classification, Ingredients and Properties of Iron 
 and Steel. 
 
 95. The Three General Classes. It is essential to understand the 
 difference between the several classes of iron and steel, and the 
 effects of the substances which they always retain from the blast 
 furnace. These substances are frequently spoken of as impurities, 
 but some of them are always more or less desirable in the iron in 
 giving it certain properties. It may be stated that chemically pure 
 iron is not known, except possibly as a laboratory curiosity. 
 
74 MECHANICAL PROCESSES 
 
 The three general classes of iron are (1) wrought iron, (2) steel, 
 and (3) cast iron. Within each class there are many grades, due 
 to the varying quantities of the substances which each grade con- 
 tains. These substances affect the metal adversely or otherwise 
 according to their quantity and the use for which the metal is 
 desired. 
 
 All grades and classes of iron and steel gradually merge one into 
 another, and the difference between them is due primarily to carbon. 
 The approximate limitations of carbon contained by each class are 
 as follows : 
 
 Wrought Iron Trace to .08 per cent 
 
 Mild Steel (also known as " Ingot Iron," " Low Carbon 
 
 Steel," " Soft Steel ") Trace to about 0.25 per cent 
 
 High Carbon Steel About 0.25 to 2.2 per cent 
 
 Cast Iron *2.2 to 4.5 per cent 
 
 Carbon in iron and steel has a direct effect upon their properties, 
 and other elements usually contained govern somewhat the power 
 of the metal to take up carbon, and their influence is both direct 
 and indirect. Iron and steel are affected similarly by the same 
 ingredients, and in discussing these the general term iron is meant 
 to include steel. 
 
 It will assist, in the study of the several elements taken up by 
 iron, to regard the metal in its molten state as a solvent which has 
 a stronger tendency to dissolve some elements than others, and 
 which, when certain elements have been dissolved, has a decreased 
 or an increased power to dissolve other elements. 
 
 96. Carbon in Iron. When iron is fused in smelting, it gets its 
 first carbon, the amount depending upon its temperature, and upon 
 the manganese, silicon and other substances present in the furnace. 
 This amount increases with the temperature and is influenced in 
 different ways by the other substances contained, but is rarely less 
 than 1.8 per cent. When the metal solidifies, its carbon may assume 
 either an invisible form, called combined carbon, in which case the 
 
 * The International Association for Testing Materials has, for specific 
 reasons, based upon investigations of Messrs. Carpenter & Keeling, 
 recommended that the line be drawn between steel and cast iron at 
 2.20 per cent of carbon. 
 
IRON AND STEEL 75 
 
 metal sh^ws a white fracture ; or it may be visible in the fracture, 
 giving a mottled or grey color, and known as uncombined carbon 
 or graphite. The condition assumed by the carbon as the metal 
 solidifies depends (1) upon the rate of cooling, and (2) still more 
 on the kind and quantity of the other substances contained by the 
 metal. 
 
 As with other solvents, iron forms a non-crystalline mass if 
 cooled rapidly, and none of the carbon is precipitated, thus showing 
 the white fracture of iron, but slow cooling allows formation of 
 metal crystals, and, if the carbon is above 3%, some of it separates 
 as uncombined carbon. 
 
 Carbon renders iron and steel hard, less ductile and more fusible, 
 directly according to the amount contained, and it is well to un- 
 derstand that a small alteration in the amount of combined carbon 
 has very marked effect upon the metal, while a moderate alteration 
 in the amount of uncomlined carbon has very little effect. 
 
 97. Silicon in Iron. Cast iron ordinarily contains silicon up to 
 4% or slightly more, although " silicon pig/' the form in which 
 silicon is handled for foundry and similar uses, is made in the blast 
 furnace containing up to 18% of silicon; and ferro-silicons, made 
 by the electric furnace, may contain up to 95% of silicon. 
 
 Next to carbon, silicon is most important in determining the 
 suitability of cast iron for foundry use, because its presence up to 
 2% assists the softness and fluidity of the metal. It softens the 
 metal, making it tough and less brittle, by decreasing the per cent 
 of combined carbon, which acts as a hardening element. Also, in 
 increasing the fluidity of molten cast iron, silicon contributes to 
 the prevention of blow holes in making foundry castings by allow- 
 ing time for the gases formed or entrained in the molten metal to 
 escape. 
 
 Beyond 2%, silicon renders iron weak and hard. The solution 
 of carbon in iron is rendered more difficult by the presence of 
 silicon, as iron dissolves silicon in preference to carbon. 
 
 98. Sulphur in Iron. This element is particularly objectionable, 
 but is always present in iron and steel, rendering them brittle 
 when hot, a condition known as " red short " or " hot short." Iron 
 and steel for high-grade forgings must not contain more than .04% 
 of sulphur, although for castings the metal may safely contain up 
 
76 MECHANICAL PROCESSES 
 
 to .15%. Sulphur in iron tends to cause the carbon to assume the 
 combined form. 
 
 99. Phosphorus in Iron. Neither the quantity of carbon dis- 
 solved in iron nor its condition as combined or uncombined carbon 
 is much affected by phosphorus, but this element has the effect of 
 hardening iron slightly. It is, however, highly objectionable in 
 forged iron and only slightly less so in foundry iron for castings, 
 as it causes brittleness when iron is cold, a condition known as 
 " cold short," and may cause the metal to break, when worked cold 
 or when receiving repeated shocks in use. It should not exist in 
 iron for important forgings beyond .06%, nor in foundry iron for 
 strongest castings beyond .5%, although it is used in railroad rails 
 to harden them against wear. Iron high in phosphorus does not 
 make good grate bars nor other castings subjected to high heat, as it 
 renders them spongy. 
 
 Phosphorus renders molten iron very fluid and causes it to take 
 an excellent impression of the mould, hence in small castings where 
 strength is not the first requisite, iron may be used containing up 
 to 1% of phosphorus. 
 
 Neither phosphorus nor sulphur can be avoided in iron making, 
 and both are difficult to eliminate. The best means of keeping them 
 below objectionable amounts is to select ore fuel and flux for smelt- 
 ing which are as free as possible from them, although materials 
 for the smelter are seldom ideal and cannot always be selected as 
 desired. 
 
 100. Manganese in Iron. The smelting process always leaves in 
 iron a small amount of this element. Up to 2% it increases 
 tenacity and hardness, but beyond that amount it causes brittleness. 
 It tends to eliminate sulphur and neutralize silicon, hence its effect 
 within this range would act to render iron less hard by decreasing 
 the hardening effects of these elements. Much manganese increases 
 the soluble power 01 cast iron for carbon. 
 
 In foundry iron, manganese is added, if not already present, up 
 to about 1.5% for its effect in making a hard, close-grained iron 
 and in eliminating sulphur absorbed during re-melting for the pur- 
 pose of casting. 
 
 In steel making, manganese is always added up to about .05% 
 for improving the working qualities of the steel, particularly when 
 hot. 
 
IRON AND STEEL 77 
 
 The extensive use of manganese as an ingredient in steel making 
 has made common two alloys of manganese and iron. One, known 
 as spiegel-eisen, contains from 1.5 to about 20% of manganese, 
 and presents a brilliant fracture. The other, known as ferro-man- 
 ganese, contains from 20 up to 86%, has a light gray fracture and 
 is so brittle that it may be readily pulverized in a mortar. Both 
 of these products are obtained from the oxide of manganese, a 
 mineral. 
 
 101. Properties of Cast Iron. Cast iron is brittle, non-elastic, 
 and the easiest fused of all iron, these properties varying directly 
 with the amount of combined carbon and to a less degree with the 
 amount of uncombined carbon contained. It can be cast into 
 intricate forms and has the advantage of expanding upon cooling, 
 but it cannot be forged, nor united by the usual welding process 
 of heating and hammering. It it not malleable nor ductile, and 
 cannot be hardened like steel, because it contains uncombined car- 
 bon. It has either a crystalline or a granular fracture, determined 
 by rapidity of cooling, and melts at about 2100 F. 
 
 102. Properties of Wrought Iron. In composition, wrought 
 iron differs from cast iron and steel in two important features, viz. : 
 (1) In having had removed, as an essential of its manufacture, 
 the greater part of the five elements usually contained in iron. In 
 this respect it is near the composition of mild steel. (2) In con- 
 taining, as a result of the process of manufacture, a quantity of 
 slag (usually called cinder) which surrounds each iron crystal in a 
 thin sheath, and preserves the identity of the crystal as a fiber 
 when a bar of wrought iron is elongated by rolling or hammering. 
 In this respect it differs from steel, which is crystalline and with- 
 out much slag. 
 
 The chief properties of wrought iron are as follows, viz. : 
 
 (a) It is very malleable and ductile, and can be readily forged, 
 particularly when heated. 
 
 (b) It cannot be cast, as it is fusible only at a very high tem- 
 perature (about 2800 F.), and merely becomes pasty at the usual 
 furnace temperatures, though because of this quality it is readily 
 united by welding. 
 
 (c) It cannot be hardened, due to lack of carbon. 
 
 (d) If pulled apart, the fracture shows a fibrous break. 
 - 6 
 
78 MECHANICAL PROCESSES 
 
 Wrought iron gets its name from the fact that it may be wrought 
 into various shapes readily under the hammer; also it is called 
 malleable iron in England, because of its great malleability, but it 
 must not be confused with malleable castings, also called malleable 
 cast iron or merely malleable iron in America. 
 
 While wrought iron and mild steel resemble each other, there are 
 certain distinct advantages of wrought iron which cause it to be 
 retained for some uses. Among its advantages are (1) it welds 
 better than does steel, (2) lasts longer when exposed to weather or 
 to water, (3) is better to resist shock and vibration (fatigue), in 
 use, and (4) its fibrous structure arrests fracture, as its breaking 
 is in the nature of a gradual tearing, which often gives warning of 
 a dangerous stress, while steel breaks suddenly. 
 
 Among the disadvantages of wrought iron are, ( 1 ) its elastic and 
 tensile strength are lower than those of steel, (2) and its produc- 
 tion is more costly. 
 
 103. Properties of Steel. When steel first came into practical 
 use, its distinguishing characteristic was its ability to harden if 
 heated to a red heat and cooled suddenly, as in water or oil. Present 
 methods of steel making have, however, brought out a product of 
 iron containing too little carbon to harden when cooled suddenly, 
 yet its composition differs from the old form of steel only in con- 
 taining less carbon. 
 
 Primarily, the differences between wrought iron, the several 
 grades of steel, and cast iron are due to the per cent of carbon in 
 each class of metal, and for this reason steel is said to occupy a 
 place between wrought iron and cast iron. However, the processes 
 of manufacture give steel a composition and a molecular structure 
 which affect its properties aside from this simple relation. The 
 properties of steel depend primarily upon the carbon it contains, 
 influenced by the kind and quantity of the other ingredients (or 
 impurities, they may be called), and further influenced by the cool- 
 ing of the steel from its molten state. This last-named influence 
 determines the size and composition of the crystals which steel 
 assumes upon cooling. 
 
 Despite the somewhat complex conditions determining the prop- 
 erties of steel, the grades of steel are classed according to their 
 hardness due to their contained carbon. The higher the per cent 
 
IRON AND STEEL 79 
 
 of carbon, the greater the strength and brittleness, and the less the 
 elongation before breaking. The grades of steel merge so gradually 
 one into another that only two classes are distinguished, viz., mild 
 steel which will not harden when suddenly cooled, and high-carbon 
 steel which will harden when suddenly cooled from a red heat. 
 This property of hardening begins to show when the steel contains 
 .25$ of carbon though is not of much practical use in hardening 
 tools until the carbon has reached about .75% in the steel. 
 
 A quick means of showing whether a piece of iron is wrought 
 iron or steel is to place it in a somewhat dilute mixture of sul- 
 phuric and hydrochloric acids, after it has been cleaned to show a 
 metallic surface. Steel shows a granular and wrought iron shows 
 a fibrous structure after a few minutes action of the acid. 
 
 The conditions determining the properties of iron and steel can 
 only be touched upon lightly here, and the pursuit of this subject 
 is in itself a special study. 
 
 III. The Manufacture of Wrought Iron. 
 
 104. History of Wrought Iron. Wrought iron is the form in 
 which iron was probably first known to man. The ancients reduced 
 it directly from the oxide ores in small furnaces, using charcoal as 
 fuel and depending at first for a blast upon the pressure of a strong 
 wind to force air through a tuyere in the side of the furnace. 
 The heat generated was barely sufficient to reduce the ore, and not 
 high enough to cause an absorption of carbon to any degree, nor the 
 decomposition of the silicon, phosphorous and manganese com- 
 pounds. The iron, mixed with cinder and slag, was taken from the 
 furnace in a pasty state (because it did not melt at the temperature 
 of the furnace) and was hammered to squeeze these substances out. 
 
 This process was improved and enlarged, until finally the blast 
 furnace was developed. As the degree of heat in the reducing 
 furnace became higher, due to a closed furnace, thicker walls, more 
 tuyeres and more rapid combustion of the fuel by improved methods 
 of supplying a pressure blast, the production of pig iron gradually 
 resulted in place of wrought iron. 
 
 Wrought iron was produced from the ore merely because the 
 heat was not high enough to make the metal take up carbon, the 
 absorption of which would have changed the product to pig iron. 
 
80 MECHANICAL PROCESSES 
 
 105. Methods of Production. This method of producing 
 wrought iron direct from the ore is called the direct method. It 
 it still used to a small extent in a few places in Europe where char- 
 coal is cheap, but its output is not important in the commercial 
 world. The method by which most of the wrought iron is now 
 produced is known as the indirect method. It is so named because 
 the ore is first smelted to produce pig iron, and this is then con- 
 verted into wrought iron. 
 
 106. The Indirect Process of Wrought-Iron Making. This proc- 
 ess consists essentially of the following steps, viz. : 
 
 (1) Melting pig iron in a form of reverberatory furnace called 
 a puddling furnace, and burning out the impurities principally by 
 oxygen supplied from iron oxides. 
 
 (2) Subjecting the product of the furnace, after its removal 
 therefrom and while in a hot and plastic state, to mechanical treat- 
 ment to press out furnace slag. 
 
 (3) Cutting into short pieces the bars of impure iron resulting 
 from the preceding step, binding together, re-heating, then ham- 
 mering or rolling. This eliminates more slag, welds the several 
 pieces of the mass thoroughly, and shapes it into plates or bars for 
 market. 
 
 Carbon and other impurities are seldom entirely removed, but 
 are merely greatly reduced in quantity. It is impossible to burn 
 out carbon and other impurities without also burning some of the 
 iron. 
 
 107. The Puddling Furnace. Fig. 18 shows two sections of a 
 double puddling furnace, built double to save space, building mate- 
 rial and heat. This furnace is built of common brick, and lined 
 with refractory brick. It is held together by vertical iron braces 
 spaced along the sides and connected across top and bottom by tie 
 rods. 
 
 A particular feature of the puddling furnace is its hearth. Be- 
 side forming a basin for holding the molten contents of the furnace, 
 the materials of the hearth have an essential chemical purpose in 
 assisting the changes brought about by the process. 
 
 The foundation of the hearth is three cast-iron plates resting on 
 masonry supports. Hollow cast-iron air-chambers, A A, rest on 
 these plates and extend through the sides of the furnace, opening 
 
IROX AND STEEL 
 
 81 
 
 into the air. These strengthen the ends of the hearth and assist 
 greatly in relieving the fire and flue bridges of the intense heat. 
 
 The hearth is made of furnace slag and iron ore. This slag is 
 composed mainly of iron oxide and silica and is called cinder. The 
 hearth is prepared by fusing large and small lumps of ore and 
 cinder upon the plates to a depth of about 6 inches. The sides of 
 
 FIG. 18. Double Puddling Furnace. 
 
 the hearth basin are also formed of lumps of iron oxide, fused to- 
 gether by the heat of the furnace. Hoop iron is burned to an oxide 
 over this mass to give it an even surface of pure oxide. 
 
 The materials of which the hearth and its sides are prepared are 
 designated as the fettling of the furnace. They are gradually con- 
 sumed as a part of the operation of the furnace and must be re- 
 newed occasionally. 
 
82 MECHANICAL PROCESSES 
 
 The hearth materials are kept from melting during the operation 
 of the furnace by the radiation of heat from .the plates on which 
 it is built. 
 
 108. Puddling-Furnace Operation. Having prepared the hearth 
 and brought the furnace to a good heat, a charge of about 1500 
 Ibs. of pig iron is thrown in at the working door, and with it is 
 charged a quantity of cinder or squeezer scale. 
 
 (1) The door is closed tightly, and the heat is so regulated that 
 the iron and the cinder become pasty and melt down together. 
 This requires about 30 minutes, and is called the melting-down 
 stage. 
 
 (2) After the charge has been melted and the iron and cinder 
 well mixed, the clearing stage follows. The puddler's helper uses 
 an iron bar with a bent end to stir the whole charge thoroughly, 
 working through the hole in the door. The stirring brings the im- 
 purities of the iron into contact with the oxides of the hearth and 
 of the charge, and these, assisted by any oxygen coming from the 
 air which enters through the fire box, oxidize the remaining silicon, 
 manganese, and a further amount of the phosphorus. During this 
 stage, the furnace is kept very hot. A slag is formed, containing 
 the oxidized impurities and much iron oxide. 
 
 (3) The next step is the boil, from which this whole process 
 gets its name of "pig boiling." This lasts about 30 minutes and 
 the operation removes carbon and the remainder of the phosphorus. 
 During this stage the chimney damper is lowered and the working 
 door opened to reduce combustion and produce an oxidizing flame. 
 The charge is stirred thoroughly and constantly with the hoe or 
 rabble (or, to use the expression of puddling, is rabbled). This 
 vigorous action brings the carbon of the metal in contact with the 
 iron oxides of the hearth and the charge, causing carbon and 
 oxygen to unite, forming CO, which bubbles violently from the 
 surface of the molten charge. This bubbling causes the lighter 
 slag to boil over the side of the basin and flow from the furnace, 
 carrying with it many of the oxidized impurities. Sulphur is 
 eliminated mostly as iron pyrites in the slag boil. As the carbon 
 burns out, the charge becomes more and more quiet. 
 
 This removal of the carbon having lowered greatly the melting 
 temperature of the iron, small masses of plastic metal begin to 
 
IRON AND STEEL 
 
 83 
 
 collect just as butter collects in the churn. The iron is said to 
 " come to nature " in thus collecting. 
 
 (4) In the final stage, the puddler gathers these masses into 
 balls of about 150 Ibs. each, called blooms, or puddle balls. The 
 furnace temperature is gradually raised, and the puddle balls are 
 brought to a welding heat. The puddler presses them sufficiently 
 to make them hold together and they are then removed from the 
 furnace. After their removal the excess of slag is tapped out and 
 the furnace is ready for a new charge. 
 
 Each heat requires about 2 or 2y 2 hours. 
 
 109. Treatment of Puddle Balls. The furnace treatment just 
 described burns out almost all of the usual impurities in iron, but 
 
 FIG. 19. 
 
 this treatment produces a slag or cinder of iron oxide and silica 
 which mixes with the iron and forms a sheath around each iron 
 crystal. 
 
 When the puddler has formed a ball for removal from the fur- 
 nace, his helper takes it out by means of a pair of heavy tongs sus- 
 pended from an overhead trolley, and pushes it over to the squeezer. 
 
 This machine (Fig. 19) consists of a heavy cast-iron casing B, 
 within which revolves a rough-surfaced cast-iron cylinder C. The 
 space A between the cylinder and the casing is wide at one opening 
 and somewhat narrower at the other. The cylinder is constantly 
 revolving slowly, and when the puddle ball starts at D, it is rolled 
 and squeezed until it emerges at E. This operation presses out 
 
84 
 
 MECHANICAL PROCESSES 
 
 masses of cinder with more or less violence and noise. Fig. 20 
 shows a squeezer for heavy work. 
 
 FIG. 20. Squeezer for 400-lb. Bloom. 
 
 FIG. 21. Puddle Rolls. 
 
IRON AXD STEEL 
 
 85 
 
 The bloom emerging at E, Fig. 19, still at a high heat, is immedi- 
 ately grasped with heavy tongs and started through the rolls shown 
 in Fig. 21. The end of the bloom is presented first to the largest 
 pass, I, and when it has gone through this pass, it is sent back over 
 the top of the upper roll and is in turn run through the entire 
 seven passes. Some cinder is pressed out, and the iron particles 
 are pressed into a more tenacious mass. The last pass, which is 
 near the center of the rolls, leaves the bar about 6 inches wide and 
 less than an inch thick. 
 
 This product is known as muck bar or puddled bar. The rolls 
 have elongated the iron crystals, giving the bar. a fibrous structure, 
 and each fiber is enclosed in a thin sheath of cinder, with streaks 
 of cinder between many of the fibers. 
 
 110. Re-heating and Welding Muck Bar into Wrought Iron. 
 Muck bar still contains too much cinder and is too lacking in homo- 
 geneity for use. 
 
 FIG. 22. Re-heating Furnace used in Making Wrought Iron. 
 
 When cold, it is cut into lengths of about 3% feet. Bundles 
 measuring about 20 inches wide by 20 inches high are then made 
 up of muck-bar lengths and wrought-iron scrap. Each bundle, 
 called a pile, is held together by a wrapping of heavy wire or thin 
 
86 MECHANICAL PROCESSES 
 
 iron bands. A number of these piles are shown on the right in 
 Fig. 22, ready for wrapping. These piles are placed in a re-heating 
 furnace of the general type shown in Fig. 22, heated about three 
 hours until they reach welding heat and are then taken out one at 
 a time, and quickly passed through heavy rolls adjacent to the 
 furnace. 
 
 A few passes back and forth through these rolls, called the rough- 
 ing rolls, squeeze out a great amount of the remaining slag with 
 much explosion and noise and thoroughly weld together the several 
 pieces composing the pile. The rolls then work the mass down to 
 approximate shape as plates or bars and it is then conveyed along 
 the roller table to the finishing rolls by which it is shaped into 
 sheets, bars, or rods as may be required. 
 
 For rapidity and economy of handling piles there are several 
 re-heating furnaces and at least one set of roughing rolls placed 
 along the arc of a circle, at the center of which is a heavy electric- 
 ally operated crane so mounted with a horizontal arm that piles 
 may be transferred from the furnaces to the roller table with a 
 minimum loss of time. 
 
 111. Rolls for Shaping Wrought Iron. Fig. 23 shows the gen- 
 eral type of rolls used for wrought-iron piles. This machine is 
 very simple, and consists essentially of three chilled cast-iron rolls 
 A, B, C, mounted in a frame DD (called the housings) so that 
 the axes of the rolls are horizontal and one above another. Kolls 
 A and C are driven by a large engine through the connecting shafts 
 G and H, and the middle roll is free. The bearings of the lower 
 -roll are fixed in the housings of the machine, the bearings of the 
 middle roll are free to raise or lower, and those of the upper roll 
 are raised or lowered by long screw rods worked simultaneously by 
 the gearing on top of the machine. In this way the space between 
 the rolls is adjusted readily by the operator to suit the thickness 
 to which the iron is to be reduced as it passes through. 
 
 The mass of iron which passes back and forth through these rolls 
 is handled by a roller table on each side of the machine. The roller 
 table on one side is shown in the foreground. Its rollers are con- 
 nected by gearing (not shown) so that all rollers may be made to 
 revolve in either direction simultaneously. As the table now rests, 
 it shows a plate L which has just come through between the middle 
 
IRON AND STEEL 
 
 87 
 
 FIG. 23. Rolls for Making Wrought Iron Plates. 
 
88 MECHAXICAL PROCESSES 
 
 and lower rolls. In order to run this plate back between the middle 
 and upper rolls, the end of the table is lifted by hydraulic power. 
 The table end having been lifted to the required height, its rollers 
 are reversed and the plate is conveyed into the rolls of the machine. 
 
 Houghing and finishing rolls are of similar construction, but the 
 former is a heavier machine than the latter. Most the shaping is 
 done in the roughing rolls to save the smoother surface of the 
 finishing rolls for the more careful work they have to do in finish- 
 ing plates to a smooth surface and to uniform thickness. 
 
 A machine for rolling bars or rods has passes in the rolls similar 
 to those in the puddle rolls in Fig. 21. 
 
 When material has been rolled to the shape and size required, it 
 is carried by the roller table to another part of the shop where it 
 is inspected for defects, and is then cut by the power shears to the 
 required dimensions. 
 
 IV. The Manufacture of Steel. 
 
 112. History of Steel. The first known steel was possibly pro- 
 duced accidentally by the primitive method which smelted wrought 
 iron direct from the ore. The increase of the degree of heat in the 
 primitive smelting furnace caused the iron to become hot enough to 
 absorb in a combined form that quantity of carbon which gave it a 
 new property. It was found that, although this newly discovered 
 grade of metal had to a greater or less degree the malleability of 
 wrought iron when cooled slowly, it further had the property of 
 becoming hard and brittle w T hen cooled suddenly from a red heat. 
 
 The uses of steel made in this primitive way must have been very 
 limited because of the uncertain means of producing it. 
 
 Not until the cementation process of steel making was discovered 
 and developed, about 1770, did steel become a fairly dependable 
 and practical product, although its uses remained confined for a 
 long time, by the limitations of this process, to the making of 
 cutlery, edged tools, and special parts of machinery. The cementa- 
 tion process could not supply steel for a wider field of use because 
 
 (1) the product in large quantities lacked uniform composition; 
 
 (2) it could not always be depended upon when strength was of 
 first importance, and (3) its production was expensive. 
 
IRON AND STEEL 89 
 
 The need for a steel of uniform quality, dependable strength, 
 and low cost in large quantities, led to investigations along other 
 lines of possibility in steel production. The puddling process, as 
 used in wrought-iron making, was tried for steel making, with the 
 idea that the burning out of carbon should be stopped when enough 
 remained in the charge to give the grade of steel desired, but this 
 was not satisfactory because the stopping of the oxidizing process 
 at the point to retain the necessary amount of carbon left too much 
 of the other impurities in the metal. 
 
 Finally, in 1856, Sir Henry Bessemer made public the process 
 which bears his name. In 1868 Sir Wm. Siemens in England and 
 Messrs. Martin in France perfected the Siemens and the Siemens- 
 Martin processes (almost identical) which are developed from the 
 puddling process for wrought iron. These processes have revo- 
 lutionized the manufacture of steel, and have so extended its limits 
 in regard to its carbon content, that a new definition of the product 
 became necessary, particularly as mild steel cannot be hardened by 
 sudden cooling. 
 
 It was early discovered, in the use of these processes, that a 
 reliable steel could not be made from pig iron containing more 
 phosphorus or sulphur that the steel should contain, because these 
 impurities do not remain oxidized in a furnace or converter with 
 a silica lining, as then used, and therefore could not be disposed of 
 with the slag. Silicious materials are acid materials, and they re- 
 duce oxidized phosphorus and sulphur as soon as it is formed, caus- 
 ing these impurities to re-enter the steel. The use of silica linings 
 in the furnace and converter classed these processes as acid proc- 
 esses of making steel. This limitation of the newly discovered 
 processes restricted them to the use of pig iron low in phosphorus 
 and sulphur, and this restriction caused investigators to seek and 
 develop the basic method of steel making. This method differs 
 from the acid process primarily in having a lining of basic material 
 for the furnace and converter. Such a lining permits the use of a 
 lime flux, which will remove phosphorus and surphur, while a silica 
 lining will not permit the use of a lime flux, because chemical 
 action between lime and silica would soon disintegrate the furnace 
 or converter lining. 
 
90 MECHANICAL PROCESSES 
 
 113. The Cementation Process. By this process, wrought-iron 
 bars are converted into steel. Alternate layers of sifted wood char- 
 coal and iron bars are placed in fire-brick basins or " pots/' the tops 
 of which are made air tight with a layer of clay. This prevents 
 burning the charcoal. The pots are then heated in a large furnace. 
 Maximum heat is reached in about 48 hours, and this is continued 
 for 8 to 12 days. The fire is then allowed to die out and the bars are 
 removed when cold. 
 
 The high temperature has caused the iron to absorb the carbon 
 in sufficient quantity to change it into steel. 
 
 The product thus obtained is called blister steel because the bars 
 are covered with blisters as a result of the process. This steel is 
 not yet ready for use, as the carbon is very unequally distributed in 
 it, making some spots very hard while the interior remains soft. 
 
 To correct this lack of homogeneity the blister steel is further 
 treated by one of the two f olloAving-named processes : 
 
 (1) Cut or broken into small pieces, melted in covered crucibles, 
 and poured into ingots suitable for rolling or forging to the shape 
 desired. This equalizes the distribution of carbon and any other 
 elements in the steel, gets rid of the slag or cinder which formed a 
 part of the wrought iron, and makes a very superior grade of steel. 
 This is known as crucible steel. 
 
 (2) Cut into suitable lengths, piled, welded and rolled as in the 
 case of muck bar. This process helps to average up the distribution 
 of carbon in the steel, particularly when several times repeated, but 
 it does not make the steel homogeneous, as when melted in the 
 crucible, and each repetition of heating and welding adds to the 
 expense of the product. This product is known as shear steel. 
 
 The cementation process has practically passed into history, 
 except that its use continues in some place in Europe, particularly 
 in Sheffield, England, where it has been long in vogue, and much 
 skill has been acquired in using it. Steel is there made by this 
 process from the purest wrought iron for a superior grade of 
 cutlery. 
 
 The crucible part of the process, however, is still retained, as will 
 be outlined later on, and is an important branch of steel making. 
 
IRON AXD STEEL 91 
 
 114. Present Processes of Steel Making. At present there are in 
 extensive use three processes of steel making. These are, in order 
 of the annual quantity of steel produced by each : 
 
 (1) The Bessemer process. 
 
 (2) The open-hearth process (Siemens and Siemens-Martin). 
 
 (3) The crucible process. 
 
 Each process is particularly adapted to removing the impurities 
 from certain grades of iron, and also to producing certain grades 
 of commercial steel. The Bessemer and open-hearth processes have 
 made possible a low-carbon steel (mild steel) which finds extensive 
 use as a structural material in buildings, bridges, hulls of vessels, 
 steel rails, etc. This material is stronger and more uniform in 
 quality than is wrought iron, which was formerly the only suitable 
 material for these uses. The Bessemer process is the least expensive 
 in operation, and the quality of its product depends upon the grade 
 of pig iron used. It is, however, being gradually displaced by the 
 open-hearth process because of the diminishing quantity of ores 
 suitable for supplying pig of the required composition. 
 
 High-carbon steel, limited in use to tool making, springs, and 
 for special needs in which extreme hardness is an important feature, 
 is made by the crucible process. Of the three processes, the crucible 
 process produces the highest grade and most expensive steel. 
 
 115. The Bessemer Process. This process converts pig iron into 
 steel by blowing cold air through the molten metal to burn out the 
 carbon. After the carbon is removed (and incidentally some other 
 impurities are removed), and the air blast stopped, enough carbon 
 is re-introduced into the charge to give the steel the amount re- 
 quired. 
 
 This operation is carried on in a large vessel called a converter, 
 a view of which, partly in cross section, is shown in Fig. 24. The 
 shell of the converter, marked D, is built of steel plates in three 
 sections, held together by brackets E. To the bottom is bolted two 
 castings J and K which form a hollow receptacle called the blast 
 box or wind box. Two other plates may be seen in the bottom, the 
 upper serving to strengthen the bottom, and the lower, marked L, 
 serving to hold the tuyeres M in place. The shell is lined for the 
 acid process with ganister, and for the basic process (not used in 
 
92 MECHANICAL PROCESSES 
 
 America) with magnesite, chromite or dolomite. The lining is 
 marked C. 
 
 The vessel is supported by an encircling band G, which carries 
 two trunnions BB, by means of which it can be tilted when neces- 
 
 M 
 
 FIG. 24. Bessemer Converter. 
 
 sary. One trunnion is solid, and carries a large-toothed wheel A 
 to which is geared the rotating mechanism. The other trunnion 
 is hollow to afford a means of conveying air to the blast box K, 
 through the pipe H. The small sketch M at the side shows one of 
 the tuyeres, made of refractory material, which conveys air from the 
 box to the interior of the converter. 
 
IRON AND STEEL 93 
 
 116. Operation of the Converter. The essentials of operating 
 an acid converter are here given. The operation for the basic 
 method is but slightly different. 
 
 After the converter has been emptied of a charge, the vessel is 
 revolved another quarter of a turn until it is upside down. In this 
 position it rests for a moment to drain out the excess of slag, and 
 another quarter revolution places the vessel horizontally. In this 
 position it receives a new charge. Ten tons or more of metal are 
 brought over from the mixer in a large ladle and poured into 
 the converter. Cranes * and other lifting appliances handle the 
 ladle and other movable equipment, and all the movements of the 
 converter are managed by mechanical appliances, handled by an 
 operator on a high platform at a safe distance from its heat. 
 Metal poured into the mixer is always hot enough to remain fluid 
 for an hour or more and it needs no re-heating when conveyed to 
 the converter. 
 
 The converter, with its new charge, is now revolved to an upright 
 position, and the air blast is turned on just as soon as the metal 
 begins to reach the tuyeres, to prevent it flowing into the blast box. 
 The air pressure is about 20 or 25 Ibs. per square inch, sufficient to 
 push through the molten metal. 
 
 The chemical part of the operation at once begins when the air 
 enters the molten metal, and a yellow flame of burning impurities, 
 accompanied by a profuse shower of sparks of burning iron, issues 
 from the mouth of the converter. Silicon and iron are first at- 
 tacked by the oxygen, and these form, when oxidized, a slag which 
 tends to rise, but is kept more or less agitated and mixed with the 
 charge. After the silicon is burned out, the carbon is next attacked, 
 and the formation of carbonic oxide causes a violent bubbling of 
 the charge, a stage known as the boil. The small quantity of 
 manganese usually present is now oxidized, and passes into the slag. 
 
 After about 20 minutes, the flame from the mouth of the con- 
 verter has about died out, indicating the complete oxidation of car- 
 bon, silicon and manganese. A continuation of the blast would 
 ruin the charge of metal by filling it with iron oxide. The blow is 
 
 * Figs. 25 and 27 show cranes and appliances for handling large 
 ladles. Each of these views shows a ladle suspended from the crane. 
 
 7 
 
94 MECHANICAL PROCESSES 
 
 then stopped, but just before doing this, the converter is turned 
 horizontal to prevent metal entering the tuyeres. Little, if any, 
 of the sulphur and phosphorus originally in the iron are removed, 
 because in the presence of the silicious lining these impurities can- 
 not remain oxidized. 
 
 After the blow the charge consists of molten iron without carbon 
 silicon or manganese, but it contains phosphorus, sulphur and iron 
 oxide. Enough carbon must now be supplied to produce the kind 
 of steel desired, also the iron oxide and gases mixed with the charge 
 as a result of the blow must be removed, so far as can be done. 
 These are accomplished by adding to the charge about 10$ of ferro- 
 manganese. This is melted in a small cupola near the converter, 
 or may be thrown cold into the converter in small quantities. The 
 quantity and composition of the ferro-manganese must be so ad- 
 justed that the carbon therein will give the converter contents just 
 the needed amount, and the quantity of manganese must be suffi- 
 cient to reduce the iron oxide and also consume the free oxygen 
 absorbed in the charge, the oxide of manganese so formed rising 
 into the slag. The slight agitation caused by these reactions helps 
 to expel inert gases from the charge. 
 
 The stopping of the blow allows the charge to become quiet, and 
 most of the slag and gases rise to the surface. After the ferro- 
 manganese has been stirred in thoroughly (which must be done 
 promptly, as the metal must not become chilled) the process is 
 completed by tilting the converter and pouring its contents into a 
 large ladle, previously heated inside by a charcoal fire or an oil 
 flame. The greater part of the slag flows from the converter into 
 the ladle and floats on the surface of the metal, affording it pro- 
 tection against oxidation and rapid cooling. Some slag sticks to 
 the converter' lining. This protects the lining, assists in the con- 
 verter reactions of the next charge, and retains much heat. 
 
 117. Pouring the Steel into Moulds. The ladle is at once con- 
 veyed by the crane to a row of large cast-iron ingot moulds, and the 
 metal is poured, or " teemed," into them as shown in Fig. 25. Most 
 large ladles are now poured from a hole in the bottom, but with 
 ladles poured over the edge, care must be taken to skim away the 
 slag to keep it from going into the mould. The slag is later poured 
 
IRON AND STEEL 
 
 95 
 
96 MECHANICAL PROCESSES 
 
 from the ladle into a steel-bodied slag car and conveyed to the 
 dump. The crane moves the ladles readily along the row of moulds. 
 In this view the moulds are filled through a clay-lined iron pipe, 
 or " runner," leading into the bottom of each mould. These run- 
 ners are, in this view, behind the moulds. The moulds are not 
 lined nor are they previously heated, but ladles, pipes, troughs, and 
 other refractory lined holders or conveyers of molten metal must 
 be heated and must never contain any moisture when metal is 
 poured into them. 
 
 The subsequent treatment of the ingots produced in these moulds 
 is described in the next chapter. 
 
 118. Features of the Bessemer Process. Pig iron of a certain 
 range of composition must be selected for this process. It must 
 not contain more phosphorus nor sulphur than is allowable in the 
 steel, as these elements are not burned out in the acid Bessemer 
 process. Silicon is desirable to increase the heat in the charge when 
 it burns in the converter, and its is also the chief slag producer, 
 although too much silicon would unduly prolong the blow while 
 burning it out and this prolonged oxidation would consume much 
 iron. 
 
 The converter charge is considerably increased in temperature by 
 the oxidation from the blast and it may become at times so hot 
 that the chemical reactions are upset, and much iron is consumed. 
 To reduce the temperature, either a quantity of steel scrap of cor- 
 rect composition is thrown into the converter during the blow, or 
 steam is forced through with the air, absorbing heat as it is de- 
 composed in the charge. 
 
 Bessemer steel is not regarded as the equal of open-hearth or 
 crucible steels in purity, as the removal of impurities is under 
 better control in the two last-named processes. The Bessemer 
 product is used for railroad rails, structural steel for buildings, 
 steel castings, forgings, and other purposes where the strength of 
 the steel is not put to its supreme test. 
 
 119. The Open-Hearth Process. This and the Bessemer process 
 convert pig iron into steel by first burning the impurities from the 
 molten iron, but the equipment used in the open-hearth process 
 differs considerably from that used in the Bessemer process. 
 
IROX AND STEEL 97 
 
 The open-hearth process was developed along the lines of the 
 puddling process for making wrought iron, and was made successful 
 only after an improvement in the furnace used and after a modifi- 
 cation of some of the steps in the puddling process. The two ob- 
 stacles which had to be overcome in perfecting the open-hearth 
 process were (1) supplying suitable fuel and burning it in such a 
 way that higher temperature could be maintained than in the 
 puddling furnace, and (2) building a furnace capable of resisting 
 this high heat and serving the practical needs of the process. It 
 was found that in burning out all the carbon and other impurities 
 a much higher heat was necessary in order to maintain the purified 
 iron in a molten state and not let it " come to nature " in a pasty 
 condition, as in the puddling process. 
 
 To supply higher heat, the manufacture of producer gas was de- 
 veloped, and the principle of the regenerative stove, as used with 
 the blast furnace, was applied to the steel furnace. A better fur- 
 nace, to withstand the heat,' was obtained principally by a careful 
 selection of pure refractory materials and by a skillful mixing and 
 burning of these into high-grade refractory bricks. 
 
 The open-hearth process includes both the Siemens process, which 
 ures iron ore to assist in decarbonizing the pig iron, and the Martin 
 process which melts scrap steel with pig to dilute the impurities in 
 the latter. The combination of these two is the Siemens-Martin 
 process, but their individual distinctions are now lost sight of as 
 all their combinations are included in the one designation of open 
 hearth. 
 
 The composition of available iron ores from different deposits of 
 the earth renders necessary the use of both the acid and the basic 
 methods in open-hearth steel making, and the control now possible 
 of the various steps of this process, particularly in the removal of 
 impurities, renders the product thoroughly reliable as a mild steel 
 for high grade uses. 
 
 120. The Open-Hearth Furnace. This is a reverberatory furnace 
 to which is connected a regenerative system of heating. A longi- 
 tudinal section of a furnace, lined for the basic process, is shown in 
 Fig. 26, and the diagram below the furnace is a simplified arrange- 
 ment to show plainly the connections and passages for air and fuel 
 gas in the regenerative system. 
 
98 
 
 MECHANICAL PROCESSES 
 
 FIG. 26. Open-Hearth Steel-Furnace. 
 
 The hearth or basin, built on flat steel plates FF which are 
 supported by /-beams, is composed of brick and magnesite as shown. 
 The charging doors D are on the side of the furnace next to the 
 charging platform (about 12 feet above ground level) and the 
 tapping hole is on the opposite side of the furnace. The roof of 
 the furnace is made of silica bricks arched across the furnace. 
 
 The lower sides of the air ports RE' and the gas ports GG f are 
 covered with a layer of chrome brick, a basic material, as these 
 bricks may become loosened and fall into the metal in the hearth. 
 Above the level of the molten charge, where no chemical reaction 
 will result, the furnace is built of silica bricks to save expense of 
 basic materials. 
 
IRON AND STEEL 99 
 
 Opening into each end of the furnace are two ports (R and 
 on one side and R'G' on the other) which convey air and fuel gas 
 into the space above the charge where they mix and the gas burns, 
 causing a long flame of intense heat which sweeps across the length 
 of the basin or hearth. The regenerative system operates as follows : 
 A supply of producer or natural gas from the gas main, marked 
 in the diagram, passes along the conduit A, through the highly 
 heated checker-brick work in the gas regenerator G, and enters the 
 furnace through the port G. Air drawn from the atmosphere passes 
 through the air inlet, along the conduit B, through the checker- 
 brick work of the air regenerator, and enters the furnace by its 
 port R. Both gas and air are highly heated by passing through the 
 incandescent checker-brick work of their respective regenerators, 
 and as soon as they come into contact they unite in a flame of in- 
 tense heat. The draft of the chimney causes the products of com- 
 bustion to pass into the gas and air ports G r . and R' at the opposite 
 end of the furnace, through the two regenerators below (to which 
 they give up much heat) and along the conduits K and L into the 
 culvert T which leads into a tall chimney. 
 
 At intervals of about half an hour, the valves M and N are re- 
 versed, this causing a reversal of the path of air and gas through 
 the furnace and regenerative systems. In this way the regenerators 
 at the opposite ends of the furnace act alternately as heaters of 
 gas and air as they pass to the furnace, and absorbers of heat from 
 the burned gases after they leave the furnace. This system makes 
 possible the maintenance of the high heat which the open-hearth 
 process requires. 
 
 The hearth is so supported as to leave a large space underneath 
 open to the air. This allows a radiation of heat and prevents over- 
 heating of the materials composing the hearth. The entire brick 
 work of the furnace is rigidly braced by vertical steel beams joined 
 above and below the brick work by tie rods as shown in Fig. 27. 
 
 121. Charging the Open-Hearth Furnace. The capacity of the 
 average open-hearth furnace is about 60 tons of metal. 
 
 Supposing the furnace to be at a moderate heat, ready for the 
 charge, the tapping hole, which leads from the lowest part of the 
 basin through the far side of the furnace, is stopped by ramming 
 into it a quantity of magnesite from the outside. 
 
100 MECHANICAL PROCESSES 
 
 The charge consists of pig iron, limestone, usually iron oxide, 
 and steel scrap if any of this is available. A quantity of limestone, 
 determined by experience, is first thrown in through the charging 
 door. The pig iron is then brought molten in a large ladle from the 
 mixer or directly from the blast furnace, and is transferred from 
 the ladle to the furnace hearth by means of a portable refractory- 
 lined trough. Sometimes solid pigs may be thrown in at the charg- 
 ing door, but this is not the best practice, as there is considerable 
 saving of fuel and handling by using molten pig. A quantity of 
 steel scrap is next thrown in if available, but scrap must not be 
 used unless its composition is known to be suitable to the grade of 
 steel to be made. Steel scrap of the proper composition is highly 
 desirable, as its impurities have been greatly reduced in its manu- 
 facture. A small quantity of iron ore, low in sulphur and phos- 
 phorus, is added to the charge. 
 
 122. Operation of the Open-Hearth Furnace. The purpose of 
 this operation is to remove, so far as can be done by the process, the 
 silicon, manganese, carbon, phosphorus and sulphur in the charge. 
 The removal of sulphur is difficult and uncertain, phosphorus is re- 
 moved only in the basic process, and the remaining ingredients are 
 usually reduced below the quantities desired in the finished steel 
 and are re-introduced at the end of the process. 
 
 The doors are tightly closed after charging and the heat is regu- 
 lated to melt the whole charge gradually, requiring from 2 to 4 
 hours. The furnace temperature begins at once to rise, and the lime- 
 stone (CaC0 3 ) begins to decompose, forming CaO and C0 2 . The 
 increase of heat soon causes the silicon, manganese and carbon to 
 begin to oxidize. The oxygen for this purpose is supplied mainly 
 from the iron ore in the charge, to a less extent from the C0 2 of the 
 lime, and to a small extent from the air entering through the re- 
 generators. As the charge becomes more and more fluid, the iron 
 and scrap become mixed, distributing their impurities evenly 
 throughout their combined mass. The lime (CaO) and iron oxide 
 float to the surface of the molten iron and become fused, mixing with 
 the slag which has begun to form from the oxidized silicon and man- 
 ganese and from the earthy matter of the charge. The slag spreads 
 out evenly over the bath of iron, protecting it from the oxidizing 
 action of the flame. 
 
IRON AND STEEL 101 
 
 Unlike puddling, no stirring or rabbling is done, though the 
 bottom of the basin is raked over by a long iron bar inserted 
 through the small openings in the charging doors to loosen any part 
 of the charge which may have stuck to the hearth. 
 
 From the time the metal is thoroughly melted, samples are 
 occasionally dipped from the bath by means of a small ladle with a 
 long handle. These samples are cast in a small iron mould kept 
 my the melter, and when cold, are taken from the mould and 
 broken. The melter judges instantly by inspection of the fracture 
 the amount of carbon and phosphorus contained, and regulates the 
 process accordingly. Another practice, more reliable, is to take the 
 sample, after it has been cast and cooled, to the laboratory nearby 
 and determine the quantity of these elements by exact chemical 
 methods, requiring 15 or 20 minutes. 
 
 As the silicon and manganese decrease in the metal, the oxidation 
 of carbon increases, causing the charge to ' boil " as in wrought-iron 
 making, due to the formation and escape of CO. 
 
 The melter watches the progress of the operation through peep 
 holes in the furnace doors, protecting his eyes with dark-colored 
 glasses. His experience enables him to regulate the furnace tem- 
 perature to suit requirements. He must so reduce the temperature 
 that carbon will be burned out last. If the carbon is burning too fast, 
 it is necessary to " pig up " the charge by adding solid pig to in- 
 crease the carbon and chill the bath. If phosphorus (the last 
 element to be attacked) is going too fast, as compared with the 
 carbon, as shown by the sampling, the consumption of carbon may 
 be hastened by " oreing down," that is by adding iron to supply 
 oxygen to consume the carbon. It is essential that an excess of 
 iron oxide should not be added, particularly toward the end of the 
 process, as an undue amount of iron oxide cannot be carried by the 
 slag, and, at the end of the process, distributes itself throughout the 
 steel, greatly impairing its quality. 
 
 Toward the last of the process when the heat is still intense, and 
 the bath is comparatively quiet from the cessation of other chemical 
 action, the phosphorus is removed by becoming oxidized and at 
 once combining with lime to form a stable compound. This com- 
 pound, phosphate of lime, enters the slag. The burning out of the 
 carbon continues at varying rates throughout the entire operation, 
 
102 MECHANICAL PROCESSES 
 
 and the last of it is not burned out until after the removal of the 
 phosphorus. 
 
 When the carbon has been, burned out, the purified metal has a 
 higher melting point than before, and would " come to nature/ 7 or 
 collect in plastic masses as in wrought-iron making were it not for 
 the high heat of the furnace to keep it thoroughly fluid. 
 
 In making high-carbon steel it is the practice to stop the process 
 when the carbon has burned out to just below the per cent desired 
 in the steel, and the small quantity needed is introduced by re- 
 carburizing as in the Bessemer process. 
 
 The elimination of sulphur is very irregular. It is safest to use 
 iron for the charge which has a sulphur content below that allow- 
 able in the steel, but this is not always practicable. Some sulphur 
 will unite with lime and enter the slag, if very fluid, a condition 
 assisted by throwing into the furnace a quantity of fluor-spar. Man- 
 ganese ore added to the charge causes the formation of manganese 
 sulphide, which also enters the slag. 
 
 The melter judges by the appearances in the furnace and particu- 
 larly by the sampling, when the heat is finished. 
 
 123. Tapping Out. It requires from 6 to 9 hours to bring a 
 charge to the condition for tapping out. In this condition the bath 
 of slag-covered metal contains some iron oxide and more or less 
 oxygen, carbon monoxide, or other gases absorbed during the, process. 
 These must be removed so far as can be done, and the metal must 
 be re-carburized to give it the quantity of carbon needed to make 
 the grade of steel desired. In the basic process, the materials used 
 to accomplish these results cannot be placed in the furnace in pres- 
 ence of the basic slag as they will reduce the phosphorus from the 
 slag and cause it to re-enter the metal, therefore these materials are 
 mixed with the metal after it is tapped from the furnace. 
 
 The best material for this use is ferro-manganese, as used in the 
 Bessemer process. Calculation and experience determine the 
 amounts of carbon and manganese needed for each furnace charge 
 and the quantity of "ferro" necessary to give these amounts is 
 heated and thrown into the metal as it flows into the ladle. 
 
 In some cases, the metal charge may be re-carburized by throwing 
 pig iron into the furnace. Still another method of re-carburizing 
 is to throw into the ladle the necessary quantity of pure coke or 
 
IRON AND STEEL 
 
 103 
 
104 
 
 MECHANICAL PROCESSES 
 
 coal ground fine and held in paper bags, or a better way of dis- 
 tributing this form of carbon is to allow it to run into the ladle, as 
 the metal runs in, from a hopper suspended above the ladle. Con- 
 siderable experience is needed in using powdered carbon, to intro- 
 duce the correct quantity, as some of it burns before it can be 
 absorbed by the steel. 
 
 The manganese in the re-carburizer decomposes iron oxide, takes 
 up oxygen in the metal, forming MnO, which floats to the surface 
 as slag. Its action assists mechanically in removing some of the 
 other gases and some of the slag in the metal. 
 
 Preliminary to tapping out, a heated ladle large enough to re- 
 ceive the entire contents of the furnace is placed under the tapping 
 spout. The view in Fig. 27 shows several large ladles along a cast- 
 ing pit adjacent to a row of iron-bound brick furnaces on the right. 
 Fig. 28 shows the cross section of a large steel-cased ladle lined 
 
 FIG. 28. Bottom-Poured Steel Ladle. 
 
 with basic refractory material. This ladle is poured, or teemed, 
 from the bottom as shown in Fig. 25. The bottom opening is con- 
 trolled by a rod A, protected by refractory brick sleeves inside of 
 the ladle. The rod is manipulated by the handle II held in suitable 
 guides on the side of the shell. 
 
IRON AXD STEEL 105 
 
 A long steel bar is used to dig out the magnesite in the tapping 
 hole. The metal flows into the ladle and nearly fills it. The slag 
 flows from the furnace after the metal has flowed out, filling the 
 ladle completely. Much of the slag runs over the edge of the ladle 
 into a pit below, where it cools and is later lifted out by large 
 hooks attached to the crane. 
 
 124. Pouring the Moulds. When all the slag has flowed from 
 the furnace, the crane lifts the ladle and carries it while the steel 
 is teemed into the moulds, just as shown in Fig. 25. Small pieces of 
 aluminum are thrown into each mould with the steel, reducing a part 
 of any remaining iron oxide it may contain. The aluminum also 
 assists further to remove gases, which would cause blowholes in the 
 steel. 
 
 The ground space adjacent to the row of furnaces on the tapping 
 side is called the " casting pit." A long narrow pit is usually dug 
 for holding the tall moulds in order that the workmen may remain 
 at the ground level when performing their work during pouring. 
 
 125. The Talbot Process. This is a continuous open-hearth proc- 
 ess, and seems destined to fill an important place in steel produc- 
 tion. The furnace used embodies the same principle as the ordinary 
 open-hearth furnace, but it is mounted on rockers so that any 
 quantity of metal or slag may be poured out at will. Slag is 
 poured from the charging side of the furnace and metal from the 
 side opposite. When the charge is ready for tapping out, a part of 
 the slag is first poured off and then only about one-third of the 
 metal is poured out. That part of the charge which remains in 
 the furnace is replenished with new stock to replace that poured 
 out. In this way the process is continued from day to day, al- 
 though it is necessary to empty the furnace about once a week for 
 repairs to the hearth and the lining. 
 
 To the charge remaining in the furnace after each pour, there is 
 added mill scale or ore, and limestone. These form a highly basic 
 and a highly oxidizing slag, and when these materials are thoroughly 
 fused, a quantity of molten pig iron is slowly poured into the fur- 
 nace from the ladle. As this metal passes through the slag, a very 
 vigorous reaction takes place between the iron oxide and the im- 
 purities in the metal, thus quickly burning out a large percentage 
 of these impurities and thereby shortening the process. 
 
106 MECHANICAL PROCESSES 
 
 The advantages of this process are as follows, viz. : 
 
 (1) A wider range is made possible in the grade of pig iron 
 which can be used. 
 
 (2) The process is not dependent on steel scrap, which may be 
 difficult to obtain. 
 
 (3) The wear and tear on the furnace hearth and lining are 
 much reduced. 
 
 (4) A greater output of steel is obtained in a given time. 
 
 A tilting furnace, used in this process, has a capacity of 200 tons 
 or slightly more. 
 
 126. The Duplex Process. This is merely a combination of the 
 Bessemer and open-hearth processes. 
 
 Pig metal is blown in an acid Bessemer converter until silicon, 
 manganese, and part or all of the carbon are removed. It is then 
 practically a molten steel high in phosphorus. From the converter 
 it is conveyed to the basic open-hearth furnace for refining, for re- 
 moval of the phosphorus, and for re-carburization. 
 
 The advantage claimed for this process is that it saves time, 
 brings less wear and tear on the open-hearth furnace (which is the 
 expensive furnace in steel making), and gives a better product than 
 by the open-hearth process alone. It combines the acid process of 
 the converter with the basic process of the furnace. 
 
 127. Uses of Open-Hearth Steel. Open-hearth steel combines 
 the two requisites of (1) a very reliable steel made in large quanti- 
 ties, and (2) moderate cost of production. Steel made by this 
 process is used for bridge material, ship plates and frames, axles, 
 tires, springs, wire, steel castings and tools not requiring extremely 
 hard-cutting edges. 
 
 Armor plate, common projectiles, gun forgings and boiler 
 material are made of open-hearth steel from selected materials 
 especially treated to insure a minimum of phosphorus in the steel. 
 
 High-carbon steel can be made by the open-hearth process, but 
 there is difficulty in eliminating sulphur and phosphorus. Because 
 of this condition, high-carbon steel is made mostly by the crucible 
 process, in which the impurities can be carefully regulated. 
 
IRON AND STEEL 107 
 
 The amount of phosphorus in iron ore determines whether the 
 >acid or the basic process must be used in making steel from the 
 iron smelted from this ore. The basic process is the one used to 
 reduce phosphorus down to safe limits, but there is always the risk 
 that phosphorus may by some accident get back from the slag into 
 the steel before tapping out. 
 
 128. The Crucible Process. The method of melting steel in 
 crucibles or pots was brought into use as a means of improving the 
 product of the cementation furnace, as mentioned in Par. 113. 
 The introduction of the Bessemer and the open-hearth steel-making 
 processes left very limited need for the product of the cementation 
 furnace, but the method of purifying steel and iron scrap by melt- 
 ing it in the crucible gave a means of producing a higher quality 
 of steel than could be supplied by other processes. The crucible 
 melting feature of the cementation process was therefore retained 
 and turned to excellent use. The expense of the crucible process 
 (about three times that of the open-hearth process) would soon 
 cause the disuse of crucible-made steel if the steel made by other 
 processes could be substituted for it. 
 
 The ingredients in crucible steel can be regulated as desired, 
 giving full control of the kind of product turned out, and making 
 possible the manufacture of many alloy steels containing small 
 quantities of unusual ingredients which would not bring dependable 
 results by the Bessemer and open-hearth methods. 
 
 The crucible method is in many cases a method of steel refining 
 rather than one of steel making. 
 
 The method of manufacture melting in small pots containing 
 about 100 Ibs. makes the crucible-steel output very small when 
 compared with Bessemer and open-hearth outputs, and the product 
 is disposed of entirely in making metal-cutting tools, wood-working 
 tools, piano and other wires of high quality, highly tempered 
 springs, armor-piercing projectiles and other steel articles demand- 
 ing exceptional purity or hardness. Crucible steel is sometimes 
 designated as cast steel, or crucible cast steel, because it may be cast 
 into various shapes by pouring from the crucible into suitable 
 moulds, and it is the first method by which steel castings were made. 
 
108 MECHANICAL PROCESSES 
 
 129. Materials used in Crucible Steel. Crucible steel is made 
 principally from steel scrap, with which is combined cast iron if 
 the carbon is to be increased, or muck bar if the carbon is to be 
 lowered. All of these materials are of known chemical composition 
 and are selected for their purity. 
 
 In the central space of the building devoted to this process is 
 usually placed the set of crucible-steel furnaces, and along the walls 
 on one or two sides are placed a number of bins not unlike horse 
 stalls in a barn. In these bins are stored scraps or punchings of 
 steel, pieces of muck bar, and chunks of pig iron, all cut or broken 
 small enough to be readily packed in the crucibles. A highly im- 
 portant feature of these bins is that great care is taken not to let 
 any metal be placed in them until samples are chemically analyzed 
 and found suitable as crucible steel material; also each bin is re- 
 served strictly for scrap of but one composition. It is essential 
 that there be received no scrap which contains a greater per cent 
 of sulphur or phosphorus than is admissible in the finished steel, 
 because there is no practical way of removing these impurities in 
 this process. It is a common saying in crucible-steel making that 
 everything which goes into the pot comes out, meaning that none 
 of the ingredients of the charge are lost by either an oxidizing or a 
 reducing action of the furnace flame as in the other processes. 
 
 The materials for the highest grade of this steel are usually of 
 Swedish or other iron exceptionally pure. These materials are in 
 the forms of muck bar and pig iron mixed to give the per cent of 
 carbon required in the finished steel. Wrought iron (muck bar) 
 may be melted with enough charcoal in the pot to bring it up to 
 the degree of carbon required, or cast iron may be mixed with a 
 little good scrap to lower the carbon. 
 
 Other materials more or less needed in making up a crucible 
 charge are ( 1 ) charcoal free from sulphur for carburizing the steel ; 
 (2) ferro-manganese for reducing any iron oxide in the scrap of 
 the charge (usually stirred in just before the crucible is taken from 
 the furnace) ; and (3) some form of silica (sand or ground silica 
 brick) to act as a flux for taking up slag and oxides melted from 
 the scrap. 
 
IRON AND STEEL 
 
 109 
 
 130. Crucibles. In America, crucibles are made of a mixture of 
 half graphite and half fire clay, carefully kneaded, and moulded 
 compactly by hand to shape as shown in Fig. 29. After they are 
 
 FIG. 29. 
 
 moulded, they are allowed to dry for several days or weeks, and 
 those not cracked or distorted in drying are burned in a kiln. 
 
 The clay crucible is used in England, but is not so strong when 
 hot nor so durable as the clay and graphite mixture. However, for 
 low-carbon and alloy steels, a graphite crucible must have an inside 
 lining of clay to keep the graphite from being absorbed by the 
 molten steel. 
 
 A clay crucible lasts only through the two or three heats of a 
 single day, while the graphite crucible, more expensive, lasts for 
 ten or twelve heats and is not so easily broken in handling. The 
 bottoms of discarded crucibles are sawed off to be used as lids for 
 new crucibles. 
 
 131. The Crucible Furnace. Modern crucible steel furnaces are 
 heated with natural or producer gas by the regenerative system, 
 though many coke-heated furnaces, similar to a brass-melting fur- 
 nace, are still in use. Fig. 30 shows a vertical transverse section of 
 a typical modern gas furnace for melting crucible steel. The 
 greater part of the structure is in the regenerators, their walls and 
 ports, while the furnace proper (the brick work surrounding the 
 crucibles) occupies a comparatively small space. The regenerators 
 have gas, air, and chimney connections as shown in Fig. 26 and 
 need not be further described here. The top of the brick work is 
 8 
 
110 
 
 MECHANICAL PROCESSES 
 
 covered with steel plates A, A, to form a suitable charging floor for 
 the convenience of the furnace men. The structure contains usually 
 four or more receptacles, B, which are the spaces for holding the 
 crucibles and are commonly called the " melting holes." Each 
 hole is large enough for six crucibles, and is covered with three 
 movable lids, one of which is marked C. Linings of melting holes 
 and of gas and air ports are so built of refractory brick that they 
 may be easily renewed when worn out. 
 
 
 FIG. 30. Crucible-Steel Furnace. 
 
 The several sets of melting holes are separated by thick fire-brick 
 partitions. The bottom brick work of the melting holes and 
 these partitions are supported by ribbed cast-iron plates, D , placed 
 edge to edge over the vault F, which extends the entire length of 
 the structure. Each melting hole has a 7-inch opening through the 
 bottom to allow the steel to flow into the vault in case a crucible 
 breaks. The vault F is kept closed at the ends while the furnace 
 is in use. 
 
 Directly over the line of melting holes and enough above to allow 
 ample head room, is a trolly bar equipped for lifting and lowering 
 crucibles. The melting-hole covers are usually dragged aside and 
 pushed in place again by an iron rod suitably made for this use. 
 
IRON AND STEEL 111 
 
 Crucibles are lifted from or lowered into the furnace by means of 
 tongs supported from the trolley bar. 
 
 132. Charging a Crucible. A memorandum directing the sup- 
 erintendent of the crucible department to make a particular grade 
 of steel gives him the analysis of what the steel must contain. 
 
 From the several bins are selected such materials in composition 
 and quantity as will average up the composition required, and any 
 special alloy material is introduced in the form of a compound. 
 When each kind of material has been weighed out and piled by 
 itself on the charging floor, enough crucibles are set out to hold 
 the entire charge. Each crucible is packed cold with its proportion 
 from each kind of material. Flux may be put in first or may be 
 thrown in over the material when packed in. A little wet sand is 
 plastered around the top edge of the crucible, the lid is put on, and 
 the crucible is then lifted by the tongs, swung from the trolley 
 bar and lowered into the furnace. 
 
 Crucibles just poured may be again lowered in the furnace and 
 charged by aid of a funnel. 
 
 133. Operation of the Crucible Furnace. After the regenerators 
 have brought the furnace up to a high heat, the charged crucibles 
 are lowered one by one into the melting holes. The chimney draft 
 prevents flame from coming out of the melting-hole openings while 
 the crucibles are being lowered in, but these openings should not 
 be left open longer than absolutely necessary. 
 
 The path of the gases through the regenerators is changed about 
 every 20 minutes to keep the crucibles from eating away on the hot 
 side. In about an hour the melter looks into the pots to see if the 
 melting has begun, using a pair of blue glasses framed in a small 
 board to protect his eyes. His experience enables him to make such 
 other inspections as will keep him in thorough touch with the 
 progress of melting. In from 3 to 6 hours the charge is thoroughly 
 melted. It is slightly stirred with an iron rod to lift any lumps of 
 muck bar possibly at the bottom, and to mix the charge thoroughly. 
 The seal of the lid on the crucible is broken by such inspections, 
 but a new joint is soon made by the heat of the furnace. 
 
 After becoming molten, the temperature of the metal will in- 
 crease, and soon the occluded gases begin to boil out. This step 
 lasts about 20 minutes and is called a killing " or " melting to a 
 
112 MECHANICAL PROCESSES 
 
 dead heat." It requires skill to determine when this has gone far 
 enough. At the proper time., the crucible is lifted from the furnace 
 and is set into a holder shown in Fig. 31 to be poured directly into 
 a small mould, or into a hot ladle in which the contents of several 
 crucibles are assembled if a large mould is to be poured. 
 
 If a crucible is taken from the furnace before the metal is te dead " 
 it will pour " fiery/' throwing off sparks and showing some agita- 
 tion due to the escape of gasses, but if kept too long in the furnace, 
 the metal will pour quietly, and the moulded insrots will be solid, 
 but will be brittle and weak. The cause of this is uncertain, but is 
 possibly to the absorption of an excess of silicon from the crucible 
 walls at a very high heat. 
 
 In pouring from the crucible into the mould, which is washed 
 inside with lime-wash to prevent the steel from sticking, great care 
 
 FIG. 31. Ladle Shanks. 
 
 must be exercised to keep the metal from striking the side of the 
 mould as this would chill a film of it and cause a lamination in the 
 ingot. 
 
 It requires a large crucible plant, expert skill and quick handling 
 to assemble enough crucible steel to make successfully a large cast- 
 ing. The Krupp works in Germany make crucible-steel ingots large 
 enough for high-powered guns and armor plate. 
 
 134. Properties of Crucible Steel. The reason for the superiority 
 of crucible steel over steel of like composition from other processes 
 is not always apparent, but is no doubt due in greater part to the 
 following conditions, viz. : 
 
 (1) The stock is carefully selected, and has had the advantage of 
 more or less refining by having been previously produced in a steel- 
 making process. 
 
 (2) The covering of the crucible enables the elements of the 
 charge to be better controlled in melting by avoiding losses due to 
 the action of the flame. 
 
 (3) The melting of the charge distributes the carbon and other 
 
IRON AND STEEL 113 
 
 elements equally throughout the mass, and sets free the slag and 
 oxides which the scrap metals contained, allowing them to float to 
 the surface. 
 
 (4) The boiling out of occluded gases before pouring gives a more 
 compact steel. 
 
 (5) Before a crucible-steel billet is rolled, it is thoroughly ham- 
 mered,, while hot, under a steam hammer to make it compact and 
 dense. This is called tilting because of the old method of hammer- 
 ing newly made iron under a tilting machine. 
 
 About the only important chemical changes are (1) the reducing 
 of iron oxide by the introduction of ferro, when this is found neces- 
 sary, and (2) the absorption of carbon by the metal. Incidentally 
 the metal will absorb some manganese from the charge, silicon from 
 the crucible walls, and sulphur and phosphorus from the slag, if 
 these elements are present in the crucible. 
 
 135. Special Steels. Iron will alloy with most metals, and some 
 of these alloys have 'been highly developed for special purposes. 
 These alloys are all alloys of steel and a small per cent of another 
 metal. The metals most commonly used are nickel, chromium, man- 
 ganese, vanadium, and tungsten, and investigations will possibly 
 develop some surprising results from the use of other metals. Car- 
 bon is always present, but apparently as a secondary element. 
 
 These steels have several names, as " alloy " steel, " high-speed " 
 steel, " self -hardening " steel and others assigned as commercial or 
 trade names. 
 
 The advantages of these alloy steels are numerous, although these 
 advantages are not embodied alike in all of the different composi- 
 tions. Among the advantages are increased hardness, greater elastic 
 and tensile strength, increased elongation before breaking, resist- 
 ance to corrosion, and retention of hardness under the influence of 
 high-friction heating. The most important uses for alloy steels 
 are ( 1 ) for very hard, cutting tools which can stand heavy machine 
 cutting with but little wear, and (2) for high-grade rolled or forged 
 structural material for use where minimum weight and maximum 
 strength of material are required. Much alloy steel is now used in 
 automobiles. 
 
 Nickel-steel has a very wide range of use for bridge material, 
 ordnance forgings, wire cables, automobile parts, large axles, engine 
 
114 MECHANICAL PROCESSES 
 
 shafts, and moving parts of marine and other high-grade engines. 
 It contains from 1.5 to 4.5$ of nickel, has a high elastic limit and 
 the tensile strength is between 70,000 and 100,000 Ibs. per square 
 inch, according to treatment, while the best low-carbon boiler-plate 
 ranges around 72,000 Ibs. The presence of nickel in steel greatly 
 retards corrosion. 
 
 Chromium has a more intense effect than nickel, in the same 
 directions. Chrome steel is used for automobile axles and other 
 forgings. Chromium is frequently combined in the alloy with 
 nickel, and nickel-chrome steel is used for toothed wheels requiring 
 great strength and resistance to wear, for very hard steel plates as 
 in plows or burglar-proof safes, for jaws of rock crushers, and for 
 armor and armor-piercing shells. Specimens of chrome steel shows 
 an elastic strength of 180,000 Ibs. and a tensile strength of 
 210,000 Ibs. 
 
 Manganese steel possesses to a high degree the rare combination 
 of extreme hardness and high ductility in one piece of metal. It 
 is also non-magnetic. Its uses are restricted because cutting it to 
 shape is extremely difficult. It may be forged, rolled hot, or cast, 
 but any finishing of the shapes so produced must be done by grind- 
 ing. It is used for burglar-proof safes, rails for curves on railways, 
 jaws for rock crushers, etc. Castings of manganese steel may be 
 battered badly out of shape without breaking, but they are too hard 
 to be machined. 
 
 8 elf -hardening steel is so named because the steel hardens in the 
 air upon cooling, and does not need to be plunged hot into oil or 
 water as is the case in hardening carbon steel. High-speed steel is 
 so named because when used for machine tools, it can cut metal at 
 a very rapid rate without losing its hardness or without wearing 
 away under the friction and resistance of cutting. 
 
 The hardest steel so far recorded contains .68$ of carbon, 3.01$ 
 of chromium, 19.37$ of tungsten, and .04$ of silicon. 
 
 136. Ingot Moulds. Stripping Ingots. The usual form of ingot 
 mould for Bessemer and open-hearth steel is shown in Fig. 32, 
 which shows three moulds sitting on a common base of heavy cast 
 iron carried by an ingot car. Fig. 33 shows a longitudinal cross 
 section of one of these moulds. 
 
IRON AND STEEL 
 
 115 
 
 FIG. 32. Ingot Car. 
 
 n L 
 
 } 
 
 FIG. 33. Mould for Steel Ingots. 
 
116 
 
 MECHANICAL PROCESSES 
 
 The moulds are made of cast iron, are open top and bottom, and 
 are provided with suitable lugs for handling. The mould cavity for 
 standard moulds is 17% x 19% inches at the top, 20i/ 2 x 22% at 
 the bottom, and about 6 feet high, for a 6500-lb. ingot. It is 
 slightly larger at the bottom than at the top to facilitate forcing the 
 ingot out when it has become sufficiently cooled. The mould 
 corners are rounded to avoid forming laminations which would re- 
 sult from square corners when rolling the ingot, and to relieve the 
 ingot corners of a chilled and crystalline condition such as would 
 result from the rapid cooling of sharp corners in the mould. The 
 walls of the mould are about 5 inches thick, and the weight is suffi- 
 
 FIG. 34. Crucible-Steel Billet Moulds. 
 
 cient to hold the mould down firmly on its base during the pouring 
 of the steel. A fin of steel may run under the lower edge of the 
 mould, but it is thin enough to chill very quickly and thus stop 
 the opening. 
 
 The moulds shown are poured at the top, but for higher-grade 
 steel, a mould is arranged with a long clay-lined tube up the side 
 so that the metal may enter the mould space from the bottom. 
 
 For crucible steel, ingot moulds are much smaller and of differ- 
 ent design from the larger moulds, although the shape of the ingot 
 is nearly the same, i. e., rounded corners, long, and sometimes 
 tapering. For crucible steel, Fig. 34 shows two views of an ingot 
 
IRON AND STEEL 
 
 117 
 
 mould made in halves, closed at the bottom and held together by 
 iron rings and wedges. 
 
 The operation of " stripping " a large mould, i. e., removing the 
 ingot from it, is accomplished by a specially built traveling crane, 
 such as shown in Fig. 35. A train of ingot cars is run under the 
 crane and the crane-tongs T lift each mould by the heavy lugs at 
 the top and if the ingot does not drop out, it is pressed out by a 
 hydraulic plunger, K, rigged for this purpose. 
 
 FIG. 35. Ingot Stripper. 
 
 Four ingots stripped from the moulds are shown on the right in 
 this view. 
 
 Ingots for armor plates, large gun parts, and other special forg- 
 ings are cast in very large moulds, specially shaped and sometimes 
 lined inside with clay. Some ingots are cast in long fluted columns 
 for special advantages in cooling and working. 
 
 137. Impurities in Steel. Segregation. Besides carbon, which 
 determines hardness, steel contains a trace or more of manganese, 
 silicon, phosphorus and sulphur, which came to it from the ore, or 
 during the various stages of manufacture. Traces of other metals 
 
118 MECHANICAL PROCESSES 
 
 also come from ores, but these are not frequent. In additin to these 
 impurities, almost all steels contains some slag and oxides acquired 
 during the molten state in the furnace, and more or less occluded 
 gas acquired in furnace reactions or during pouring into ladle and 
 moulds. 
 
 Skill and modern equipment in the manufacture of steel have 
 made it possible to control in a great degree the quantity of im- 
 purities in the steel, but there is no way to control the distribution 
 of these impurities throughout the mass of the ingot while it is 
 cooling in the ingot mould. As the ingot cools, these impurities 
 tend to go to the hottest part, which is the center of the mass. 
 Through this tendency the metal is not uniform in composition and 
 hence not uniform in strength and quality. This concentration of 
 the impurities at the center of the ingot is known as segregation. 
 
 After steel is poured into the mould, and becomes quiet, there is 
 an effort of the gases, slag, oxides, and of some other impurities to 
 rise to the top, as most of them are lighter than the metal. After 
 the ingot has cooled or after it has been re-heated to be rolled, a 
 quantity of the impurities is eliminated by cutting off the upper end 
 of the ingot before it is used. This is called the discard or crop end, 
 and is frequently as much as 30^ of the whole ingot. A discard of 
 from 3 to 6^ is frequently made from the bottom end of an ingot. 
 Steel for uses not particularly requiring strength may have little 
 or no discard cut from the ingot. 
 
 138. Defects in Steel Ingots. Besides the presence of gas bubbles, 
 and the result of segregation in a steel ingot, there are other defects 
 which result from the pouring and cooling of the ingot in the 
 mould. 
 
 A mass of molten metal naturally begins to cool at the surface, 
 and as this chills, it forms a solid envelope about the molten mass 
 in the interior. The contraction which results from cooling causes 
 the metal to be drawn to the solid part as it cools, and in this way 
 the central part of the ingot finally cools in a honey-combed state. 
 The formation of the cavity at the center of the ingot is called 
 piping. By the action of gravity on the molten metal this cavity 
 is formed well toward the upper end of the ingot, and for this 
 
IRON AND STEEL 119 
 
 reason, the ingot is always cast on end. The piping should be cut 
 off in the discard. 
 
 Surface cracks will appear if the ingot is taken hot from the mould 
 and exposed to air sufficiently cold to make this surface contract 
 enough to disrupt. These cracks may ruin steel otherwise good, be- 
 cause in rolling the ingot, cracks simply close up but do not weld 
 together, and in this way the material is more or less weakened. 
 
 In pouring, globules of steel are apt to splash against the sides 
 of the mould and become chilled into shot. These fall into the 
 molten metal but may not be wholly re-melted, particularly if they 
 rest against the sides of the mould. When the ingot solidifies these 
 shot are more or less separate from the metal surrounding them. 
 These defects are called cold-shuts. 
 
 Also in pouring, a film of metal from the ladle may strike on the 
 inside of the mould and become chilled, sticking to the mould. This 
 forms a lamination, as molten metal rising in the mould does not 
 entirely re-melt it. 
 
 139. Fluid Compressed Steel. Many efforts have been made to 
 improve open-hearth and Bessemer steels, with the view to having 
 them approach crucible steel in quality without having its high 
 cost of production. 
 
 One of the methods used for improving open-hearth steel is 
 known as the Whitworth process of fluid compression. This con- 
 sists of applying to a mass of molten steel which has been poured 
 from the ladle into a suitably shaped mould, a pressure varying 
 from 2500 to 4000 Ibs. per square inch. 
 
 This process is of benefit because the reliability of steel is in- 
 creased if (1) the density of the mass is increased, and (2) if the 
 mass is made homogeneous, i. e., the composition is the same 
 throughout the mass. It is unlikely that this process increases the 
 density of the steel itself, but it does decrease greatly the size of the 
 gas bubbles in the steel, and compresses the particles of slag into 
 compact masses. Piping is lessened but not prevented by this 
 process, and possibly segregation is lessened. The steel under 
 pressure is longer in solidifying, which gives the gas, slag, and 
 oxides more time to rise into the discarded part of the ingot. 
 
120 
 
 MECHANICAL PROCESSES 
 
 140. Compressing Steel. The method of compressing steel is 
 briefly as follows : On a specially built car not unlike an ingot car 
 is placed a large cylindrical mould built up of very heavy cast-iron 
 sections, one of which is shown in Fig. 36, bolted by their end 
 flanges to each other and to a cast-iron bottom. For very .heavy 
 pressures, however, a steel tube forms the length of the mould, and 
 this is fortified by a series of short steel tubes slipped over the long 
 
 Ef7T| 
 
 i ; v 
 
 FIG. 36. Mould Section for Whitworth Press. 
 
 tube, as shown in Fig. 37. The inside diameter of the mould is 
 about 42 inches and its depth about 16 feet. The inside of the 
 mould is lined with cast-iron bars as shown at A A in Fig. 36, 
 plastered over with about % inch of loam, a refractory mixture of 
 sand and clay. Two edges of each of the bars are champfered to 
 form vertical openings, as at BB, by which air in the loam and some 
 gases in the metal may escape. 
 
 The inside of the mould, having been thoroughly dried and 
 heated very hot by a charcoal or oil fire, is poured nearly full of 
 steel tapped from the furnace. The car is then run under a hydrau- 
 
IRON AND STEEL 
 
 121 
 
 lie press (Fig. 37), the upper head D of which is stationary and 
 carries a heavy plug E which will exactly fill the upper end of the 
 open mould. The car having been correctly placed, the hydraulic 
 ram P lifts the car body and the mould until the plug E is pressed 
 to the intensity desired against the surface of the molten steel. A 
 
 FIG. 37. Whitworth Press for Molten Steel. 
 
 film of metal squeezes up between E and the mould lining, but it 
 soon solidifies and prevents the escape of more metal. The pressure 
 is held on the steel for about four hours, until the ingot has solidified. 
 Some gas and slag are pressed out at the top and also from the 
 surface of the metal in contact with the mould, but pressure cannot 
 squeeze anything from the interior of the molten mass. However, 
 it reduces the size of the bubbles and compresses the slag particles 
 
122 MECHANICAL PROCESSES 
 
 densely together in the interior of the mass. An ingot fifteen feet 
 long is decreased about 12 or 14 inches in length by this pressure. 
 From 20 to 30% is cut from the top of this ingot,, after it is cold, as 
 a discard. 
 
 Steel of this kind is used for guns, armor, and marine-engine 
 shafting. Its uses are not extensive because the expensive equip- 
 ment for making it add to its cost and thus prevents a great de- 
 mand for this steel in preference to other grades. The Whitworth 
 process is not applied to Bessemer steel because open-hearth steel 
 has the preference as a better product to begin with. 
 
 141. The Electric Refining Furnace. Another method of im- 
 proving the quality of steel, recently perfected, is that of electric 
 refining. This method seems destined for a wide range of useful- 
 ness in steel making, as it does more than the Bessemer or open- 
 hearth methods can do in eliminating initial impurities and in turn- 
 ing out a product freer from slag, oxides and gases. In fact the 
 electric furnace promises to rival the crucible furnace in quality of 
 product at lower cost. 
 
 The ability of the electric furnace to eliminate sulphur and 
 phosphorus brings into the range of practical usefulness the enor- 
 mous deposits of iron ores which have heretofore been excluded be- 
 cause none of the iron or steel-making processes could eliminate 
 these impurities without undue cost. The success of this furnace is 
 due (1) to the higher temperature which can be maintained and 
 regulated as compared with the open-hearth furnace, and (2) to the 
 control of the chemical reactions exclusively through the action of 
 the slag which can be made of the right chemical composition for 
 the reactions desired, and which forms over the metal a covering 
 protecting it from the oxidizing or reducing action of atmospheric 
 oxygen. 
 
 In the high temperature of the electric furnace, the chemical 
 affinities of sulphur and phosphorus for iron can be overcome by 
 certain elements placed in the slag, and by this means these im- 
 purities are reduced to within safe limits. 
 
 These furnaces will melt and refine the poorest grade of steel and 
 iron scrap, but it is more economical to refine the steel prelimi- 
 narily in the Bessemer converter or the open-hearth furnace and 
 transfer it to the electric furnace for further purification. 
 
CHAPTEE Y. 
 
 MECHANICAL TREATMENT OF METALS. HEAT TREATMENT 
 
 OF METALS. 
 
 142. Forms of Newly Produced Metals. The common metals are 
 taken in a molten state from the furnaces which produce them and 
 are cast into the forms outlined in this and the following paragraph. 
 It must be mentioned that most of the pig iron produced by the 
 smelting furnace is not cast into form as pig iron, but is converted 
 into steel without leaving the molten state, and is cast as steel into 
 ingots, billets and steel castings. 
 
 The courses followed by metals immediately after they are tapped 
 from smelting furnaces are given in the appended table : 
 
 Metal. How disposed of when tapped from the producing furnace. 
 
 Iron. ... 1. Conveyed in the molten state as hot metal or direct metal 
 to the mixer or retaining reservoir which supplies the 
 Bessemer converter and the open-hearth steel furnace; 
 or conveyed directly to these without going to the 
 mixer. Or, when tapped from the smelter is: 
 2. Cast into pigs: 
 
 (a) To be used in the foundry for making castings; 
 
 (b) To be converted into wrought iron in the puddling 
 furnace; 
 
 (c) To be remelted for steel making as in item 1. 
 Copper . . 3. Cast into : 
 
 (a) Pigs or ingots (about 50 Ibs.) to be remelted for 
 brass and other alloys; 
 
 (b) Billets for making seamless copper tubes and pipes; 
 
 (c) Cakes for rolling into sheet copper; 
 
 (d) Bars to be drawn into rods and wire. 
 Zinc 4. Cast into slabs for subsequent uses. 
 
 Lead 5. Cast into : 
 
 (a) Pigs for remelting; 
 
 (b) Cakes or slabs for rolling into sheets; 
 
 (c) Bars for pressing through dies into wire and lead 
 pipe. 
 
 Tin 6. Cast into blocks for remelting. 
 
 When steel is produced it is cast into : 
 
 (1) Ingots or billets for rolling into various forms of metal 
 stock, or for making very large forgings. 
 
 (2) Steel castings of definite form for specific uses. 
 
124 MECHANICAL PROCESSES 
 
 The uses of the words " ingot " and " billet " are somewhat con- 
 fused. In steel making, ingots are large masses of steel usually 
 about 20 x 20 inches in section and 5 or 6 feet long, but they may be 
 smaller and even much larger and of various shapes of cross section 
 for particular reasons. Small ingots, about 6x6 inches in section 
 and smaller, are called billets. Billets may be formed either 
 directly by casting steel into billet moulds, or by rolling red-hot 
 ingots down to billet sizes. Billets are usually made in specified 
 sizes as ordered by mills which manufacture them into a particular 
 class of articles, as tubes, rods for wire drawing, tool steel, spring 
 material, etc. 
 
 143. Primary Outline of the Shaping of Metals. It will be seen 
 from the preceding paragraph that all objects made of iron and steel 
 may be divided into two general classes in regard to the methods 
 of shaping them. These are : 
 
 (1) Objects poured from molten cast iron or molten steel, and 
 known as castings. 
 
 (2) Objects shaped by mechanical pressure from hot-steel ingots 
 and billets, or from wrought-iron " piles " bundled and heated for 
 welding together. 
 
 Objects of the first-named class are cast usually in sand moulds 
 made in more or less complicated shapes to produce a piece of metal 
 for a particular purpose, as a steam-engine cylinder in cast iron or 
 stern and stem posts of a ship in cast steel. Objects of this class 
 are not hammered, rolled or otherwise changed in shape for final 
 use except the finishing of them by more or less superficial cleaning, 
 chipping, filing and machining. 
 
 As cast iron and steel castings are made in the iron and steel 
 foundries respectively, which are subjects of another chapter, it 
 is not intended to give them more than general mention here. It 
 may be stated, however, that small steel castings are frequently 
 made in steel works of steel directly from the converter, open-hearth 
 or crucible furnaces; and that very large steel castings are neces- 
 sarily made at steel works, where molten steel is produced in large 
 quantities, rather than in the steel foundry, which is usually 
 equipped for producing steel only in quantities of a few tons at a 
 time. Large steel castings include such objects as rotor drums for 
 steam turbines, rudder frames, stems and stem-posts for ships, 
 
MECHANICAL AND HEAT TREATMENT OP METALS 125 
 
 hydraulic cylinders, gun carriages., etc., which require a strength 
 and elasticity not possessed by cast iron. These castings are made 
 from low-carbon Bessemer or open-hearth steel. 
 
 The object of this chapter is mainly to outline the mechanical 
 operations of the rolling mill and of the large forging press, both of 
 which handle ingots of steel in their primary forms. The rolling 
 mills converts ingots and billets into such well-known forms of 
 metal as rods, bars, plates, railroad rails, and structural shapes 
 used in bridge, ship and architectural construction. In these forms 
 metals are supplied as stock to be re-manufactured into articles for 
 mechanical, agricultural, domestic and many other uses. 
 
 Copper, brass, the bronzes and other metals are shaped into bars 
 and sheets by rolling, and these metals, including the ductile grades 
 of brass and bronze, are also shaped from their primary forms by 
 the process of extruding, by which a solid mass of metal is forced 
 hot or cold through a die of definite shape placed at the end of a 
 steel cylinder which contains the metal. 
 
 144. Reducing an Ingot to Marketable Forms. An ingot 
 stripped from its mould should go while hot to the soaking pit, a 
 large furnace in which it is placed to be brought to a red or yellow 
 heat preparatory to rolling. From the soaking pit it is transported 
 to the rolls, known specifically as the rolling mill, where it is passed 
 several times back and forth between heavy rolls, the pressure of 
 which reduces its cross-section size and at the same time greatly 
 increases its length. 
 
 This reduction is known as breaking down. Ingots rolled square 
 or nearly so in cross section and left larger than billets are called 
 blooms. These are used for making large forgings, such as piston 
 rods, crank shafts, connecting rods, etc., in engine-building works. 
 Ingots rolled flat and wide are called slabs. An ingot rolled into 
 blooms, billets or slabs is cut into suitable lengths for reheating 
 and further working. Mills are now constructed which handle an 
 ingot quickly enough to roll it into finished railroad rails, structural 
 shapes, plates, billets, etc., without reheating; but rods, bars, and 
 similar shapes of small cross section cannot be rolled directly from 
 a large ingot because the metal gets too cold before it can be rolled 
 so small, and the amount of material in an ingot would stretch out 
 too long for practical handling in one piece of small section. 
 9 
 
126 
 
 MECHANICAL PKOCESSES 
 
 Steel blooms which come from the rolling mill must not be con- 
 fused with wrought-iron blooms or puddle balls. 
 
 145. Reheating of Ingots. The Soaking Pit. Although the 
 stripped ingot may be at a glowing red heat as it comes from the 
 mould,, it cannot be rolled because the interior is yet liquid and the 
 solid exterior would merely disrupt and allow the liquid interior 
 to squirt out under the pressure of the rolls. The heat throughout 
 the mass of the ingot must be nearly equalized in order that each 
 part may be affected about alike under the rolls, although an ingot 
 
 FIG. 38. Soaking Pit for Steel Ingots. 
 
 rolls best when hotter at the center than on the surfaces. To 
 equalize external and internal heat, i. e., to stop the loss of heat 
 from the exterior surface and allow it to become heated from the 
 inside while, at the same time, the inside metal is solidifying, the 
 ingot is placed in the soaking pit. The original soaking pit was 
 merely a hole in dry ground lined with fire brick and provided with 
 a thick fire-brick cover. The ingot radiated its heat to the walls 
 of this pit and the non-conducting walls retained the heat until the 
 ingot was of nearly equal temperature throughout. 
 
 It frequently happened that ingots became too cold before they 
 
MECHANICAL AND HEAT TREATMENT OF METALS 
 
 127 
 
 reached the pit, due to unavoidable delays, to be hot enough for 
 rolling after they were " soaked." This condition necessitated some 
 way of supplying external heat to the pits. The necessity of heat- 
 ing soaking-pits has gradually developed the soaking-pit shown in 
 Fig. 38. This, pit is heated by the regenerative system described 
 with the open-hearth furnace. 
 
 As soon as ingots are stripped, they are hauled to the pits, weighed, 
 lifted by a specially fitted crane and lowered into the pits. From 
 
 FIG. 39. View over Tops of Soaking Pits. 
 
 6 to 8 ingots are placed in one pit, and they are kept in there, with 
 the pit covered, for an hour or more, until they are at or above a 
 bright red heat. No gas need be turned on if the ingot is stripped 
 very hot, and mere " soaking " is all that is needed. 
 
 Fig. 39 shows a number of soaking pits. The crane is in the act 
 of lowering an ingot into an open pit. The pit covers are slid 
 horizontally by means of hydraulic cylinders, marked C, in the 
 figure. 
 
128 MECHANICAL PROCESSES 
 
 146. Rolling an Ingot. When an ingot has reached the tem- 
 perature for rolling, it is lifted from the pit and carried by the 
 crane to the ingot buggy, where it rests until a lever is released to 
 dump it on the roller table. The greater the reduction in size 
 to be made in the ingot, the hotter it needs to be, because of the 
 longer time required for rolling. It is best, when possible, to roll 
 the ingot to the finished shape in a single heat, as a second heating 
 adds to the cost of the finished materials. An ingot, for example, 
 may be rolled into a length of five railroad rails of 33 feet each, 
 making 1G5 feet in one piece, and this length could not be reheated 
 without cutting it into pieces and much handling. 
 
 Fig. 40 shows the first stages in the process of rolling a large 
 ingot. The mill in this view is known as a reversible blooming mill. 
 This mill has too heavy rolls, the upper of which is shown at R. 
 These rolls revolve in opposite directions and are driven by a large 
 reversible engine or by a motor. The function of a blooming mill 
 is usually merely to reduce the cross section of the ingot to a con- 
 venient size for finishing in smaller rolls to the exact cross section 
 desired. The ingot A rests on the ingot buggy R, awaiting the 
 breaking down of the ingot 0. 
 
 The roller table consists of a succession of horizontal rollers TT 
 driven in unison by the cogged bevel wheels DD from a single shaft 
 running the length of the table. This table extends out from both 
 sides of the mill, and conveys the ingot back and forth into contact 
 with the mill rolls, which engage it and send it through, reducing 
 its vertical dimension a given amount at each pass. When the ingot 
 has passed through the rolls, it is turned on its side by a device 
 called the manipulator. The motion of the table rollers and of the 
 mill rolls is then reversed, and the ingot passes back between the 
 rolls. After each pass, the upper roll, R, is let down a given amount 
 by heavy screws which control its ends in the mill housings, and 
 which are operated by the mechanism seen on top of the mill, under 
 control of the man in charge. The roller table is driven by a re- 
 versible motor G. 
 
 After a few passes through the rolls, the ingot or bloom, as it 
 may now be called is conveyed along the roller table to a heavy 
 hydraulic-shearing machine which cuts off the discard from the 
 bloom. The hvdraulic shears are so mounted that the roller table 
 
MECHANICAL AXD HEAT TREATMENT OF METALS 
 
 129 
 
 conveys material to and from them in the same way that it is con- 
 veyed to the rolls, and these shears are powerful enough to do their 
 work instantly, without loss of time. 
 
 After the crop ends are sheared off, the bloom,, still red hot, is 
 conveyed back to the mill. Its passage back and forth between the 
 rolls is repeated, and it is shifted by the manipulator from side to 
 side of the roller table to direct it into the different sections or 
 
 FIG. 40. Starting an Ingot through the Blooming Rolls. 
 
 passes along the rolls until it is reduced to the size desired. It is 
 then either cut into bloom length of 6 feet, more or less, by the 
 hydraulic shears, or is conveyed by the roller table to another mill 
 which rolls it in one length into railroad rails or other shapes of 
 about the same cross-sectional area. - However, a blooming mill 
 may be fitted with rolls not only to do the work of breaking ingots 
 down into blooms, but to do certain classes of finishing, as in rolling 
 large billets or large structural shapes. 
 
 Throughout the rolling, the material is at a red heat. 
 
130 
 
 MECHANICAL PROCESSES 
 
 147. Mill Scale. In heating an ingot in the pit, particularly in 
 an oxidizing flame, and in exposing the red-hot ingot to contact 
 with the atmosphere, a film of iron oxide forms over its surface. 
 This oxide is very brittle, and as soon as the ingot goes through the 
 rolls, it drops off and falls through under the mill. This is known 
 as mill scale or roll scale, and is valuable for use in wrought iron 
 and steel furnaces, as has been mentioned. 
 
 148. Structural Steel Shapes. The use of mild steel for struc- 
 tural purposes, i. e., bridge building, ship building, architectural 
 structures, railroad and other rails, etc., has developed certain 
 standard shapes especially for these needs. The object sought in 
 any structure built for strength is to dispose of the structural 
 material in such a way as to get maximum strength for minimum 
 
 I-Beam. Channel Bar. Angle Bar. T-Bar. 
 
 FIG. 41. Structural Shapes. 
 
 Z-Bar. 
 
 weight of material. This does not mean that in a structure the least 
 possible amount of material must be used, but it means that the 
 required safe strength having been determined, the material must 
 be so disposed that a minimum weight of material will suffice to 
 give this strength. 
 
 To carry out this principle, various shapes in mild steel have been 
 standardized, but these shapes are not necessarily ideal, and are 
 subject "to improvement under experimentation. These shapes are 
 shown in cross section in Fig. 41. 
 
 The cross-section form of each size of these shapes is standard- 
 ized in area, thickness, length, slope and curvature of each part, and 
 each running foot of length must weigh a given amount. Standard 
 shapes of similar section are made of different weights per running 
 foot. Special shapes are often rolled for particular uses or for a 
 
MECHANICAL AND HEAT TREATMENT OF METALS 131 
 
 particular class of uses, and are practically standards too, inasmuch 
 as they are extensively used. 
 
 Other shapes, for special uses are shown in Fig. 42. 
 
 Bulb Beam. Railroad * Trolley Rail. Tie Rod or Eye Bar 
 
 For Decks. Rail. For Bridge and Truss Work. 
 
 FIG. 42. Special Shapes. 
 
 Large steel mills issue an elaborate hand-book giving much valu- 
 able information of sizes, dimensions, weight, strength and other 
 particulars of steel shapes. 
 
 149. Types of Boiling Mills. The number of rolled products 
 now common in the iron and steel trade, consisting of blooms, 
 billets, structural shapes, plates, rails, bars, rods, etc., necessitates 
 rolling mills of a variety of types and sizes for their production. 
 
 The largest mills, known as blooming, cogging and slabbing mills, 
 roll ingots into blooms, slabs, or large billets. Some of these mills, 
 as Fig. 44, have roll passes for rolling the larger structural shapes 
 immediately after other passes of the rolls have broken the ingot 
 down into a bloom of the required size. This saves much expense 
 in reheating. Figs. 40, 43 and 44 are examples of the largest mills. 
 
 Mills next in size are in greater variety because of the greater 
 diversity of products rolled by them. They receive blooms, slabs, 
 and billets from the heavier mills, and roll them into a variety of 
 forms such as small billets, structural shapes, railroad rails, sheet 
 bars and plates. 
 
 The small type of mills, known as merchant and sheet mills, re- 
 ceive sheet bars and small billets from the second group of mills. 
 Merchant mills roll billets into small rods and bars of a great variety 
 of sizes and cross-sections, known as merchant bar and familiarly 
 seen as stock in the blacksmith shop. Sheet mills roll sheet bars 
 into thin sheets commonly seen as sheet iron. 
 
 * The thumb projection on this rail projects horizontally when rolled. 
 The last pass through the rolls bends it up as shown. 
 
132 MECHANICAL PROCESSES 
 
 Besides the foregoing classification of mills according to size and 
 work they do, they are also classified according to design as follows : 
 
 (1) The reversible mill is one in which the two rolls are reversible 
 and the material rolled is fed between them alternately from opposite 
 sides of the mill. Figs. 40, 43, and 44 are examples of this class. 
 
 (2) The three-high mill is one with three rolls, which are not 
 reversed. Fig. 45 is an example of this class. 
 
 (3) The universal mill is one which is provided with a pair of 
 vertical rolls in addition to a pair of horizontal rolls. These four 
 rolls press on all sides of a square piece of material as it passes 
 through the mill. Figs. 40 and 44 are examples. 
 
 (4) The pull-over mill is a small two-roll mill which is not re- 
 versible. This mill is used for rolling thin sheet metals. When a 
 slab passes between the rolls, it is pulled back over the top roll to 
 be passed through again. A type of this mill is shown in Fig, 55. 
 
 (5) The continuous mill is a succession of small two-roll mills 
 placed near together in line. They are used to roll merchant bar. 
 In rolling small bars the metal loses its heat so rapidly that it is 
 necessary to roll it quickly. The continuous mill accomplishes this 
 by passing the material from one set of rolls to the next, and in this 
 way a bar may be in the process of rolling between as many as ten 
 pairs of rolls at once. 
 
 (6) The looping mill is another arrangement of several small two- 
 roll mills to operate on small material quickly. These mills are 
 placed edge to edge along a line and a red-hot rod a hundred or 
 more feet long passes from the first mill in a U-shaped loop through 
 the next, and so on through each successive mill in a snake-like curve 
 until it is coiled up after passing through the last mill. This, 
 material is used mostly for drawing into wire, which will be 
 described later. As in the continuous mill, the material is passing 
 through several pairs of rolls at the same time. 
 
 150. The Cogging Mill. Fig. 43 shows a cogging mill, so named 
 because its rolls are roughed or cogged to grip the end of the 
 ingot firmly and force it into the rolls. The blooming mill in Fig. 40 
 does the same kind of work. 
 
MECHANICAL AND HEAT TREATMENT OF METALS 133 
 
134 
 
 MECHANICAL PROCESSES 
 
 151. The Structural Mill. Fig. 44 shows a universal, reversible, 
 structural mill. This mill has two horizontal rolls CC, and two 
 vertical rolls DD. The mill shown in this view is for rolling large 
 I-beams, and the vertical rolls make the top and bottom flange sur- 
 faces parallel. The vertical rolls are run by beveled-gear wheels 
 
 FIG. 44. Universal, Reversible, Structural Mill. 
 
 under the casing K f connected to the engine by the shaft L. They 
 may be readily adjusted so that the distance between them is in- 
 creased or decreased. The universal type of mill does its work 
 more rapidly than is the case with other types of large mills. It 
 is also much used in rolling plates to avoid the necessity of trim- 
 ming the plate edges after rolling. 
 
MECHANICAL AND HEAT TREATMENT OF METALS 
 
 135 
 
 152. The Billet Mill. Fig. 45 shows a three-high billet mill. 
 Each of the rolls of this mill runs continuously in one direction as 
 shown by the arrows. To allow a bloom (or a small ingot) to be run 
 between the upper and middle rolls, this form of mill is equipped 
 with lifting tables. A section of the roller table about 20 or 30 
 feet long which lies next to the mill on each side is so hinged that 
 
 FIG. 45. Three-High Billet Mill. 
 
 the ends adjacent to the mill can be lifted to the level B in the figure. 
 After the bloom A passes through the mill with the table in the 
 position now shown, the table ends on both sides of the mill are 
 lifted by hydraulic mechanism. The table rollers, are then re- 
 versed and the bloom passes back to this side. Both tables are 
 then lowered to the position shown in the figure and the bloom 
 is again passed between the middle and the lower rolls. 
 
 The rolls of this mill remain the same distance apart, and the 
 bloom is reduced by being sent through the different passes between 
 
136 
 
 MECHANICAL PROCESSES 
 
 the rolls, which are successively smaller along the rolls. The several 
 fingers or prongs M are for the purpose of turning the bloom over 
 and directing it to any pass through the rolls as may be desired. 
 These fingers belong to the manipulator, various types of which are 
 fitted to mills, and are so controlled by hydraulic mechanism that 
 they can be lowered, raised and moved from side to side between the 
 rollers at will. 
 
 153. The Rail Mill. Fig. 46 shows the several mills for shaping 
 railroad or street-car rails. These are three-high mills. 
 
 FIG. 46. Rail Mill. 
 
 The blooming mill first breaks the ingot down to about 8x8 
 inches, the hydraulic shears cuts off the discard at the ends, and the 
 ramainder of the bloom is then rolled by the mills shown in the 
 view. 
 
 Quick handling and several mills are necessary to get the rail 
 shaped before it loses its redness, as it is shaped completely without 
 reheating. The bloom passes back and forth through one set of rolls 
 
MECHANICAL AND HEAT TREATMENT OF METALS 137 
 
 five times, is carried along the roller table to another set, which it 
 passes through five times and then it passes once through the finish- 
 ing rolls which merely smooth its surface. 
 
 These rolls are held the same distance apart throughout the entire 
 operation, and the passes in them give the desired shape to the rail. 
 When the ingot is rolled out into a rail it is something over 165 feet 
 long 5 rails of 33 feet each. This length is sawed hot by steel 
 circular saws, shown at S in Fig. 46, so that when each rail is cold 
 it measures 33 feet in length. 
 
 154. The Sheet-Bar Mill. Thin sheets of iron or steel are rolled 
 hot from bars about 8 inches wide known as sheet-bars. The 
 sheet bars for this industry are rolled in the sheet-bar mill, not 
 unlike the billet mill in Fig. 45, and the method of rolling them 
 from the ingot or from the wrought-iron " pile " is similar to that 
 mentioned for rolling rails. The ingot is rolled out into a long 
 strip 8 inches wide and varying from % to 1% inches thick. This 
 strip is cut into lengths of 30 feet for convenience in handling, and 
 is shipped to the sheet mill, the work of which is described in the 
 next chapter. 
 
 The sJcelp mill is a special sheet-bar mill for rolling steel or 
 wrought iron bars or " skelp " for the manufacture of iron pipe. 
 
 Plates of steel of i/4-inch or less in thickness are designated as 
 sheets. 
 
 155. Plate Mills. Slabs from the blooming or slabbing mills are 
 reheated and rolled by the plate mill into plates for many uses, in- 
 cluding boiler plates, ship plates, tank plates, etc. 
 
 Plate rolling was described under the making of wrought iron. 
 
 The largest plates now rolled are about 145 inches wide. The 
 length depends upon the size of the ingot less the discarded ends. 
 
 In rolling plates, care must be taken to keep the upper surface 
 of the plate free of mill scale, which would make a defective surface 
 if rolled into the plate. 
 
 156. Names of Rolling-Mill Parts. The more commonly desig- 
 nated rolling-mill parts include rolls, housings, roller table, manip- 
 ulator, guides, guards, passes, and collars. Several of these parts 
 have been mentioned. 
 
138 
 
 MECHANICAL PROCESSES 
 
 Fig. 47 shows the outline of a pair of rolls with examples of 
 typical passes between the rolls. A and C are open passes, i. e., a 
 fin of metal may be squeezed out from the sides of the billet if it 
 
 FIG 47. Forms of Passes in Rolls. 
 
 is pressed hard enough. To avoid the forming of a side fin, the 
 closed pass B is used. F, F, are collars on the rolls. C is called 
 a diamond pass, and D is a bearing to support the upper roll be- 
 cause of its great reduction of diameter at the middle. 
 
 FIG. 48. Example of Rolling an Angle Bar. 
 
 Fig. 48 shows six passes necessary for rolling a billet into angle 
 bar of unequal legs. Successive changes in cross-section from the 
 billet to the finished shape must be gradual, as here shown. The hot 
 
MECHANICAL AND HEAT TREATMENT OF METALS 139 
 
 material could not stand a radical change between successive shapes, 
 as it would tear or distort. To avoid stretching one leg of the bar 
 more than the other in rolling, the passes must be so made that the 
 two ends of the legs will lie in a line parallel to the axis of the roll. 
 Both rolls run at the same number of revolutions per minute, but 
 the upper roll is slightly larger in diameter than the lower roll so 
 that the rolled material will peel from the upper roll. To make the 
 material peel from the lower roll when the first end passes through, 
 a guard is fitted, as in Fig. 49. To prevent material from being 
 engaged by the roll collars, and to direct it into the right passes, 
 guides are fitted as shown in Fig. 49. Fig. 45 shows guides leading 
 
 FIG. 49. 
 
 to the lower roll, and guards may be seen along the piece marked 
 B in that figure. 
 
 Finishing rolls, which do not exert much pressure, and plain 
 rolls for plates and sheets, are made of cast iron with the roll sur- 
 face chilled to harden it. Blooming and roughing rolls are made 
 of cast steel to withstand the enormous shocks of heavy work. 
 Structural rolls are made of cast steel. 
 
 Roll surfaces are first turned to shape in large lathes and are 
 then ground by special appliances to a true surface. 
 
 157. Reheating of Blooms, Slabs and Billets. Reheating fur- 
 naces are of many forms according to the fuel used, the size and 
 shape of the material to be reheated, and the rapidity demanded 
 in handling the heated material. The largest types of reheating 
 furnaces are those used for heating armor and other large ingots 
 
140 
 
 MECHANICAL PROCESSES 
 
 to be shaped under the hydraulic forging press. These furnaces 
 are heated usually by the regenerative system. The smallest types 
 are possibly the small portable oil-burning furnaces for heating 
 rivets, and used also for heating small material to be forged. The 
 fuels used are long-flame coal, crude oil, or gas, and usually a smoke 
 stack is necessary to take away the products of combustion, but 
 
 FIG. 50. Furnace for Reheating Billets. 
 
 many oil and gas furnaces have no smoke stacks. The reverbera- 
 tory type of furnace, with end or side door in the fuel space, and 
 end or side doors in the heating space, according to the convenience 
 of each specific case, is much used for reheating. 
 
 Fig. 50 shows a small furnace for reheating billets. This is 
 -equipped for burning oil and has a door at each end. The flame 
 from the oil burner (at the side) is directed into the heating space 
 through a hole in the furnace wall. 
 
MECHANICAL AND HEAT TREATMENT OF METALS 141 
 
 10 
 
142 MECHANICAL PROCESSES 
 
 A reheating-furnace bottom is usually a flat magnesite bottom, 
 sloping slightly to one side. The soaking-pit is a reheating fur- 
 nace, but it is adapted only to ingots, which can stand on end. 
 
 The continuous furnace is a type much used. This is equipped 
 with a gravity slide or suitable mechanism for moving a continuous 
 line of material through the furnace in a given time, and the heat- 
 ing is accomplished while the material is passing through. 
 
 158. Reheating Furnace for Large Blooms. Fig. 51 shows the 
 front of a regenerative heating furnace for blooms and other large 
 material, with the charging crane used to handle heavy material. 
 This furnace is modeled like the open-hearth steel furnace. The 
 whole of one side is enclosed by doors D, which open into one com- 
 mon heating space. Connection with the regenerative heating sys- 
 tem at one end of the furnace is shown at R. 
 
 The crane has an arm A, with electrically controlled tongs or 
 fingers at the end, which now holds a bloom ready to be conveyed 
 through the open door into the furnace. This arm may be swung 
 in a horizontal plane, with slight vertical movement for lifting or 
 lowering blooms. The roller table T may be used to convey cold 
 blooms within reach of the crane, and to convey hot blooms to the 
 hydraulic shears in the background of the view. 
 
 159. Precautions in Reheating High-Grade Steel. To avoid the 
 formation of scale in reheating metals, i. e., the waste of the sur- 
 face by oxidation, the furnace flame should be a reducing and not 
 an oxidizing flame. Xo risks of oxidation can be taken with high- 
 carbon and alloy steels (usually crucible steels) as any change in 
 the carbon or alloying metal would reduce the quality of the steel. 
 To avoid oxidation, each billet is coated with fire clay, sand and 
 borax, or other harmless, refractory mixture, and placed in the 
 furnace. After removing from the furnace, this mixture is broken 
 off before the billet goes to the rolls or the hammer. 
 
 160. Points for the Inspection of Rolled Material. Steel may 
 be good or bad in quality due to the substances it contains, and 
 steel which is good when tapped from the furnace may be made 
 bad by subsequent casting, reheating and mechanical treatment. 
 Rolling improves the strength of a metal and tends to cover up 
 defects. 
 
MECHANICAL AND HEAT TREATMENT OF METALS 143 
 
 Specifications for metals,, particularly iron and steel,, usually re- 
 quire (1) surface inspection, (2) physical testing, which is the 
 actual pulling and bending of specimens of the metal, to determine 
 its strength and ductility, and (3) chemical analysis to determine 
 its chemical constituents. It is intended to mention here only the 
 requirements of surface inspection, as the defects so disclosed are 
 closely associated with casting and subsequent rolling or forging of 
 metals. 
 
 Specifications usually provide that the surfaces of metals shall 
 be free from the following-named defects : 
 
 (1) Slag. (6) Sand or scale marks. 
 
 (2) Foreign substances. (7) Scabs. 
 
 (3) Brittleness. (8) Snakes. 
 
 (4) Laminations. (9) Pits. 
 
 (5) Hard spots. 
 
 These defects are usually caused by : 
 
 (1) Slag and oxides which entered the ingot or billet mould 
 from the ladle. 
 
 (2) The chilling of ingot corners in cold moulds, and surface 
 laminations and shot caused by pouring metal against the sides of 
 the mould and thus chilling it. 
 
 (3) The sudden chilling of the surface of a hot ingot, billet, 
 bloom, or slab when it is taken from the mould or reheating fur- 
 nace, causing small surface cracks called snakes. These cracks, 
 when not too numerous nor too deep, are chipped from the surface 
 before the material is rolled or forged, as their sides do not weld 
 together when the metal is rolled. 
 
 (4) Failure to discard enough of the ends of an ingot or a billet. 
 
 (5) Squeezing metal in rolling so that fins press out between 
 the rolls, and subsequently rolling these fins down as laminations 
 or hard streaks. 
 
 (6) Not cleaning the mill scale from the upper surface in roll- 
 ing plates, or other wide shapes, from which scale will not readily 
 fall away due to the movements and jolting of the rolls. 
 
 Further than the defects named, rolled products should not be 
 crooked or warped, nor should plates show undue variation of 
 thickness across their width nor along their length. 
 
144 MECHAXICAL PROCESSES 
 
 It is a common practice to keep a record of the identity of every 
 ingot and billet cast, as in this way many defects in finished pro- 
 ducts may be traced back to their causes. 
 
 161. Effect of Mechanical Treatment of Metals. The pressure 
 of the rolls and the impact of the forging hammer on a piece of 
 metal increase the strength of the metal from 2 to 5 times, accord- 
 ing to the composition, the degree to which the metal is heated, and 
 the pressure applied. The composition of a metal determines its 
 ductility and the degree to which its form can be changed by work- 
 ing, while the heat and pressure to which it is subjected determine 
 the depth to which the rolling or hammering is effective. The roll- 
 ing of a cold metal makes the surface very hard. The strength of a 
 metal is increased by rolling or hammering because (1) blow holes 
 (including microscopic gas cavities throughout the metal) are 
 pressed very small, and because (2) mechanical pressure crowds the 
 metal crystals more closely together, breaking up planes of cleavage 
 along which tearing would naturally take place. The second effect 
 increases strength and hardness, but decreases ductility and the per 
 cent of elongation before breaking. Working a metal very hot 
 does not cause marked changes in its crystalline structure because 
 the crystals are more or less mobile according to the heat, and are 
 helped by the heat to assume their natural positions relative to one 
 another. 
 
 Two ingots from the same heat, i. e., produced from the same 
 heat in a converter or furnace, will show different elastic and tensile 
 strengths and different degrees of elongation according to the degree 
 of reduction each undergoes in rolling or hammering. 
 
 162. Cold-Rolled Steel. The colder a metal is when rolled or 
 hammered, the greater the resulting hardness. The depth of the 
 hardness depends upon the depth to which the rolling or hammering 
 pressure penetrates. 
 
 There is extensive use for steel rods and bars which have hard, 
 smooth surfaces, both for the hardness and for the smoothness. 
 These resist wear and take an excellent polish. They also show 
 smoothly when nickel-plated. Also, a hot-rolled rod or bar cannot 
 be rolled to exact dimensions, as cooling after rolling decreases its 
 cross-section area an uncertain amount. To produce small steel 
 bars and rods which are hard, smooth, and of exact dimensions in 
 
MECHANICAL AND HEAT TREATMENT OF METALS 145 
 
 cross-section, cold rolling is resorted to. The metal is first rolled hot 
 to near the finished size,, pickled to remove the oxidized coating 
 and is then passed many times between chilled rolls. Kods up to 
 5 inches in diameter are rolled in this way, and the resistance to 
 twisting, due to so hard a surface, makes this product useful as 
 shafting for transmitting power in shops. 
 
 163. Large Forgings. Many massive steel products, as. armor 
 plate, large gun parts, and large shafting for marine engines or 
 turbines, cannot be rolled because of their shape, or because their 
 size makes rolling far more expensive than forging. These products 
 are shaped from unusually large ingots which are forged either 
 under impact of the steam hammer, or preferably pressed under 
 the hydraulic forging press. 
 
 The blow of the steam hammer is delivered quickly, and its force 
 is absorbed at first locally by the metal directly under the impact 
 of the hammer, and as this becomes compacted, the force is trans- 
 mitted deeper into the metal mass. The hydraulic forging press is 
 preferable to the hammer for large forgings because its pressure 
 makes itself felt entirely through the metal mass. 
 
 Some large forgings are made from rolled blooms, but these are 
 commonly made in large manufacturing plants, as shipbuilding 
 plants and locomotive works, by means of steam hammers. 
 
 164. The Hydraulic Forging Press. Fig. 52 shows a press for 
 heavy work. The diagram in Fig. 53 shows the interior features 
 of the press. 
 
 This equipment consists of the press, the hydraulic intensifier, 
 and the auxiliary water tank. 
 
 A piece of work W is pressed between the dies DD'. Different 
 shapes of dies may be used. The press head H is forced down by 
 hydraulic pressure on the ram P in the cylinder N f and is raised 
 by steam pressure under the two pistons in the cylinders CC. The 
 vertical motion of the press head is guided by the four colums G 
 which conect the anvil with the entablature B and hold the press 
 rigidly against distortion. 
 
 Water pressure of about 5500 Ibs. per square inch is supplied 
 through the pipe from the steam intensifier which consists essen- 
 tially of a steam cylinder J and a much smaller hydraulic cylinder 
 K. Steam admitted under the piston in J communicates the pres- 
 
146 
 
 MECHAXICAL PROCESSES 
 
 sure to the water in A" through the rod L. Knowing the pressure 
 per square inch of steam in J ' , the water pressure per square inch 
 in the hydraulic system is found from the relation 
 
 FIG. 52. Hydraulic Forging Press. 
 Steam pressure per sq. in. in J Area of end of plunger L 
 
 Water pressure per sq. in. in K Area of lower face of piston in -7 
 
 A mechanism is fitted to shut off the steam automatically in case 
 the water pressure in K is suddenly lost by any accident. 
 
MECHANICAL AND HEAT TREATMENT or METALS 147 
 
 The entire working of the press is controlled by a single hand- 
 lever ingeniously connected to control the valves numbered 1, 2, 3 
 and 4. 
 
 ft 
 
 < If 
 
 *\ 
 
 .. 
 
 I' 
 
 m 
 
 ^ / 
 
 
 
 
 
 PIG. 53. Diagram of Hydraulic Forging Press. 
 
 Valve No. 1 controls steam to the cylinder J, No. 2 controls ex- 
 haust from the cylinder J, Xo. 3 controls steam and exhaust from 
 the cylinders CC, and No. 4 controls water to and from the tank T 
 through the valve M. 
 
148 MECHANICAL PROCESSES 
 
 The auxiliary tank T contains air and water under a pressure of 
 60 Ibs. per square inch, and is used as a reservoir for supplying 
 water to or receiving it from the main pipe 0. The plunger L may 
 remain quiet and the press head may be lowered by allowing water 
 to flow through the valve M from the pressure tank. Likewise, the 
 press head may be raised by the cylinders (7(7, with the valve M 
 opened to admit water to the tank against the tank pressure. The 
 system is so arranged that when L moves upward the valve M will 
 close, as great pressure must not be communicated to the tank T. 
 
 165. Handling Large Ingots for Forging. Special equipment 
 must be installed to transport large ingots between the reheating 
 furnace and the forging press and to hold them for the work of 
 forging. The furnace and the press are located conveniently near 
 each other, and a specially built traveling crane is installed for this 
 work. 
 
 The upper end of every ingot made for forging is a ee crop-end." 
 This end is used to hold the ingot for forging and is cut off when 
 the forging is completed. This end is cast smaller than the body of 
 the ingot and is called the " chuck stub " in the forge shop. Fig. 
 54 shows, the equipment for holding ingots. It consists of a cliuck 
 B, shown partly in section ; a porter bar P for balancing and guid- 
 ing the chuck and ingot ; and an endless chain C suspended from a 
 block D. The whole equipment is suspended from and transported 
 by the crane. 
 
 The chuck stub is clamped by the set screws in the open end of 
 the chuck. The porter bar is attached to the other end of the chuck. 
 The swivel block D allows the apparatus to be turned readily in a 
 horizontal plane. The heavy spiral spring between the swivel 
 block and the crane hook relieves the crane of any undue shock in 
 forging. It is frequently necessary to hang heavy iron weight to 
 the end of the porter bar to balance ingot, chuck, and bar nicely on 
 the chain. In this way the forge men can easily swing the work 
 by hand pressure on the porter bar. The ingot is turned on its 
 horizontal axes by ratchet attachment geared to the groove G, or 
 it may be turned by an iron bar placed in one of the holes beside 
 the groove. 
 
MECHANICAL AND HEAT TREATMENT OF METALS 149 
 
 When the ingot is carried to the furnace for reheating, which 
 may be necessary a number of times in the course of making the 
 forging, the chuck stub sticks out of the furnace door, and the 
 space below the door, when it is closed down on the stub, is stopped 
 temporarily with bricks. 
 
 Many different chucks and porter bars are provided in a large 
 forge shop, and some of the porter bars axe 60 feet long and nearly 
 
 ! Q 
 
 FIG. 54. Chuck and Porter Bar. 
 
 a foot in diameter, which gives an idea of the heavy forgings 
 handled. Gun tubes are forged by the processes just described. 
 Some forging presses, as for forging car wheels, use an intensified 
 pressure of 40,000 Ibs. or more per square inch. 
 
 166. The Heat Treatment of Metals. An essential part in the 
 mechanical shaping of a metal is the heating required to make it 
 easily workable without injury to its strength and other properties. 
 Heat treatment includes all heating from the time a metal is cast 
 
150 MECHANICAL PROCESSES 
 
 into ingots or billets until it goes out in the form of finished prod- 
 ucts. This is a very extensive subject which is now recognized as 
 highly important by manufacturers of all metal articles, particu- 
 larly so by manufacturers of articles in steel, because heating not 
 only makes metals plastic, but it changes the crystalline structure 
 of most of them, affecting their strength, ductility and other use- 
 ful properties. 
 
 Carbon and iron are associated in several different relations which 
 are, according to investigators, more or less stable or complicated 
 chemical combinations, all of which may exist in the same mass of 
 steel, and each of which imposes certain properties on the metal 
 and is affected in different ways by heat. This condition makes 
 steel very complex, but a careful study of all these characteristics 
 and of the experimental effects of several kinds of treatment have 
 brought out much useful knowledge on the proper methods of heat- 
 ing steel. Other metals are far less complex, and the changes which 
 come to them in heat treatment are much simpler. , 
 
 167. Changes in Steel Due to Heating. It is necessary to heat 
 steel not only to shape it, but to anneal and harden it. That heat- 
 ing for any of these purposes may be properly done, it is necessary 
 to understand certain peculiarities, particularly of high-carbon 
 steels (those containing .2$ and over of carbon). 
 
 As steel rises in temperature it reaches a point, about 1400 F. 
 (red heat), called the absorption point, at which it absorbs a per- 
 ceptible amount of heat before its temperature again increases. 
 Likewise, having been raised above the absorption point and allowed 
 to cool slowly, it reaches a temperature about 50 F. below the 
 absorption point where it seems to give out more heat than is ac- 
 counted for by loss of temperature. Its glow shows an increase of 
 brightness if observed in a dark room. This is the recalescence point. 
 Both of these points are known as critical points. 
 
 Heating to the absorption point brings the grain of steel to its 
 finest texture. The higher the heating beyond this point and the 
 lower the carbon, the larger the resulting crystals upon cooling. 
 This may be seen, in many cases, by examining fractured specimens 
 
MECHANICAL AND HEAT TREATMENT OF METALS 151 
 
 with the unaided eye. This enlargement of crystals reduces 
 strength, hence the size of crystals is a visible sign indicating 
 strength. The smallest crystals may be restored in high-carbon 
 steel by heating it to the absorption point. It may then be cooled 
 slowly or suddenly without change of grain. 
 
 Steel need never be heated above its absorption point except to 
 have it amply hot for shaping in a single heat. If high-carbon 
 steel is heated much above the absorption point, its strength is 
 injured, its fracture looks dull, and it is said to be " burned/' Such 
 a condition may be impossible to remedy. However, low-carbon 
 steel escapes injury at high heats in most instances, but becomes 
 brittle if heated repeatedly below 1650 F. It is restored to its 
 elasticity if heated above 1650 F. 
 
 The crystalline structure of a piece of steel as affected by heat is 
 determined by the five conditions as follows : 
 
 (1) Temperature, (2) duration of heating, (3) mass, (4) 
 rapidity of cooling, and (5) whether or not steel cools without be- 
 ing rolled, hammered, or otherwise subjected to pressure or impact. 
 
 The presence of nickel, tungsten and other metals used to pro- 
 duce alloy steels have a marked effect upon the critical points of 
 steel. These points are lowered, and the presence of the alloying 
 metals seems to accomplish this by their influence upon the carbon 
 which the steel contains. 
 
 168. Annealing- of Metals. When a metal is heated to unequal 
 degrees throughout its mass, or the parts of the mass are cooled at 
 different rates, as is common with large forgings or large castings, 
 or when hammering, rolling, or other work is done on cold metal to 
 change its shape, an arrangement of crystals is forced upon the 
 metal such that some parts of the mass are under stress. For ex- 
 ample, a large forging or casting may cool quickly on the surface 
 and, by contracting, pull the hotter parts of the interior into a 
 shape which they would not assume naturally as they cool. Ex- 
 cessive hammering or rolling makes cold metals brittle. In steels, 
 internal stresses and brittleness are most marked when the per cent 
 of carbon is greatest. 
 
152 MECHANICAL PROCESSES 
 
 Internal stresses, which may be dangerous in man}'' cases, and 
 brittleness in metals worked cold, are relieved by annealing. This 
 consists of heating the mass to a red heat and allowing it to cool 
 very slowly in the case of steel, or plunging into water in the case 
 of copper and some of the copper alloys. Annealing brings metals 
 to their softest and most ductile states. 
 
 Steel should be heated to the absorption point for best results 
 and finest grain in annealing, though this is not always done 
 possibly because its importance is not well understood. Steels 
 purposely hardened would lose their hardness if annealed at a high 
 heat, though they may be partially annealed by moderate heating 
 in oil or molten lead, which will relieve the greatest stresses. 
 
 Slivers have been known to break and fly with considerable force 
 from extremely hard projectiles while they were awaiting annealing, 
 due to internal stresses. 
 
 Annealing is usually done in furnaces not unlike reheating fur- 
 naces, though the degree of heat is not so great in annealing as in 
 reheating for working. Coal or wood fires can be better regulated 
 to maintain the low temperatures needed in annealing. To prevent 
 oxidation in annealing, particularly with thin or delicate pieces, 
 the material is placed in a muffle furnace which transmits heat 
 through a brick partition to it, thus preventing contact with the 
 flame, or, better, the pieces are placed in cast-iron boxes, the lids 
 of which are luted with clay, and these boxes with their contents 
 are placed in an ordinary furnace. 
 
 Steel forgings and castings demand slow cooling for proper an- 
 nealing, and it is a common practice to heat them for two or three 
 days in a furnace, then seal up all furnace openings with clay and 
 allow several days for the furnace and contents to cool gradually. 
 
 All annealing furnaces must be fitted with pyrometers to gage 
 the degree of heat in obtaining the best results. 
 
 169. The Hardening of Steel. Steels containing above .25^ of 
 carbon (approximately) will become hardened if heated to or above 
 the absorption point and suddenly cooled, in water or by other 
 means. The degree of hardness depends upon (1) the amount of 
 combined carbon, (2) the rapidity of cooling, and (3) upon the 
 
MECHANICAL AND HEAT TREATMENT or METALS 153 
 
 range of temperature through which cooling takes place below the 
 absorption point. The rate of cooling of a piece of metal is de- 
 pendent upon its mass, as well as upon its degree of temperature 
 above that of the cooling medium. 
 
 These statements do not apply to steels alloyed with manganese 
 and tungsten. They harden by being heated nearly to melting 
 heat and being cooled fairly rapidly in a blast of air. In this con- 
 dition they do not lose their hardness when raised to a red heat, 
 and can be used at a red heat for cutting. 
 
 170. Oil Tempering of Steel. Much medium-carbon steel is 
 alloyed with nicked, chromium or vanadium to provide material of 
 superior strength and elasticity for moving parts of marine engines, 
 automobile parts and other fittings where lightness and great 
 strength are desirable in a steel of moderate cost. The strength 
 and reliability of these forgings are increased by a process of heat- 
 ing to a red heat, quenching in oil (a residue of petroleum or a 
 fish oil) and then annealing slightly. The effects of this treatment 
 vary with different percentages of contained carbon and with differ- 
 ent quenching temperatures. These have been studied and tabu- 
 lated at some length by investigators. Gun forgings, and in some 
 processes, armor and projectiles, are oil tempered. 
 
 171. Kolling Sheet Copper. The Sheet Mill. For the manu- 
 facture of sheet copper, the metal is cast either direct from the re- 
 fining furnace, or from remelted pigs, into flat cakes 3 or 4 inches 
 thick. As soon as these cakes have " set " they are dumped into 
 cold water to make them soft for rolling. They must be not less 
 than 99.75$ pure for rolling, though all of the impurity allowed 
 must not be wholly arsenic, bismuth or antimony, because the cakes 
 may crack slightly on the surface in rolling. 
 
 As soon as the cakes have cooled, their surfaces are examined 
 for spots of cinder, oxide, scale, etc. Large spots are chipped out, 
 or the whole cake may be pickled in dilute sulphuric acid and then 
 scrubbed and rinsed to remove all surface scale. The cakes are 
 taken over to the rolling mill and several are heated at a time to 
 redness in a reheating furnace in order to keep the rolls supplied. 
 
154 
 
 MECHANICAL PROCESSES 
 
 One cake at a time is taken from the furnace and passed re- 
 peatedly through rolls such as are shown in Fig. 55. This view 
 shows three 26-inch pull-over sheet mills. This type of mill 
 is used for rolling thin sheets of commercial metals, and is called a 
 pull-over mill because a man on the far side of the rolls receives the 
 sheet as it comes through and, by aid of tongs and a guide bar, lifts it 
 so that the man on the front side can pull it over the top roll to pass 
 it again between the rolls. 
 
 FIG. 55. Sheet Mills, Pull-Over Type. 
 
 If the sheet is to be finished as soft copper, it is rolled hot down 
 to the thickness required, is then annealed in a furnace to make it 
 of uniform softness throughout, and is pickled to remove roll and 
 furnace scale. The sheet is then straightened by sending it through 
 straightening rolls, or it may be straightened in a stretching 
 machine which grips the ends and pulls the sheet. 
 
 If the sheet is to be finished as hard copper, suitable for making 
 pipes, or tanks which must stand pressure, it is rolled hot nearly to 
 the finished thickness, pickled, and then rolled cold in the finishing 
 rolls down to gage. It is then straightened and trimmed to size. 
 
MECHANICAL AND HEAT TREATMENT OF METALS 155 
 
 To avoid the formation of furnace scale when heating copper and 
 brass to be rolled, it is a common practice to do the heating and 
 annealing in muffle furnaces. 
 
 Cold rolling increases tensile strength, but makes copper and 
 brass more brittle and springy, which is a decrease in ductility. 
 
 Sheets of copper, known as planished copper, which are springy 
 and show highly polished surfaces, are cold rolled after having 
 been hot rolled and pickled. 
 
 172. Rolling of Sheet Brass. Brass of the usual compositions is 
 rolled cold into sheets or other forms because the metal will not 
 roll hot. However, if the brass contains less than about 62$ of 
 copper it may be rolled hot. 
 
 In cold rolling of brass, it takes but a few passes through the 
 rolls to make the metal very brittle. To relieve this brittleness, 
 frequent annealings are necessary. Each annealing must be fol- 
 lowed by pickling in weak acid and thorough washing to prepare the 
 sheet for further rolling. 
 
 Annealing is done in muffle furnaces at about 700 F., and the 
 metal is cooled by exposure to air, or its cooling may be hastened by 
 sprays of water, if the alloy is such as not to be injured thereby. 
 
 In the manufacture of high-grade sheet brass, the plate is sub- 
 jected to a process called " scalping/ 7 after about the second anneal- 
 ing. This process is in lieu of pickling which would otherwise fol- 
 low this annealing. It consists of placing the sheet on a machine 
 which scrapes the surfaces bright and clean by means of a rapidly 
 oscillating scraper. Successive rollings, annealings and picklings 
 are then given the sheet until it is reduced to the required thickness. 
 
 If the sheet is to be finished as soft brass, it must be annealed 
 after the last rolling, and the dull surface due to this annealing is 
 removed by dipping in weak acid, rinsing, and polishing with bran. 
 
 Brass may be left with different degrees of hardness and springi- 
 ness by more or less rolling after the last annealing and not anneal- 
 ing again. New hard brass always has a shiny surface. 
 
 173. Extruded Brass. The process of extrusion produces brass 
 and bronze shapes similar to rolled shapes. Shapes of more com- 
 plicated cross section can be produced by the extruding process than 
 by rolling. Many brass and bronze compositions will stand cold 
 rolling, but will not stand the extruding process. 
 
156 
 
 MECHANICAL PROCESSES 
 
 Extruding is the process of forcing metal or other substance 
 through a hole in a block of hard metal, usually hard steel. This 
 block of metal is called a die and the hole in it determines the shape 
 of the cross section of the substance forced through it. 
 
 Fig. 56 illustrates the principal features of the extruding press as 
 used for brass and bronze. A round billet of brass is cast of such 
 a size as will easily go in the heavy cast-steel cylinder or container 
 A. The container may be lifted or revolved so that the billet can 
 be placed readily in the open end at the right. The die D having 
 been placed as shown in the view, the red-hot billet is taken from 
 the reheating furnace, is scraped or struck to remove any clinging 
 scale, and is quickly placed in the container which is at once lowered 
 to the position shown. By means of intensified hydraulic pressure 
 
 FIG. 56. Extruding Press. 
 
 in the cylinder C, the ram P is forced against the billet with 
 sufficient pressure to force the metal through the hole in the die. 
 A man stands with tongs ready to grasp the end of the piece as it 
 emerges through the die and conduct it along the metal-covered 
 table T, keeping the piece straight so that it may cool straight. The 
 lower sketch shows the front view of a die such as is used for mak- 
 ing bronze deck-beams. 
 
 A hydraulic pressure, several times intensified,, amounting to 
 60,000 Ibs. per square inch is sometimes needed for this work. The 
 weight of billets, limited by the capacity of the container, does not 
 exceed 175 Ibs. The quality of the extruded bars is said to be 
 better than that of bars produced by rolling, and certainty the pres- 
 sure leaves no blow holes and crowds the molecules of the metal 
 closely together. The extruding of metals, hot or cold, is a matter 
 of the power of the extruding press and of the ductility of the 
 metal. 
 
MECHANICAL AND HEAT TREATMENT OF METALS 
 
 157 
 
 174. Extruded Shapes. Fig. 57 shows cross sections of some of 
 the shapes produced by this process. Besides the four shapes of 
 bars at the top there are shown a few special shapes as follows : 
 
 FIG. 57. Extruded Shapes. 
 
 A Fluted column for interior architectural work. E Moulding. 
 
 B Hand railing for interior architectural work. F Angle bar. 
 
 C Stair tread. G I-Beam. 
 D Door sill. 
 
 Extruded shapes are extensively used for high-grade interior 
 architectural trimming, as well as for ornamental structural work 
 where strength is a factor. In many cases the bars may be cut in 
 short pieces and thus supply shapes which ordinarily must be pro- 
 duced by casting. The extruded metal needs no further finishing, 
 as it has smooth and even surfaces. 
 
 Lead pipe is produced by the extruding process. 
 
 11 
 
CHAPTER VI. 
 THE RE-MANUFACTURE OF METALS. 
 
 175. Scope of Metal Re-Manufacturing. This branch of metal 
 working includes a great variety of manufacturing industries which 
 shape metals for final uses. In general, the re-manufacture of 
 metals includes all processes which start with rolling-mill products, 
 such as plates, bars, rods, etc., and turn out an endless variety of 
 metal articles which enter into almost every range of service. 
 Possibly the most familiar branch of metal re-manufacturing is 
 that in the shop of the village blacksmith. The blacksmith shapes, 
 by manual labor, many articles from bars, rods and sheets of metal 
 which are supplied by the rolling mill. 
 
 By far the greater part of re-manufacturing is carried on in 
 large workshops and factories in which the main part of the work is 
 done by machines operated by persons of more or less skill. A 
 single manufacturing establishment may be employed wholly in 
 making one kind of article, wire for example, or its range may be 
 extended to making articles closely associated, as rivets, bolts and 
 nuts, or automobile forgings. 
 
 Only a few of the re-manufacturing industries can be given 
 particular mention here, and those outlined in this chapter are 
 selected either to give information of metal-shaping methods which 
 produce well-known articles, or to show the possibilities of metal 
 Working. 
 
 A great many metal articles familiarly seen are products of the 
 foundry, where pigs of metal are melted and cast into shape. 
 Foundry products are not usually classed as products of re-manu- 
 facture, and will be dealt with later on. They can usually be readily 
 recognized by their more or less irregular form. Superficial in- 
 spection will generally show that they are not made from shapes 
 supplied by the rolling mill. 
 
 176. Tool Making. One of the most important branches of re- 
 manufacture is that of tool making. Nearly all tools are made of 
 
THE KE-MANUFACTUKE OF METALS 159 
 
 steel. Those used for measuring and trying, such as calipers, gages, 
 squares and scales, are sufficiently hard and durable when made of 
 low-carbon steel. 
 
 Tools for metal cutting are forged from high-carbon or alloy- 
 crucible steels of the best quality. Carbon steel for tools is commonly 
 known as. machinery steel. 
 
 A lasting keen edge on a cutting tool requires hardness, but hard- 
 ness and brittleness go together, hence those tools which must stand 
 extreme shocks, battering, twisting, or bending, must sacrifice some 
 of the hardness to tenacity and ductility. 
 
 Cutting tools may be forged or cast to approximate shape. The 
 rougher tools may be hardened and then ground to finished shape, 
 but the tools for finer work, as taps and dies, must be machined to 
 shape before they are hardened. The process of hardening may dis- 
 tort a tool slightly, which may ruin it unless it can be brought to its 
 true shape by grinding after hardening. 
 
 177. Special Methods of Heating and Hardening Steel Articles. 
 In the older methods of heating, hardening, tempering and anneal- 
 ing steel, results depend entirely upon the eye and practice of the 
 workman. To insure uniform results, various methods of heating 
 and hardening have been devised which eliminate judgment, and 
 secure automatically the same results in each case. 
 
 In manufacturing establishments, tools and small articles to be 
 hardened are usually heated in a bath of red-hot molten lead. 
 Heating may also be. done in closed iron tubes or in small muffle 
 furnaces. A pyrometer must be used to regulate the temperature of 
 a heating furnace or a lead bath. 
 
 To avoid burning off the sharp points of file teeth and the sharp 
 cutting edges of threading dies, etc., during heating or while trans- 
 ferring these articles from the heating bath to the quenching or 
 hardening bath, the articles are dipped before heating into a thin 
 hot paste of salt, flour and charred leather, or into a hot salt solu- 
 tion. This mixture dries at once and remains on the surface until 
 after the articles are hardened. 
 
 For hardening steel, quenching baths of fish oil, petroleum 
 residue, or brine are much used, and are kept at constant and uni- 
 form temperature by agitation or by a constant flow from one 
 receptacle to another. These quenching baths are not so sudden 
 
160 MECHANICAL PROCESSES 
 
 in their cooling effect as is pure water, hence the shock to the metal 
 is less, and the degree of hardness given is sufficient. The con- 
 sistency and temperature of a quenching bath is determined by ex- 
 periment to give the degree of hardness required without further 
 process. 
 
 178. Sheet Iron. This product is. familiar in many forms. 
 Most of the so-called sheet iron of to-day is sheet steel and not 
 wrought iron as it was before the days of mild steel. This sheet 
 steel for common uses is a very soft grade of mild steel, very 
 pliable and easily worked. It is much used by the tinsmith and is 
 the stock material for the sheet-metal-shaping trades and manu- 
 facturers. It is familiarly seen made up as stove pipes, steam-pipe 
 lagging protectors, oil guards, etc., and is either of dull surface 
 presenting faint waves of color due to annealing, or is shiny black. 
 
 The dull black sheets may be marketed either as such or in the 
 following forms: (1) Crimped into corrugated iron, much used 
 for covering warehouses or other buildings; (2) coated with zinc 
 and known as galvanized iron; (3) coated with tin and known as 
 tin; and (4) planished with carbon and called planished or Russia 
 iron. 
 
 179. The Manufacture of Sheet Iron. Sheet iron (as it is com- 
 monly known) is made by rolling sheet-bar into thin sheets, as was 
 stated in Par. 154. 
 
 At the sheet mill, the operation of rolling sheets is as follows: 
 The 30-foot sheet-bars are cut into short lengths, heated in a re- 
 heating furnace, and run through the rolls sidewise, as the width 
 of the bar is stretched out to form the length of the sheet. Rolling 
 stretches metal in the direction of its travel through the rolls and 
 very little if at all in the direction of the axes of the rolls, hence 
 bars are cut into lengths but slightly longer than the width of the 
 sheets to be rolled from them. A mill similar to that for rolling 
 sheet brass and sheet copper is iised for this work. 
 
 After about the first five passes through the roughing rolls the 
 bar has stretched out greatly, is very thin, and wobbly while 
 hot, hence, for easy handling it is folded double, and two thick- 
 nesses of metal pass through the rolls at once. The sheets are not 
 hot enough to weld, and their scale keeps them from sticking to- 
 gether. This doubling is called " matching." This doubled sheet 
 
THE RE-MANUFACTURE OF METALS 161 
 
 is then reheated with three other matches, and all are given one 
 pass through the smoothing rolls together, thus making six thick- 
 nesses of metal in one pass. These six sheets are allowed to cool 
 and are then sheared along the ends and the edges, after which 
 they are " opened " or taken apart. 
 
 The sheets then go to the cold rolls through which they are 
 passed singly one or more times to give density and smoothness, 
 after which they are piled about one hundred in a pile for anneal- 
 ing. Fig. 58 shows a heavy tray C on which sheets are piled for 
 annealing. The cover T is placed over the pile and sand is placed 
 all around the lower edge of the cover to exclude air. The cover 
 and tray are lined with fire bricks and suitable lugs are fitted for 
 handling by the crane. 
 
 FIG. 58. Annealing Tray for Sheet Iron. 
 
 Annealing requires about 12 hours. When cold, the cover is 
 lifted and the sheets are stripped apart by hand. After inspection, 
 they may be bundled for market as " dead soft " sheets, or may be 
 sent to other departments to be corrugated, tinned, galvanized or 
 planished. 
 
 If hard sheets are required they are selected from the colcU 
 rolled stock before annealing. 
 
 180. Galvanizing. This consists, of covering articles of iron or 
 steel with a coating of zinc for the purpose of resisting corrosion. 
 
 Articles to be galvanized must first be pickled in a dilute acid 
 to remove or loosen all surface dirt and scale. Upon lifting from 
 this bath, the articles are well brushed with brooms or steel brushes 
 and are washed with fresh water from a hose. They are then 
 placed in a second bath of weak acid (usually HC1) to insure a 
 clean metallic surface and must be taken directly from this bath 
 
162 MECHANICAL PROCESSES 
 
 to a "flux tank" to avoid rusting, which would occur if exposed 
 unduly to the air. The fluxing mixture consists of a solution of 
 sal ammoniac kept hot by steam pipes and covered with beef tallow, 
 and is used to neutralize the acid of the two preceding baths. From 
 the fluxing bath articles are lifted dripping, and immediately 
 lowered into the galvanizing bath, known as the " zinc pot." This 
 bath consists of molten zinc, which soon becomes covered with flux 
 and dross, and is protected by these from the oxidizing action of 
 the air. The zinc pot is an iron tank which is surrounded by brick 
 walls with space enough between the walls and the tank to main- 
 tain a coke fire for keeping the zinc melted. 
 
 Small articles are lowered for a moment into the zinc bath in 
 wire baskets. They are lifted out and allowed to cool. 
 
 The best grade of galvanized sheets is produced by feeding the 
 sheets taken directly from the fluxing bath into a machine which is 
 submerged in the zinc pot. This machine is merely a series of 
 rolls which draw the sheet into the bath, carry it down near the 
 bottom, and finally send it out over the further edge of the pot. 
 These rolls insure an even coating of zinc over the surface of the 
 sheet and roll down all lumps and uneven places. Sheets from the 
 zinc pot are placed on edge in racks to cool, and are then run 
 through straightening rolls and sorted to pick out sheets which are 
 imperfectly galvanized. The imperfect sheets are returned to the 
 second acid bath if very imperfect, or are bundled and sold as 
 e< seconds " if only slightly imperfect. All sheets are branded be- 
 fore bundling for market. 
 
 181. Tinning. Tinning, like galvanizing, is a practical method 
 of coating iron and steel to render it non-corrodable. Tinning 
 gives a smoother, brighter and better-looking surface, and it forms 
 a more durable coating, than does galvanizing. Yery common 
 among tinned products are tinned wire, roofing tin, tin-lined cook- 
 ing vessels, and cans in which preserved fruits and vegetables are 
 held. 
 
 182. The Manufacture of Tin Plate. This process is very similar 
 to the process of galvanizing, but is more elaborate, and requires 
 more care, as the product is used where resistance to corrosion is 
 more essential. 
 
THE RE-MANUFACTURE OF METALS 
 
 163 
 
 Sheets to be tinned are rolled from sheet-bars and are then 
 trimmed to measure 14 x 20 inches, the standard size for tin plate. 
 
 After rolling and trimming, the sheets are selected with more 
 care than for galvanizing. They are then pickled and rinsed to 
 expose smooth, clean surfaces, and are annealed on a covered tray. 
 Annealing makes them too pliable for use, hence each sheet is given 
 two passes through finishing rolls to make the surfaces smooth and 
 to make the sheet springy or elastic. This annealing and rolling 
 makes another pickling necessary, after which they are kept under 
 water to avoid oxidation while waiting to go into the tinning pot. 
 
 The coat of tin is applied by immersing one sheet at a time in an 
 iron pot containing molten tin. The sheet enters the tin through 
 
 FIG. 59. Tinning Pot. 
 
 a flux of ammonium chloride (sal ammoniac) which floats on the 
 surface of the molten metal and prevents the formation of dross, 
 which would cling to the surface of the sheet. Fig. 59 shows a dia- 
 gram of the upper part of the tinning pot, on the back edge of 
 which is mounted a grease pot G filled with molten palm oil, in 
 which revolve several pairs of rollers as shown. The sheet is 
 lifted from the pot until gripped by the lowest pair of rolls, and it 
 is carried upward by these and the other rolls which deliver it to a 
 table above the grease pot. The palm oil serves to keep the plate 
 hot and to prevent oxidation while the rolls are pressing off super- 
 fluous tin and smoothing that retained on the sheet. The slower 
 running of the rolls allows a heavier coating of tin to stick to the 
 sheet. The tin in the pot is kept molten by gas burners not shown. 
 After emerging from the grease pot, each sheet is forced up. 
 
164 MECHANICAL PROCESSES 
 
 edge on, through a bin of sawdust and lime to clean it, and is then 
 passed through buffing and dusting rolls, after which it is carried 
 to the sorting tables. The work of sorting is usually done by girls, 
 who grade all sheets as "primes" (1st grade) or "wasters" (2d 
 grade). Some "wasters" having no defects except a few poorly 
 tinned spots may be "mended" by cleaning and retinning, thus 
 making " primes," but " wasters " with bad defects must either 
 be sold as seconds or x thrown out entirely for remelting and re- 
 covering the tin. 
 
 Tin plates are usually packed 112 sheets to the box. 
 
 183. Terne Plates. This is a grade of tin plate used for roofing. 
 Terne plates are slightly heavier than tin plates and are much 
 cheaper, as they are covered with a mixture of about 25$ tin and 
 7'5$ cent lead. Many tin vessels, not intended for food receptacles, 
 are made of terne plates. 
 
 184. Russia Iron. This name is applied to sheet iron of very 
 highly polished or glazed surface also known as planished iron. 
 
 Mt is used for protecting the lagging of engines and boilers and for 
 other uses where a non-corroding black iron of finished surface is 
 desired. 
 
 These sheets are made by piling together about fifty pickled sheets 
 of soft steel with powdered charcoal sprinkled between adjacent 
 sheets. The pile is wrapped in old sheets, wired and heated in a 
 furnace to a cherry-red heat for about 6 hours. Upon cooling, each 
 sheet is swept free of loose charcoal and is then sprayed with steam 
 to form a thin oxide. Again the sheets are piled together, heated 
 and then placed on the hammer table, several in a bundle, and 
 pounded with a steam hammer. This brings about a grinding 
 action which grinds the carbon and oxide on the surface down to a 
 highly polished coating. 
 
 185. Wire Drawing. Metals to be made into wire are first cast 
 (or rolled in the case of wrought iron) into long square billets. A 
 billet intended for wire is about 4 x 4 x 56 inches. Brass and 
 copper billets are also called "wire bar," when cast for making 
 wire. 
 
 The first operation is to break down these billets in billet and 
 rod mills. A billet is run hot through a continuous mill of about 
 eight sets of rolls, which break it down to about 1%-inch square 
 
THE RE-MANUFACTURE OF METALS 
 
 165 
 
 cross section. It then goes at once through the looping rod-mill 
 which delivers it as coiled rod varying from 3/16 to % inches 
 diameter, and a hundred or more feet in length. 
 
 These coils are sent to the wire mills and the remainder of the 
 process of reducing them to the diameter of wire required is ac- 
 complished by drawing them cold through dies. 
 
 At the wire mill, coils must first be pickled to remove all scale. 
 After this they are dipped in lime water and dried in a steam- 
 drying room where they remain until removed to be drawn. 
 
 Fig. 60 shows in cross section a steel die for wire drawing. The 
 work of drawing is done on the draw bench, as shown in Fig. 61, 
 
 FIG. 60. 
 
 Wire 
 Drawing 
 
 Die. 
 
 FIG. 61. Wire-Drawing Bencn. 
 
 which is a long bench against the shop wall. Along this bench 
 are- mounted, on vertical spindles, a row of short cylindrical drums 
 about 22 inches in diameter. These drums, known as " drawing 
 blocks," are made to revolve by being geared to a long shaft under 
 the bench. A drum resembles somewhat a car wheel, with the 
 flange at its lower edge, and each drum may be stopped at will 
 while the remainder on the bench continue in motion. Near each 
 drum, at the edge of the bench, is a small vise, or " frame," which 
 holds the die. 
 
 A coil of rod from the drying room is placed on a reel fastened to 
 the floor near each frame on the draw bench, and a rod end is filed 
 
166 MECHANICAL PROCESSES 
 
 or hammered so that it will pass through the die. An appliance on 
 the bench pulls about 6 feet of this end through the die. A work- 
 man fastens this end to the drawing block and starts the block in 
 motion. The revolutions of the block draw the rod through the die 
 and the wire is wound on the block, which continues in motion 
 until the entire rod is drawn through. 
 
 The percentage of reduction in diameter accomplished by the die 
 depends upon the softness of the rod. Drawing must necessarily 
 pull a metal beyond its elastic limit, else the metal would not re- 
 main in the shape drawn, but the metal cannot be pulled too near 
 its tensile strength, else it would break. 
 
 After one or more drawings, the coil must be taken from the 
 block and annealed to soften it and relieve it of brittleness. To 
 prevent scale forming on the wire in annealing, several coils are 
 placed in an annealing pot which is sealed and heated in the an- 
 nealing furnace. Successive drawings and annealings are con- 
 tinued until the wire is reduced to the diameter required. 
 
 Manufacturers lubricate wire dies with oil, solid grease or a fer- 
 ment of bran and yeast in water. Common wire is made usually 
 of acid Bessemer steel. Sounding wire, piano wire and other high- 
 grade wires are made of crucible steel or of open-hearth steel re- 
 fined in the electric furnace. 
 
 186. Gaging the Sizes of Wire. For designating the diameters 
 of wire, thicknesses of sheet metals, and thicknesses of the walls of 
 tubes, various arbitrarily chosen scales of sizes are used in America 
 and in Europe. These sizes are designated as wire-gage units. 
 For example, a wire may be designated as No. 5, B. & S. (Brown & 
 Sharpe) or No. 5, B. W. G. (Birmingham Wire Gage). 
 
 The several systems use numbers to designate sizes ranging from 
 0000000 (usually expressed as 7/0) to 50, although the sizes are of 
 different dimensions in the different systems.* 
 
 In America the B. & S. gage (prepared by Messrs. Brown & 
 Sharpe Mfg. Co., Providence, E. I.) is standard among manufac- 
 turers for designating wire sizes and metal thicknesses, although 
 the U. S. Navy Department has adopted the B. W. G. (Birmingham 
 
 * A table in the Appendix gives a comparison of the different wire- 
 gage systems. 
 
THE RE-MANUFACTURE OF METALS 167 
 
 Wire Gage) for designating thickness of walls of pipes and tubes, 
 and the U. S. standard gage for designating steel and iron-plate 
 thicknesses. 
 
 The finest wire drawn is a copper wire of about .001-inch 
 diameter. 
 
 187. Coating Wire for Protection from Corrosion. Most of the 
 iron wire of to-day is made of low-carbon steel, which corrodes very 
 quickly. The cheapest protection is galvanizing, though tinned or 
 coppered wires are more effectively protected. 
 
 Galvanizing and tinning are done by passing wire from one reel 
 to another first through a bath of weak hydrochloric acid to clean 
 it, then through a wiper of waste. It is then pulled under suitable 
 guides through a bath of molten zinc or tin, according to whether 
 the process is galvanizing or tinning, and from this bath it passes 
 through a wiper of asbestos fiber to remove lumps of the coating 
 material before it cools and is wound into a coil. 
 
 Pickled wire coils dipped into copper-sulphate solution take a 
 coating of copper, and when drawn the wire has a bright copper 
 surface. 
 
 188. Hard Wire. Spring Material. Drawing hardens wire and 
 the hardness differs in degree according to the composition of the 
 wire and the amount of reduction without annealing. Wire which 
 is not annealed after drawing is called "bench-hardened" wire. 
 Steel wire containing as high as 1.20$ per cent of carbon is drawn 
 cold, and this may, if desired, be made harder just as steel tools 
 are hardened. High-carbon steel wire is generally marketed in 
 straight lengths of a few feet, annealed, and it is hardened as may 
 be desired by the user. 
 
 Flat wire or ribbon wire, containing about .9$ of carbon, such 
 as is used for clock and watch springs, is drawn the same as round 
 wire, though the large sizes for coiled springs must be rolled. This 
 material is hardened and tempered while winding it from one reel 
 to another. It passes through an oil flame to heat it to redness, 
 then through cold fish oil to harden it, and last through molten 
 lead, kept at a fixed temperature by oil burners, to anneal it. The 
 hardness cannot be such that the material will snap if rolled into 
 coils. 
 
168 MECHANICAL PROCESSES 
 
 Wire is very soft and pliable if thoroughly annealed after 
 drawing. 
 
 189. Pipes and Tubes. These two words are much confused in 
 their applications. Commercially, there are many kinds of pipes 
 and tubes of many sizes and materials. 
 
 The pipe and tube-making processes described in the following 
 paragraphs embody the essential principles of making pipes and 
 tubes of all kinds in which ductile metals are used. 
 
 Cast-iron pipes are much used for large water, oil and gas mains. 
 These are products of the foundry and will not be described here. 
 
 All pipes and tubes made of wrought iron or mild steel are 
 manufactured by one of two general processes; either by shaping 
 metal strips called " skelp " into cylindrical form and welding the 
 edges together; or by drawing the tubes from solid billets or flat 
 plates. The products of these two processes are classed respectively 
 as welded or seamless. 
 
 190. The Manufacture of Welded Pipe. Most of the welded pipe 
 is now made of a low-carbon acid Bessemer steel. This steel will 
 weld readily, and it has nearly displaced wrought iron for this use. 
 
 Billets are rolled into skelp (which is similar to sheet-bar) of the 
 width and thickness required for the pipe. Each strip of rolled 
 skelp is cut into lengths of about 20 feet, and each length is made 
 into a pipe. 
 
 Welded pipe is made either by lap or butt welding of skelp 
 strips. Pipes of 1*4 inches diameter and under are butt welded, 
 as shown in Fig. 62 and those over 11/4 inches diameter are lap 
 welded as shown in Fig. 63. 
 
 The methods of welding are as follows, viz. : 
 
 For Butt Welds. In a long flat-bottomed heating furnace with a 
 door at one end for receiving strips and a door at the other end for 
 removing them, a number of strips are kept side by side at various 
 degrees of heat up to welding heat. When a strip has reached weld- 
 ing heat, a man reaches in at the removing door with a long pair of 
 tongs and curls over the edges for a few inches along the end of 
 the strip. Working quickly, he pulls the end from the furnace, 
 
THE KE-MANUFACTURE OF METALS 
 
 169 
 
 points it through a tapered ring known as a bell (B, Fig. 64) and 
 grips this end with the nippers R. Just the instant the nippers 
 grip the strip, the hook H is caught by a moving endless chain 
 under the bench and the strip is pulled through the bell. The bell 
 is so shaped that it rolls the strip into cylindrical form and forces 
 
 FIG. 62. FIG. 63. 
 
 Butt and Lap-Welded Pipe Joints. 
 
 the edges together firmly enough to make the weld. The bell rests 
 against a shoulder 8 on the bench while the strip is passing through, 
 but when through, the bell falls into a basin of cooling water and 
 another bell is held in place by tongs ready for another strip to 
 start through. 
 
 FIG. 64. Equipment for Making Butt-Welded Pipe. 
 
 For Lap Welds. The shaping and the welding are accomplished 
 in two heatings. The first heating is merely a red heat for shaping 
 the strip into cylindrical form, a process similar to that for butt 
 welding. The second heating is for welding the pipe. 
 
 It is apparent that the bell of Fig. 64 will not bring the lap 
 firmly together for a lap weld, hence after the pipe has been given 
 a cylindrical shape, it is reheated to welding heat in another fur- 
 
170 
 
 MECHANICAL PROCESSES 
 
 nace and run through the welding rolls RE, Fig. 65. A view of 
 the actual machine is shown in Fig. G6. The rolls are two grooved 
 
 FIG. 65. Rolls and Mandrel for Making Lap-Welded Pipe. 
 
 wheels which press the lapped edges together against a mandrel M 
 placed in the end of the pipe as it enters the rolls. The mandrel 
 is held directly between the two rolls by the long rod 8. The pres- 
 
 FIG. 66. Machine for Lap-Welding Pipe. 
 
 sure of the rolls forces the pipe against this mandrel and makes 
 the weld. 
 
 After welding, both butt and lap-welded pipes are run cold through 
 sizing rolls,, which gives them correct outside diameter, and through 
 
THE KE-MANUFACTURE OF METALS 171 
 
 cross rolls, which straighten them and give the surface a clean 
 finish. The pipes then go to the inspection table, ends are sawed 
 off, and the short pieces are crushed cold to show the effectiveness 
 of the weld. The pipe is carefully inspected outside, is tested by 
 hydraulic pressure of at least 600 Ibs. per square inch, and, if 
 passed, it is annealed to reduce the size of the crystals and increase 
 the elasticity. 
 
 Pipes are threaded on the ends after annealing and are then 
 ready to be made up in bundles for shipping. Each length of pipe 
 is shipped with a short threaded sleeve called a coupling screwed 
 on one end of the pipe. This is used in joining lengths of pipe 
 together. Some grades of boiler tubes are produced by the lap- 
 welding process. 
 
 191. Defects in Welded Pipe. Besides defective welds, the fol- 
 lowing named defects in welded pipes, with their causes, may be 
 mentioned : 
 
 (1) Cracks or Seams. These originate in the ingot as blow 
 holes, shrinkage, cracks or other defects. An ingot defect lengthens 
 out when the material is rolled into skelp. 
 
 (2) Blisters. These are caused by piping in the ingot. Heat 
 swells them above the surface of the skelp. 
 
 (3) Scale Pits and Sand Marks. These are small indentations 
 caused by rolling scale or sand into the surfaces of the skelp. 
 
 192. Iron Pipe. Welded pipe is commonly seen and much used 
 as steam, gas and water pipe, and is commercially known as iron pipe. 
 It is made in standard sizes designated in inches as follows, viz. : 
 %, a /4, %, y 2 , 3 /4, 1, 1%, iy 2 , 2, 2V,, 3, 31/3, 4, 41/2, and in sizes of 
 even inches from 5 to 12, both inclusive. These sizes refer to the 
 inside diameters of the pipe, but, as a matter of fact they are only 
 nominal, as the actual diameters differ more or less from the desig- 
 nated diameters. While iron pipe is referred to by its nominal inside 
 diameter, it is standardized in size in outside diameters.* 
 
 Iron pipe is marketed either galvanized or plain, and some makers 
 coat pipe with asphalt or tar. 
 
 For very heavy pressures, or for driving oil or artesian wells, two 
 special thicknesses of iron pipe are made, known commercially as 
 
 * Paragraph 437 of the Appendix gives a table of sizes and dimen- 
 sions of standard iron pipe. 
 
172 MECHANICAL PROCESSES 
 
 extra strong and double extra strong. These have the same ex- 
 ternal diameters as the standard piping. Also, iron pipe is made 
 much larger than 12 inches in diameter for many uses. 
 
 Iron pipe is much used as underground conduits for electric wires. 
 193. Seamless Tubes. It is not commercially practicable to pro- 
 duce a welded tube which shall uniformly have the same strength 
 at the weld as in other parts of the metal. The temperature to 
 which it is necessary to heat the metal for welding is such that the 
 material may be burned to a greater or less extent, a condition 
 which it is not always possible to detect. 
 
 For these reasons, boiler tubes and other tubes or pipes which 
 must stand high pressures and which are subjected to great varia- 
 tions of temperature, are preferably made without welds or seams. 
 There are several methods for producing seamless tubes which 
 are applied to various materials, including steels of practically all 
 compositions, brass, copper, etc. The method of making seamless 
 tubes in general use consists in piercing a hole axially through a 
 billet of circular cross section, reducing the wall thickness of the 
 tube so produced by rolling, and finishing, when the conditions 
 require, by further reducing the wall . thickness by cold drawing. 
 Some compositions of brass will not stand piercing, hence tube 
 billets of these compositions are cast hollow and reduced in size by 
 drawing. 
 
 194. Piercing Billets for Seamless Tubes. This first operation 
 in making seamless steel tubes begins with small ingots supplied 
 by the rolling mill, free from surface flaws. These ingots are 
 heated and rolled into cylindrical form, and are sawed hot into 
 lengths required. Each of these lengths, called a blank, may range 
 in weight from 40 to 1000 Ibs., according to the size of tube to 
 be made. 
 
 When cold, a hole about %-inch diameter and %-inch deep is 
 drilled in the center of one end of each blank, and the blanks are 
 then reheated to about 2200 F. for piercing. 
 
 The reheating furnace may be any of the various types used for 
 heating billets. The bed of the furnace is usually inclined so that 
 blanks may gradually roll in a continuous line one against another 
 through the furnace. 
 
THE RE-MANUFACTURE OF METALS 
 
 173 
 
 From the furnace, each hot blank is taken directly to the piercing 
 mill, the principle of which is shown in Fig. 67. This is the 
 Stiefel mill, and is used more than other mills in this work. The 
 principle of operation is the same in all piercing mills, and they 
 vary only in their mechanism. 
 
 The discs A and B, beveled alike on the faces, revolve in the 
 same direction, and their axes X and Y are parallel. The blank K 
 is supported in a trough so placed that its axis, DD, makes equal 
 angles with the face C and with the bevel F of the two discs; also 
 the axis DD is in the same plane which contains the axes X and Y 
 of the discs. 
 
 FIG. 67. Making Seamless Tubes. Piercing Rolls. 
 
 The blank is pushed by a bar in the hands of workmen until 
 gripped by the discs, which take hold of it, giving it a rotary 
 motion and forcing it against the piercing mandrel P, a conical 
 piece of cast steel held in place by the piercing bar R. The pier- 
 cing mandrel is made to start centrally by the small hole drilled in 
 one end of the blank, and the piercing bar is held to its place by a 
 thrust bearing which allows it to revolve freely. The motion of the 
 discs gives the blank a motion of translation in the direction of its 
 axis, besides the rotary motion. This forces the blank entirely 
 over the piercing mandrel in a few seconds, and the operation of 
 piercing lengthens the blank into a tube from two to four times the 
 length of the blank. 
 12 
 
174 
 
 MECHANICAL PROCESSES 
 
 This tube is in a rough state after piercing, not -uniform in 
 diameter and with a surface somewhat wavy. The original process 
 of piercing tubes,, invented by the Messrs. Mannesmann gave the 
 pierced blank a spiral twist. This was found to be a disadvantage, 
 giving an unnecessary strain to the metal of the tube walls, and the 
 Steifel process is among those devised to reduce this fault. 
 
 To smooth the tube up and give it uniform diameter, it is sub- 
 jected to five finishing operations, with or without reheating, ac- 
 cording to the size of the tube. These operations are : 
 
 FIG. 68. Making Seamless Tubes. Tube Rolls. 
 
 (1) Rolling the pierced blank to give uniform diameters and 
 thickness of wall. 
 
 (2) Cross rolling, to remove scratches and smooth the tube 
 surface. 
 
 (3) Sizing, to reduce the tube to a specified diameter. 
 
 (4) Straightening. 
 
 (5) Cutting to length. 
 
 195. Rolling Pierced Blanks. This operation is done by two 
 grooved rolls. Fig. 68 shows a plan view of this machine with the 
 upper roll removed. 
 
THE KE-MANUFACTURE OF METALS 
 
 175 
 
 These rolls force the tube over a fixed mandrel A supported be- 
 tween the rolls by a bar B. The bar is supported by a yoke C. 
 Several passes through the rolls over the mandrel A reduce the 
 tube wall to the thickness desired, and give uniform diameters. 
 The size of the mandrel and of the roll passes determine the thick- 
 ness and diameters of the tube. This operation leaves scratches 
 inside the tube which are removed in the next operation. 
 
 196. Cross Rolling. This work is done in a reeling machine, 
 the principle of which is shown in Fig. 69. 
 
 ii 
 
 FIG. 69. Making Seamless Tubes. Tube Reeling Machine. 
 
 Supposing the axis of the tube to lie in the plane of the page, 
 the axis of the upper roll is inclined downward toward the right, 
 and that of the lower roll is inclined downward toward the left. 
 The revolutions of the rolls inclined in this way not only revolve 
 the tube, but push it forward over the mandrel M. The mandrel 
 is supported by its bar It, and is free to revolve with the tube. This 
 operation may change the tube diameter somewhat. 
 
 197. Sizing. This is done by a small two-high rolling mill the 
 rolls of which have circular passes of two sizes. The first pass 
 reduces the tube to within 1/32 of an inch of the finished diameter 
 and the second pass reduces it to finished diameter plus a small 
 amount which the diameter will contract in cooling, as the tube is 
 no-w at a dull red heat. 
 
176 
 
 MECHANICAL PROCESSES 
 
 198. Straightening and Cutting to Length. After sizing, the 
 tube is transferred to a machine which consists essentially of a pair 
 of cross rolls as shown in Fig. 70. The axes of these rolls, BC and 
 DGr, are inclined at equal angles on each side of the tube axis KL. 
 The tube is pushed through in the direction of its length between 
 the two rolls, which revolve in the same direction. 
 
 The arrangement of these rolls is identical with that in the 
 reeling machine. They are much longer than the reeling rolls. 
 Their surfaces are hyperboloids of revolution and each face is 
 generated by a straight line K'L' revolving about an axis B'C' at 
 a fixed distance 08 from it. The two rolls are so inclined that the 
 
 FIG. 70. Rolls for Straightening Tubes. 
 
 contact of the tube with the rolls approximates a generating element 
 as near as possible. 
 
 Suitable guides prevent the tube from taking any lateral move- 
 ment. 
 
 From the straightening rolls, the tube is sent to the cooling 
 table, down which it rolls gradually, against other tubes, to keep it 
 straight as it cools. 
 
 The hot work on the tube is now complete, and without further 
 operation than cutting to length and testing, these tubes are suit- 
 able for use as boiler tubes or for many mechanical and structural 
 purposes. 
 
 After cutting to length in a simple cutting machine, each tube is 
 tested to an internal hydrostatic pressure of 1000 Ibs. per square 
 inch, is carefully inspected and marked. 
 
THE BE-MANUFACTURE OF METALS 
 
 177 
 
 FIG. 71. Three Views of a Cold-Draw Bench. 
 
178 
 
 MECHANICAL PROCESSES 
 
 Annealing is not necessary, as the increase in its grain size is 
 reduced by the constant working of the material after it left the 
 furnace. 
 
 199. Cold-Drawn Tubes. Tubes can be produced from 2 to 6 
 inches outside diameter by the hot finishing process. When neces- 
 sary to produce (1) tubes of less than 2 inches diameter, or (2) 
 larger tubes requiring the smoothest surfaces, or (3) tubes requir- 
 ing greater accuracy in diameter and thickness of wall than can 
 be produced by the hot process, this process must be followed by a 
 series of cold drawing operations. 
 
 FIG. 72. The Operation of Cold-Drawing Tubes. 
 
 These operations consist of drawing the hot-rolled tube through 
 dies and over mandrels to reduce its diameters and thickness of 
 wall. 
 
 The various steps in the cold drawing operations may be de- 
 scribed as follows : The hot-rolled tube, after having cooled, is 
 heated at one end and forged down to a rough point or tag, as 
 shown at PI, Fig. 72. After pointing, the tube is cleaned of dirt 
 and scale by pickling in hot dilute sulphuric acid. It is washed in 
 an alkali water to remove all traces of acid, and is then immersed 
 in a lubricating vat. The lubricant consists of flour, water and 
 tallow. After lubricating, the tube is taken to the cold-draw bench 
 shown in the lower sketch of Fig. 72.* 
 
 * Fig. 71 shows three views of a cold-draw bench in the shop. 
 
THE EE-MANUFACTURE OF METALS 179 
 
 This machine consists of a frame arranged with a support for a 
 die D, and is provided with a traveling chain or other means of 
 moving a gripper or plier G away from the die. The other end of 
 the machine forms a support for the end of the mandrel rod B. 
 A die shown in cross section at DD of the upper view is placed in 
 the die support. The pointed end of the tube is then pushed 
 through the opening in the die and a cylindrical mandrel M on the 
 end of the rod B is entered into the tube. A head C formed on the 
 rod B engages with the frame of the bench, so that the mandrel and 
 die are held rigidly in proper relation to each other as shown in the 
 figure. 
 
 The opening in the die is smaller by from % inch to y 2 inch 
 than the diameter of the tube operated upon. The mandrel M is 
 also smaller than the inside diameter of the tube, but to a slightly 
 less degree than the die, so that the difference between the die and 
 the mandrel size is less than the difference between the outside and 
 inside diameters of the tube operated upon. The result is that in 
 passing the tube through the die and over the mandrel, the diameter 
 and wall thickness are simultaneously reduced. 
 
 The point of the tube having been placed through the die with 
 the mandrel M in position, is gripped by the gripper Cr, which in turn 
 is engaged by a hook with a moving chain /. The tube is pulled 
 through the die and over the mandrel at the speed of the gripper. By 
 this means, the sectional area of the tube is reduced about 15% for 
 small tubes of light wall and up to 25% or to the strength of the 
 bench for larger sizes. The drawing operation is repeated from 2 
 to 10 times until the desired diameter and wall thickness are ob- 
 tained. 
 
 After each cold-drawing operation it is necessary to anneal the 
 tube in order to soften it for the succeeding, cold drawing. After 
 annealing, the tube is pickled and lubricated as before. For many 
 purposes the cold-drawn tube is used without annealing; but for 
 purposes which require ductility in the material the tube is annealed 
 at various degrees corresponding to the physical properties required. 
 A temperature of 1200 F. removes all traces of the effect of cold 
 drawing. 
 
 After receiving final operation, the tube is transferred to the 
 finishing department where it is straightened and cut to length, 
 inspected, gaged and tested and is then ready for shipment. 
 
180 
 
 MECHANICAL PROCESSES 
 
 200. Brass and Copper Tubing. The same methods of piercing 
 and cold drawing described for making steel tubes are used to make 
 tubes of copper and brass. Billets of brass are sometimes turned in 
 a lathe to remove the rough outer surface before piercing. 
 
 FIG. 73. Mannesmann Piercing Rolls. 
 
 Fig. 73 shows plan and side views, partly in section, of a pair of 
 Mannesmann rolls much used for piercing billets of copper and 
 brass. 
 
 Brass pipe cannot be made by welding. It is made by piercing 
 (or casting hollow) and then cold drawing. It is usually sent from 
 the factory partially softened by annealing after drawing. 
 
THE KE-MAXUFACTURE OF METALS 181 
 
 201. Tubes of Thin Walls and Small Diameters. A tube may be 
 cold drawn over a mandrel, as previously described, until its wall 
 is too thin to stand further pulling through the die. If the tube 
 wall is to be made thinner, further drawing is done by placing the 
 tube over a solid steel arbor and drawing it down as shown in Fig. 
 74. The tension of drawing is then taken by the arbor and the tube 
 wall may be drawn very thin. Large rigid arbors are pushed 
 through the die. When the drawing is done, the tube is removed 
 from the arbor by hammering it gently with a wooden mallet or by 
 passing it between rolls. 
 
 Very small tubes are made without a mandrel. They are first 
 cold drawn over a mandrel to a diameter of % inch or less and are 
 then " sunk " by drawing through the die without a mandrel. 
 
 FIG. 74. Arbor for Drawing Thin Tubes. 
 
 This reduces inside and outside diameters, but increases the thick- 
 ness of wall. If the wall is to be very thin, an arbor is placed in 
 the tube after it has been sunk nearly to the required inside diameter 
 and the wall may then be drawn down as thin as required. 
 202. Defects in Seamless Tubes. 
 
 (1) Snakes are small surface cracks developed from surface 
 cracks of the ingot. They are elongated in rolling, and are very 
 small and hard to detect. They are more common in rolled plates 
 than in tubes. 
 
 (2) Laps are thin fins of metal stretched and folded over the 
 adjacent metal of the tube. They are caused in piercing. 
 
 (3) Pits are small depressions caused by over pickling or by 
 rolling sand or scale into the tube surface*. 
 
 (4) Slivers are tongue-shaped pieces of metal developed from 
 blow holes or shrinkage cracks in the ingot. 
 
182 
 
 MECHANICAL PROCESSES 
 
 (5) Tears are ragged 'openings in the tube surface caused inside 
 by metal not passing freely over the mandrel at the draw bench, or 
 caused outside by a rib of metal not passing evenly through the die. 
 They are due many times to hard or weak spots in the metal. 
 
 (6) Checks are very small tears. 
 
 (7) Rings are transverse corrugations in the tube wall. They are 
 caused by the jumping of the tube in drawing, due to poor bench 
 equipment. 
 
 (8) Sinks are depressions extending around the inside of the 
 tube. They are caused by a displaced mandrel, which allows the 
 tube to draw to a smaller diameter than intended. 
 
 FIG. 75. Making Hot-Drawn Tubes. Press for Cupping Discs. 
 
 (9) Scratches are due to rough dies and mandrels, to grit picked 
 up by the tube after lubricating for drawing, or by insufficient 
 lubricating. 
 
 203. Hot-Drawn Seamless Tubes. For producing seamless tubes 
 larger than 6 inches outside diameter, a hot drawing process is 
 used. In this process a plate of the required thickness is punched 
 or sheared into a circular disc. This disc is then heated to a bright 
 red heat and placed in a hydraulic press arranged as in- Fig. 75. 
 The disc P is placed over the circular opening in the die block D 
 of the press, and the plunger H is forced down on the plate, carry- 
 ing it completely through the opening in the die block. The differ- 
 ence in the diameters of the openings of the die block D and the 
 
THE RE-MANUFACTUKE OF METALS 
 
 183 
 
 plunger H is such as to give the sides of the cup the thickness of the 
 disc. The squeeze between the plunger and the die block,, as the 
 disc passes through, presses the sides of the cup free from wrinkles. 
 This operation is repeated with or without reheating until a cup is 
 
 FIG. 76. Making Hot-Drawn Tubes. Re-Drawing Cupped Discs. 
 
 produced of considerable length. The form of the die used in the 
 succeeding operation is shown in Fig. 76. The die is recessed to 
 receive and locate the cup produced by the previous operation and 
 frequently the bottom of the cup is cooled by water to keep the 
 plunger from punching a hole through it. 
 
 PIG. 77. Cupped Discs. 
 
 The plate after receiving one or more cupping operations in 
 vertical presses, is in a cupped form as shown in Fig. 77. Each cup 
 is reheated and transferred for further reduction to a horizontal 
 press usually called a hot-drawing bench, the essential features of 
 
184 
 
 MECHANICAL PROCESSES 
 
 which are shown in Figs. 78 and 79. The bench consists, of a 
 heavy frame placed horizontally and connected to a hydraulic 
 cylinder C. In operating, the cup K is placed over the end of the 
 
 FIG. 78. Hot-Draw Bench for Elongating Cupped Discs. 
 
 plunger rod, which is arranged to travel the entire length of the 
 bench frame. 
 
 Dies X, Y and Z , with openings of successively smaller diameters, 
 are placed in suitable holders in the bench frame. The cup K is 
 
 FIG. 79. Hot-Draw Bench. 
 
 pushed through the dies successively as shown in the figure, re- 
 ducing the diameters and the wall thickness. Several drawings 
 are made in this manner, reheating between each operation until 
 the tube is reduced to its final diameter and wall thickness. The 
 
THE RE-MANUFACTUKE OF METALS 185 
 
 bottom of the cup is cooled with water from a hose to keep the 
 plunger rod from punching a hole through it while the cup is pass- 
 ing through the dies. 
 
 After reducing the tube to its final diameter, the bottom is sawed 
 off, the ragged edges of the open end are trimmed off, and the tube 
 is then inspected and tested under hydrostatic pressure. 
 
 To show the change of form possible in hot drawing, a tube 22 
 feet long 9*4 inches inside and 10 inches outside diameter is made 
 from a round plate 54 inches in diameter and 1% inches thick. 
 This requires ten passes through as many different-sized dies. 
 
 Hot-drawn tubes may be further cold drawn to produce tubes up 
 to ten inches in diameter. 
 
 204. Steel Cylinders for Storage of Gases. From the hot-drawn 
 steel tubes just described are made seamless-steel cylinders for 
 
 r n 
 
 FIG. 80. Reducing the Opening in a Hot-Drawn Tube 
 
 storage of gases under pressure. The bottom is left on the tube and 
 the open end, after having had the defective part trimmed off, is 
 heated and pressed under the dies B and C to a shape shown in 
 Fig. 80. The opening is suitable for attaching a controlling valve 
 to the cylinder. 
 
 These containers are made as large as 18 inches in diameter and 
 12 feet long. 
 
 Another method of closing the tube end is to hold the tube 
 strongly in a rapidly revolving machine of great rigidity and bring 
 the pressure of a steel roller against the side of the tube end. This 
 pressure is so great that its friction heats the tube and closes it to 
 the amount desired. The process is called spinning and may even 
 be used to close and weld a tube end of mild steel. 
 
 205. Cold Pressing of Metals. The ductility of many metals, in- 
 cluding many of the alloys, is sufficient to allow sheets of the metals 
 
186 MECHANICAL PROCESSES 
 
 to be pressed cold, without injury, into a great variety of forms. 
 A considerable change of shape from the flat sheet may be accom- 
 plished by a succession of gradual changes, as was seen in forming 
 large tubes in the operations of making hot-drawn tubes. The 
 amount of distortion which can be accomplished at each step de- 
 pends upon the power applied, and upon the ductility of the metal. 
 The metal must be annealed after a certain degree of change of 
 shape, else its ductility is lost and further pressure would disrupt 
 the piece. 
 
 Common examples of the application of this process are cartridge 
 cases, small round tin boxes, embossed metal ceilings, man-hole 
 covers for boilers, metal ends of lead pencils, spoons, and many 
 domestic utensils. 
 
 Many articles are pressed completely at one operation, and many 
 others of more complicated shape are pressed in two or more suc- 
 cessive operations under different dies, with or without annealing, 
 according to the ductility of the metal used. This process is now 
 applied to the shaping of articles from cold plates of mild steel as 
 great as % of an inch thick, although the thickness of steel which 
 can be shaped cold is limited only by the power of the shaping press 
 and the ductility of the steel. 
 
 The machines which shape thin sheets do their work by power 
 transmitted through geared wheels, levers, cams, etc., to properly 
 placed punches, dies and plungers, and the proper lubrication of 
 the work is essential. These machines are built to turn out work 
 with a minimum of attendance, and many of them carry a piece of 
 metal through the several steps and turn out the finished product 
 automatically so long as sheet metal is fed to them. 
 
 The shaping of heavier sheets, particularly those of steel, usually 
 requires hydraulic presses, although very powerful machines are 
 built for heavy work similar in design to those for lighter work. 
 
 As with all metal-shaping processes, particularly do these proc- 
 esses require means of holding the metal to be shaped firmly in the 
 position or positions required. 
 
 206. Steps in Shaping Articles from Sheet Metals. Fig. 81 shows 
 the steps in the process of shaping a vessel from tin, brass, copper or. 
 other sheet metal. The first step is to stamp out the disc, No. 1, 
 
THE RE-MANUFACTURE OF METALS 
 
 18? 
 
 from the flat sheet, called cutting or blanking. The shapes 2, 3 and 
 4 are then successively stamped between upper and lower dies 
 which are counterparts of these shapes. This kind of shaping is 
 
 FIG. 81. Steps in Shaping Sheet Metal by Drawing and Spinning. 
 
 known as drawing. Shape 5 is produced by spinning, and is done 
 on a type of lathe shown in Fig. 82. A solid shaping roll of the 
 contour of the work is held inside the shape as it revolves, and the 
 
 
 
 FIG. 82. Spinning Lathe. 
 
188 
 
 MECHANICAL PROCESSES 
 
 FIG. 83. Steps in Pressing a Vehicle Hub from Steel Plate. 
 
THE KE-MANUFACTUKE OF METALS 189 
 
 spinning is done from the outside by pressure of a burnishing roll 
 mounted on the lathe carriage. 
 
 Any embossing or lettering raised from the surface of the metal 
 is done by stamping. 
 
 Cylindrical metal boxes several inches long and less than half an 
 inch in diameter, can readily be formed from discs of sheet metal 
 by this process. 
 
 Another example of cold pressing is shown in Fig. 83. This 
 shows the gradual changes of form in shaping a vehicle hub from a 
 steel disc % inch thick and 15 inches in diameter. The flange of the 
 finished hub is 7% inches in diameter. The steps are numbered 
 consecutively. Annealing is necessary after about each third step, 
 judged by the workmen for each piece. 
 
 207. Drop Forcings. The process of forging small articles of 
 iron on the blacksmith's anvil is well known. Hand work of this 
 kind is very expensive for making intricate shapes and is a slow 
 process even for making simple shapes. Various processes have 
 been employed to shape iron articles in quantity which will be at 
 least as good in quality and less expensive than forgings made by 
 hand. One of the processes so employed is drop forging. By this 
 means, a great variety of forgings of plain and intricate shapes can 
 be produced in large quantities far cheaper and possibly better than 
 by means of hand forging. Drop forgings must be needed in large 
 quantities to warrant making a pair of dies, as these are expensive. 
 
 A drop forging is made by the drop of a heavy hammer on a 
 piece of hot iron held by a workman on the anvil of the machine. 
 The hammer carries a die which shapes the upper half of the 
 forging, and the anvil holds another die which shapes the lower 
 half. 
 
 13 
 
190 
 
 MECHANICAL PROCESSES 
 
 FIG. 84. Drop Hammer. 
 
THE KE-MANUFACTURE or METALS 191 
 
 208. The Drop Hammer. Fig. 84 shows a type of drop hammer 
 such as is used for making drop forgings. The lower die is held 
 on the anvil A and the upper die is held under the hammer B, by 
 keys in the dovetails shown. The dies are not shown in this view. 
 The uprights of the machine form guides between which the ham- 
 mer is raised and dropped. The hammer is raised by a smooth 
 board which passes between two cylindrical rollers at the top or 
 " head " of the machine. One of these rollers is marked (7. Each 
 roller is driven by its own shaft and belt wheel. The two belt wheels 
 are marked WW. The bearings of the roller shafts are arranged so 
 that the rollers may be made to grip the board or may be separated 
 to allow the board to drop between them. This adjustment of the 
 rollers is controlled by the rod D, connected to the foot lever G. 
 The workman may instantly release the pressure of the rollers on 
 the board and cause the hammer to drop, without checking the 
 speed of the rollers themselves. A lever H, shown in front of the 
 machine, is arranged to trip the hammer automatically so that it 
 may not go too high. 
 
 The hammer weighs 1000 Ibs. or more, and it takes but a few 
 strokes to forge a considerable mass of iron into shape. 
 
 209. Drop-Forging Dies. Making a Drop Forging. Dies for drop 
 forgings are made of hardened forged steel, of cast steel or, for 
 roughing out large work, they are made of chilled cast iron. Dies 
 are made in pairs, as shown in Fig. 85. The lower contains an im- 
 pression of the lower part of the forging, and the upper contains 
 an impression of the upper part. For some forgings the face of the 
 die contains a rough and a smooth impression of the forging. 
 
 The dies in Fig. 85 are used as follows : A bar of iron of con- 
 venient length for handling and of sufficient cross section to fill the 
 dies is heated in a small oil or gas furnace nearby. The first opera- 
 tion is to place the end of the heated bar along the lower die over 
 the impression B and give it one or more blows with the hammer 
 to shape it roughly to the outline of the forging to be made. This 
 is called breaking down, and the impression at the opposite edge 
 of the dies is also used to assist in this work. This operation is 
 immediately followed by placing the broken-down end over the die 
 D and dropping the hammer on it, usually about twice. The metal 
 is forced into both dies, completely filling them, and the surplus 
 metal is forced into the slight depression surrounding the dies. But 
 
192 
 
 MECHANICAL PROCESSES 
 
 for this depression, the dies could not come together and the forging 
 would be too thick. The fin or " flash " of metal thus formed 
 around the forging is shown on the wrenches marked F. The flash 
 is cut off in another machine called the trimming press which 
 stands alongside the drop hammer. The finished wrenches are 
 shown at G. 
 
 FIG. 85. Drop-Forging Dies and Specimens of Work. 
 
 To keep from cutting off the end of the bar in process of being 
 forged, and leaving the forging with no holding piece, a notch is 
 cut in one end of each die as shown at the ends of the wrench dies. 
 A cutter at the side of the die usually cuts off a forging when 
 shaped as shown at F. Frequently forgings are pickled to remove 
 the forge scale before trimming off the flash. Large forgings and 
 high-grade small forgings are annealed. 
 
 Fig. 86 shows a pair of dies B, B, for an automobile engine 
 crank-shaft, and C, C, show the two parts of the trimming dies. 
 
 Fig. 87 shows the steps of shaping the crank shaft from the bar a. 
 A few blows of the hammer break it down at the side of the die to 
 the shape b, and then the die shapes it in about a dozen strokes as at c. 
 
THE EE-MANUFACTURE OF METALS 
 
 193 
 
 Fiu. 86. Dies for Forging and Trimming a Small Crank Shaft. 
 
 FIG. 87. Steps in Forging an Automobile Crank Shaft. 
 
194 
 
 MECHANICAL PROCESSES 
 
 The trimming press, in which are mounted the dies C, C, cuts off the 
 flash as at d, and the bull-dozer or upsetting press presses a flange 
 on the end e after a reheating. 
 
 FIG. 88, Specimens of Drop Forgings. 
 
 After annealing, the forging is ready for machining to its re- 
 quired dimensions. 
 
 Fig. 88 shows a number of specimens of drop forgings, and Fig. 
 
THE RE-MANUFACTURE OF METALS 
 
 195 
 
 89 shows a high-grade alloy crucible-steel forging twisted and bent 
 cold to show its quality. 
 
 Long forgings are forged one end at a time to avoid making an 
 unduly long die and having to handle an unwieldly piece of work. 
 An automobile axle is about the longest drop forging made. 
 
 PIG. 89. A High-Grade Drop Forging Bent and Twisted Cold. 
 
 210. Bolts, Nuts and Rivets. Bolts, rivets and nails are pressed 
 into shape, and nuts are punched, by machines specially built for 
 this work. 
 
 Fig. 90 shows the general arrangement of a machine for pressing 
 bolts, rivets and wire nails. The end of a coil of wire or rod R is 
 fed by two or more pairs of grooved roller wheels through a guide 
 
 FIG. 90. Rivet-Pressing Machine. 
 
 (r. When the end is far enough through, the feeding wheels stop 
 and the two clamps CC close together and grip the material firmly. 
 The die D then moves forward through its guide, in the direction 
 of the arrow, presses the head H into shape, and then moves back. 
 The clamps CC, release their hold, move back, a cutter moves 
 along the face F8 of the guide G and shears the rivet from the rod 
 at S, and it falls into the box under the machine. When the cutter 
 
196 MECHANICAL PROCESSES 
 
 has moved out of the way, the feeding wheels again revolve, the 
 material is fed in, and the operation is repeated. 
 
 The die D may be replaced by others to give different shaped 
 heads (for nails or bolts). 
 
 The clamps C may take part in the shaping, as in pressing barbs 
 on the body of a nail, in addition to performing their work of 
 gripping and holding. 
 
 Eivets and rough bolts up to %-inch diameter may be pressed 
 cold from soft-steel material. If hot material is fed into the 
 machine, it is in the form of straight bars and not in coils. Only 
 a few feet of the bar is heated and when this is used up by the 
 machine, the remaining end is then heated. 
 
 Boiler rivets and the better grades of bolts are hot pressed. 
 Sometimes they are cut to length before heating for pressing, and 
 the head may be pressed in two heats. This is done in high-grade 
 work. Boiler rivets are always annealed after they are formed. 
 
 Bolts are often cut from rods of solid metal in bolt-cutting 
 machines. 
 
 Square and hexagonal nuts are pressed, punched, and sheared 
 from long, flat bars. Nuts are also cut by machines from bars of 
 square or hexagonal cross sections. 
 
 211. Screw-Cutting Machines. These are machines of ingenious 
 design which make a great variety of small metal objects from 
 round, square, hexagon or other shaped rods of brass, bronze and 
 steel. They embody a very high degree of mechanical ingenuity, 
 and the rapidity and accuracy with which they turn out a superior 
 grade of work is remarkable. Xot only do they make all kinds of 
 machine and other screws, particularly in medium and small sizes, 
 but they make an endless variety of small articles too thick or 
 intricate to be made by the drawing and spinning processes men- 
 tioned for shaping sheet metals. 
 
 Fig. 91 shows an automatic screw machine. It is so equipped 
 and geared that when a rod of metal, usually about 16 feet long, 
 is placed through the main spindle at ~B, and the machine started, 
 it continues work unattended until the rod is entirely cut into 
 articles which the machine is at the time set to produce. 
 
 The rod is gripped by a small chuck C, with enough of the rod 
 end extending beyond the chuck to be operated upon by the various 
 
THE RE-MANUFACTURE OF METALS 
 
 197 
 
 cutters. Most of the cutters are mounted on a small turret T, the 
 axis of which is horizontal and at right angles to the axis of the 
 spindle. The shaft which carries the turret is mounted on a 
 .carriage D which can slide back and forth parallel to the direction 
 of the spindle axis. The whole mechanism is so geared together 
 that the part of the rod extending beyond the chuck is operated on 
 successively by each of the six tools clamped on the turret and re- 
 
 FIG. 91. Automatic Screw-Cutting Machine. 
 
 volved into place at the proper time. In this way the accumulated 
 cutting of the several tools on the rod end, each tool doing its par- 
 ticular part of the cutting, shapes the pieces as required. When so 
 shaped, a cutter cuts the piece off the rod end, and it falls into a 
 box below. The rod is then automatically fed in a definite amount 
 for the cutting operations to be repeated. 
 
 The machine has an attachment, not here shown, for cutting a 
 screw driver slot in the head of a screw after it is cut from the rod. 
 
198 
 
 MECHANICAL PROCESSES 
 
 212. Examples of Work from the Screw Machine. Fig. 92 
 shows a variety of small articles made on screw machines. The 
 sizes of these articles vary in length from a fraction of an inch to 
 
 
 
 
 vv- 
 
 FIG. 92. Products of the Automatic Screw Machine. 
 
 more than two inches. The specimens shown are pointed to the 
 right the same as they were held in the machine during the process 
 of making.* 
 
 * Paragraph 439 of the Appendix outlines the work of cutting the 
 piece W of Fig. 92. 
 
CHAPTER VII. 
 
 SHOPS OF MACHINERY BUILDING AND REPAIRING PLANTS. 
 DRAWINGS FOR SHOP USE. 
 
 213. Distinctive Features of Building and Repairing Plants. 
 
 The building of ships,, engines, locomotives, machine tools and 
 large machines for a great diversity of purposes necessitates bring- 
 ing together the products of several different shops. While each of 
 these shops considered alone is virtually a place for the re-manu- 
 facture of metals along its own particular lines, the assembled 
 products of the several shops present such a diversity of construc- 
 tion and each machine or structure so built has so distinctive an 
 identity of its own, that an establishment made up of an assemblage 
 of such shops is regarded as beyond the limitations of a re-manu- 
 facturing plant. 
 
 For example, a ship or a locomotive is a much more distinctive 
 product than the plates, castings, bolts, rivets, pipes, etc., which 
 compose it, and the assemblage in one establishment of the different 
 metal-working shops required to build either embodies the capacity 
 for turning out, quite as readily, machines or structures of many 
 other kinds. 
 
 Assemblages of shops capable of uniting such a diversity of roll- 
 ing mill and re-manufactured products into highly complex con- 
 structions are also most advantageously fitted as general repair 
 shops, and particularly, because of its accessibility, is a shipbuild- 
 ing plant also an extensive ship-repairing plant. 
 
 214. Shops Composing a Building and Repairing Plant. The im- 
 portant shops of a large building and repairing plant are : 
 
 (1) The Woodworking shop, including the Pattern and the 
 Joiner shops, sometimes separate. 
 
 (2) The Foundry. 
 
200 MECHANICAL PROCESSES 
 
 (3) The Blacksmith or Forge shop. 
 
 (4) The Machine shop. 
 
 (5) The Boiler shop. 
 
 (6) The Copper and Sheet Metal shop, sometimes divided into 
 two shops. 
 
 (7) The Plate and Angle shop, for shipyards and, to a less ex- 
 tent, for bridge material plants. 
 
 Of prime importance to any manufacturing plant is the drafting 
 room, or drawing room, in which the design of machinery parts is 
 worked out and drawings of these parts are made to guide the 
 several shops in shaping their respective parts for the complete 
 machine. In a ship-building plant the drawings of the ship's hull 
 are elaborated by scribing them out to full size on the floor of the 
 mould loft as the best means of obtaining the exact form of the 
 various individual frames and plates of which the hull is composed. 
 
 A very essential adjunct to the machine shop is the erecting 
 shop, where the finished parts of a machine are assembled and 
 secured together as a complete unit. All engines and large 
 machines are thus assembled and tried, after which they are dis- 
 mantled and moved away. 
 
 Of indispensable importance in metal producing and many metal 
 shaping establishments are (a) the chemical laboratory for analyz- 
 ing materials, (b) the testing room, for testing the strength of 
 materials, and (c) the inspecting department for inspecting and 
 testing finished products. 
 
 215. The Drawing Room. When a designer has, determined 
 upon the action, position, form and material of each part of a 
 machine, his ideas are sent to the drawing room in one or more 
 sketches. From these an assembled drawing is made of the whole 
 machine, to a definite scale, and by aid of the sketches and the 
 assembled drawing, detail drawings are made in larger scale, con- 
 venient for showing the details of each part and for recording the 
 dimensions. 
 
 In the design of a ship, bridge, structure or machine of any kind, 
 the kind and quality of materials to be used must be determined by 
 
SHOPS OF MACHINERY BUILDING PLANTS 201 
 
 the designer., who must also determine the size and shape of each 
 part with a view to giving it the required strength. 
 
 216. Drawing-Room Methods. Assembled and detail drawings 
 are first made in pencil on a quality of heavy white or straw-colored 
 paper which will stand considerable erasing. A sheet of tracing 
 cloth is placed over this work, when completed, and the work 
 copied,, or traced, in ink. The tracing is then used for making 
 blue prints or black prints and is kept on file in the drawing room. 
 Many drawing rooms are provided with a fire and water-proof 
 vault for the safe keeping of valuable tracings. 
 
 217. Shop Drawings. The shops must be supplied with draw- 
 ings of any piece of machinery to be made,, as guides to the work- 
 men. These drawings are usually blue or black prints made from 
 the tracings, as mentioned in the preceding paragraph. 
 
 The information in the following items should be shown by a 
 drawing : 
 
 (1) One or more views of the article, amplified by cross-section 
 views where needed, to show fully its form. 
 
 (2) Dimensions sufficient to make the article to the exact size 
 required, and sufficient to save the workman the necessity of adding 
 several dimensions to find another dimension. 
 
 (3) Designation of the material or materials of which the piece 
 is to be made. 
 
 (4) Designation of the number of pieces required. 
 
 (5) Indications of any special features of material, finish, or 
 changes from usual conditions. 
 
 (6) The scale to which the drawing is made, or the designation 
 of the scale of each of the parts if they are drawn to different scales 
 on the same drawing. 
 
 (7) The title and number of the drawing, giving names and uses 
 of the parts shown, date of authorization and name of authority 
 approving the drawing, and, if the drawing supersedes another 
 drawing, a statement to this effect, giving name, date and number 
 of superseded drawing. 
 
202 MECHANICAL PROCESSES 
 
 218. Methods of Representing Articles on Drawings. Figures 
 93 and 94 are examples of two methods of showing an article on a 
 drawing. The former is the orthographic method which shows 
 three views projected upon three planes of reference as used in 
 descriptive geometry, and the latter is the isometric method, used 
 particularly in free-hand sketches and now used on finished 
 drawings. 
 
 In many cases, two orthographic views will show fully the details 
 of an article, particularly if one is a cross-section view. Simple 
 articles may be shown by one view. In Fig. 94 the isometric axes 
 AB, AC and AD are 120 apart, that is, the angles CAD, DAB and 
 CAB are 120, with AB vertical. 
 
 219. Consecutive Order of Shop Work. It is a part of the work 
 of the designer of any mechanical structure or machine to determine 
 not only the material of which each piece of the structure is to be 
 made, but the general method of making it, which necessarily in- 
 cludes a designation of the shops in which the work is to be done. 
 
 If an article is to be shaped in cast iron, cast steel, or other cast 
 metal, a pattern, usually of wood, must first be made in the pattern 
 shop. This is made according to dimensions and other information 
 given on the drawing. This pattern is used in the foundry as a 
 model for a mould, which, when prepared, is poured with molten 
 metal. The piece thus cast more or less roughly, is cleaned and 
 used sometimes without further work upon it, but if accurate 
 fitting and exact dimensions are necessary for the casting, it goes 
 to the machine shop to be machined, and possibly ground if very 
 accurate fitting is needed. 
 
 If the article is to be made as a forging, a bloom, billet, or 
 smaller piece from the rolling-mill stock kept on hand is forged 
 to the required shape either by hand or by steam hammer in the 
 blacksmith shop, and the forging may, in some cases, be used just 
 as it comes from the anvil, or, if it must be finished to particular 
 shape and dimensions, it goes to the machine shop. 
 
 Many articles may be made in the machine shop directly from 
 rods, bars, plates and shapes from the rolling mill, without having 
 been given preliminary form in the foundry or the blacksmith shop. 
 
SHOPS or MACHINERY BUILDING PLANTS 
 
 203 
 
 FIG. 93. Orthographic Projections. 
 
 FIG. 94. Isometric Projection. 
 
204 MECHANICAL PROCESSES 
 
 The boiler shop works into shape plates, sheets, tubes, ete.j, direct 
 from the rolling mill, and fittings produced in other shops. 
 
 The copper and sheet-metal shop draws its sheet material direct 
 from the rolling mill. Much copper and brass tubing, obtained 
 from the tube mills, is used in the copper shop. 
 
 The plate and angle shop uses plates and structural shapes sup- 
 plied direct from the rolling mills. 
 
 All shops of building and repairing plants find more or less use 
 for bolts, rivets, screws, and various other products of the re- 
 manufacturing industries in connection with their own shop 
 products. 
 
CHAPTER VIII. 
 THE PATTERN SHOP. 
 
 220. Work of the Pattern Shop. This shop is a woodworking 
 shop devoted to the making of wood patterns for the foundry. 
 These patterns are used as models for shaping moulds of articles to 
 be cast from molten metals. 
 
 A pattern maker must be an expert woodworker, and must be 
 skilled in reading correctly the most intricate mechanical drawings. 
 He must also be versed in the methods used by the foundryman in 
 making moulds, to know how to make patterns in forms best suited 
 to foundry requirements yet not unnecessarily costly. 
 
 Cabinet making and joiner work may be done by pattern makers 
 with pattern-shop equipment, but in large ship and machine-build- 
 ing establishments, the pattern shop and joiner shop are usually 
 separate. 
 
 221. Pattern-Shop Equipment. The woodworking appliances 
 which compose the pattern-shop equipment may be divided into 
 (1) power tools (machine tools driven by power), (2) hand tools, 
 and (3) accessory appliances such as work benches, clamps, glue 
 pots, etc. 
 
 222. Power Tools. Machines of this kind are, in all kinds of 
 shops, labor-saving devices. While many such machines might be 
 omitted from a shop equipment, the time and cost for turning out 
 work without them would be greater than if the machine were used, 
 and in many cases hand work would be less accurate. 
 
 The usual power-tool equipment of pattern shop includes : 
 
 (1) Circular saw. t v 
 
 (2) Wood lathes, usually large and small sizes. 
 
 (3) Face lathe. 
 
 (4) Band saw. 
 
 (5) Hand planer, or jointer. 
 
 (6) Surface planer. 
 
 (7) Boring machine. 
 
 (8) Mortise machine. 
 
 (9) Scroll saw. 
 14 
 
206 
 
 MECHANICAL PROCESSES 
 
 (10) Emery wheel. 
 
 (11) Grind stone. 
 
 The variety and quantity of work to be done in a shop determine 
 its power-tool equipment, hence in many small shops some of the 
 tools of the foregoing list may be omitted, while in the most ex- 
 tensively equipped shops some special tools not here named may be 
 installed. 
 
 223. The Circular Saw. Fig. 95 shows a type of circular-sawing 
 machine such as is used for pattern-shop work. This machine con- 
 
 FIG. 95. Circular Saw. 
 
 sists essentially of (1) a frame which carries the saws, saw mech- 
 anism and table; (2) a flat-topped saw table of ribbed cast iron, 
 and (3) one or two saws mounted ready for use. 
 
 The saw table is made in two sections, divided along AB. Both 
 sections always remain in the same plane relative to each other, 
 but the part C is mounted on suitable slides on which it may be 
 moved back and forth in the direction AB parallel to the plane of 
 the saw. Small work to be sawed is held by hand against the guide 
 or " fence " D which may be set so that the end of the piece of 
 work will be cut off at any angle desired as the movable table carries 
 
THE PATTERX SHOP 207 
 
 it past the saw. The block G may be adjusted along the stop rod 
 for gaging the length to which pieces are sawed. 
 
 When the machine is used for ripping boards into narrower 
 widths, the ripping fence F is set as a guide at the distance from 
 the saw necessary for cutting the widths required. Eipping, or 
 sawing along the grain of wood, is done by the coarse-toothed saw 
 for more rapid working. 
 
 While the upper saw is in use, the belt which drives the saws is 
 not in contact with the belt wheel of the lower saw, hence this saw 
 
 H- 
 
 PIG. 96. Woodworking Lathe. 
 
 is idle. When the lower saw is to be used, it is revolved into posi- 
 tion by turning the wheel W while the machine is not running, and 
 as one saw is carried into position for use, the other is simulta- 
 neously carried below the table. 
 
 The saw table may be tilted about AB as an axis for sawing at 
 an angle. The saws should run at about 600 revolutions per 
 minute. 
 
 224. The Speed Lathe. This is the common designation for a 
 small wood-turning lathe, which turns at high speed. As the 
 cutting is done by hand tools, this lathe is sometimes called a hand 
 lathe. Fig. 96 shows a view of this lathe. Its main parts are : A, 
 Bed; B, Head stock; G, Tail stock; D, Tool-rest holder. 
 
208 
 
 MECHAXICAL PROCESSES 
 
 Work is held in the lathe between the live center F and the dead 
 center G t or the live center is punched out by means of the rod II 
 and the work is fastened by screws to the face K, shown in Fig. 97. 
 As the work revolves it is shaped by hand tools steadied on the tool 
 
 FIG. 97. Lathe Headstock. 
 
 rest M. The live center drives the work when it is suspended 
 between centers. 
 
 The head stock carries a hollow steel spindle which is made to 
 revolve at different speeds by a belt on one of the cone pulleys E. 
 Fig. 97 shows a cross section of the moving parts of the head stock. 
 
 FIG. 98. Specimens of Wood-Lathe Work. 
 
 Fig. 98 shows two examples of work turned in this lathe. The 
 piece C is held between centers and the piece F is held only on the 
 face plate. 
 
 The tail stock may be moved along the lathe bed to suit the 
 length of work, and when it is clamped to the bed, the dead center 
 may be moved back and forth by turning the wheel L. 
 
THE PATTERN SHOP 209 
 
 These lathes are used not only for turning wood, but are adopted 
 to finishing articles of metal after they have been roughed to shape 
 in a machine lathe. For hand turning of metals, different tools 
 are used from those for turning wood. 
 
 The swing of a lathe is the diameter of work which can revolve 
 freely between the centers and the lathe bed or its attachments. 
 The distance between centers is the length of work which may be 
 held between the lathe centers. These definitions apply to all 
 classes of lathes, in either pattern or machine shop, and are the 
 measurements by which the sizes of lathes are designated. 
 
 '" 
 FIG. 99. Turning Tools for Wood Lathes. 
 
 225. Turning Tools. Fig. 99 shows the turning tools ordinarily 
 used with wood lathes. Xaming from left to right they are: 
 
 (1) Round-nose chisel. (5) Skew chisel. 
 
 (2) Flat scraping chisel (6) Double-end skew chisel. 
 
 (3) Gouge. (7) Combination roughing and 
 
 (4) Diamond-point chisel. smoothing chisel. 
 
 lumbers C and 7 are used only on larger size lathes, and are 
 clamped in a tool holder. Fig. 100 shows a tool holder which 
 may be used on small or large lathes. It is at present rigged for 
 holding hand tools. 
 
 226. The Wood Lathe. This designation is given to the pattern- 
 shop lathe for turning large work. 
 
 It embodies the same features as the small lathe, and is operated 
 in the same way. Hand tools may be used for cutting, or a heavier 
 
210 
 
 MECHANICAL PROCESSES 
 
 tool may be clamped in the tool post which holds the bar of the 
 hand-tool holder shown in Fig. 100. 
 
 Most large lathes are equipped with a movable tool carriage in 
 place of the tool-rest holder, which moves by hand or by power 
 
 FIG. 100. Tool Holder. 
 
 feed along the lathe bed. The view in Fig. 100 shows the upper 
 part of a carriage of a large lathe. 
 
 227. The Face Lathe. This lathe consists merely of a head 
 stock mounted for carrying a large face plate. It is used for turn- 
 
 FIG. 101. Face Lathe. 
 
 ing flat work of large diameter. This type of lathe is shown in 
 Fig. 101. 
 
 228. The Band Saw. This machine is shown in Fig. 102. It is 
 used for sawing along straight or curved lines, and may be used for 
 
THE PATTERN SHOP 
 
 211 
 
 light or heavy work, according to the size of the saw on the 
 machine. Several saws are provided. They are endless steel bands 
 with teeth along one edge. 
 
 FIG. 102. Band Saw. 
 
 Work is placed on the table T. The saw., which is carried on two 
 large rubber-tired wheels, moves through a slit in the table, and is 
 driven by the lower wheel. 
 
 For most work, the table T is perpendicular to the path of the 
 saw, but the table may be tilted about the slot as a horizontal axis, 
 for sawing at an angle, and is clamped by the handle P. 
 
212 
 
 MECHANICAL PROCESSES 
 
 To prevent the saw being pushed gradually off the wheels by the 
 pressure of the work against it, the back edge rubs against two 
 guides, the upper of which is carried by a stem // which may be raised 
 or lowered to suit various thicknesses of work, and which is clamped 
 in position by the handle K. The saw is kept taut over both wheels, 
 which are kept in the same plane by the tilting screw M. 
 
 It is well to note that the more recent designs of all classes of 
 machines in all shops are provided with guards and protectors to 
 
 FIG. 103. Hand Planer. 
 
 protect workmen from injury. The saw here described is guarded 
 by casing not shown in the figure. Many machines are provided 
 with means for stopping them automatically in case of accident. 
 
 229. The Hand Planer. This machine, shown in Fig. 103, is 
 also known as a jointer. It is used to cut the face or edge of a 
 board to a plane surface, to chamfer corners, to gain, check, plow, 
 match, etc. Board edges and parts of patterns are cut true in this 
 machine to enable them to fit closely together for gluing. This 
 machine does the work of a man with a hand plane, and is best 
 adapted to small work which may be easily lifted and handled. 
 
THE PATTERN SHOP 213 
 
 The machine consists essentially of a base, on which is mounted 
 two flat tables B and C, one slightly higher than the other, a cutter 
 head H, and a " fence " D which serves as a guide for the work. 
 
 Either table may be raised or lowered a small amount to regulate 
 the cut of the knives carried by the cutter head, and may be 
 moved horizontally to or from the cutter head to give ample clear- 
 ance for the knives and for shavings. The work to be planed is 
 pushed along on the table by hand over the rapidly revolving 
 cutter head, the two knives of which are set to take equal depths of 
 cut from the under surface of the wood. The cutter head consists 
 of a steel cylinder slotted for holding the two long knives which 
 are held in place by small screws. 
 
 Many forms of grooves may be cut by setting in one of the knife 
 slots a knife with its edge of the required contour. 
 
 230. The Surface Planer. This machine is constructed with the 
 same method of cutting provided for the hand planer, but it is a 
 much heavier machine, and is used for surfacing rough boards and 
 timbers. Its table is made in one flat piece fitted to be raised or 
 lowered readily to suit the thickness of the board or timber passing 
 under the knives. The work, resting on the table, passes under the 
 cutter head, also it passes under rollers which hold it down before 
 and after it reaches the cutter head. These rollers feed the work 
 along the table. 
 
 231. The Boring Machine. This machine is used for boring 
 holes, and consists essentially of a round spindle held horizontally 
 or vertically in suitable bearings. The spindle carries a bit or 
 auger and is made to revolve rapidly. The work to be bored is 
 placed on a suitable stand and remains stationary while the spindle 
 moves in the direction of its length as it revolves, until the bit 
 cuts into the material to the desired depth. In some designs of this 
 machine the spindle merely revolves and the material is fed against 
 the bit. 
 
 232. The Mortise Machine. This machine is used to cut square 
 or rectangular holes in wood. It consists essentially of a vertical 
 shaft which is made to oscillate in the direction of its length, and 
 which carries a heavy chisel at the lower end. Mortising machines 
 are often worked by the pressure of the foot, without machine 
 power. 
 
214 MECHANICAL PROCESSES 
 
 233. Hand Tools. The hand tools of pattern making are more or 
 less familiar as those used in carpentry work. Attention will be 
 called to a few special tools and features. 
 
 Saw Teeth. In sharpening saw teeth,, the file should be held 
 at an angle to the plane of the saw blade so that the teeth will 
 present an appearance shown in Fig. 104. The teeth should also 
 be " set " to keep the wood from binding the sides of the saw. 
 This is done by bending the teeth marked c slightly to one side of 
 
 FIG. 104. 
 
 the plane of the saw, and by bending those marked b slightly to 
 the other side. In this way the saw cut is slightly wider than the 
 blade thickness of the saw. 
 
 The teeth of circular saws may be " set " or may be " swaged/' 
 In swaging, the teeth are not bent to one side, but the tooth end 
 is expanded by a swage and hammer so that its cut is wider than 
 the thickness of the saw. 
 
 Y 
 
 FIG. 105. Trammel Points. 
 
 Trammel Points. For describing arcs of large radii, a pair of 
 trammel points, A and B, are mounted on a bar of wood or metal 
 as shown in Fig. 105. These points may be clamped at any posi- 
 tion along the bar. 
 
 Wood Trimmer. A very useful pattern-shop tool is the wood 
 trimmer, shown in Fig. 10G. This machine is much used to cut 
 ends of wood pieces to an exact angle "(usually square) with the 
 face or edge of the piece. It consists essentially of a flat table B 
 along the rear edge of which slides a triangular-shaped piece, carry- 
 
THE PATTERN SHOP 
 
 215 
 
 ing two knives C and D. The plane of these knives is exactly 90 
 to the plane of the table. The guide pieces F and G have their 
 faces perpendicular to the plane of the table, and they may be 
 swung around on vertical axes and clamped at any desired angle 
 to the plane of the knives. A piece of work to be cut is held 
 securely by the hand in the angle formed between one of the guides 
 F or G and the table, and the knife cuts off the projecting edge. 
 
 FIG. 106. Wood Trimmer. 
 
 The large wheel at the back of the trimmer moves the knives back 
 and forth along the table edge. 
 
 234. Materials used for Patterns. The usual and best adapted 
 material for patterns is wood, although a great many foundries 
 which make large quantities of one article use patterns made of 
 brass or other metals, to avoid excessive wear on them. 
 
 A suitable wood for patterns must have the following-named 
 requisites : 
 
 (1) It must be well seasoned and must not warp. 
 
216 MECHANICAL PROCESSES 
 
 (2) It must be straight grained and free from large or small 
 knots which will interfere with ready working or prevent a smooth 
 finish. 
 
 (3) It must not be subject to shrinkage with age. 
 
 The three woods much used for patterns are white pine, mahog- 
 any, and cherry, although other woods are more or less used in 
 many localities. Red wood is much used on the Pacific coast. 
 Mahogany is the best of these woods, but it is expensive and its use 
 is therefore limited to small and medium-sized patterns requiring 
 durability and permanence of shape. 
 
 Pine is much used for large patterns and for the ordinary run of 
 small patterns. 
 
 235. Joints and Cuts in Woodworking. 
 
 Ripping is sawing wood along the grain. 
 
 Cross cutting is sawing across the grain. 
 
 A warped board is said to be out of wind. It may be planed 
 straight in the planer if only moderately out of wind so that but 
 little material needs to be removed. 
 
 In Fig. 107 the cuts commonly designated in woodworking arc 
 lettered as follows : 
 
 a. a. Chamfering or cornering. 
 
 b. Rabbeting. 
 
 c. Filleting (in contrast to square corner d). 
 /. Plowing. 
 
 g. Gaining. 
 
 h. Checking. 
 
 /. Raised paneling. 
 
 Specimens of wood joints are : 
 
 I. Mortise and tenon. 
 
 m. Tongue and grove, or matched joint. 
 
 n. Dovetail. 
 
 p. Miter joint. 
 
 r. Half joint. 
 
 s, t, u. Scarf joints. 
 
 w. Segment work. 
 
 x. Stave work. 
 
THE PATTERN SHOP 
 
 217 
 
 FIG. 107. Cuts and Joints used in Woodworking. 
 
218 MECHANICAL PROCESSES 
 
 236. Essential Features of Patterns. A pattern must serve the 
 purpose of making a mould which, when filled with molten metal, 
 will produce a casting of a certain form and size. It would at first 
 thought appear that to serve this purpose the pattern should be 
 made an exact model of the desired casting. This is true only for 
 some small simple patterns. There are some styles of patterns, or 
 rather substitutes for patterns, which bear little if any resemblance 
 to the moulds to be shaped from them. 
 
 The essential features which enter into the making of patterns 
 and which are made necessary by considerations of their practical 
 use are outlined in paragraphs 237 to 241 inclusive. 
 
 237. Shrinkage Allowance. Metals contract more or less in 
 cooling; hence when the molten metal which fills a mould begins to 
 cool, it also begins to contract, and when cold the casting is smaller 
 than the mould. To obtain a casting of the size designated on the 
 drawing, its pattern must be made slightly larger than the casting. 
 This enlargement in the size of a pattern is called the shrinkage 
 allowance. The amount of this allowance varies with different 
 metals and with different-sized castings of the same metals, hence 
 the allowance necessary for each pattern is judged more or less 
 by the experience of the pattern maker. The usual shrinkage 
 allowances average about as follows, viz. : 
 
 Cast iron 1/8 inch per foot. 
 
 Heavy brass 1/8 
 
 Steel 3/16 " " " 
 
 Thin brass 3/16 " " " 
 
 Aluminum 7/32 
 
 Lead 7/32 " 
 
 In laying out a pattern from the drawing the pattern maker 
 uses the shrinkage rule for measurements. This is a rule which has 
 the shrinkage allowance added, as, for example, a two-foot shrink- 
 age rule for cast iron would be 24*4 inches long, graduated in 
 inches and fractions. Each standard inch and fraction is thus in- 
 creased by an amount equal to the shrinkage allowance. 
 
 Castings which are to be machined to a definite size must not 
 only have an allowance made for shrinkage, but a certain amount 
 
THE PATTERN SHOP 219 
 
 of extra metal must be allowed for finishing. Also that part of 
 the casting which is uppermost in the mould frequently has a still 
 further allowance of metal to contain impurities and air bubbles 
 which float to the top of the casting and may be imprisoned therein 
 when the mould is poured. 
 
 The shrinkage allowance for small castings is sufficiently pro- 
 vided for by the rapping given a pattern to loosen it when it is 
 removed from the sand of the mould. 
 
 238. Drawing a Pattern from the Mould. After the sand is 
 packed about the pattern in a mould, the pattern must be with- 
 drawn before the mould can be filled with metal. In determining 
 how a pattern shall be built, the first consideration is to decide 
 how it shall rest in the mould with relation to the joints between 
 the parts of the mould, so that it may be withdrawn without tear- 
 ing the sand. It is usual to give a pattern a slight taper to facili- 
 tate its withdrawal. 
 
 This taper or " draft " is all that is necessary for the ready with- 
 drawal of small and simple patterns, but the majority of patterns 
 are of such shapes that they must be made in two or more parts, 
 easily separable, to get them out of the mould. These parts are 
 held together by dowel pins. A pattern is usually divided along 
 its plane of symmetry into two parts, and is so moulded that this 
 division coincides with the parting of the mould. A mould is also 
 usually made in two parts, the upper of which is called the cope 
 and the lower is called the drag or nowell. When the upper part 
 of the mould is lifted away from the lower part, the upper part of 
 the pattern is lifted with it. Each part of the pattern can then be 
 lifted from the sand after a light rapping. 
 
 If either part of the pattern has any projection which would 
 tear the sand in withdrawing, it must be dowelled in place in such 
 a manner that it will be left behind when the part to which it is 
 attached is withdrawn, or else the mould must be so built that 
 a section of it may be taken away as a " drawback " before that part 
 of the pattern is lifted out. 
 
 Figs. 108 and 109 show examples of simple patterns suitably 
 made for withdrawing from the moulds. 
 
220 
 
 MECHANICAL PROCESSES 
 
 Fig. 108 shows two views of a gland G to be cast hollow. The 
 bolt holes 1) in the flange and the taper at the end d are cut in the 
 machine shop after the casting is made. This gland is cast from the 
 
 Y/////////////////////// 
 
 G 
 
 FIG. 10S. Metal Casting and its Pattern. 
 
 FIG. 109. A Casting and its Patterns. 
 
 pattern H, placed horizontally in the mould. The halves of the 
 pattern are separated in the view to show the line of parting. The 
 bolt holes are reinforced by small raised pieces li, cast with the 
 flange. If these projections were made fast on the pattern they 
 
THE PATTERN SHOP 
 
 221 
 
 would tear the sand of the mould when each half of the pattern 
 was lifted out in the directions of the arrows, hence they are held on 
 the pattern flange by small wires Jc which are withdrawn when 
 enough sand has been rammed against the flange to hold the pro- 
 jections in place. The pattern may then be withdrawn from the 
 mould, leaving the projections behind, and these are drawn out 
 horizontally into that part of the mould space which was occupied 
 by the flange. 
 
 In Fig. 109 the moulds B and C, of the same casting A, show two 
 methods of constructing a pattern for ready w-thdrawal from the 
 sand. The mould B is the simpler. In this mould, the cope is 
 
 FIG. 110. Pattern and Mould of Gear Wheel. 
 
 lifted, the parts marked 1 are lifted out together, and the parts 
 marked 2 and 3 are then removed by first drawing them horizon- 
 tally into the space left by the lower part of 1. 
 
 In the mould C f parts 4 and 5 are merely dowelled together. The 
 cope is lifted, part 4 is lifted, and the cheek is then lifted, leaving 
 part 5 on the parting between the cheek and the drag. In a mould 
 of three parts, the middle part is called the cheek. 
 
 The pattern of the bevel wheel shown in Fig. 110 is made in two 
 parts. The hub and the spokes are made as one part. The mould 
 of the wheel is parted along the line a b c d g I m n o, so that the 
 hub and spokes will lift with the cope. 
 15 
 
222 
 
 MECHANICAL PROCESSES 
 
 239. Core Prints and Core Boxes. A hollow, recess, or cavity in 
 a casting is usually made by means of a baked-sand core. This 
 core is placed in the mould after the pattern is removed. It occu- 
 pies the space to be made hollow and is surrounded by metal when 
 the mould is poured. 
 
 The pattern is not recessed nor made hollow to correspond with 
 the casting, but, instead, is made as shown in Fig. 108, with solid 
 projections or core prints extending from the part to be hollowed 
 out. The prints in the figure are marked m and n, and when the 
 two parts of the pattern are together, the end view of each print is, 
 in this case, a circle. These prints have the same axis and are of 
 the same diameter as the hollow part of the casting. The im- 
 pressions which core prints make in the mould serve as bearings 
 to support the ends of the core. 
 
 The pattern maker must supply with the pattern a core box, as 
 in Fig. Ill, in which the moulder shapes the core. A core box is 
 
 FIG. 111. Core Box. 
 
 usually made in symmetrical halves for the purpose of removing a 
 core readily after the sand composing it is properly rammed therein. 
 The halves are placed correctly together by aid of wooden dowel 
 pins and the moulder holds the box together with a clamp. 
 
 In many cases, cavities or hollows can be moulded without the 
 aid of cores. Patterns, are then made, without core prints, to the 
 contour of the desired casting. 
 
 FIG. 112. Square and Filleted Corners. 
 
 240. Fillets. Sharp angles caused by the meeting of surfaces in 
 different planes should be avoided in solid metal work wherever 
 possible. A sudden change in the direction of a surface, causing a 
 
THE PATTERN SHOP 
 
 223 
 
 sharp angle as at B, Fig. 112, is detrimental to the strength of a 
 casting or forging in the angle. This condition may be avoided 
 by making the change of direction gradual, as at (7. In shop par- 
 lance, the corner C is said to be filleted. 
 
 Pattern shops are supplied with a soft metal fillet material wound 
 on reels. This is tacked in all angles of patterns where fillets are 
 not made in the wood itself in the course of shaping it for the 
 pattern. 
 
 241. The Prevention of Warping. Intricate patterns, whether 
 small or large, must be made of several pieces of wood so joined 
 together by glue that the tendencies of the several pieces to warp 
 may be counteracted. This is accomplished by placing the pieces 
 
 FIG. 113. Tendency in Warping. 
 
 together so that the grain of adjacent pieces runs in different 
 directions. A very common example of this is seen in the segment 
 work of Fig. 107. Also, it may in some cases be advantageous to 
 note the part of the log from which the wood is cut. The direction 
 in which a board tends to warp is shown by the log end in Fig. 113. 
 
 242. Marking and Preserving Patterns. It is very essential to 
 shellac or varnish wood patterns to keep them from absorbing 
 moisture from the sand of the mould. This smooth coating also 
 assists in drawing them from the mould. 
 
 After applying shellac or varnish, many shops paint patterns red 
 for cast-iron castings and brown for steel castings. Core prints 
 and core boxes are almost always painted black. Occasionally some 
 part of a pattern is made merely to enable the pattern to be drawn 
 from the mould and is not to be reproduced in the casting. Such 
 
224 MECHANICAL PROCESSES 
 
 a part is usually striped with black to designate to the moulder 
 that the space it leaves in the mould is to be filled up with sand. 
 
 Patterns are too expensive to be thrown away when the castings 
 desired are made from them. Each pattern should be marked or 
 tagged with a number and its name, and should be stored in a 
 store room where it can be readily found. A record book of 
 patterns is kept to show, among other things, how many patterns 
 are in a complete set for making, for example, the several castings 
 of an engine. 
 
 243. Pattern-Shop Accessories and Methods. Experience in 
 pattern building has brought into use a number of helpful appli- 
 ances and methods which greatly assist efficiency and rapidity of 
 work, and which are mentioned specifically in this and the two para- 
 graphs following. 
 
 The work bench is the center of the pattern maker's activities. 
 This bench is particularly designed and equipped for his conveni- 
 ence in saving time. Essential fittings are (1) the bench vise, (2) 
 the adjustable bench stop against which work is held for planing, 
 (3) the bench hook for steadying work while sawing, chiseling, 
 boring, etc., (4) the miter box to guide the saw in cross cutting a 
 piece at angle of 30, 45, 60% or 90 to its length, and (5) a rack 
 at the back of the bench on which tools can be placed in a certain 
 order for finding them readily. 
 
 244. The Laying-Down Board. Adjacent to each bench is a 
 large drawing board, about 6x8 feet in size, made of clear soft wood 
 of sufficient thickness to be rigid, and conveniently supported. 
 
 When the pattern maker receives from the drawing room a work- 
 ing drawing from which a pattern is to be made, his first step, after 
 determining the allowances for shrinkage and finishing, is to copy 
 the drawing to full size on the board, marking with compasses and 
 steel scriber, and using the shrinkage rule for measurements. 
 
 The next step is to decide how the pattern shall be drawn from 
 the mould, and then the method of putting it together is decided, 
 i. e., the way in which the various pieces of wood composing it shall 
 be joined. The pattern maker is now ready to get out the needed 
 material and work it into shape. 
 
 245. The Marking-Off Table. The building of patterns and 
 finishing them accurately to shape is greatly assisted in many cases 
 by a marking-off table. This is a flat cast-iron slab about 4x6 feet 
 
THE PATTERN SHOP 
 
 225 
 
 surface which is ribbed underneath for rigidity. It is mounted as 
 shown in Fig. 114. The sides and ends are at right angles to the 
 top. 
 
 Such a table affords a level base for the purpose of accurate build- 
 ing up or measuring a pattern, particularly when its parts are 
 intricate. 
 
 FIG. 114. Marking-Off Table. 
 
 246. Varieties of Patterns. In forms of construction, patterns 
 may be divided into three varieties, viz., (1) solid patterns, (2) 
 hollow and skeleton patterns, and (3) sweeps. 
 
 Small patterns are built solid, made up in most cases of parts so 
 glued together as to prevent warping. Some large patterns are also 
 made solid for rigidity. Hollow and skeleton patterns and sweeps 
 are made to save expense. 
 
 FIG. 115. Steam Nozzle. 
 
 Large hollow patterns may be built up of segment work or stave 
 work as shown in W and X, Fig. 107. 
 
 247. Skeleton Patterns. The skeleton pattern is well adapted to 
 irregular hollow castings, such as the steam nozzle with three out- 
 lets, a drawing of which is shown in Fig. 115. The pattern is made 
 in two parts divided along the plane of symmetry AB. In building 
 
226 
 
 MECHANICAL PROCESSES 
 
 this pattern, the three outlet flanges are built in halves of segment 
 work, and these are joined by skeleton framing made up as a back- 
 bone, ribs and battens for each half. The marking-off table may be 
 used to great advantage in this work. 
 
 Fig. 116 is a simple form of skeleton pattern shown merely to 
 illustrate the method of building and using this kind of pattern. 
 This is the pattern of a plain length of cylindrical pipe. Each 
 half is formed of a backbone, two ribs, and four battens. 
 
 The lower half of the pattern is made so that the inner- surfaces 
 of the backbone and other parts are faired to the contour of the 
 inner surface of the casting, and the upper half is made so that its 
 
 FIG. 116. 
 
 outer surfaces are faired to the contour of the outer surface of the 
 casting. The battens C occupy part of the space of the walls of the 
 casting. 
 
 In making a mould from this type of pattern, the moulder beds 
 the lower half of the pattern in the sand of the lower half of the 
 mould, making the parting along the line 1, 2, 3, 4, 5. 
 
 The core for the casting is then formed of sand and other 
 materials in the space enclosed between the two halves of the 
 pattern. The core is built up as far as can be done before placing 
 the upper half of the pattern. When this half is placed, the core 
 surface is carried to the outline of the semi-circle 6. Non-plastic 
 pasting sand is sprinkled over this surface (as was done over the 
 joints 1, 2, 3, 4, 5) and the upper half of the mould is built thereon. 
 
THE PATTERN SHOP 227 
 
 When completed, the upper half of the mould is lifted off, and 
 the sand is scraped from between the several battens and backbone 
 joining the two end ribs of the upper half of the pattern by means 
 of the small strike or strickle S, which scrapes away the sand to 
 the thickness of the batterns c. The upper half of the pattern is 
 then lifted away, exposing the true surface of the upper half of 
 the core. The core is then lifted out, and the strike T is used to 
 scrape away the sand between the longitudinal parts of the lower 
 half of the pattern, after which this half is lifted out. 
 
 The strikes S and T have scraped out the sand which occupied 
 the space for the casting. After the lower half of the pattern is 
 lifted out, the mould is smoothed, the cavities left by the four end 
 ribs are filled to the extent needed, and the core is replaced in the 
 mould. The mould is now complete, ready for pouring. 
 
 248. Sweeps. When the surface of a casting, such as a steam 
 cylinder, a propeller blade and hub, etc., is wholly or in its main 
 features a surface of revolution, or may be generated by the revo- 
 lution of a line about a fixed axis, the mould for such a casting may 
 be formed almost entirely by the use of sweeps in place of patterns. 
 Such parts of the casting as are not surfaces of revolution are 
 moulded from patterns used in conjunction with the sweeps. 
 
 Sweeps are made up of pieces of pine board cut to such a profile 
 that they will form the surfaces desired when revolved on a vertical 
 spindle which is the axis of revolution of the casting to be made. 
 The generating edge of the sweep forms a surface in plastic sand 
 on a facing of brick work gradually built up to the contour of this 
 edge as the sweep is moved back and forth by the moulder. 
 
 Sweeps are used in making very large moulds built of bricks, 
 known as loam moulds, and not for small moulds made of sand in 
 boxes or flasks. Several SAveeps are required to make a complete 
 set. The use of sweeps will be shown in a description of making a 
 loam mould in the next chapter. 
 
CHAPTER IX. 
 THE FOUNDRY. 
 
 249. The Work of the Foundry. The work of this shop is divided 
 principally between moulding and casting. Moulds are prepared 
 by aid of patterns sent from the pattern shop, and are filled with 
 molten metal which solidifies to the more or less rough outline of 
 the casting desired. 
 
 250. Iron, Brass and Steel Foundries. The methods used in iron 
 and brass foundries are closely associated, and these two branches 
 are usually under one shop superintendent and in adjacent build- 
 ings. The steel foundry is separate, as its methods are enough dif- 
 ferent to be classed alone. 
 
 In location, it is highly important that a foundry site shall be 
 well drained and without an excess of sub-surface moisture. Large 
 moulds must be bedded in pits 8 or 10 feet deep to secure them for 
 withstanding the great pressure of a large bulk of molten metal. If 
 the soil over which the foundry is built is not a loose sand or loam, 
 it must be dug out to a depth of several feet where large moulds 
 are to be bedded and filled in with friable earth not pasty with an 
 excess of clay. 
 
 251. Classes of Moulds. There are four general classes of 
 moulds, designated as follows : 
 
 (1) Open sand moulds. (3) Dry sand moulds. 
 
 (2) Green sand moulds. (4) Loam moulds. 
 
 Open sand moulds are the cheapest class of moulds. They are 
 merely depressions made in a carefully leveled bed of sand in the 
 foundry floor. The upper surface of the casting remains exposed 
 to the air when poured. Only rough castings, flat on top, for 
 foundry uses, are made in open sand moulds. 
 
 Green sand moulds are so called because they are moulds in damp 
 sand, not baked or dried. They are the cheaper class of moulds, 
 and are usually made in wooden flasks. With increased skill in 
 moulding they are now extended to embrace moulds for large and 
 
THE FOUNDRY 
 
 229 
 
 somewhat complicated castings, thus reducing the cost of produc- 
 tion. The greater part of the castings of commercial objects are 
 made in green sand. 
 
 Dry sand moulds are virtually green sand moulds carefully made, 
 generally in iron flasks, and dried in a mould oven to make the sand 
 firmer and more stable. This class of moulds is used for castings 
 which have a complex form, and which must be smooth, sound, 
 correct in shape, and free from internal strains. Superior castings 
 are produced by this method, and the cost is about 1.5 times the 
 cost of similar castings from green sand moulds. A dried mould 
 surface can be given a very smooth finish, producing very smooth 
 castings. 
 
 FIG. 117. An Open Sand Mould. 
 
 Loam moulds are used for large complicated and important cast- 
 ings, such as large steam cylinders, propeller blades, etc. A loam 
 mould is built of bricks on large, flat, rigid, cast-iron plates. The 
 bricks of these moulds are faced with loam to form the mould 
 surface. 
 
 Loam and dry sand castings are about the same in quality, and 
 the relative expense of the two kinds of moulding depends upon 
 the shape of the casting and the quantity to be made. 
 
 252. Example of an Open Sand Mould. Fig. 117 shows an open 
 sand mould in course of preparation. This is very simple and de- 
 mands no particular skill. Two boards, A and B, are imbedded on 
 edge in the foundry floor and are leveled along their length and 
 across from one to the other. The sand between them is tamped 
 
230 
 
 MECHANICAL PROCESSES 
 
 down and leveled off by a straight-edged board drawn along A and 
 B, and a tracing of the plate to be cast is marked on this bed of 
 leveled sand. The outer edge and the center core of the mould are 
 formed by pressing damp moulding sand with the hand firmly 
 against wooden segments made to the necessary curvature. The 
 center core will core a hole in the center of the plate, and smaller 
 holes may be cored anywhere desired in the plate by small baked 
 cores C, C, which are kept from floating or washing out of position 
 by convenient weights, as at D. Lifting-lugs are provided at the 
 edges of the plate. This is a type of plate frequently used to form 
 the top of a loam mould. Small projections or prickers are usually 
 
 FIG. 118. Example of a Small Green Sand Mould. 
 
 cast on the under side of the plate to assist in holding the loam 
 coating which the plate must carry as a part of a loam mould 
 surface. Impressions are made for these prickers by sticking holes 
 in the sand with a small stick, or the prickers may be formed by 
 sticking two-inch nails in the bottom of the mould so that metal 
 poured in the mould will solidify about the nail heads. 
 
 253. Example of a Green Sand Mould. Fig. 118 shows a typical 
 small green sand mould in a two-part flask. This is a mould of 
 the pattern shown in Fig. 108. The upper half of the mould is the 
 cope and the lower half is the drag or nowell. The two parts of the 
 mould are separated at the parting. The casting is made hollow 
 by the core, resting in its bearings. A number of vents are punched 
 by a small steel wire before the pattern is removed. The vents con- 
 
THE FOUNDRY 231 
 
 duct away gas and steam generated in the sand by hot metal, and 
 prevent the escape of these into the mould. Before pouring, the 
 mould is weighted down to keep the cope from floating. Metal 
 is poured from a ladle into the 'basin, entering the mould through 
 the runner and gate. Many moulders designate the runner as the 
 sprue. As pouring continues, metal gradually fills the mould and 
 rises to the top of the riser. Vent gases escape at the top, around 
 the parting and along the bottom board. Air escapes from the 
 mould cavity through the riser as metal is poured in: A small vent 
 channel runs through the core, conducting gases to the parting. A 
 single flask often contains several moulds of small castings, all run 
 from the same sprue. 
 
 254. Essential Features of a Mould. All moulds, whether for 
 steel, iron or brass, must fulfill the following general requirements, 
 viz. : 
 
 (1) They must be made so that the pattern can be removed 
 readily therefrom. 
 
 (2) Not only must an opening be made in the sand for pouring 
 metal into the mould, but a riser hole must lead upward through 
 the sand from each of the high parts of the mould cavity. This 
 serves (a) to keep air from being imprisoned in the mould when 
 metal is poured in; (b) to allow for loose sand and scum on the 
 metal to float out, and (c) to provide a bulk of hot metal to " feed " 
 the casting as it shrinks in solidifying. 
 
 (3) A mould must resist burning and crumbling when filled 
 with molten metal, and must resist bursting from the static pres- 
 sure of the metal. 
 
 The requisite qualities of sand for moulds will be mentioned later. 
 
 255. Foundry Equipment. The main equipment of the foundry 
 may be stated as follows : 
 
 (1) Moulding sands in bins, and other moulding materials. 
 
 (2) Flasks in which moulds are made. 
 
 (3) Moulders' tools and accessories used in making moulds. 
 
 (4) One or more traveling cranes equipped with various lifting 
 and transporting appliances. 
 
 (5) Usually two or more cupolas for melting pig and scrap 
 cast iron. 
 
MECHANICAL PROCESSES 
 
THE FOUNDRY 233 
 
 (6) A reverberatory oil or coal furnace for melting bronze or 
 brass for large castings. 
 
 (7) A crucible furnace for melting brass. 
 
 (8) Ladles for holding molten metals. 
 
 ( 9 ) A drying room or " oven " for drying dry sand and loam 
 moulds. 
 
 (10) A core oven for drying or "baking" cores. 
 
 (11) Equipment for cleaning castings, as wire brushes, emery 
 wheel, and tools for cutting fins and other refuse parts from cast- 
 ings, tumbling barrels, etc. 
 
 Moulding machines are used to make small moulds in foundries 
 which turn out duplicate work. There are several subsidiary 
 machines for foundry use, such as sand mixers, clay grinders, etc., 
 but these are not universally needed. Fig. 119 shows a view of a 
 moulding floor of a foundry. 
 
 256. Moulding- Sand. This is the most important of the mould- 
 ing materials. In different forms, it has different uses and is given 
 different names, such as green sand, loam, facing sand, core sand, 
 brass sand. All moulding sands are essentially mixtures of silica 
 to give porosity and clay to give tenacity. Silica grains are re- 
 fractory and have no cohesion. Clay is a fine powder, is refractory 
 and when wet is adhesive and plastic. These two ingredients are 
 mixed in different proportions, the silica grains varying in size, to 
 make mixtures suitable for different uses. 
 
 "Other materials are mixed with moulding sands for various pur- 
 poses, as will be mentioned. 
 
 All moulding sand mixtures are more or less wet when formed 
 into moulds. The requirements of a good moulding sand are : 
 
 (a) Sufficient porosity to allow the escape of gas and steam gen- 
 erated in the body of the mould by the heat of the molten metal. 
 The greater the bulk of metal the coarser the sand used, and the 
 greater the need for careful venting. 
 
 (b) Sufficient plasticity and tenacity to hold its form in the 
 mould and to resist the erosive action of hot metal. These qualities 
 are due to clay, which is more or less detrimental, because it fills 
 the spaces, or pores, between the silica grains. 
 
 (c) A high enough fusing point not to melt and stick to the face 
 of the casting-. 
 
234 MECHANICAL PROCESSES 
 
 There are many trade names for foundry sands, but all must ful- 
 fill the requirements mentioned. Vegetable or other combustible 
 matter,, sea salt, lime, and substances easily decomposed by heat 
 should not exist naturally in moulding sand, as they may cause 
 failure in casting. 
 
 Brass sand is green sand of fine grain used in moulds for brass 
 castings. 
 
 Facing sand is also a fine-grained sand placed next to the pattern 
 in small moulds to make a smooth casting. 
 
 Core sand is used for cores. 
 
 Loam is a very course moulding sand made up for loam moulds. 
 
 257. Other Materials Used in Moulding. Designating moulding 
 sand as first on the list, other important moulding materials are 
 named as follows : 
 
 (2) Fire clay is a pure clay (oxide of aluminum) much used when 
 mixed with water as a plastic refractory material for patching ladle 
 and cupola linings, and for use in moulding. 
 
 (3) Clay wash or clay water is a thin mixture of fire clay and 
 water. It is added to moulding sand mixtures (particularly loam 
 mixtures) to give them the necessary plasticity. It is also used to 
 wet sticks, nails, iron rods, core irons, etc., imbedded in moulds and 
 cores to make sand adhere to them, thus strengthening the body of 
 the mould. 
 
 (4) Common red bricks are used to make the body of loam 
 moulds and to fill up remote spaces in large dry sand moulds. They 
 are piled evenly in the spaces they occupy, and afford porosity. 
 
 (5) Parting sand is sprinkled on the joints or partings of moulds, 
 as between the cope and the drag, to keep the two parts of the mould 
 from sticking at the joint. Any fine-grained non-plastic material, 
 such a brick dust, silica sand, ground cinders, etc., may be used. 
 
 (6) Slurry js clay wash and fine moulding sand mixed thick. 
 It is used as the first smooth coating over the rough loam surface 
 of a loam mould. 
 
 (7) Cinders from completely burned coal are used in venting to 
 assist the porosity of large cores and sand projections in moulds, 
 and are placed under large moulds to receive and convey gases from 
 the moulds. 
 
THE FOUNDRY 235 
 
 (8) Blacking and sleeking mixtures are used as a final smooth 
 coating over the surface of a mould after the pattern is withdrawn. 
 These are known as mould facings, facing mixtures, etc. They 
 give a smooth surface to the casting. Some mixtures contain mo- 
 lasses, stale beer, or other viscous substances, to prevent the sand of 
 the mould washing away when metal is poured. Facings of 
 powdered slaty coal, charcoal, graphite, soapstone, or ground silica, 
 are dusted on the faces of green sand moulds from small muslin 
 bags. These are applied wet, with a brush, to dry sand and dried 
 loam moulds, and are slicked when nearly dry to make a smooth 
 glossy surface. 
 
 (9) Flour, stale beer, oil, and molasses are used to increase the 
 tenacity of sand in moulds. A more important feature of flour is 
 that it chars when metal is poured into the mould, allowing core sand 
 to disintegrate and crush as the casting contracts in cooling. Flour 
 paste and putty are used to make a tight joint between a core and its 
 bearing. 
 
 (10) Oil is used to coat large patterns in loam moulding to keep 
 the loam from sticking to the pattern. 
 
 (11) Loose or chopped straw and dry horse manure are used in 
 loam moulds to increase porosity, and straw rope is wound on " core 
 barrels," or large metal pipes, which are then covered with loam and 
 dried for use as cores for moulding large water and gas-main piping. 
 
 The moulder applies "the name of sharp sand or fire sand to silica 
 or any other kind of gritty, non-adhesive sand. Burnt sand is a 
 sand which has lost its tenacity by having been highly heated next to 
 a casting in the mould. Burnt sand must have new sand mixed with 
 it to fit it for moulding, though the worst of it is thrown away. 
 
 Loose sand and refuse must not be allowed to accumulate about 
 the foundry floor. 
 
 It will be seen that many of these materials are to assist one or 
 more of the three essentials, a, b, c, mentioned in the preceding 
 paragraph, for moulding sands. 
 
 258. Flasks for Green and Dry Sand Moulds. Moulds of these 
 two classes are made in flasks of various shapes and sizes. Wood or 
 iron flasks are used for green sand molds and cast-iron flasks are 
 used for dry sand and steel moulds. 
 
236 
 
 MECHANICAL PROCESSES 
 
 Fig. 120 shows three flasks extensively used for small moulds. 
 Each of these consists of three parts cope, drag and bottom board. 
 Suitable lugs and pins are provided to insure the cope and the drag 
 going together always in the same relative position. No. 2 may be 
 poured from the top, or may be set on end and poured through one 
 of the holes in the end to insure a better metal pressure in the 
 mould. No. 1 is a snap flask, which may be removed from a mould 
 and used for making other moulds of the same size. When this 
 flask is removed, a rectangular box is slipped over the mould in its 
 place to support the sand. No. 3 is for general use for small moulds. 
 Each size of small flasks for general use should 1 3 made inter- 
 changeable, i. e., the upper part of any flask should fit the lower part 
 of any other flask. 
 
 FIG. 120. Small Moulding Flasks. 
 
 Fig. 121 shows two flasks for medium-sized moulds. The weight 
 of sand in the cope" is too great to hold in place without the cope 
 bars B. The drag needs no bars, but it must have a bottom board 
 if it is to be turned over in the course of making the mould. 
 
 The upper" view shows a three-part flask for a pattern which can- 
 not be removed from a single parting in the two-part flask. The 
 cheek, or middle part of the flask, also has bars. These extend 
 radially from corners and sides of the cheek toward the pattern, but 
 bars should not be within less than about % inch of the pattern 
 surface. 
 
 Many cast-iron flasks are shown in the view in Fig. 119. They 
 are made up of flat cast-iron sections bolted together, or of round 
 sections made in one piece. A large cope is shown at C with rods 
 and bars arranged for a particular casting. A circular cope and 
 drag clamped together are marked B and D. Each of these parts 
 
THE FOUNDRY 
 
 237 
 
 has a pair of trunnions by which it may be suspended and re- 
 volved while giving the mould its finishing touches. 
 
 Several minor devices are used for assisting cope bars to hold a 
 body of sand firmly in place. Nails are frequently driven along 
 the under edge of a bar to hold projections of sand in an irregularly 
 shaped parting. Bent iron rods, called gaggers, are imbedded in the 
 
 FIG. 121. Moulding Flasks. 
 
 sand to anchor the unstable parts to the firmer bodies of sand in a 
 cope or a cheek. Small tapered sticks, called soldiers, are used when 
 the mould is delicate and cannot stand the weight of gaggers. 
 
 Loose nails are often imbedded in corners of sand or are stuck 
 in the surface of a mould to hold the sand firmly against breaking 
 or wearing away by erosion. Gaggers, nails, etc., are wet with clay 
 water to make the sand stick to them. 
 16 
 
238 
 
 MECHANICAL PROCESSES 
 
 259. Tools Used in Moulding. The moulder's tool kit is simple 
 and includes articles of the following list, most of which are shown 
 in Fig. 122 : 
 
 (1) Vent wire for sticking vent holes through the sand of the 
 mould. 
 
 (2) Pattern lifter. 
 
 (3) Joint trowel and (4) heart trowel for smoothing and finish- 
 ing the parting and flat surfaces of the mould. 
 
 (5) Gate cutter and pattern lifter. 
 
 FIG. 122. Moulding Tools. 
 
 (6) Slick and oval spoon for finishing mould surfaces. 
 
 (7) (8) Sand lifters and slicks. 
 
 (9) Yankee heel lifter and flat slick. 
 
 (10) Flange and bead slick. 
 
 (11) Corner slick. 
 
 (12) Edge slick. 
 
 (13) Round corner slick. 
 
 (14) Pipe slick. 
 
 (15) Button slick. 
 (16.) Oval Slick. 
 
 (17) Hand rammer for ramming sand in flasks (not shown). 
 
THE FOUNDRY 239 
 
 (18) Spirit level for leveling open sand moulds (not shown). 
 
 The slickers are used for finishing the surface of the mould after 
 it has been dusted or painted with mould facing. 
 
 Additional equipment, usually a part of the foundry outfit, in- 
 cludes : 
 
 ( 1 ) Small bellows for blowing loose sand from moulds. 
 
 (2) Sieves (riddles) for sifting sand. 
 
 (3) Brushes for applying liquid mould facing and for dusting 
 moulds. 
 
 (4) Small bags for dusting dry mould facing. 
 
 (5) Heavy and pneumatic rammers for ramming sand in flasks. 
 
 (6) Larger hand tools, as spades, picks, hoe, rake, hand spikes, 
 crow bars, wrenches, buckets and sprinklers. 
 
 260. Example of Making a Small Mould. The work of making 
 a mould of the pattern in Fig. 108 is here given briefly to show the 
 
 PIG. 123. 
 
 essential steps in sequence. This is applicable in general to green 
 sand and dry sand work. The completed mould is shown in Fig. 
 118. 
 
 Having selected a suitable flask, place one-half of the pattern on 
 the bottom board, as shown in Fig. 123. Place the drag bottom side 
 up on the board, and sift about a half inch of facing sand over the 
 surface of the pattern, then fill the drag heaping full from the pile 
 of moulding sand, sifting part of it in. Earn this sand down firmly, 
 but not too hard, and level it off even with the top edge of the flask 
 by rubbing the sand surface with another bottom board, then lift the 
 board and use the vent wife to probe several vent holes which will 
 reach all parts of the pattern's surface. Dig down with the small 
 trowel carefully until the wires aa can be reached and drawn out. 
 Replace this sand and probe a few vent holes through it. Replacing 
 the upper bottom board, turn the drag over and remove the other 
 board, which is now on top. 
 
240 
 
 MECHAXICAL PROCESSES 
 
 The drag now rests right side up, as shown in Fig. 124. Place 
 the cope and the other half of the pattern in position, as shown, and 
 stick a riser stick R slightly into the sand, about 2 inches from the 
 pattern. Sprinkle a layer of parting sand over the parting to keep 
 the sand of the cope and that of the drag from sticking together. 
 The cope is now filled, rammed, and otherwise prepared, as was 
 described for the drag. The riser stick S is placed on the upper 
 edge of the flange when there is enough sand in the cope to hold it 
 up, and both sticks are withdrawn after the cope is vented. 
 
 When the cope is rammed and vented, lift it from the drag and 
 remove the pattern by using the lifting screw. Eap it a few times 
 to loosen the pattern before lifting. A little water squeezed from a 
 swab around the edges of the pattern will help hold the sand in 
 
 FIG. 124. 
 
 place. .Patch the broken corners of the mould, cut the gate with a 
 piece of bent tin, lift out any loose sand, and dust the mould sur- 
 face with graphite or other dry facing. 
 
 In the meantime the core-maker makes the core. The core box, 
 shown in Fig. Ill, is clamped and gradually rammed full of core 
 sand. Two wires are rammed in with the sand along the axis of the 
 core. One of these remains in the core to strengthen it, and the 
 other is removed when the core is rammed up to leave a vent hole. 
 
 The core must be carefully removed from the box. It rests on 
 some loose sand placed on an iron plate, and is slowly baked in the 
 core oven. Cores are usually sprinkled with, molasses water to make 
 them more flinty when baked. 
 
 When the core is taken from the oven and cleaned, it is placed in 
 its bearings in the drag, and the mould is closed and weighted ready 
 for pouring. 
 
THE FOUNDRY 241 
 
 261. Moulding Machines. These machines are profitably em- 
 ployed in foundries which make a great number of small duplicate, 
 castings. They are designed and built to repeat certain motions 
 and operations which occur in the work of moulding all small cast- 
 ings. Each machine is operated by a workman who directs the 
 machine and who performs those steps in the work which the 
 machine cannot perform. 
 
 There are two types of moulding machines, known as the vibrator, 
 and the squeezer. 
 
 Snap flasks of special design and uniform sizes are used with 
 these machines. 
 
 Moulding machines do not require skilled labor to operate them, 
 and many small patterns may be moulded in a single flask. 
 
 262. Cores. Cores are more or less surrounded by molten metal 
 and are therefore subjected to more concentrated heat than other 
 parts of the mould. To serve their purposes they must be made 
 especially (1) to resist erosion from flowing metal, (2) to resist 
 fusing, and (3) to allow the escape of air, steam and carbon gases 
 contained in the core. 
 
 Clean silica sand of more or less coarse grain is the principal 
 material of cores. About 15% of flour is mixed with this and the 
 mass is wet with thick clay wash until the sand grains stick 
 together. 
 
 All cores must be carefully vented to assist the natural porosity 
 of the sand. Vent holes are usually formed by straight wires. 
 Crooked vent holes are formed by greased strings. Vent wires and 
 strings are pulled out before the core is taken from the core box. 
 Large cylindrical cores may be made in halves for better venting, 
 and all large cores contain cinders at the center to increase porosity. ; 
 All vents must lead to the core bearings from which gases escape 
 along the mould parting or through especially provided pipes or 
 channels. 
 
 Small cores are strengthened by wires. Specially made core irons 
 are enclosed in large cores to make them rigid enough for handling, 
 and to support them in the mould. 
 
 The baking of cores makes the sand much firmer, and decreases 
 the gases and moisture in them. Baking is usually necessary, but 
 there are many shapes of cores which can be made of green sand as 
 
24:2 MECHANICAL PKOCESSES 
 
 a part of the mould. These are well vented and are well enough 
 supported to avoid the necessity of baking. 
 
 Large cores for loam moulds are built of bricks and surfaced with 
 loam and slurry. 
 
 For smoothness of surface, cores are blacked and slicked. This 
 is done after drying. 
 
 263. Chaplets. There are many cases in moulding in which a 
 core is not adequately supported by its bearings in the sand of the 
 mould, particularly if it has but one bearing or is not a straight core. 
 
 It is the practice in these cases to support the core by pieces of 
 metal called chaplets, placed in the mould space. When metal is 
 poured into the mould around the chaplets, they soften and become a 
 part of the casting. 
 
 / 2 
 
 FIG. 125. Chaplets. 
 
 Fig. 125 shows four of the many shapes of chaplets much used. 
 These are of iron or brass as may be needed. Chaplets must be 
 cleaned before placing them in a mould. They are often tinned. 
 
 It is frequently necessary to place a chaplet above a core to keep 
 the metal from floating the core out of position, beside placing a 
 chaplet under the core to support it before the metal is poured in. 
 
 There will be noticed often on the outer surfaces of hollow-cast 
 pipe elbows, cone-shaped projections or rough spots which mark the 
 position of chaplets. 
 
 Chaplets are sometimes used in narrow mould spaces to insure 
 the required thickness of metal in the casting. 
 
 264. Chill Moulds. Surfaces of cast-iron castings subjected to 
 constant wear, such as car-wheel rims, anvil faces, and vehicle 
 wheel boxes, are chilled to render them hard and tough. The chill- 
 ing is done by sudden cooling of the molten iron when it is poured 
 
THE FOUNDRY 
 
 243 
 
 into the mould. A part of the mould is formed of a piece of iron, 
 and when the molten metal comes in contact with this, its surface 
 is quickly cooled. 
 
 FIG. 126. Chill for a Mould. 
 
 Fig. 126 shows a chill for a car wheel. This forms, the cheek of 
 a three-part flask. Chills are made of cast iron or cast steel. 
 
 265. Example of a Loam Mould. Fig. 127 shows a cross-section 
 of a loam mould, with the parts assembled and bound together 
 
 FIG. 127. Loam Mould. 
 
 firmly. It is now ready to be lowered into a pit dug in the foundry 
 floor and surrounded by sand packed inside a circular curbing of 
 iron plates to fortify the sides against the pressure of the molten 
 
244 
 
 MECHANICAL PROCESSES 
 
 metal when poured. Fig. 128 shows a drawing of the cylinder for 
 which this mould is made. 
 
 Loam moulds are used only for the largest castings, particularly 
 large propellers and steam cylinders. The bricks of these moulds 
 may be used many times. 
 
 The mould here shown is made in three detachable parts carried 
 on the heavy cast-iron plates B, D and T. The bricks are laid in a 
 mortar of old moulding sand and water. Venting is aided by plac- 
 ing cinders between bricks, and by mixing chopped straw or dry 
 horse manure with the loam. 
 
 FIG. 128. Cylinder to 
 be Moulded. 
 
 FIG. 129. Beginning a Loam Mould. 
 
 266, Building a Loam Mould. Each of the detachable parts of a 
 loam mould is so built on its own plate that it can be handled sepa- 
 rately from the other parts. 
 
 The mould is begun by leveling the heavy foundation plate B 
 (Fig. 129) on firm supports, and supporting the spindle 8 vertically 
 in its bearings in which it is free to turn. Sweep No. 1, with edges 
 iron bound to prevent wear from the rough loam, is then bolted to 
 the strap A. The foundation brickwork C is built up with this 
 sweep as a guide, and about half an inch of loam is swept evenly 
 over the top of the brickwork by revolving the sweep about the 
 spindle. This loam facing, shown in Fig. 130, is allowed to dry and 
 the joint JJ is well oiled. 
 
 The next part of the mould, the main body (marked GG in Figs. 
 127 and 131), is swept up on the lifting ring D by using sweeps 2 
 
THE FOUNDRY 
 
 245 
 
 and 3. The steps of this work are shown in Figs. 130 and 131. 
 The lifting ring is bedded in a layer of wet loam spread over the 
 joint JJ. This loam sticks to the ring when dry and is lifted with it. 
 Sweep No. 2 merely sweeps the temporary brickwork FF, which is 
 
 FIG. 130. Sweeping up Dummy Flange. 
 
 loam coated to serve as a pattern against which the lower part of 
 the main body is built. The revolving of the sweeps as the bricks 
 are placed serves as a guide in placing them, and after the brick- 
 work is done, the loam coating is plastered on by hand and swept 
 
 FIG. 131. Sweeping up Main Wall. 
 
 to shape on the brick surface to form the surface of the mould, which 
 is later made very smooth. 
 
 Any part of the casting, as the nozzle of the cylinder in Fig. 128, 
 which projects beyond the surface of revolution, is moulded by bed- 
 ding suitable wooden patterns of these parts in the brickwork. The 
 pattern H 9 with its core print P (Fig. 131) and its detachable 
 
246 
 
 MECHANICAL PROCESSES 
 
 flange, is surrounded by a loam coating as it is built in the wall of 
 the mould. These patterns are removed after the mould is lifted 
 apart. 
 
 When sweep No. 3 has completed its work, as shown in Fig. 131, 
 the main part is lifted away on its lifting ring D, the temporary 
 work FF is torn away, and the main core K, for making the cylin- 
 der hollow, is swept up as shown in Fig. 132. L is a small core 
 print for the nozzle core, and R is a flat bar of cast iron imbedded 
 in the core. The bar is removed just after the cylinder is cast, by 
 digging down to its end and attaching the crane thereto. This re- 
 
 FIG. 132. Sweeping up Main Core. 
 
 moval allows the casting to crush the core sufficiently in contracting 
 to avoid cracking. 
 
 The assembled mould in Fig. 127 shows the top plate TT placed 
 over the oiled joint EE. Loam has been swept on the under side 
 of this plate and after the parts of the mould are assembled and 
 bound, the riser and pouring basins are shaped of green sand held in 
 place by the sheet-iron ring V and the heavy tube Q. The four- 
 armed cross M, resting on distance pieces Q and SS, is bound to the 
 foundation plate B as shown. 
 
 The parts of the mould are dried after they are swept up and 
 lifted apart. This is done in a large brick oven and requires about 
 60 hours. Before finally assembling, the mould surfaces are painted 
 with a liquid mould facing and carefully slicked by hand slickers. 
 
THE FOUNDRY 247 
 
 267. The Cupola. Pig and scrap iron for castings are generally 
 melted in a cupola, although a reverberatory furnace may be used. 
 Fig. 133 shows a typical cupola in cross-section. A cast-iron or 
 cast-steel base ring B is supported about 3 feet from the ground by 
 four iron posts C. This ring carries a shell D of steel plates lined 
 inside with refractory bricks. The top of the cupola acts as a 
 chimney, although the two or more cupolas necessary in a foundry 
 may lead into a common chimney. 
 
 Under the base ring are hinged two iron doors, FF, held up by 
 an iron prop when the cupola is in use. About 12 inches above the 
 sand bed is the slag hole, and about 8 inches further up are the 
 tuyere holes. The tuyeres are merely pieces of iron pipe extending 
 through the cupola shell and brick lining. The tuyere holes are 
 encircled by the blast or wind box which receives ordinary air at a 
 low pressure from a blower and delivers it through the tuyeres when 
 the cupola is in operation. The blast box has a small mica peep 
 door opposite each tuyere to enable the melter to see the surface of 
 the molten iron. The cupola is charged from the charging platform 
 through the charging door about 9 feet above the bottom. The 
 lining bricks are supported at intervals by angle iron lining-shelves 
 as shown. 
 
 Cast iron melts at about 2200 F. If the cupola blower breaks 
 down, a jet of steam in the base of the cupola chimney will induce 
 a draft sufficient at least for slow melting. 
 
 268. Operation of the Cupola. A cycle of service for a cupola 
 in active use is usually repeated each 24 hours. Briefly the opera- 
 tion throughout the 24 hours is as follows : A day's melting hav- 
 ing been finished, and the blower stopped, all metal and slag are 
 drained out at the tapping hole. The prop is knocked away, and the 
 doors FF swing down. The sand bottom and any unburnt fuel 
 drop out. 
 
 Next morning the cupola is cool and the melter and his helper 
 proceed to prepare it for use. Slag is chipped from the lining, 
 which is patched where needed with plastic fire clay. Old sand is 
 dug from the doors, breast and tapping spout. The doors are then 
 propped up and the melter goes down through the charging door to 
 prepare a new bottom. This is made about 4 inches thick, and con- 
 
248 MECHANICAL PROCESSES 
 
 sists of a thin layer of cinder, a layer of new moulding sand and a 
 coating of thick clay wash. The sand bottom continues out to the 
 end of the tapping spout. 
 
 After the bottom has dried about an hour, a wood fire is built in 
 the cupola. The breast is rammed with new sand around an iron 
 pipe, and the pipe is then withdrawn to form the tapping hole. 
 
 Coke and iron are weighed out for the charge and are hoisted to 
 the charging platform. A hot coke fire is gradually built up, the 
 blower is started, and the charging begins. The charge consists of 
 alternate layers of coke and- iro^ and each layer must be weighed 
 to make the operation of the cupola uniform and to insure enough 
 coke to melt the iron. Pig and scrap iron are charged together. 
 Molten metal appears at the tapping hole about half an hour after 
 iron is charged, and this hole is stopped with a clay plug jammed 
 into place on the end of a heavy round stick. 
 
 In the meantime, the f oundrymen are -assembling the ladles to be 
 used in pouring the moulds. A wood fire is built in each ladle to 
 keep it from chilling the molten metal it receives. When enough 
 molten metal accumulates in the cupola, the clay plug is dug out 
 with, an iron bar, ladles are filled, and the tapping hole is again 
 stopped. 
 
 Charging continues from the upper platform so long as metal 
 is needed, and when all moulds are poured, the remaining iron is 
 run from the cupola and the blower is stopped. 
 
 269. Ladles. Iron is received in ladles from the cupola and is 
 poured from these into moulds. Ladles are made of rolled steel 
 plate and plastered inside with a wet mixture of silica sand and fire 
 clay. Large ladles are lined with fire-clay bricks, plastered over 
 with clay. Small ladles are carried in ladle shanks by one or more 
 men, and large ladles must be carried by the crane. A " bull 
 shank" is shown in Fig. 31. Before receiving molten metal, ladles 
 must be thoroughly dry. 
 
 Metal for a very large casting must be gradually assembled in 
 several large ladles until there is enough to fill the mould. After 
 it is tapped very hot into the ladles, it is kept hot by a charcoal fire on 
 the surface of the metal. 
 
 All ladles and crucibles must be skimmed 'at the pouring spout 
 
THE FOUNDRY 
 
 249 
 
 with an iron bar while pouring. Very hot metal makes a good im- 
 pression in the mould, but is very searching, requires more venting 
 of the mould, and shrinks more than a metal not so hot. 
 
 FIG. 133. Foundry Cupola. 
 
 270. Foundry Iron. Although foundry iron is now selected by 
 its composition as shown by chemical analysis, yet the designations 
 of white, mottled, and grey irons, are still used to classify pig iron 
 .according to the carbon it contains. White iron, with no uncom- 
 
250 
 
 MECHANICAL PROCESSES 
 
 bined carbon, is too hard for castings which must be machined. 
 Grey iron, with much uncombined carbon, is easiest to melt and 
 easiest to cut. A mottled iron is strong, tough and not difficult to 
 machine. 
 
 Cast iron containing much free carbon expands upon cooling., 
 due to separating out of graphite from solution. This is an ad- 
 vantage in casting, as it balances the contraction due to cooling. 
 
 Scrap iron must not be used in high-grade castings unless it 
 comes from similar castings. 
 
 L/c/ 
 
 FIG. 134. Brass Melting Furnace. 
 
 271, Brass Furnaces. The materials and methods used in mak- 
 ing iron and brass moulds are practically the same, although the 
 means of melting these metals for castings are different because 
 brass melts at a lower temperature (brass about 1700 F., copper 
 about 2000 F.) than does iron. 
 
 Fig. 134 shows a typical crucible furnace for melting brass. It 
 is shown as arranged for oil fuel, but may be used for hard coal 
 or coke by removing the oil burner, stopping up the burner hole D 
 and removing the bricks K from the grate bars. 
 
THE FOUNDKY 
 
 There are patented forms of oil furnaces which are self-contained 
 and may be set at any place desired about the foundry floor. 
 
 A reverberatory furnace is used to melt brass for a large casting, 
 but if this is not installed,, a large casting can be made by assem- 
 bling in a large ladle the molten metal from several crucibles. 
 
 In Fig. 134, the furnace is built of brick in a concrete-lined pit. 
 The melting space H is enclosed by fire-brick walls and covered by a 
 movable lid. A furnace is composed of a number of these melting 
 spaces in a row. 
 
 The burner forces oil and air through the opening D into a flame 
 which strikes the corner of the base B and surrounds the crucible C. 
 The chimney conduit G conducts gases of combustion to a tall 
 chimney. 
 
 Two bricks on edge, or better, a bed of glowing hard 
 coal must hold the crucible off the grate bars when 
 coal or coke heating is done, otherwise its bottom 
 would be too much cooled from the air through the 
 bars to allow melting of the contents. The ash pit A 
 is large enough to afford a good draft for coke or coal. 
 
 Brass is alloyed by melting the required amount 
 of copper and then stirring in the zinc in small pieces 
 with an iron rod. Salt, sal ammoniac, or charcoal 
 may be used as a flux to avoid oxidation of the sur- 
 face of the molten metal. Scrap brass must not be 
 used in high-grade castings unless its composition is 
 known to be the same as that intended for the cast- 
 ings. Even then, a careful fluxing is required to 
 remove any possible oxidized metal contained in the 
 scrap. 
 
 Fig. 135 shows a pair of tongs for lifting crucibles from brass 
 or crucible-steel furnaces. A tackle hooked to the eyebolt B lifts 
 the crucible and lowers it into a ladle shank. The mould is poured 
 from the crucible. 
 
 272. Defects in Castings. The following defects and their causes 
 are well known to foundry men : 
 
 (1) Surface and interior cavities are caused by too little metal, 
 or by runners and risers too small to remain liquid and feed the 
 casting until it has " set " throughout its mass. 
 
 FIG. 135. 
 
 Crucible 
 
 Tongs. 
 
252 MECHANICAL PROCESSES 
 
 (2) Cold shuts are caused by drilled metal. When poured, 
 sluggish metal becomes so chilled that it does not unite when it 
 meets from opposite sides of the mould. 
 
 (3) Blow holes are caused by air, gas, or steam under the sur- 
 face of the casting when it solidifies. Blow holes are from air 
 entrained in a partially filled runner, from air entrapped in the 
 mould space and from steam forced into the mould from the sand 
 due to improper venting and drying. If a metal is very fluid when 
 poured, air and gases will rise to the surface and escape. The metal 
 itself contains little or no gas before pouring. 
 
 (4) Sand holes and cuts are formed by loose sand in the mould. 
 Sand from the mould surfaces may come off in patches known as 
 " scabs " due to poor venting. If the patch of sand breaks up, it 
 forms sand holes, but if it remains intact, metal encloses it and 
 forms a cut. Sand will float if the metal is sufficiently fluid. 
 
 (5) Shrinkage cracks are caused by a mould or core too rigid to 
 allow a casting to shrink without cracking. 
 
 (6) Strains and warps are caused by uneven cooling. A strain 
 is not visible, but may cause the casting to crack if hammered. A 
 warp distorts the shape of the casting. 
 
 (7) Sponginess is caused by impurities in the metal when poured. 
 It generally shows in brass or bronze castings when tested under 
 hydrostatic pressure and is caused by porous oxidized metal in the 
 casting. The defect is revealed by a sweating of the casting under 
 high pressure. Globules of water seep through more or less rapidly 
 and trickle from the surface. 
 
 (8) Castings may be of poor material, too hard for machining, 
 or defective in strength. These defects are avoided by an analysis 
 of the material before casting. 
 
 273. Remedies for Defective Castings. In some cases defective 
 castings may be remedied. 
 
 (1) Strains are removed from castings by annealing. This is 
 usually necessary only with steel castings, or chilled cast-iron 
 castings. 
 
 (2) A warped casting may be straightened by weighting it and 
 building a charcoal fire under it to heat it red hot. Provision must 
 be made not to let the weight bend the casting more than is needed. 
 
THE FOUNDRY 253 
 
 (3) A small hole caused by sponginess may be drilled out and 
 plugged. A small blow hole or small collection of blow holes may 
 frequently be remedied in the same way. 
 
 (4) Cracked or broken castings may in many cases be repaired 
 by " burning on/ ? by electric welding., or brazing. 
 
 The Steel Foundry. 
 
 274. Steel Castings. In strength and other qualities steel cast- 
 ings resemble steel forgings much more than they do cast-iron cast- 
 ings. But for their marked superiority over cast-iron castings 
 doubtless their greater cost would have stopped their production. 
 Properly made steel castings are not brittle, but will stand a re- 
 markable degree of cold bending without showing cracks or flaws. 
 They are much stronger than wrought-iron forgings, and approach, 
 or in many qualities equal or exceed, the elastic and tensile strength 
 of rolled or forged steel. They are cheaper than forgings, except 
 possibly those forgings made by the drop-forging process. Cast- 
 steel castings are usually low enough in carbon to stand welding. 
 
 In considering the strength of steel castings, the elastic strength 
 is highly important, as a casting is practically ruined after its 
 elastic strength has been exceeded. A high per cent of elongation 
 and high elastic limit are desirable. Absence of these is an indi- 
 cation of brittleness. 
 
 275. Steel and Iron Foundries Compared. Although the work of 
 making steel castings is closely associated with the steps in making 
 cast-iron castings, yet there are several requirements of great im- 
 portance in the preparation of steel moulds which mark the produc- 
 tion of steel castings as an art by itself. 
 
 The steel foundry is generally an independent branch of industry 
 just as are many branches for the re-manufacture of metals. 
 
 Comparing the steel and the iron foundry, their locations are alike 
 in requirements, equipment and interior arrangement are very 
 similar, moulds must embody the same essentials, the same re- 
 quirements hold for sand used in moulding, and the tools, acces- 
 sories, and most of the minor moulding materials are the same. 
 
 The differences between the requirements of moulds for making 
 cast-iron and steel castings are differences in degree rather than 
 17 
 
254 MECHANICAL PROCESSES 
 
 differences in kind. These differences are due (1) to the effects of 
 higher heat of molten steel when poured into the mould, and (2) 
 to its greater shrinkage in cooling, for it does not expand as does 
 cast iron, which precipitates some of its carbon. 
 
 The shrinkage of steel is about twice that of cast iron. 
 
 276. Moulds for Steel Castings. Dry sand moulds made in iron 
 flasks are used for steel castings, although small steel castings are 
 frequently made in green sand moulds contained in wood flasks. 
 The boundry between the use of green and dry sand moulds in this 
 work depends upon the care and skill of the moulder, but castings 
 of over a few pounds are safest and soundest when made in dry 
 sand. A dried mould must be dried thoroughly to prevent damage 
 from steam, and it is the practice of some steel foundries to heat 
 green sand moulds gently over night in a drying room. 
 
 277. Particular Requirements of Steel Moulds. The higher heat 
 of steel when cast requires that (1) particular attention be paid to 
 the venting of moulds, and that (2) the mould surfaces be especially 
 treated to prevent washing away, or " scabbing/' when metal is 
 poured into them, and to prevent fusing in contact with the highly 
 heated metal. The greater shrinkage of cast steel requires (1) that 
 large feeding heads be attached to the heavy parts of a casting to 
 prevent shrinkage cavities in the casting, and (2) that cores and 
 moulds be composed of materials which will crush readily or which 
 can be dug out to avoid shrinkage cracks. 
 
 Steel moulds are rammed up harder than iron or brass moulds. 
 
 278. Surfaces of Steel Moulds. After the pattern has been re- 
 moved from a steel mould, the face of the mould and particularly 
 any sand projections subject to the wash of the metal, are stuck 
 with wire nails more or less close together. The heads of these nails 
 are often visible in the face of the mould, and their imprints may 
 be seen on the surfaces of many steel castings. 
 
 The surface of the mould is sprinkled with molasses water or 
 similar sticky preparation to make the sand hold together better, 
 and a powder or wash of ground quartz or other pure silica is 
 dusted or brushed over the entire mould surface and over the part- 
 ing adjacent to the mould cavity, to make these surfaces highly 
 refractory. The molasses water also aids to hold this silica facing, 
 as the facing is not adhesive itself. 
 
THE FOUNDRY 255 
 
 279. Means of Avoiding Shrinkage Cracks. Shrinkage cracks 
 may occur where thin and thick parts of a casting join, due to the 
 unequal rate of cooling of the different masses of metal. These are 
 prevented by making changes of thickness very gradual, even at the 
 expense of making the casting heavier and necessitating machining 
 away later of some of the extra metal. 
 
 A very common practice to prevent shrinkage cracks where two 
 surfaces meet at an angle, is shown in Fig. 136. The sides c and d 
 cool quicker than the larger mass of metal at the corner, and in 
 cooling they tend to shrink away from it and to cause a fracture 
 in the hotter and weaker metal there. To prevent fracture, the 
 moulder cuts thin webs or gussets I, about 4 or 5 inches apart, in 
 the mould. These webs cool first, keeping the sides together at the 
 corner while the metal mass of the corner is cooling. These webs 
 
 cause an internal strain by their cooling, but this is relieved by 
 annealing the casting, and the webs are then cut, away, leaving a 
 fillet as at a. 
 
 280. Avoiding Surface or Interior Cavities. The great shrinkage 
 of steel would cause surface or interior cavities in the casting were 
 it not fed by its runners, risers, and feeding heads. The static 
 pressure of the metal in these injures the filling of the mould pro- 
 vided they are large enough in diameter to remain liquid until the 
 casting has solidified. A feeding head is merely an extra riser over 
 a heavy part of the casting, and the fluidity of both feeding heads 
 and risers is prolonged by churning the metal in them with small 
 iron rods. Often a riser or feeding head is % or % the weight of 
 the casting, and is as much as ten inches in diameter for large 
 castings. 
 
 The removal of large risers, runners and feeding heads requires 
 considerable work, and adds much to the expense of steel castings. 
 
256 MECHANICAL PROCESSES 
 
 An old and effective method is to saw them off with a cold steel saw, 
 but where a shop has facilities for electric cutting, a much cheaper 
 way is to cut them off by use of the electric arc. One electrode is 
 fastened to the riser and the other, suitably rigged to be handled 
 by a workman, is passed around the riser neck close to the casting. 
 The intense heat of contact melts a groove around the riser, reducing 
 its diameter until it can be knocked off by a sledge. The brilliancy 
 of the arc is such that the workman must wear a metal head shield 
 provided with black glass sight openings, and the work is done 
 within an enclosure to keep others from looking at the arc. 
 
 Another method lately developed for such cutting is the oxy- 
 acetylene burner. 
 
 281. Steel for Castings. In steel works, where steel is made, 
 castings are poured from open-hearth, Bessemer, or crucible steel, as 
 may be required. The making of steel castings in large steel works 
 is usually an incidential operation, as steel is made principally for 
 rolling into various shapes, as described in Chapter Y. 
 
 In steel foundries, where steel is made only for castings, a small 
 converter is used to make steel by " blowing " pig iron melted in 
 the foundry cupolas. This is essentially the Bessemer process. The 
 steel-making equipment of the usual steel foundry consists of (1) 
 two or more cupolas for melting cast iron, (2) one or more small 
 converters (usually in America the Tropenas type of about two 
 tons capacity), and (3) a small cupola for melting the ferro-man- 
 ganese or other recarburizer which is mixed with the converter con- 
 tents after blowing. 
 
 In quality, steel for castings must be low in phosphorus and sul- 
 phur, although these ingredients are not so objectionable in cast as 
 in rolled steel. Silicon and manganese should be kept within limits, 
 and particularly should iron oxide and dissolved gas be reduced to 
 the lowest limits possible. The hardness of the casting, and directly 
 its tensile strength and brittleness, depend upon the per cent of 
 carbon contained. Hard castings contain up to .9% of carbon, 
 medium castings contain around .5%, and soft castings contain 
 around .3%. Most castings contain between .35% and .50%. Soft 
 castings are hardest to obtain because of the higher melting point 
 of low-carbon steel. This grade of castings often looks very rough. 
 The very best steel castings contain about 2>y 2 % of nickel. 
 
THE FOUNDRY 257 
 
 282. The Tropenas Converter. The product of this converter is 
 acid steel produced as in the Bessemer process except that the 
 Tropenas converter directs its blast against the surface and not 
 through the metal. Fig. 137 shows a Tropenas converter in cross- 
 section. The lining is the same as that for an acid Bessemer con- 
 verter, and the tuyeres, arranged in two horizontal rows in the side 
 of the converter, are formed of lining-bricks with holes through 
 them. The lower tuyeres, used throughout the blow, are called the 
 reaction tuyeres and they open into the main wind box (7. The 
 upper tuyeres, used during the latter part of the blow, are called the 
 combustion tuyeres, and open into the auxiliary wind box D. The 
 advantages claimed for this converter are (1) the blast pressure is 
 
 PIG. 137. Converter for Steel Foundries. 
 
 very low (not over 5 Ibs.) as it is not forced through the metal, and 
 therefore requires a less powerful blower; (2) the surface impact 
 agitates the metal less, causing it to take up less gas than the 
 through blow ; and ( 3 ) the combustible impurities in the metal are 
 more completely burned. 
 
 The converter is charged with very hot metal from the cupola, the 
 blast is admitted through the lower tuyeres, and the burning out of 
 the impurities proceeds as in the acid Bessemer process. As the 
 blast enters through the tuyeres, it strikes the surface of the metal 
 at an angle, agitating it slightly, and when the flame from the 
 mouth of the converter begins to die down, air is admitted through 
 the upper tuyeres for a greater supply and better distribution of 
 oxygen. The blow lasts but a few minutes, and when the flame dies 
 
258 MECHANICAL PROCESSES 
 
 out, the recarburizer is poured in and stirred. The steel is then 
 poured into ladles and taken to the moulds. 
 
 283. Temperature of Steel for Pouring. The temperature of 
 steel when poured into moulds is highly important, and varies with 
 the size of the casting. An experienced foundry superintendent 
 judges the right pouring temperature by simple inspection. Hotter 
 metal is needed for small intricate castings than for large and 
 massive castings. 
 
 If metal is too hot, it is very searching, and causes piping or 
 cavities, and possibly shrinkage cracks, by excessive and unequal 
 contraction in the mould. If below a certain fluidity, the mould 
 may not fill completely or cold shuts may be formed. Small bits of 
 aluminum thrown into the ladle reduce iron oxide, thus helping the 
 fluidity of the steel. 
 
 After pouring steel moulds, they are watched to see that the 
 mould feeds from the risers and feedings heads, and when the metal 
 has "set," clamps are removed from the flasks, and the mould is 
 somewhat loosened to allow the casting free contraction, yet the cast- 
 ing must not be laid bare to sudden chilling. 
 
 284. Annealing Steel Castings. Because of the considerable 
 change in form by contraction during cooling, steel castings of large 
 bulk and particularly varying thickness, are apt to be under stress 
 due to the contraction of a heavier and hotter part after a thinner 
 part has cooled. Especially is this the case with castings naturally 
 brittle from a high per cent of carbon. The stresses are removed, 
 or at least are reduced within safe limits, by annealing. 
 
 This may be done in any kind of a brick furnace which can be 
 evenly heated to the temperature required. After the heat has re- 
 mained for a while at its maximum, the furnace openings are 
 stopped with bricks or clay to insure slow and even cooling as the 
 fire dies out. Castings may be covered with sand to assist in the 
 gradual and even heating and cooling of light and heavy parts. 
 Castings are heated red, and annealing requires from 60 to 180 
 hours. 
 
 The elastic and tensile strength of a casting is controlled to such 
 a degree by annealing that many investigators are seeking to find 
 the factors controlling this process. Method of heating, time and 
 
THE FOUNDRY 259 
 
 temperature,, all enter into the problem. Annealing furnaces need 
 pyrometers to insure best results. 
 
 By exercising care in allowing small and medium-sized castings 
 to cool in the moulds, the necessity of annealing may be avoided. 
 
 285. Defects in Steel Castings. Steel castings are subject in gen- 
 eral to the same defects named for cast-iron castings, but particu- 
 larly does the manufacturer of steel castings have to be continually 
 on guard against three classes of defects named, as follows : 
 
 (1) Cavities on the surface or hollows in the body of the casting 
 (piping) caused by runners, risers and feeding heads too small to 
 feed the casting as it cools. The hollows are so small at times as to 
 resemble blow holes. 
 
 (2) Shrinkage cracks or internal strains due to unequal rates of 
 cooling of various parts or resistance of the mould to contraction 
 of the metal. 
 
 (3) Blow holes or small globules of gas or air enclosed in the 
 metal. They may be due to (a) poorly vented or poorly dried 
 moulds in which air and steam do not escape from the mould cavity, 
 or (6) to carbon monoxide and other gases dissolved in the metal 
 while very hot in the converter and which are thrown out of solu- 
 tion as the metal cools, a defect greatly remedied by the chemical 
 action of ferro-silicon or aluminum. 
 
 One test usually specified to determine the soundness of steel cast- 
 ings is to suspend and strike them with a hammer, or to hammer 
 without suspending. This does not alwa}^s show the defect a cast- 
 ing may have. 
 
 Sometimes a cracked casting which has been annealed may be 
 made good by welding on a piece to repair the crack. 
 
CHAPTER X. 
 THE BLACKSMITH SHOP. 
 
 286. The Blacksmith and Forge Shop, The work of shaping 
 iron into many forms by heating and hammering is a process 
 which has been long in vogue, and it is far more widely known and 
 practiced to-day than any of the other metal-shaping processes. 
 Every village, and every farming and mining community has its 
 blacksmith shop. The simple equipment needed for blacksmith 
 work of the cruder sort makes this process readily available at any 
 place where heat, hammer, and improvised anvil are at hand. 
 
 Blacksmithing is, strictly speaking, a re-manufacturing process, 
 and it is practiced independent of other shops in turning out ready 
 for use many products of forged iron with which everyone is 
 familiar. 
 
 In a large building and repairing establishment the work of mak- 
 ing forgings is divided between (1) the blacksmith shop, where 
 forgings are made by manual labor on the anvil as in the village 
 shop, and (2) the forge shop, where large forgings are made by the 
 steam hammer. 
 
 The forgings made in the blacksmith shop are for the most part 
 used just as the shop turns them out, or else they may require no 
 other finishing than a little filing or grinding. Large forgings 
 made under the steam hammer are almost always rough shapes to 
 be machined accurately to required dimensions in the machine shop. 
 Examples of this class of large forgings are crank and line shafts, 
 cross-heads, connecting and piston rods, large braces and bolts, used 
 in marine and stationary engines. Many parts of engines subject 
 to stresses in motion are made of large forgings because of the 
 greater homogeneity and reliability of their material as compared 
 with cast steel. 
 
 The largest class of forgings, as large gun parts, shafts of large 
 engines, etc., are special products in size and quality of material, 
 and these are made, as was outlined in Chapter V, by the steel 
 works which produce the special ingots necessary for them. 
 
THE BLACKSMITH SHOP 261 
 
 The process of drop-hammer forging has narrowed the field of 
 work for the blacksmith shop, and not only has the drop hammer 
 succeeded in making many forgings formerly made on the anvil 
 by hand, but it makes many superior and complicated forged shapes 
 heretofore made only as iron or steel castings or cut to shape at 
 great expense in the machine shop. 
 
 287. Materials for Forcings. The stock for working into small 
 forgings comes from the rolling mill as rods and bars of various 
 sections. This material, at the present day, is principally mild 
 steel, this having displaced most of the wrought iron used before 
 the days of mild steel. However, many blacksmiths use only 
 wrought iron in work which must be welded, as this material has 
 the quality of becoming very plastic at a high heat before melting. 
 High-carbon steel and cast iron cannot be welded on the anvil be- 
 cause the carbon in them begins to burn out before welding heat is 
 reached, and because the melting point is not preceded by a helpful 
 condition of plasticity. 
 
 Oftentimes for special work in marine use, the stock of the black- 
 smith shop includes rods and bars of certain bronzes which can be 
 forged and welded as can iron. 
 
 A shop always carries in stock some bars of high-carbon or alloy- 
 crucible steel for making metal-cutting tools. . 
 
 For steam-hammer forgings, billets and blooms, of designated 
 dimensions and quality, are ordered from the rolling mills. These 
 are usually of mild steel, but may be of wrought iron. For high- 
 grade forgings, nickel steel is much used. 
 
 Steel castings are occasionally heated and shaped differently from 
 the shapes given by the mould,, though this adds much to their 
 cost and they should be annealed afterward. 
 
 288. Shop Equipment for Hand Forging. This equipment con- 
 sists of (1) a suitable forge for heating, (2) an anvil mounted solidly 
 at a convenient working height, (3) hammers in form and weight 
 suitable for shaping forgings to best advantage, and (4) appliances 
 to hold and to assist in shaping material worked upon. Also, there 
 is always more or less accessory equipment in the blacksmith shop, 
 such as vise and bench, cold chisels, files, grindstone, taps and dies, 
 hand-power drill, and other appliances from machine-shop equip- 
 ment, employed for cold iron work. 
 
262 MECHANICAL PROCESSES 
 
 289. The Forge. Forges are of various forms, portable and sta- 
 tionary, and framed of brick or iron. Most of them use coal for 
 fuel, but brick-lined furnaces for oil or gas fuel are now in common 
 use. For coal-burning furnaces, the essential parts are (1) the 
 forge-pan or hearth, into which leads a tuyere from underneath 
 for conveying air to the under side of the fire, (2) the chimney, or 
 exhaust hood and duct for conveying away smoke, and (3) the 
 bellows or blower for forcing air through conduits to the tuyere. 
 
 The oil or gas-burning forge is a brick-lined box open at the top 
 or on one side for putting in work to be heated. It is provided with 
 a burner which blows air and fuel into the enclosed space where it 
 burns in a continuous flame. The products of combustion usually 
 escape into the surrounding atmosphere. 
 
 FIG. 138. Anvil. 
 
 Attached to or beside a forge is an iron or wood quenching basin 
 filled with water, and racks for holding tools which the smith uses 
 in forging. A small iron poker and hooked scraper are essential 
 fire tools. 
 
 290. The Anvil. Fig. 138 shows an anvil of usual form. The 
 body and horn are made of wrought iron or forged mild steel, with 
 a %-inch face of crucible tool steel welded on the body. However, 
 some anvils are made by casting upon a tool-steel face and horn a 
 body of a gun-metal grade of cast iron. The face and horn are cast 
 to shape from crucible steel, and are then placed to form the bottom 
 of a mould. They are heated to a red heat when the mould is poured 
 to insure complete welding of the two metals. After the tool-steel 
 face is welded on, it is hardened by heating and quenching in water 
 and then ground to a working surface. 
 
THE BLACKSMITH SHOP 263 
 
 When a hole is to be punched in a forging, it is done over the 
 round hole of the anvil. The square hole is for receiving the stems 
 of anvil tools. 
 
 FIG. 139. Hand Hammer. PIG. 140. Sledge Hammer. 
 
 291. Smiths' Hammers. These are made of a medium-carbon 
 crucible cast steel. They must be hard though not brittle. Hand 
 hammers weigh about two pounds, and sledge hammers weigh 
 from 5 to 20 pounds, though for ordinary work about 10 pounds. 
 
 Fig. 139 shows a hand hammer with a cross pene shape of small 
 end. Fig. 140 shows a sledge with a straight pene shape of small 
 end. 
 
 Straight Lipped Tongs. 
 
 Single Pick Up Tongs. 
 
 " Gad " Tongs. 
 FIG. 141. Tongs. 
 
 292. Tongs and Anvil Tools. Fig. 141 shows three varieties of 
 tongs much used in blacksmithing, though there are many special 
 forms for holding peculiarly shaped forgings. 
 
264 
 
 MECHANICAL PROCESSES 
 
 Fig. 142 shows tools used in anvil work, 
 follows : 
 
 They are designated as 
 
 (1) Top and "bottom swages, for rounding. 
 
 (2) Top and bottom fullers, for necking. 
 
 (3) Hardie, for cutting off. 
 
 (4) Flatter, for smoothing. 
 
 (5) Hot chisel (thin edge), for cutting hot iron. 
 
 (6) Cold chisel (thick edge), for cutting cold iron. 
 
 PIG. 142. Anvil Tools. 
 
 (7) Round punch, for punching holes in hot iron. 
 
 (3) Heading tool, for forming a bolt head. 
 
 The stems of the bottom swage, bottom fuller, and the hardie, 
 fit in the square hole in the anvil. The heading tool has a metal 
 handle, and the remaining tools in the figure have hickory handles. 
 
 Fig. 143 shows a swage block, a very useful adjunct to the anvil 
 in shaping and bending bars of any shape. 
 
 Many sizes of the tools shown and many tools for special work, 
 as chain making, are not uncommonly seen in a well-equipped shop. 
 
THE BLACKSMITH SHOP 265 
 
 Anvil tools are made of a tough grade of medium-carbon crucible 
 cast steel., and they should be harder than forgings. 
 
 293. Fuel for Use in Forges. Up to recent years soft coal was 
 the most extensively used fuel for forges, but petroleum residue is 
 now much used, and natural gas is used in localities which supply it. 
 
 Soft coal is used because its gaseous constituents distil off con- 
 tinuously during burning and assist the solid carbon to maintain 
 a steady fire. The coal used must be of a quality containing very 
 little if any sulphur, and almost free from mineral matter which 
 will not burn or which will form a pasty mass of slag or clinker in 
 the fire. It should be a free coking coal, broken into small lumps 
 
 FIG. 143. Swage Block. 
 
 which will stick together slightly during burning. The air blast is 
 supplied in a forge to increase the rapidity of combustion in one 
 spot, and thus supply a concentrated quantity of heat for needs of 
 local heating. 
 
 Oil used in forges is the same as supplied for steam boiler uses, 
 although the grades low in sulphur are preferable. To attempt the 
 used of undistilled, or crude, petroleum would be dangerous because 
 of the gasolene and other highly volatile constituents. 
 
 294. Heating in a Forge. A clean fire of incandescent coal all 
 around a piece to be forged will insure even heating. There must be 
 a substantial layer of burning coal between the forging and the 
 tuyere, else the oxygen of the air entering through the tuyere will 
 burn the forging. Also the supply of air must be regulated by the 
 
266 MECHANICAL PROCESSES 
 
 damper to avoid letting more in than can be consumed by the burn- 
 ing fuel, as any excess will be taken up by the hot iron, forming a 
 scale of iron oxide over the surface. 
 
 The simple means of regulating the air and oil, or air and gas 
 supply to oil and gas furnaces by merely turning the controlling 
 valve of each, makes these forges superior to coal forges. 
 
 The degree of heat to which a forging should be raised varies 
 somewhat for different kinds of work. Welding requires a high 
 heat to bring the parts to be joined near the fusing temperature, but 
 for shaping it is sufficient to bring the piece to a red heat. A large 
 forging should be heated as bright as can be without burning and 
 it is often heated yellow because fewer heats are necessary and the 
 more plastic condition at high heat insures the hammer impact 
 reaching further into the mass of metal. The finishing of work at a 
 low red heat shapes the surface, and the blows then should not be 
 heavy. No forging should be done below a red heat, except that 
 light blows may be given to smooth the surface. 
 
 The heating of forgings is a p.art of the subject of the heat treat- 
 ment of steel, which is now a matter of careful study among those 
 experienced and interested in steel working. Wrought iron is less 
 affected by overheating because it has no carbon to be burned out, 
 and is not subject to the internal crystalline conditions to anything 
 like the degree affecting steel, if at all. 
 
 295. Terms Commonly Used in Forging. Among the terms used 
 may be mentioned the following : 
 
 (1) Upsetting is the increase in thickness and decrease in length 
 produced by hammering a hot piece of metal on the end. Up- 
 setting is resorted to for forging bolt heads, and for forming a 
 bulk of metal as ample stock for further heating and hammering 
 operations in welding, etc. 
 
 (2) Drawing out is the opposite of upsetting and is used when 
 work is to be pointed or made smaller in cross-section. 
 
 (3) Scarfing is the tapering of two ends of metal so that they 
 may fit together at their surfaces of contact as if one continuous 
 piece. 
 
 (4) Swaging is the reducing of cross-section, and finally the 
 shaping and finishing a bar or rod by use of the swage block or by 
 use of the top and bottom swages on the anvil. 
 
THE BLACKSMITH SHOP 
 
 267 
 
 296. Measuring Stock for Forging. Fig. 144 shows two dimen- 
 sioned sketches such as would be given a blacksmith for making an 
 angle and a ring. To cut stock to the exact length for the angle, take 
 the length of the neutral axis ab, which is practically 15 inches, in this 
 case. Likewise, stock for the ring is cut to a length equal to the length 
 of the neutral axis plus an amount needed for scarfing and lapping 
 for a weld. In homogeneous bars or plates of malleable metals, the 
 neutral axis is practically in the middle plane, and bending stretches 
 metal on one side of this plane about as much as it compresses metal 
 on the other side. 
 
 297. Welding. This process of joining together two pieces of 
 iron has long been practiced in blacksmith ing, but is now by no 
 means confined to the blacksmith shop nor to the metal used therein. 
 
 In welding wrought iron or mild steel in the blacksmith shop, 
 care is required to heat both pieces evenly. Mild steel must be heated 
 and worked with skill and judgment in welding, as its temperature 
 range between the time it becomes cohesive and the time it melts or 
 begins to oxidize rapidly is not as great as the corresponding tem- 
 perature range of wrought iron. 
 
 To assist welding a flux is used. The surfaces of metals brought 
 to a welding heat are unavoidably oxidized more or less, i. e., scale 
 is formed on them. If this is allowed to remain, it prevents contact 
 of metal to metal, thus preventing a weld. The flux is sprinkled 
 in the ends at about a yellow heat. This melts and forms a film 
 over the hot metal protecting it against further oxidation and caus- 
 ing the oxide formed to melt at a low heat. The liquid oxide and 
 flux are readily displaced as the metal is hammered into contact. 
 Scale formed on wrought iron melts at about its welding tempera- 
 ture, hence some smiths may not use flux for wrought-iron welding. 
 
268 
 
 MECHANICAL PROCESSES 
 
 Fluxes commonly used are silica (sand), borax, or sal ammoniac. 
 A borax flux should be first fused to get rid of its water of crystaliza- 
 tion and then it does not bubble when powdered and sprinkled on 
 the hot metal. 
 
 Anvil welding requires preliminary shaping of the two surfaces 
 to be welded. The forms of welds much used are as follows: 
 
 (1) Faggot weld. A frequent example of faggot welding is that 
 used to make a large mass of metal in a bar as shown by the doubled 
 part in Fig. 14.5. 
 
 FIG. 145. 
 
 FIG. 146. 
 
 (2) Lap weld. Fig. 146 shows the ends of two pieces prepared 
 for a lap weld. Their contact surfaces are made convex to force 
 out any scale or dirt as the weld is hammered together. 
 
 FIG. 147. 
 
 (3) Link weld. This is a lap weld much used in chain links, 
 eye bolts and ring welding, and is shown at a, Fig. 147. 
 
 (4) Butt weld. The two pieces are shaped with convex ends as 
 shown at ~b, Fig. 147. 
 
 (5) Split weld for thin material. The form, shown at c, is used 
 because the two pieces can be jammed together quickly on drawing 
 them from the fire and hammered without loss of time, as the pieces 
 cool quickly. 
 
 (6) Split weld for heavy material. Pieces shaped for this weld 
 (d, Fig. 147) give much bearing surface within a small radius. 
 This is much used in welding together wrought iron and mild 
 
THE BLACKSMITH SHOP 269 
 
 steel. A bulk of metal holds its heat longer for welding, and much 
 bearing surface gives a greater per cent of strength of the weld as 
 compared to the strength of the solid piece. 
 
 (7) T weld. The pieces for this weld are shaped as shown at g, 
 Fig. 147. 
 
 298. Hardening and Tempering at the Forge. The forging, 
 hardening and tempering of steel tools for cutting metals have long 
 been practiced as a part of blacksmithing. The process used by 
 blacksmiths to give an edged tool the correct degree of hardness is 
 accomplished in two steps vaguely designated as " tempering." To 
 illustrate blacksmith-shop hardening and tempering, which, though 
 crude, is highly useful and very convenient, an example of hardening 
 and tempering a cold chisel will be given : 
 
 Having forged the cutting end to shape, place this end in the fire 
 and heat about half the length of the chisel to cherry red (the 
 critical temperature, as near as can be judged). Plunge most of 
 the red hot part into water, holding it still until cold, then with- 
 draw and quickly rub a bright metallic spot near the cutting edge 
 with a piece of grindstone or other abrasive material. This quench- 
 ing gives the cutting end the maximum hardness which can be 
 given it, but this is too hard for use, and the heat left in the un- 
 quenched part of the chisel is now used for the purpose of tempering 
 this extreme hardness, or " drawing the temper." 
 
 Holding the chisel in the tongs, watch the gradual changes of 
 color on the rubbed spot, as the heat travels down from the un- 
 quenched end. As soon as the color reaches that denoting the hard- 
 ness desired (dark purple in this case), plunge the whole chisel at 
 once into water to prevent further " drawing of temper." 
 
 The water must not be extremely cold, as the sudden change of 
 temperature may be great enough to cause small cracks over the 
 surface of the steel. 
 
 299. Color Table for Judging Hardness. The first color observed 
 after rubbing a bright spot on a piece of quenched steel is a light 
 straw, denoting the greatest degree of hardness possible for that 
 particular piece of steel. As the heat travels into the quenched end, 
 the hardness decreases, as denoted by the change of colors in the 
 order of light, medium and dark straw, light and dark purple, dark 
 and light blue. These colors are temperature indicators, and as the 
 
 18 
 
270 MECHANICAL PROCESSES 
 
 reduction in hardness of the steel is dependent upon the amount of 
 annealing which the hardened end gets from the heat in the other 
 end, these colors correspond with degrees of relative hardness in 
 regular order. A color, purple for example, does not indicate the 
 same degree of hardness in all grades of carbon steels, as the hard- 
 ness in different carbon steels at a given temperature depends upon 
 the contained carbon. 
 
 300. Hardening of Alloy-Steel Tools. The alloy steels are so 
 various in composition that no general rule can be given for their 
 hardening. The best method is to follow the directions given by 
 the maker of each grade of this steel, and not attempt to harden 
 all grades by the method one may be familiar with for hardening any 
 particular alloy. However, many alloy steels are hardened by heat- 
 ing to a white heat and cooling in a blast of air less rapidly than 
 by quenching. 
 
 301. Influence of the Cooling Medium in Hardening. The prac- 
 tice of using water, brine, oil and other liquids for quenching a steel 
 tool after heating for hardening, varies with different blacksmiths. 
 As was previously mentioned, two of the factors controlling the 
 hardness of a piece of quenched steel are the rapidity of cooling 
 and the range of temperature through which cooled. These may 
 be combined as one condition, viz., the range of temperature through 
 which a piece of steel is cooled in a given time. In any cooling 
 liquid this condition depends (1) upon the difference in tempera- 
 ture of the steel and the liquid, and (2) upon the rapidity with 
 which the liquid will conduct away the heat imparted to it by the 
 metal. It is seen that the 2d item depends upon the ability of the 
 liquid as a conductor of heat, upon its specific heat, and whether 
 or not its vapor forms around the hot metal or whether a sticky 
 film, as of oil, forms around the metal from charring. Experience 
 is best to determine all these factors, and there is no mysterious 
 virtue about any of the cooling media. 
 
 302. Annealing in the Blacksmith Shop. Occasionally it is 
 necessary to take the temper from a piece of tool steel for forging 
 into another shape, i. e., the steel is to be softened. It is heated 
 to a red heat and is placed between two heavy pieces of pine board. 
 Weighted down, or pressed together in a vise, the steel soon burns 
 a cavity in the wood, and as the two boards come together they com- 
 
THE BLACKSMITH SHOP 
 
 pletely bury the steel, shuting off all oxygen and stopping further 
 burning. The charred wood surrounding the steel allows it to cool 
 only very slowly, and in a few hours the metal is cold and soft. 
 
 A red hot piece of steel may be softened by burying it in hot sand. 
 The object is slow and even cooling. Some alloy steels cannot be 
 softened by any known means after they are once hardened. 
 
 303. Equipment of the Forge Shop. As this part of the black- 
 smith shop is intended for heavy work its principal equipment is 
 one or more steam hammers of the small single frame type or of the 
 heavy double frame type. Other essential equipment includes: 
 
 (2) Tools and holding appliances to assist in shaping the forging 
 and in holding the billet forged. 
 
 (3) A suitable furnace, preferably oil or gas fired, for heating 
 billets. 
 
 (4) An upsetting machine (not always installed) which works 
 much like a rivet-heading machine in squeezing a length of red-hot 
 metal into a shorter and larger bulk. 
 
 304. The Steam Hammer. Steam hammers are single acting 
 when the hammer is raised by steam and falls by gravity alone; or 
 are double acting when the hammer is raised and forced down by 
 steam. 
 
 The smaller hammers have single frames and the larger hammers, 
 as shown in Fig. 1-48, have double frames. This view shows a 
 2500-lb. hammer, i. e., one whose hammer and moving parts at- 
 tached thereto weigh 2500 Ibs. 
 
 The hammer H is raised and forced down by steam acting on a 
 piston in the cylinder C. One of the levers at the side governs the 
 steam supply to the hammer, and the other controls the rapidity 
 and force of the blows. The hammer oscillations synchronize with 
 the controlling lever movements, and an experienced man or boy 
 can regulate the force of the Wow with great nicety. The dies DD 
 are keyed to the hammer and to the anvil cap A. 
 
 305. Appliances Used with the Steam Hammer. Blooms and 
 large billets are held during forging by a chuck and porter bar, or 
 by a porter bar clamped to one end of the forging. Smaller billets 
 are gripped by heavy tongs made to conform to the size of the 
 billet end. The combined weight of billet and tongs is balanced in 
 the loop of an endless chain hung from the crane. 
 
272 
 
 MECHANICAL PROCESSES 
 
 The principal steam-hammer tools are as follows, shown in Fig. 
 149: 
 
 (1) The hammer-chisel, for cutting hot iron nearly in two from 
 one side. 
 
 (2) The snapping bar, round at one end and triangular at the 
 other end, for finishing, from the opposite side the cutting begun 
 
 FIG. 148. Steam Hammer. 
 
 by the hammer-chisel. To cut completely through with the chisel 
 would injure the chisel against the anvil. 
 
 (3) The necking tool, for making a square or filletted shoulder. 
 
 (4) The fuller bar, a round bar for reducing and grooving 
 forgings. 
 
 (5) The tapering and fullering tool, used as shown at 5a. 
 
THE BLACKSMITH SHOP 
 
 273 
 
 (6) The set, a square bar for squaring corners in narrow parts 
 of a forging. 
 
 (7) The spring swage. 
 
 (8) The punch. 
 
 A tool is held against the forging and it receives the blows of 
 the hammer. The handles of these tools are from 3 to 6 feet long, 
 of iron. 
 
 FIG. 149. Steam Hammer Tools. 
 
 306. Heating Furnaces. The open forge is not well adapted to 
 steam-hammer work, but some form of closed furnace is necessary 
 to give the required amount of concentrated heat. Oil, gas or coal 
 furnaces are much used, with preference for the oil furnace be- 
 cause of its ready control. Oil furnaces of similar type to that 
 shown in Fig. 50, but usually smaller, are well adapted to forge 
 shop use. 
 
274 MECHANICAL PROCESSES 
 
 307. Notes on Steam-Hammer Forging. 
 
 (1) Upsetting in large forge work may be done by holding the 
 heated billet between the hammer and the anvil dies and bumping 
 it with a battering ram known as a " tup " or " monkey." This is a 
 heavy mass of iron with a smooth end and a long horizontal handle. 
 It is suspended from the roof, and is swung like a pendulum so that 
 it strikes the billet on end. 
 
 (2) Metal should be forged only at a red heat, though light 
 blows for surface finishing may safely be given at a blue heat. 
 Forging nearly cold iron is not advantageous and iron so forged 
 should be annealed. 
 
 FIG. 150. 
 
 (3) The energy in a small hammer forced at high speed against 
 a forging may be made the same as that in a large hammer forced 
 at a lower speed, but the effect of the blow on the forging is not the 
 same. A quickly delivered blow is superficial in its effect, while a 
 slowly delivered blow from a heavy hammer is more like the squeeze 
 of the hydraulic press, and is deeper felt. The particles of metal 
 have time to re-arrange themselves under the slower speed of the 
 heavy hammer. 
 
 (4) The effects of cold or hot forging, and of light or heavy 
 hammers as mentioned in items (2) and (3) are often shown in 
 finished forgings, sometimes to the extent of damaged parts. For 
 example 1 , the piece A, Fig. 150, shows how the edge of a forging 
 looks which is forged at a good working heat and the hammer 
 blows are felt entirely through the piece. B shows that the forging 
 was not hot enough, or the hammer was too light, or both. 
 
CHAPTER XI. 
 THE MACHINE SHOP. 
 
 308. Scope of Machine-Shop Work. The machine shop is 
 equipped for the work of finishing castings and forgings to exact 
 form and dimensions. This work is done principally by means 
 of machine tools which cut off superfluous metal, and to a far less 
 degree by chipping, filing, and scraping with hand tools. 
 
 In addition to finishing castings and forgings, there are made in 
 the machine shop many articles for particular or general use from 
 bars of iron, steel, brass and bronze supplied from the rolling mill. 
 
 An important supplementary work of this shop is that of assem- 
 bling the finished parts of an engine or other machine and fitting 
 them together in complete form ready for use. This assembling 
 is done in the erecting shop where all parts composing a machine 
 are brought to a final adjustment. 
 
 It will be noticed that the word " work " is much used in the 
 machine shop to designate a forging, casting, or other piece of 
 metal to be machined, i. e., finished to shape by means of machine 
 tools. 
 
 309. Machine-Shop Practice. The time required for work of 
 such accuracy as is done in the machine shop, and the high cost of 
 skilled labor for efficient work makes machine shop processes very 
 expensive often excessively so. Modern competition has brought 
 close attention to the desirability of avoiding machine-shop work 
 and of doing what can be done to save time and labor where this 
 grade of work cannot be obviated. 
 
 To avoid machine-shop expense, particular effort is now directed 
 to making castings smoother, and many metal articles shaped by 
 cold or hot pressing are used in place of machine-shop products 
 cut from solid metal. 
 
 In the machine shop, the work of which is not likely to wane 
 in this age of metal, particular attention is given (1) to placing 
 at the disposal of the highly skilled machinist such drawings, tools, 
 
276 MECHANICAL PROCESSES 
 
 appliances, machines and attachments as will enable him to ac- 
 complish most in a given time, and (2) to employing perfected 
 machines, tools, etc., so that efficient metal cutting may progress 
 at as rapid a speed as possible. 
 
 Modern practice requires that drawings be made clear and 
 amply dimensioned, tools be of highest quality and kept ready for 
 use, machines be kept clean and adjusted, and in short that every 
 movement of the highly skilled men be toward accomplishing 
 something definite in furthering work and that all unnecessary 
 movements be eliminated. To carry out so refined a system, the 
 highly paid machinist must be directed in the best methods for 
 doing a given piece of work by an efficient and experienced shop 
 superintendent, and all that can be done through preliminary 
 preparations or otherwise by less expensive labor is done to save 
 the time of the highly paid man. The highly paid men are selected 
 and developed because of their aptitude for their work, and judg- 
 ment must be exercised in their selection. 
 
 Much has been written on the determination of the practical 
 rate at which metals can be cut, and no little value has been de- 
 rived from efforts along this line. It may be said that a machine 
 should be run at as great a cutting speed as the work, the tool, and 
 the machine will safely stand in continued practice. 
 
 It is well to understand that there are, in machine-shop work, 
 different degrees of refinement in cutting down and finishing to 
 exact dimensions, according to the different degrees of error in- 
 cident to various methods and classes of machines. 
 
 310. Machine-Shop Equipment. The equipment of a machine 
 shop naturally depends upon the size and variety of work it has to- 
 do. There are different sizes of machines of the same kind for 
 machining different sizes of castings and forgings, also there are 
 different kinds of machines for doing the same kind of work in 
 different grades of refinement. An economic consideration is to 
 have as few machines as possible to do as great a range of work 
 as possible, and this is best accomplished by choosing high-grade 
 machines which are not only adapted to variety of work, but are 
 also able to stand the durable test of producing good work in 
 minimum time. Fig. 151 shows the general arrangement of a 
 large machine shop. 
 
THE MACHINE SHOP 
 
 277 
 
278 MECHANICAL PROCESSES 
 
 The metal-cutting machines of a machine shop are known as 
 machine tools and the work done by them is known as machining. 
 The principal equipment of the machine shop is as follows: 
 
 (1) Several types of machine tools, and their cutting tools. 
 
 (2) Vise benches equipped with suitable vises for hand work 
 and tools for chipping, filing, scraping, hand-thread cutting, etc. 
 
 (3) Small tools for measuring, trying, adjusting, etc. 
 
 (4) A laying-off table, also called a marking-off table for laying 
 out and marking work preparatory to machining it. 
 
 (5) Portable tools worked by hand or driven by compressed air 
 or electric power. 
 
 (6) Crane and other appliances for lifting and transporting 
 heavy work. 
 
 (7) A tool room where all tools are kept when not in use. 
 
 311. Marking Work to be Machined. An important prelimi- 
 nary in a machine shop is the lying off and marking of work. 
 Forgings, castings and other work to be machined must be marked 
 to indicate the location of holes to be drilled, the axis or axes of 
 hollow parts to be bored out, and in general the limits which 
 guide the machinst in cutting away superfluous metal to bring 
 the work to the finish and dimensions required by the draw- 
 ing. For example, Fig. 152 shows a casting of two small cylin- 
 ders cast in a single piece for a steam-launch engine. This 
 casting is in the rough just as it was received from the foundry. 
 The two pieces of wood WW have been placed in the cylinder ends 
 to aid in marking. The casting must be so marked that the 
 machinist can bore the cylinders to bring the axes the required 
 distance apart, face the cylinder ends to give the cylinders the 
 required length, and in short machine off all surfaces which re- 
 quire machining, and drill all holes, as required by the drawing. 
 
 The marking must be done from some point, line or plane of 
 reference which is usually chosen to agree with the axes of refer- 
 ence shown on the drawing. From this point, line, or plane, all 
 holes and machined surfaces are located on the work. 
 
 In the casting here shown a plane of reference is chosen which 
 includes the axes of the cylinders as determined by the outer 
 
THE MACHINE SHOP 
 
 279 
 
 surfaces of the cylinders. This plane is located on the casting by 
 the line KLMK, which completely girdles the casting. The line is 
 scratched by a scriber and further marked at intervals by the 
 center punch to avoid its obliteration. The axes of the two cylin- 
 ders are then located and marked by aid of the wood pieces W, 
 and from these axes all other marks are located. All dimensions 
 are supplied by the drawings. 
 
 FIG. 152. Casting Marked for Machining. 
 
 Castings and forgings are often whitewashed or chalked where 
 their reference planes are to be marked, as this helps the workmen 
 to see the marks readily. 
 
 The machining on the casting here shown is begun by planing 
 the face J\1G and then the face LK of the two steam chests. These 
 finished surfaces give convenient parallel planes for the transfer 
 of measurements. Also the face MG forms a base for securing the 
 casting on the machine which bores the two cylinders. 
 
 312. The Marking-Off Table. To afford means for marking 
 work accurately preparatory to machining it, a marking-off table is 
 provided. Certain measuring and marking tools, and suitable 
 blocks for supporting the piece to be marked, must also be provided. 
 
280 
 
 MECHANICAL PROCESSES 
 
 Fig. 153 shows a small marking-of? table made of a ribbed slab 
 of cast iron supported firmly on four posts. The top, sides and 
 ends of the slab are planed smooth and at right angles one to 
 another. The table is placed in a permanent location in the shop, 
 
 FIG. 153. Marking-Off Table. 
 
 where it is firmly supported, and its top is adjusted accurately 
 horizontal. 
 
 For very large work, a table may be made of several slabs placed 
 at or near the floor level and supported on a foundation especially 
 built to hold them level. 
 
 FIG. 154. Chocks of Marking-Off Table. 
 
 313. Tools and Appliances for the Marking-Off Table. To sup- 
 port a piece of work so that its chosen plane of reference may be 
 parallel or perpendicular to the top of the table, a number of 
 chocks and bars are used. Fig. 154 shows specimens of chocks C 
 and of rectangular bars B. These are used in pairs and each pair 
 must be exact counterparts. 
 
THE MACHINE SHOP 
 
 281 
 
 Among the tools much used on the marking-off table are the 
 following : 
 
 (1) Steel rule (Fig. 155). Made in various lengths. Opposite 
 faces and edges are ground parallel. 
 
 * J^ 
 
 FIG. 155. 
 
 (2) Straight edge. A long steel rule without graduations. 
 Used to test plane surfaces and to establish straight lines as refer- 
 ences for measurements. 
 
 FIG. 156. FIG. 157. 
 
 (3) Combination level and square (Fig. 156.) Used as a square 
 and a level. The auxiliary center head is used to locate the centers 
 of cylindrical work. The ordinary steel square is also much used. 
 
 (4) Dividers (Fig. 157). 
 
 Outside. 
 
 FIG. 158. 
 
 (5) Firm- joint calipers (Fig. 158). 
 thicknesses, etc. 
 
 Inside. 
 
 For measuring diameters, 
 
 FIG. 159. FIG. 160. 
 
 (6) Center punch (Fig. 159). This marks holes to be drilled, 
 and marks points for locating lines on work. 
 
 (7) Scribers (Fig. 160). These have hardened steel points for 
 scratching lines on metal. 
 
282 
 
 MECHANICAL PROCESSES 
 
 (8) Surface gage (Fig. 161). This is used in adjusting work 
 on the marking-off table, and for locating points or lines on the 
 work. It consists essentially of a base, a post and a scriber. The 
 under side of the base is planed to rest firmly on the table, and is 
 grooved to rest symmetrically on a cylindrical surface. The scribei 
 and post are so mounted and controlled by clamp screws that the 
 
 FIG. 161. 
 
 scriber points may be adjusted to any position desired within the 
 reach of the instrument. 
 
 314. Refined Measuring in Machine Work. The machine shop 
 is the shop on which devolves the requirement of finishing work to 
 specified dimensions within very small limits of allowable error. 
 
 The discerning of small differences in physical measurements 
 is dependent upon the degree of refinement of measuring instru- 
 
THE MACHINE SHOP 283 
 
 ments, upon variations of temperature, and upon the delicacy of 
 the sense of touch. 
 
 All products turned out by the machine shop do not require the 
 same degree of exactness in finished dimensions, and it would be a 
 needless expense to finish all work with the same high degree of 
 precision required for some grades of work. Most of the refined 
 finishing to a particular dimension is done not closer than T ^V<j 
 of an inch. A drawing of a piece of work which is to be finished 
 with especial care for making a close fit must state limits of error 
 allowable and on which side of the given dimension this is allowed. 
 
 A wheel hub may be forced or driven tightly on its shaft. This 
 is a driving or forcing fit. If the hole in the hub is bored slightly 
 smaller than the diameter of the shaft, the hub may be expanded 
 by heat until it fits over the shaft. On cooling it grips the shaft 
 and makes a shrinkage fit.* A shaft may fit more or less closely in 
 the bearing in which it revolves. If the fit is not too tight to 
 prevent free motion, it is called a working or sliding fit. 
 
 Forcing fits are made by hydraulic forcing presses, or by the 
 pull of heavy bolts. 
 
 The degree of refinement necessary in a working fit for any 
 moving part of a machine depends upon the size and degree of 
 refinement needed in the machine. The main bearing of a marine 
 engine is usually adjusted to about .012 inch. The main spindle 
 of a machine lathe is about .002" smaller than the bearing in which 
 it revolves, and a very accurate grinding machine is adjusted as 
 close as the metal of a carefully ground shaft and bearing can 
 come together without gripping. 
 
 315. Tools for Measuring. The steel rule is the simplest form 
 of measuring tool used in the machine shop. It cannot be used, 
 however, for measuring lengths smaller than can readily be dis- 
 cerned by the eye. For such measurements various forms of 
 calipers and gages are used. The accuracy of these depends upon 
 the sense of touch. 
 
 * A table of allowances for forcing and for skrinkage fits is given in 
 Par. 441, Appendix. 
 
284 
 
 MECHANICAL PROCESSES 
 
 The various forms of calipers and gages for accurate measuring 
 are as follows : 
 
 (1) Firm-joint calipers (Fig. 158). 
 
 Outside. 
 
 Inside. 
 
 FIG. 162. 
 
 (2) Screw-adjusting calipers (Fig. 162) 
 
 (3) Spring calipers (Fig. 163). 
 
 Outside. 
 
 Inside. 
 
 FIG. 163. 
 
 (4) Inside gages (Fig. 164). This instrument consists of a 
 sleeve which holds rods of different lengths for measuring inside 
 
 FIG. 164. 
 
 diameters of large cylinders. A threaded nipple on one end of the 
 sleeve provides a means for fine adjustments. 
 
 FIG. 165. 
 
 (5) Depth gages (Fig. 165). For measuring depths. The slid- 
 ing head is clamped on the rule at the point which marks the depth. 
 
THE MACHINE SHOP 
 
 285 
 
 (6) Fixed gages. Fig. 1G6 shows one of several forms of fixed 
 gages for measuring diameters within certain limits of error. The 
 gage here shown is for measuring a hole of 1" diameter, with an 
 
 FIG. 166. 
 
 allowable error of plus or minus .001". The end marked .999 should 
 go through the hole; that marked 1.001 should not enter the hole. 
 
 tWs^jSg^iVs^gV- 1 ' ?*'' 
 444^! 5 H l H'? io >vi^' 
 
 |slI<feo?<ko?0=050iOiO:OIOi:O;O:O-O5tef 
 
 I i to; 6: 6; 6 6- 6= 5; 5; 5- 5- 6- o^ 
 
 FIG. 167. 
 
 FIG. 168. 
 
 (7) Micrometer caliper. 
 Fig. 170. 
 
 Adjustable for refined measuring. See 
 
 FIG. 169. 
 
 Closely akin to the tools just mentioned are others much used in 
 the machine shop. A list of them includes the following: 
 
 (8) Protractor for measuring angles (Fig. 167). 
 
 (9) Drill gage (Fig. 168). For measuring diameters of drills. 
 
 (10) Wire and sheet-metal gage (Fig. 169). 
 19 
 
286 MECHANICAL PROCESSES 
 
 316. The Micrometer Caliper. This instrument, a type of which 
 is shown in Fig. 170, is used for measuring thicknesses and external 
 diameters. It is the instrument of the greatest degree of precision 
 used in machine-shop measuring. 
 
 Most micrometer calipers are made to show, on a graduated stem 
 or barrel, readings of measurements to T-^TT ^ an i ncn > or to y-g-g- 
 of a millimeter if graduated in the metric system. Some of these 
 instruments are supplied with verniers for showing readings vary- 
 ing by Toinnr ^ an i ncn > but measurements of less than y-^oir ^ an 
 inch are seldom used. 
 
 Material is measured between the points B of hardened steel, 
 one of which is fixed in the half-round frame. The enclosed end 
 of the spindle C is screwed into a fixed sleeve A, and when the 
 
 FIG. 170. Micrometer Caliper. 
 
 spindle is turned, its threads cause it to move in the direction of 
 its length. These threads have a pitch of 40 to an inch, hence one 
 turn of the spindle moves it -fa of an inch. The sleeve A is about 
 as long as the distance between the ends of the frame. A hollow 
 thimble D fits neatly over the sleeve, and the right-hand end of the 
 spindle is fastened to the bottom of the thimble so that the thimble 
 is used to turn the spindle and to gage its movements. 
 
 The tapered edge of the thimble is divided around its circumfer- 
 ence into 25 equal parts, and a line along the sleeve A is graduated 
 into divisions of T V of an inch. The first of these graduations is 
 marked zero. 
 
 When the space between the measuring points is closed, the zero 
 line on the edge of the thimble falls on the line along the sleeve, 
 and as the thimble is turned ^ of a revolution (or one of the 
 
THE MACHINE SHOP 287 
 
 graduations on its edge) it separates the points -fj f 3TT = r nnnr 
 of an inch. In this way the readings of T Vo ^ an i ncn are 
 observed. 
 
 Micrometer gages similar to Fig. 164 are made for refined 
 measurement of internal diameters. 
 
 317. Machine Tools. A list of machine tools for a well-equipped 
 shop is as follows: 
 
 (1) Lathe. 
 
 (2) Drilling machine, commonly called a drill. 
 
 (3) Planer. 
 
 (4) Shaping machine or shaper. 
 
 (5) Milling machine. 
 
 (6) Boring machine or boring mill. 
 
 (7) Slotting machine. 
 
 (8) Pipe cutting and threading machine. 
 
 (9) Tool-sharpening equipment. 
 
 (10) Metal saws. 
 
 (11) Forcing presses. 
 
 There are several sizes and types of each of these classes of 
 machines. The differences in the several types of one class consist 
 of durability of make, rapidity and degree of accuracy of work 
 done, and range of adaptability to various kinds of work. 
 
 Some shops may have machines other than those here named for 
 special or unusual work, though many shops have only Nos. 1, 2, 
 3, 4, 5 and 9, and even a considerable variety of work can be 
 managed with lathe, drill and planer. 
 
 The best means of driving machine tools is by means of an 
 electric motor for each machine. 
 
 318. The Lathe. In this machine, as in the wood lathe, work 
 revolves about a fixed axis between the centers and the cutting 
 tool moves either (1) parallel to the axis, cutting a cylindrical or 
 spiral surface; (2) perpendicular- to the axis, as in cutting the 
 end of a cylinder; or (3) in any combination of the two directions 
 named, cutting any variety of surfaces of revolution. The cutting 
 of screw threads is done on the lathe. 
 
288 
 
 MECHANICAL PROCESSES 
 
 Fig. 171 is a cut selected to show the principal features of a 
 lathe of medium size. The main parts are : 
 
 AA. Bed. C. Tail stock. 
 
 B. Head stock. D. Carriage. 
 
 Work is suspended between the centers PP, and is driven by a 
 dog, as shown in Fig. 172; or both centers are dispensed with and 
 flat work is secured to a chuck or a face plate screwed on the 
 spindle-end in place of the small face-plate F. The larger face 
 plate, under the lathe, is marked E. 
 
 FIG. 171. Engine Lathe of Medium Size. 
 
 The head stock carries a hollow steel spindle on which are 
 keyed the gear wheel S which drives the spindle, and the small 
 gear wheel K which drives the feed and screw-cutting gear at 
 the left of the machine. The cone wheels G and their small 
 attached gear wheel J are not attached to the spindle, but the 
 cones drive the spindle either directly by means of a small 
 sliding bolt which attaches them to the wheel S, or indirectly 
 through the back gear. The back gear consists of a spindle sup- 
 ported on the head stock parallel to the main spindle, on one end 
 of which is fixed the large gear wheel II and on the other end is 
 fixed a small gear wheel not visible. The wheels of the back gear 
 may be thrown in or out of gear with J and S by a lever L, and 
 
THE MACHINE SHOP 
 
 289 
 
 when they are in gear, the bolt connecting the cones with S must 
 be dropped out of its driving notch. The cone G is driven by a 
 belt from a corresponding cone over head. The back gear gives 
 slower speed and greater power. 
 
 The tail stock carries the dead center which may be moved 
 forward or backward by the hand wheel for adjusting it to hold 
 work in the lathe. The tail stock may be clamped at any position 
 along the bed. For supporting a bar which is to be cut tapered, 
 the dead center may be moved perpendicular to the length of the 
 bed. 
 
 A tool is shown clamped in the tool post T. Its cutting motions 
 are derived from the leading screw M or from- the feed rod N. 
 
 FIG. 172. 
 
 The leading screw is used in cutting threads. Any desired combi- 
 nation of change wheels may be placed in gear at the left to give 
 any desired speed to the tool in relation to the speed of the lathe. 
 
 The carriage D moves along the shears or top of the bed, and 
 the various attachments on the apron serve to facilitate the 
 quick adjustment and to regulate the various motions of the tool. 
 
 The compound slide rest, consisting of the two parts Q and R, 
 carries the tool post and governs the motions of the tool other than 
 in the direction along the lathe bed. The part Q travels per- 
 pendicular to the lathe bed, and the part R is mounted on a 
 vertical pivot in Q which enables its slide to move the tool in a 
 line making a greater or less angle with the direction of motion 
 of the part Q. 
 
290 
 
 MECHANICAL PROCESSES 
 
 The term back lash is frequently heard in speaking of machine 
 tools, and particularly of lathe gearing. This is the slack motion 
 noticed when reversing a train of gear wheels, due to the loose 
 fitting between the teeth of wheels which mesh together. 
 
 319. Varieties of the Lathe. Lathes are designated according 
 to their different types. Among these are (1) hand lathes; (2) 
 machine lathes; (3) gap lathes, and (4) turret lathes. 
 
 The hand lathe was mentioned with the machinery of the pattern 
 shop. This lathe is frequently made small enough to be mounted 
 on a bench and is called a bench lathe. 
 
 The machine lathe, a type contrasted with the hand lathe, cuts 
 metals by a tool fastened on the lathe carriage. A small machine 
 lathe may be driven by foot power and is called a foot lathe. A 
 
 FIG. 173. Turret of a Turret Lathe. 
 
 machine lathe is designated as a screw-cutting lathe when it is 
 equipped with a leading screw and change wheels for cutting 
 threads. 
 
 Many small lathes have no live centers nor tail stocks. A chuck 
 is screwed on the main spindle to hold a rod which is turned to 
 shape as in the screw-cutting machine. This type is called the 
 chucking lathe. 
 
 Large machine lathes are built to run at suitable speed for rapid 
 cutting made possible by high-speed steel, and are designated as 
 high-speed lathes, confusing them with small lathes run at high 
 speed. 
 
 A very important modification of the machine lathe is the gap 
 lathe. This lathe is built to be of use through a very wide range 
 of ordinary work, and is intended for a shop of limited equipment. 
 It differs from the lathe described in the preceding paragraph by 
 
 
 
THE MACHINE SHOP 291 
 
 having a gap in the bed just under the end of the main spindle to 
 provide for carrying a very large face plate which holds flat work 
 of large diameter. The lathe bed is very deep and is made in 
 two sections divided horizontally. The upper section, which carries 
 the carriage and the tail stock, may be slid along the lower part of 
 the bed to open the gap under the edge of the face plate. 
 
 The feature of the turret or monitor lathe is shown in Fig. 173. 
 The tail stock is displaced by a turret T which carries several 
 tools which are used in consecutive order on the piece of work 
 held in the chuck C. The turret is mounted on a vertical spindle 
 
 FIG. 174. Lathe Tools. 
 
 on the slide 8. This slide is moved to carry the tools into contact 
 with or away from the work by the long hand-bars. 
 This lathe saves much time in changing tools. 
 320. Lathe Tools. Fig. 174 shows the different shapes of tools 
 ordinarily used in lathe work. These are made of high-carbon 
 steel, or preferably of self-hardening alloy steel for heavy work. 
 The cutting ends are forged, hardened, tempered and ground. 
 They are designated as follows : 
 
 (1-2) Left and right-hand side-tools. 
 
 (3-7) Bent and straight cut-off tools. 
 
 (4-5) Right and left-hand diamond points. 
 
 (6) Fillet or round-nose tool. 
 
 (8) Threading tool. 
 
892 MECHANICAL PROCESSES 
 
 (9) Bent threading tool. 
 
 (10) Koughing tool. 
 
 (11) Inside boring tool. 
 
 (12) Inside threading tool. 
 
 The diamond-point tools, Xos. 4 and 5, are about superseded 
 by a round-nosed tool shown in Fig. 175 which is superior for 
 size of chip, resistance to wear, and smoothness of cut, particularly 
 on heavy work. This tool shows its advantages best when made 
 of high-speed steel. 
 
 Because of the high cost of alloy steels used for tools, much ex- 
 pense is saved by having merely a cutting end of alloy steel held 
 in a tool holder. These holders are in many styles to suit the 
 shape of the cutting end. 
 
 FIG. 175. Round-Nose Tool. 
 
 Many special tools are devised for use in turret lathes, as these 
 lathes do special work and do not use the ordinary lathe tools. 
 
 321. Lathe Attachments. Several attachments are provided to 
 enable a lathe to be used for various kinds of work. The most 
 important among these are the face plate, cliuck, mandrel , boring 
 ~bar and steady rest. There are other attachments, as taper attach- 
 ment, center-grinding attachments, etc., which are very useful, 
 but need not be described here. 
 
 A face plate is shown at E in Fig. 171. It screws on the end of 
 the main spindle in place of the small face-plate F. "Work which 
 cannot be suspended between centers is clamped by means of bolts 
 and iron clips to the face plate. 
 
 322. The Lathe Chuck. Oftentimes work can neither be sus- 
 pended between centers nor bolted to the face plate. In this case 
 it is held by a chuck, a type of which is shown in Fig. 176. The 
 four jaws (one of which is marked B) may be adjusted in a radial 
 direction by a wrench on one of the nuts (7. This nut is the end of 
 a radial screw. The jaws grip the work by clamping down on it 
 fcr by. pressing out against the inside of hollow work of large 
 
THE MACHINE SHOP 
 
 293 
 
 diameter. The jaws may be turned end for end to secure work in 
 the two ways just designated. 
 
 Chucks have usually three jaws or four jaws, and they are 
 classed as independent or universal. The jaws of an independent 
 chuck are moved separately by the wrench, while the jaws of the 
 
 FIG. 176. Lathe Chuck. 
 
 universal chuck have their controlling screws so connected by an 
 internal mechanism as to make then move outward or inward to- 
 gether. Many chucks are made to be changed by a clamp and 
 screw from universal to independent and vice versa. Chuck jaws 
 may be fitted to slotted face plates. 
 
 FIG. 177. Work Mounted on Lathe Mandrel. 
 
 323. Lathe Mandrels. There are many pieces of lathe work 
 which are pierced with a cylindrical hole and which can be mounted 
 on a bar suspended between lathe centers. Fig. 177 shows an 
 arrangement of this kind. The bar B is called a mandrel. It 
 
294 MECHANICAL PUOCESSES 
 
 has a very slight taper and rnu.st fit the work very closely, in fact 
 it is driven into the work by means of a copper maul. Such an 
 arrangement enables both sides of the work to be readily machined. 
 When the work is finished, the mandrel is driven out. 
 
 Mandrels are so frequently used in the machine shop, and they 
 must fit the work so neatly that several forms of expanding 
 mandrels have been devised so that one mandrel may suffice for 
 holo varying within a range of about 5 per cent in diameter. Fig. 
 178 shows a useful type of expanding mandrel which may easily 
 be made in the shop. It consists of a sleeve or bushing 7? and a 
 mandrel M. The mandrel is usually about 8 or 10 inches long, 
 centered for suspending between the latin- centers, threaded at one 
 
 FIG. 178. Expanding Mandrel. 
 
 end for a nut, and (ape-red for a dislanee of .". or 1 inches from the 
 threaded end so that the largest diameter of the tapered part is 
 about ."i per eent more than tin- smallest diameter. The bushing i- 
 n-aim-d in.-idi- to the taper of (he mandrel, is turned cylindrical 
 oiif-ide, has a number of slits cut along its outer surface nearly 
 through (he metal, and has one slit cut entirely through. The 
 bushing is slipped, large end first, over the threaded end of the 
 mandrel and is pushed along by aid of the nut until the taper 
 expands it ou( firmly against the work it is intended to fit. 
 
 324. The Boring Bar. K<>r boring ou( hollow cylindrical work 
 on (he lathe, it is usually secured to the face plate as shown in 
 Fig. IT'JJ. If the work does ti'.i extend more than (1 or S inches 
 from the face plate, it may be hmvd by tin- in>ide hoi-ing tool. 
 
THE 
 
 300 
 
 For longer work, a bar B is suspended between lathe centers. 
 This bar carries a cutter head C to which is clamped two or more 
 cutting tools as shown. The cutter head is fed along the bar by 
 the handle H f which is pushed by the travel of the lathe carriage. 
 
 17& Boring Bar, 
 
 The key K f traveling in a slot in the bar, keeps the cutter head 
 from revolving, 
 
 Another form of boring bar is shown in Fig, ISO, The too! 
 glide is removed from the lathe and the cylindrical work is matured 
 on the lathe carriage. The rigid bar, carrying the steel cutter A, 
 is suspended between centers, and as the bar rewires, the work is 
 
 F*c, m. Borfcas 
 
 mored slowly along by the carriage. The pin B keep? the cutter 
 firmly in place, 
 
 ** are several other types of the boring bar, bnt boring is a 
 work not usually done on a lathe except in a stoop of limited equip- 
 
 . 
 
296 
 
 MECHANICAL PROCESSES 
 
 325. The Steady Rest. When a long piece of work is suspended 
 between lathe centers it will sag more or less. Also very heavy 
 work is too heavy for safe support by the lathe centers and addi- 
 tional support must be provided. To prevent sagging and provide 
 increased support for work, a steady rest, as shown in Fig. 181, 
 is used. The principle of this may be provided in simpler form, 
 such as blocking up under the work and making a bearing on wood, 
 or metal kept lubricated. 
 
 The steady rest here shown is clamped on the bed of the lathe 
 by the yoke and bolt at the bottom, and the three sliding pieces are 
 
 FIG. 181. Steady Rest. 
 
 adjusted by the long screws to support the work at three different 
 points. When work is to be removed from the lathe, the upper 
 part of the steady rest may be opened on its hinge. 
 
 326. Centering Work for the Lathe. Lathe centers must be 
 accurately pointed to an angle of 60. They must be kept sharp- 
 pointed, smooth, and absolutely free from grit or metal chips. 
 
 A bar to be suspended in the lathe must be centered as shown in 
 Fig. 177. The center of each of the round ends of the bar is 
 located by means of dividers or otherwise, marked with a center 
 punch, drilled to a depth of about half an inch or more, and 
 countersunk to fit the taper of the lathe center. The end may be 
 
THE MACHINE SHOP 297 
 
 recessed to insure protection to the countersunk edge. It is highly 
 essential that this center be kept free from grit or chips, burrs of 
 metal, and it must be well oiled. 
 
 337. Cutting of Screw Threads. A screw thread is a helical 
 groove cut on an internal or an external cylindrical surface. The 
 cutting of threads is best and cheapest done by machine. Bolts 
 and nuts are usually cut by dies and taps held in machines for that 
 kind of work exclusively. The lathe and the milling machine are 
 employed to cut threads which must be exact in form. 
 
 FIG. 182. 
 
 The method of cutting a thread in the lathe is as follows : The 
 piece to be threaded is centered and suspended between the lathe 
 centers as shown in Fig. 182. A center gage C is placed against 
 the work for adjusting the threading tool T on the lathe carriage. 
 The notches in the center gage are angles of 60 and are so cut 
 that a line bisecting the angle is perpendicular or parallel, as the 
 case may be, to the two graduated edges of the gage. The cutting 
 end of the threading tool has been ground to a 60 point, as tested 
 by the gage notch, and the adjusting of the tool as shown insures 
 the symmetry of the thread surfaces. 
 
298 MECHANICAL PROCESSES 
 
 Change wheels are placed on the spindles and on the leading screw 
 at the end of the lathe to make the requisite combination for 
 moving the lathe carriage a definite distance along the bed for 
 each revolution of the work. When the machinist sets the lathe in 
 motion and adjusts the tool point against the work, a groove is 
 cut along the surface of the cylinder and is gradually cut deeper 
 by a number of traverses of the tool until the required depth is 
 attained. 
 
 When the tool reaches the end of each cut, it is quickly drawn 
 away, the lathe is reversed to carry the tool back to the starting 
 point, and is again reversed to begin a new cut. 
 
 FIG. 183. 
 
 328. Forms of Threads. Definitions. A screw thread may be 
 conceived as formed on a cylinder by winding thereon a piece of 
 triangular wire, as shown in Fig. 183. N is a nut, threaded inside 
 to turn on the screw. 
 
 If the wire is wound as shown on the end B, the thread is right 
 handed, if wound in the reverse direction, as on the end D, the 
 thread is left handed. A right-handed thread is one on which a 
 nut is screwed by turning the nut in the direction of the hands of 
 a watch when the bolt end is pointed toward the operator. 
 
 The distance between two adjacent ridges of the thread, as CC, 
 is the pitch of the screw. 
 
 If two triangular wires (of the same size) are wound side by 
 side on the cylinder the thread is a double thread. The pitch re- 
 
THE MACHINE SHOP 
 
 299 
 
 mains the same, but a nut turned one turn on the double thread 
 will advance twice the pitch. The distance which the nut advances 
 in one turn is called the lead of a screw, and it will be seen that in 
 this case the lead is twice the pitch. 
 
 The form of a thread is the profile it shows in a section made by 
 a plane passing through the axis of the cylinder on which the 
 threads are cut. The form most used is the V thread, and other 
 
 I-/H 
 
 1 -y/fo*i 
 
 fits/tress 
 
 Acme 
 FIG. 184. Forms of Threads. 
 
 forms used for special purposes are the square thread, the Acme or 
 worm thread, and the buttress or trapezoidal thread. These forms 
 are shown in Fig. 184. 
 
 329. Standard Threads. The unlimited forms of threads which 
 may be used has brought about efforts to standardize the form and 
 pitch of the V thread. The efforts have resulted in the U. S. 
 
 FIG. 185. 
 
 FIG. 186. 
 
 standard for the United States, the Whitworth standard for Eng- 
 land, and the metric or international standard for Continental 
 Europe. 
 
 The form of the U. S. standard is shown in Fig. 185. 
 
 The form of the Whitworth standard is shown in Fig. 18G. 
 
 The pitch of threads is standardized by designating a definite 
 pitch for threads cut on a cylinder of specified diameter; i. c., a 
 
300 MECHANICAL PROCESSES 
 
 bolt i/^-inch diameter has 13 threads per inch, and a bolt of 1-inch 
 diameter has 8 threads per inch by the U. S. standard. 
 
 Small threads may be cut on the lathe by the hand chasers 
 shown in Fig. 187, though these are more conveniently used for 
 cutting out to a greater depth a thread which was not cut deep 
 enough. 
 
 Thread gages for measuring the pitch of threads are among the 
 small tools for machine shop use. 
 
 330. Drilling Machines. The cutting of cylindrical holes of 
 greater or less size in metals is a very varied requirement in 
 machine-shop practice and many methods are employed for ac- 
 complishing this work, depending upon the diameter and length of 
 the hole. Small holes are drilled on the drilling machine, very 
 long holes, as in gun barrels or propeller shafting, are drilled in 
 
 Jns/cfe 
 
 FIG. m. Hand Chasers. 
 
 the boring lathe, and cylindrical holes of large diameter, as in a 
 steam cylinder, are bored on the boring mill. Usually a hole is 
 cast in a casting to reduce to a minimum the work of boring, and 
 in a less degree forgings are made hollow, when so required, for 
 the same purpose. Generally the term drilling is applied to the 
 cutting of small holes by a drill, and boring is applied to the cut- 
 ting of larger holes which may or may not have been previously 
 made in casting or forgings. 
 
 There are many different styles of drilling machines. The 
 principal styles among these are (1) the vertical drill; (2) the 
 radial drill; (3) the gang drill, and (4) the multiple spindle 
 drill. There are many sizes of each of these styles designed for 
 particular kinds of work. 
 
 331. The Vertical Drill. Fig. 188 shows a vertical drilling 
 machine of a type much used. The drill is carried in a socket in 
 the lower end of the vertical spindle VV. The spindle is made to 
 
THE MACHINE SHOP 
 
 301 
 
 revolve by a belt on the cones CC, and is fed gradually downward 
 either by the power-feed mechanism driven by a belt over the small 
 cones SS, or by the hand lever L which may be swung down hori- 
 zontally for convenient handling. Both power and hand feeds 
 may be readily thrown out of gear when the spindle is to be 
 
 FIG. 188. Vertical Drill. 
 
 quickly raised or lowered by the hand wheel H. The spindle 
 moves up and down in a vertical direction. 
 
 Work to be drilled rests ofi the table T, or may rest on the base 
 F. The faces of both the table and the base are horizontal, hence 
 are always perpendicular to the direction of travel of the drill. 
 The table may be adjusted vertically or swung horizontally as 
 desired. 
 20 
 
302 
 
 MECHANICAL PROCESSES 
 
 A shop usually has a small vertical drill fed only by hand and 
 used for drilling holes of i/4-inch diameter or less. This is known 
 as a sensitive drill. 
 
 Gang drills and multiple spindle drills have several spindles and 
 drill several holes at the same time. 
 
 FIG. 189. Full-Universal Radial Drill. 
 
 332. The Radial Drill. The changing of position of work on a 
 machine consumes time which may add considerably to the expense 
 of large work. The radial drill is so designed that when a piece 
 of work is secured to the drill table, which is placed on a solid 
 foundation for holding very heavy work, the drill spindle may be 
 placed over any part of the work without moving the latter. 
 
THE MACHINE SHOP 
 
 303 
 
 There are three classes of radial drills, viz., (1) the plain radial 
 drill, in which the drill spindle is always vertical, but may not be 
 swung over any point of the work; (2) the half-universal drill 
 in which the spindle may be swung over any point of the work and 
 in addition may swing in one plane at any angle to the vertical up 
 
 FIG. 190. 
 
 to complete reversal of the direction of the drill, and (3) the full- 
 universal drill in which the spindle may be swung in any plane at 
 any angle to the vertical. Fig. 189 shows a universal radial drill 
 the drill spindle of which may be moved to any position within the 
 reach of the machine and placed at any angle desired. 
 
 333. Drills and Attachments for Drilling Machines. Fig. 190 
 shows three twist drills and a countersink which are much used 
 
 FIG. 191. Drill Chuck. 
 
 with drilling machines. Drill C is made of a twisted bar of high- 
 speed steel. Drills A and C have taper shanks. They are placed 
 in a taper socket and the socket is placed in the end of the drill 
 spindle. Drill B and the countersink have straight shanks. They 
 are held in a small chuck shown in Fig. 191. Small drills have 
 
304 MECHANICAL PROCESSES 
 
 straight shanks. The countersink is used for reaming the end of 
 a hole to the shape of a lathe center. 
 
 A vise,, of which Fig. 193 is one type, is necessary for holding 
 small work accurately on the drill table. 
 
 When the drilling of holes in duplicate pieces of work is repeated 
 many times, a jig is made with the holes drilled through it in 
 correct position and this is used as a guide for drilling by placing 
 it over the work and thereby avoiding the necessity of marking the 
 holes on each piece. Work of this kind is quickest done on a 
 multiple spindle drill. Jigs in simplest form are made from plates 
 of cast iron or rolled steel. Many forms of jigs, however, are very 
 elaborate, consisting of cast-iron boxes with guide holes drilled 
 through the sides at the desired angles and protected by bushings. 
 A piece of work to be drilled is placed in one of these box jigs and 
 secured in a particular position to insure drilling similar holes alike 
 in every piece. 
 
 334. The Planer. This machine is used to cut plane surfaces 
 or straight grooves. Fig. 192 shows a type of planer much used. 
 Work is secured usually by bolts and clips to the heavy table T, 
 the surface of which is level. This table is made to move, by 
 mechanism under the machine, back and forth along two level 
 Y-shaped grooves B in the planer bed. The distance of travel of 
 the table is governed by two adjustable stops EE which strike a 
 lug of the reversing mechanism on the side of the planer bed and 
 cause the two driving belts to shift on the pulleys GrG. One of 
 these belts is open and the other is crossed to drive the pulley in 
 opposite directions. The middle wheel runs idly and merely 
 facilitates the shifting of the belts. 
 
 All that part of the machine above the table is designed for 
 holding the tool rigidly and for controlling its horizontal and 
 vertical adjustment. The housings HH carry the cross-rail C 
 which may be raised or lowered by the hand mechanism above the 
 machine. The head D slides horizontally along the cross rail, and 
 its parts are arranged for raising or lowering the tool, and for 
 setting to tool at an angle to make cuts along the sides of a piece 
 of work. 
 
 The tool is clamped by four bolts to the apron A, and it makes 
 a cut only when the table travels to the right in the view here 
 
THE MACHINE SHOP 
 
 305 
 
 shown. When the work travels back to the left, a horizontal bolt 
 J which hinges the upper edge of the apron A allows the tool to 
 swing out of the way as it drags over the work. The tool may be 
 gradually fed horizontally across the table or may be fed vertically. 
 The feeding mechanism is marked KLPRS. This mechanism 
 moves the tool after it has finished its cut and when the machine 
 is reversing. When a series cuts is finished across a piece of work, 
 the tool point is lowered slightly by the handle N for another 
 series. 
 
 FIG. 192. Planer. 
 
 The driving mechanism of the planer table is designed to give 
 the table a quicker motion for the return than for the cutting 
 stroke. This is known as the quick return motion. 
 
 335. Types of the Planer. For very heavy work of considerable 
 bulk, an open-sided planer is used. This is somewhat similar to 
 the planer just described, except that one of the housings is 
 omitted. 
 
 Another type of planer designed for planing off the end of a 
 large forging, too long to* rest cross-wise of the planer bed, is the 
 
306 MECHANICAL PROCESSES 
 
 rotary planer. The work is secured to a fixed base plate, and the 
 end is presented to the face of a heavy revolving disc which carries 
 many cutting tools. As the disc revolves, the tools cut the end 
 of the work, which is fed in a direction parallel to the face of the 
 disc. 
 
 336. Planer Tools. As in the case of lathe tools, these are 
 made of rectangular steel bar material, forged, hardened, and 
 ground to shape. The planer has fewer regular tools than the 
 lathe. There is no threading tool for the planer, but the round 
 nose and side tools are very similar for lathe and planer. A square- 
 nose finishing tool is much used with the planer. 
 
 337. The Planer Chuck and Planer Jack. The chuck or vise 
 shown in Fig. 193 is very useful for planer and shaper work. It is 
 
 FIG. 193. Planer Chuck. FIG. 194. Planer Jack. 
 
 bolted to the table and used to hold small work in exact position 
 for accurate cutting. 
 
 In the careful adjusting of heavy work on the planer table to 
 the position desired for planing, small jacks such as shown in Fig. 
 194 are used. These are of various heights, from about 1% to 6 
 inches or more. They may be left under the work, but it is best to 
 replace them with wedges of wood or iron, on which the work rests. 
 
 338. The Planing of Propeller Blades. The driving surface of 
 a propeller blade is made up of straight line elements radiating 
 from the axis of the propeller. This fact enables a true and smooth 
 surface to be machined on the blade by means of the planer. The 
 driving surface of the blade is generated by a straight line mov- 
 ing at a uniform rate along the axis of the propeller and at the 
 same time revolving about this axis at a uniform angular rate. 
 
THE MACHINE SHOP 
 
 307 
 
 A device has been perfected which rests on the planer table and 
 holds a single blade in such position that an element of the 
 blade is parallel to the direction of motion of the table. This 
 device has a feeding arrangement which gives the blade such a 
 combined motion of translation and revolution that each of its 
 elements in succession is brought into a position which the too 1 
 will follow as the table moves. 
 
 In the foundry, a propeller-blade mould is swept up in loam by 
 a sweep, the edge of which is raised and revolved at the same time 
 to generate the driving surface of the blade. 
 
 FIG. 195. Shaper. 
 
 339, The Shaper. This is virtually a planer for planing small 
 work. It is not designed like the planer, however, and the essen- 
 tial difference is that the work table remains stationary, except 
 for the feeding motion, and the tool is moved back and forth over 
 the work. The shaper is a quicker-moving machine than the 
 planer. It cuts in but one direction of its stroke. 
 
 Fig. 195 shows a type of small shaper much used. A feature of 
 all simpers is the quick-return motion, as mentioned for the planer. 
 
308 
 
 MECHANICAL PROCESSES 
 
 The Whitworth quick-return motion is much used in shaper 
 mechanism. 
 
 Work is clamped in the vise V which is bolted to the table T. 
 The table is carried by the cross-rail R which may be raised or 
 lowered by hand mechanism along its slide S at the front of the 
 column of the machine. An adjustable support B assists to hold 
 the table rigidly. 
 
 FIG. 196. Plain Milling Machine. 
 
 The tool, which is not unlike a lathe tool in form, is clamped 
 in the tool post P which is carried by an apron on the head H. 
 This head is carried by the ram M which is made to slide back and 
 forth in its guides on the top of the machine. The vertical position 
 of the tool is adjusted by the screw handle C. The length of travel 
 of the ram is adjusted to suit the work by a hand crank on the 
 spindle D, and the range of its travel, i. e., the limits of the ends 
 of its stroke, is governed by the crank above the ram. 
 
THE MACHINE SHOP 309 
 
 The machine is driven by means of a belt on one of the cone 
 wheels. As the rani moves back and forth, the table is gradually 
 fed at the end of each stroke along the cross rail by the mechanism 
 KLN until the work is carried entirely across the range of travel 
 of the tool. The tool is then slightly lowered by the screw handle 
 for a new cut, and the table is fed back in the opposite direction. 
 
 The machine is so built that the ram and table move hori- 
 zontally, one at right angles to the other, and the cross rail raises 
 or lowers vertically. 
 
 For holding small flat work of steel or iron quickly and readily, 
 a small electro-magnetic chuck has been designed for use with the 
 shaper. It is bolted to the table or clamped in the vise and is 
 supplied with direct current for the magnets. 
 
 340. The Milling Machine. This machine is shown in simple 
 form in Fig. 196. Milling machines are used for both plain and 
 intricate cutting of great variety. They are adopted to that kind 
 of cutting which is of particular or peculiar contour, which must 
 be in particular relative position to other cutting on a piece of 
 work, and which must be accurate to a high degree. 
 
 Milling machines are employed mostly on small work, yet some 
 machines are built for large and heavy work. 
 
 The teeth of plain and helical gear wheels, the spiral grooves 
 in a twist drill, the longitudinal grooves in taps and in many 
 forms of milling-machine cutters, slots and key-ways in shafts, 
 screw threads of long pitch, and hexagon nuts or other pris- 
 matic work may be mentioned as examples of milling-machine 
 cutting. A milling machine may be used for such cutting as is 
 done on a small lathe, shaper, drill, boring machine and slotting 
 machine, or for any combination of the kinds of cutting done by 
 any of these machines. With the several attachments now de- 
 signed for the modern milling machine, it can do, within the 
 limits of size of its work-table, the work of any other machine 
 tool in the shop, and even more. 
 
 341. Description of the Milling Machine. Work is held in a 
 vise or other attachment which is bolted to the slots of the table 
 (Fig. 196). Wheel-shaped cutters placed on the arbor are made 
 to revolve by means of the main spindle which is hollow, and on 
 
310 MECHANICAL PROCESSES 
 
 which is keyed the driving cone. The outer end of the arbor is 
 supported by the adjustable over-arm. The cones are driven by a 
 belt from similar cones overhead. 
 
 After work is secured on the machine and cutters are placed on 
 the arbor, the table is adjusted by hand mechanism to bring the 
 work in range of the cutters. The table may be raised or lowered 
 by the elevating screw which controls the vertical-sliding knee, 
 and it may be adjusted horizontally toward or from the body of 
 the machine by moving the saddle which, in the plain machine, 
 slides back and forth in but one horizontal direction on the knee. 
 The table, the saddle and the knee are adjusted by means of the 
 four cranks shown. 
 
 When the machine is in operation, with the work adjusted for 
 cutting, the table is fed horizontally along the saddle in either 
 direction perpendicular to the axis of the arbor, by means of the 
 feed shaft and its mechanism. The reverse lever determines the 
 direction of travel of the table, and the trip dogs are adjusted to 
 stop the table within certain limits of travel as they come into 
 contact with the trip plunger. The feed-trip lever is used to stop 
 the feed instantly by hand. The whole feed mechanism is driven 
 by a belt on the feed cones. 
 
 Some forms of cutters, which reach into grooves or slots in a 
 piece of work, have their own shanks which fit into a socket or 
 collet similar to a drill shank. This collet fits into the end of 
 the spindle. When these cutters are used, neither the arbor nor the 
 over-arm are used. 
 
 342. The Universal Milling Machine. The machine in Fig. 196 
 is known as a, plain milling machine because its table cannot turn 
 on the saddle. The machine in Fig. 197 is a universal milling 
 machine, as its saddle is made in two parts, divided horizontally 
 at H and so adjusted that the upper part may revolve on a vertical 
 spindle on the lower part, allowing the table to be turned to a 
 considerable angle from its position as shown in the plain machine. 
 The junction of the two parts of the saddle is marked by a gradu- 
 ated circle so that the angle through which the table is moved can 
 be readily measured. 
 
THE MACHINE SHOP 
 
 311 
 
 The parts of the machine (similarly named to those of the plain 
 machine) are as follows: 
 
 S. Spindle. B. Elevating screw. 
 
 C. Driving cone. //. Saddle. 
 
 F. Back gear. TT. Work table. 
 
 FIG. 197. Universal Milling Machine. 
 
 A. Arbor. 
 
 N. Arbor support. 
 
 GG. Over-arm. 
 
 MM. Over-arm brace. 
 
 D. Brace clamp. 
 
 KK. Knee. 
 
 EE. Trip dogs. 
 L. Feed shaft. 
 J. Reverse lever. 
 TV. Dividing head. 
 X. Foot stock. 
 
318 
 
 MECHANICAL PROCESSES 
 
 The dividing head and foot stock correspond to the head and tail 
 stocks of a lathe. The dividing head is used in cutting gear 
 wheels, sides of prisms, and similar work which must be divided 
 into an exact number of parts around its periphery, as shown in 
 
 THE HENDEY MACHINE CO, 
 
 TORRINGTON, CONN. 
 
 FIG. 198. Example of Milling-Machine Cutting. 
 
 Fig. 198. Divisions are regulated by the dividing wheel R. When 
 work suspended on the centers of the dividing head and the foot 
 stock must be given a motion of revolution as part of the operation 
 of milling it, the gear wheels Q (Fig. 197) are connected to the 
 feeding mechanism of the machine. For cutting spiral grooves 
 and coarse threads, the work is revolved on these centers and at 
 
THE MACHINE SHOP 313 
 
 the same time is given a motion of translation by the movement of 
 the table. 
 
 343. Milling-Machine Cutters and Arbors. Fig. 199 shows a 
 group of cutters, arbors and collets. 
 
 Cutters are made of higli-speed steel for roughing cuts and of 
 carbon steel for lighter or finishing cuts. After a cutter is 
 hardened for cutting it is ground to exact shape in a special 
 machine made for accurate grinding. In this way all the teeth 
 of a cutter are made to cut in the same path. 
 
 344. Milling-Machine Attachments. The usual milling-ma- 
 chine attachments are the vise and the dividing head, both for 
 holding work. 
 
 FIG. 199. Milling-Machine Cutters, Arbors and Collets. 
 
 There are, beside these, a number of attachments which are 
 bolted to the face of the column over the end of the main spindle 
 and connected to the spindle for changing the direction of motion 
 of the spindle or for otherwise modifying this motion to do many 
 kinds of work. Milling-machine attachments include those for 
 drilling, slotting, beveled cutting, vertical milling and other 
 purposes. 
 
 345. The Boring Machine. There are two general types of this 
 machine, both of which were designed primarily for boring hollow 
 cylinders too large for boring on the lathe. The two types of the 
 boring machine, each of which has several varieties, are (1) the 
 horizontal boring and drilling machine, and (2) the vertical boring 
 and turning mill. These machines have been developed, as their 
 names indicate, to do other work besides boring. 
 
314 MECHANICAL PROCESSES 
 
 The boring of large gun tubes, small gun barrels, and long 
 shafts, which may be forged either hollow or solid, is done on a 
 special type of lathe, and cannot be done on the boring machines 
 here mentioned. 
 
 346. The Horizontal Boring and Drilling Machine. Fig. 200 
 shows a representative type of this machine. A cylinder to be 
 bored is so clamped on the upper cross-table T, and the table is so 
 adjusted, that the cylinder axis and that of the spindle 88 are 
 coincident. This adjustment is made by raising or lowering the 
 main table MM by means of the lever B which works the large 
 
 FIG. 200. Horizontal Boring and Drilling Machine. 
 
 screws (7(7, and by sliding the table T across the main table. The 
 handle D moves the table T along the main table. The faces of the 
 tables T and M always remain horizontal, and the tables are not 
 moved while the boring is in progress. The main table is sup- 
 ported at the left by the large yoke F. 
 
 After the cylinder is adjusted, a boring bar with suitable 
 cutters is passed through the cylinder for boring. One end of 
 the bar fits into the end of the main spindle 8, and the other end is 
 supported in a bushing in the hole G. The bar with its cut- 
 ters is made to revolve by means of the wheel H, which is driven by 
 the belt cones and back gear as on the lathe. The bar and spindle are 
 
THE MACHINE SHOP 315 
 
 advanced slowly, while they revolve., by the feeding mechanism seen 
 at the right of the machine. This mechanism is fitted to give the 
 cutter different speeds of advancement in either direction of the 
 spindle's length, and the hand wheels are fitted to change the posi- 
 tion of the spindle quickly when the machine is not in operation. 
 
 This machine has the advantage of being able to bore several 
 parallel holes in a casting without having to re-adjust the casting 
 on the table, as the tables themselves provide for moving the sev- 
 eral holes into position for the cutters. 
 
 Some machines have an upper table which revolves around a 
 vertical axis on the lower table, thus fitting them for boring a 
 series of holes with horizontal axes at given angles one to another. 
 
 The ends of a cylinder may be faced off by means of a tool 
 secured to the attachment Z. This attachment is bolted to the 
 face-plate P and the tool is fed to cut at a gradually increasing 
 distance from the spindle axis. ' 
 
 A drill may be held in the end of the main spindle for drilling 
 holes as on the drilling machine. 
 
 347. The Vertical Boring and Turning Mill. This machine, 
 shown in Fig. 201, is used for boring large steam cylinders, gun- 
 hoop forgings, locomotive drive-wheel tires, fly wheels, and similar 
 large work. This work may also be faced or turned on the ends, 
 just as can be done on the face plate of a lathe. 
 
 Work to be turned or bored is clamped on the heavy revolving 
 table T , which revolves on a vertical axis. This table is virtually 
 a face plate, as on the lathe. The housings HE of the machine, 
 and all the fittings they carry, are for holding rigidly and gov- 
 erning the movements of the cutting tools. A tool is clamped in 
 each of the holders BB on the tool bars CO, and both tools may 
 be fed independently in a vertical, horizontal, or slightly inclined 
 direction as desired. Either tool may cut inside, outside or on 
 the upper end of a piece of work. 
 
 The tool bars may be inclined about 30 on the swivel head DD, 
 and these heads are readily adjusted along the cross rail RE. The 
 cross rail is readily adjusted vertically along the faces of the hous- 
 ings. The tool bars are raised or lowered by the hand wheels on 
 the swivel heads when adjusting them for cutting operations. 
 
316 
 
 MECHANICAL PROCESSES 
 
 They are made very heavy for rigidity and their weight is counter- 
 balanced by a heavy weight on the ends of the chain K. 
 
 The mechanism on top of the machine adjusts the various parts 
 preparatory to operating the machine, and the feed mechanism at 
 
 FIG. 201. Vertical Boring and Turning Mill. 
 
 the right controls the feeding of the tools while they are cutting. 
 The machine is driven by a motor, not in view. 
 
 Some designs of this machine are fitted with equipment and 
 attachments., not here shown, for many varieties of machining, in- 
 creasing its usefulness particularly in saving time required to shift 
 a heavy cylinder to another machine and adjust it thereon. 
 
THE MACHINE SHOP 31? 
 
 348. The Slotting Machine. A type of this machine is shown 
 in Fig. 202. This is known as the crank-driven type to dis- 
 tinguish it from the heavier gear-driven type. 
 
 The slotting-machine movements resemble very much those of 
 the shaper. The machine is employed particularly for slotting 
 key ways in the hubs of wheels, and is found useful for much 
 
 IT? 
 
 D 
 
 FIG. 202. Slotting Machine. 
 
 other slotting of various kinds. Work is clamped on the horizontal 
 table A which may be adjusted by giving it (1) a circular motion ; 
 (2) by moving it horizontally along the slides B, or (3) by mov- 
 ing it horizontally along the saddle C at right angles to the motion 
 of (2). These motions may be imparted to the table slowly by 
 the feed mechanism D, which changes the position of the work 
 gradually during the course of the operation of slotting. 
 21 
 
318 
 
 MECHANICAL -PROCESSES 
 
 The cutting tool moves up and down in a fixed vertical line 
 perpendicular to the face of the table. It is clamped firmly in 
 the yokes G at the end of the ram PI which works in the guides 
 KK . The ram is operated by the connecting rod L, the upper end 
 of which swings on the bolt I/", and the lower end of which is held 
 on a crank pin which may be readily adjusted along the dovetail 
 slot in the disc N to give the tool a greater or less length of move- 
 ment. The weight of the ram is counterbalanced by the weighted 
 lever P. The disc A 7 is on the end of the main spindle which is 
 driven with a quick return motion by the large wheel R geared to 
 the driving cones S. 
 
 FIG. 203. Tools for the Slotting Machine. 
 
 The path along which the point of the tool moves may be raised or 
 lowered by raising or lowering the ram in reference to the nut at M. 
 
 349. Tools for the Slotting Machine. Fig. 203 shows a few 
 slotting-machine tools for general use, although many forms may 
 be made for special uses. They are designated as follows : 
 
 (1-2) Houghing tools. 
 
 (3) Finishing and filleting tool. 
 
 (4) Key way and cutting-off tool. 
 
 (5) Holder for tool points of high-speed steel. 
 
 These tools are made to cut as they move downward in the 
 direction of their length. Other tools may be shaped to be clamped 
 on the ram so that they cut in a direction perpendicular to their 
 length. 
 
THE MACHINE SHOP 319 
 
 350. Pipe Cutting and Threading Machines, The cutting and 
 threading of steam and gas pipes is done to a considerable extent 
 by hand appliances,, but the best results are obtained by a machine 
 which cuts and threads a pipe while holding it rigidly in exact 
 position. These machines are hand or power driven, or may be 
 driven by hand and power. 
 
 Pipe cutting and threading may be done accurately in a lathe, 
 provided the pipe is not too long for the lathe. Pipe threading by 
 
 FIG. 204. Pipe-Cutting and Threading Machine. 
 
 means of hand appliances does not give satisfactory results when 
 many short lengths of pipe are to be joined in a more or less 
 intricate system, because hand appliances cannot usually cut a 
 thread so that a pipe will turn on its axis while screwing it into 
 place. 
 
 Fig. 204 shows a small machine which grips a piece of pipe in a 
 chuck C and revolves it in contact with a cutting tool at the right 
 of the machine. The die head D also carries the adjustable thread 
 chasers which thread the end of the pipe. 
 
320 MECHANICAL PROCESSES 
 
 351. Tool-Sharpening Machines. The grindstone is still em- 
 ployed for sharpening metal-cutting tools, but it has been in a 
 great measure displaced by emery or carborundum grinding wheels. 
 
 Many types of tool-grinding machines are now common among 
 machine-shop equipment. One of the smallest consists of an en- 
 cased electric motor whose shaft carries a small grinding wheel 
 on each end, with adjustable rests at the side and edge of each 
 wheel for steadying work held in the hand. This small machine 
 is usually mounted on a bench. 
 
 Another type much used is the heavy wheel, motor driven, 
 mounted on a closed base and partly covered by a hood. 
 
 A machine shop sometimes has machines other than tool-grind- 
 ing machines especially designed and built for very accurate circu- 
 lar or flat grinding, but this degree of accuracy is not required in 
 the usual run of machine-shop work. 
 
 352. Metal-Cutting Saws. It is frequently necessary to cut 
 bars, rods, standard rolled shapes, etc., into definite lengths for 
 various needs. This may be done by shearing or by sawing, and 
 the ox}f-acetylene flame is now used for metal cutting with re- 
 markable practical success. 
 
 The sawing machines gives smooth ends at any desired angle to 
 the axis of the bar sawed without wasting much metal. 
 
 The smaller metal-sawing machines consist essentially of a 
 small, straight saw blade held in a tightening frame and dragged 
 back and forth across the work to be sawed. Machines of larger 
 size are equipped with a heavy circular saw between % and 14 inch 
 thick and between 12 and 30 inches in diameter. The saw revolves 
 slowly and is fed gradually into the work which is clamped firmly 
 on the table of the machine. 
 
 353. Forcing Presses. These are used for forcing wheels on 
 spindles or shafts. They vary in size from those requiring hand 
 power applied through screw rods, to those requiring the pressure 
 of a heavy hydraulic cylinder. A heavy hydraulic forcing press 
 is used to force locomotive drive wheels and car wheels on or off 
 their axles, to force electric armatures on the shafts which carry 
 them, and to force wheels and crank discs on engine shafts. 
 
THE MACHINE SHOP 321 
 
 354. Machine-Shop Notes. Under this paragraph will be given 
 a few notes applying to machine-shop practice in general. 
 
 (1) The cutting speed of tools is determined by the heat gen- 
 erated in cutting. When the tool and the work cannot conduct 
 this heat away fast enough to prevent, the tool point becomes 
 heated and is itself ground away. This condition of heating is 
 avoided in many tools like milling cutters., metal saws, rotary 
 planer cutters, etc., where each tooth does not cut continuously. 
 For continuous cutting by one tool point as in the lathe, the high- 
 speed steels are much superior to carbon steel for removing a large 
 quantity of metal, but carbon-steel tools are better for the lighter 
 finishing cuts. Some high-speed steels will cut satisfactorily with 
 the tool point at a red heat. 
 
 (2) Oil or soapy water applied to a cutting tool assist in keep- 
 ing down the temperature, and soapy water gives a smooth bright 
 surface in the finishing cut of iron and steel. 
 
 Brass is cut at a rapid speed and is just brittle enough to be 
 given a smooth surface by the cutting tool, while copper is difficult 
 to cut by machining because it is so ductile that chips do not 
 tear away readily. 
 
 (3) Work is secured to face plates, chucks, planer and other 
 machine tables by bolts or clamps. Care must be taken that these 
 fastenings do not spring the work so that the machined surfaces 
 will be distorted when the fastenings are removed. It is well to 
 ease up the fastenings of a piece of work just before taking the 
 finishing cut, leaving enough holding pressure to keep the work 
 from slipping. 
 
 (4) Large castings which are to be machined to accurate form 
 and dimensions should be allowed to " season " for a few weeks 
 before machining is done, especially if these castings are to con- 
 tain steam. It has been found that castings undergo a gradual 
 change of shape, detected only by careful measurement, soon after 
 having been cast. This is of particular importance with castings 
 for steam turbines and with steam cylinders. In case a casting is 
 hurriedly needed, as in emergency repairs, it may be rough 
 machined after casting and then heated slowly and evenly, and 
 allowed to cool slowly. 
 
322 
 
 MECHANICAL PROCESSES 
 
 (5) To safeguard the strength of metal, a fillet should always 
 be left at the enclosed angle formed by the junction of two surfaces 
 in different planes, as was mentioned in the chapter on pattern 
 making. 
 
 It is frequently necessary to turn a shaft to two diameters as 
 shown in Fig. 205. A straight fillet as at d, or better a rounded 
 fillet as at 1), should always be left at the junction of the larger 
 and the smaller parts of the shaft. Another style of fillet, known 
 as a liidden or Hind fillet may be used where those like ~b or d 
 vrould be in the way, as, for example under a bolt head, as at k. 
 Blind fillets are advantageous where the pins and journals of a 
 crank shaft join the webs. 
 
 FIG. 205. Examples of Fillets. 
 
 ((>) The drilling of holes with large twist drills is increased in 
 speed and accuracy by first drilling a small hole, say % of an inch, 
 to act as a pilot or guide hole. . 
 
 To cut a hole accurately round and with the axis in a given 
 direction is not a simple operation, though ordinary bolt or rivet 
 holes do not require any such degree of accuracy. Hole-grinding 
 is accomplished by use of a small, rapidly revolving grinding wheel 
 of less diameter than the hole to be ground. 
 
 A round hole may be made square or polygonal by broaching out. 
 This consists of drawing or pushing through the hole, steel pins 
 of such cross sections as will cut out the hole to the shape desired. 
 
 (7) Deep-hole boring, as in boring gun tubes, gun barrels and 
 propeller shafts, is done by a long bar which carries a cutter on 
 one end. Either the work or the cutter bar revolves on its axis, 
 and the bar is pressed with sufficient firmness against the work 
 to make the cutter " bite " so long as the rotary movement con- 
 tinues. The cutter bar and cutter must be hollow to keep the 
 work cooled by a circulation of water through this hole. This also 
 
THE MACHINE SHOP 323 
 
 flushes away the chips of metal. The bar is not as large in diam- 
 eter as the hole bored so that the chips can be washed out. Finish- 
 ing to the required outside diameter is done after boring. Small 
 gun barrels are held vertically to be bored, to keep the cutter from 
 being drawn to one side of the barrel by gravity. 
 
 (8) In machining large shafts or gun tubes made from forged 
 steel ingots, the cutting away of the superfluous metal in the lathe 
 frequently reveals small cracks below the rough surface of the 
 forging. These cracks are caused by unequal cooling of the ingot, 
 and may not be numerous nor large enough to impair seriously 
 the strength of the forging, but each crack revealed must be care- 
 fully investigated to 'determine its extent. It is the practice to 
 stop the lathe when one of these cracks is revealed, and to cut out 
 the crack with a cold chisel. If its depth does not extend below 
 the metal to be machined off the forging, the machining is again 
 resumed. 
 
 (9) In machinery designations the terms bearing and journal 
 are often confused. A bearing is the support in which a shaft or 
 axle revolves, and a journal is that part of the shaft or axle which 
 is in contact with the bearing. 
 
 355. Bench Work in the Machine Shop. Some work in the 
 machine shop, as chipping, filing, scraping and reaming, is done 
 by hand. Cutting threads on small bolts and pipes is frequently 
 done at the bench, although such work is not economical. 
 
 The important tools and equipment much used in bench work 
 are as follows, many of which are well known : 
 
 (1) Bench vise. 
 
 (9) Scrapers. 
 
 (2) Hammers. 
 
 (10) Surface plates. 
 
 (3) Cold chisels. 
 
 (11) Hack saw. 
 
 (4) Files. 
 
 (12) Copper maul. 
 
 (5) Reamers. 
 
 (13) Abrasive materials. 
 
 (6) Taps. 
 
 (14) Scriber. 
 
 (7) Dies. 
 
 (15) Center punch. 
 
 (8) Wrenches. 
 
 
 (a) The vise has jaws hard enough to resist wear, but not 
 brittle enough to chip off when struck with a hammer. 
 
324 MECHANICAL PROCESSES 
 
 (b) A reamer is used to cut a drilled hole to larger diameter. 
 Reamers are either (1) cylindrical (called straight reamers) for 
 enlarging holes very slightly to exact cylindrical form and given 
 diameter., or (2) tapered for enlarging holes to a considerable de- 
 gree. The end of a straight reamer must be slightly tapered to 
 allow it to enter the hole to be reamed out. The straight reamer 
 soon wears enough to reduce its diameter and lose its accuracy if 
 used for any except light cutting. Expansion reamers have been 
 devised to be sprung out as they wear. 
 
 Rose and shell reamers are made for use on lathes, drills and 
 milling machines. A rose reamer has teeth on the end for boring 
 out a hole, as well as teeth along the body for finishing to an exact 
 diameter. 
 
 FIG. 206. Cold Chisels. 
 
 (c) The hack saw is very handy for sawing metal bars and rods. 
 It consists of a thin, narrow steel saw-blade, very hard, held in a 
 bow frame of steel by which it is kept stretched taut. 
 
 (d) The copper maul is used for such work as driving a finished 
 shaft into the hub of a metal wheel. The soft copper saves marring 
 the finished metal surfaces. 
 
 356. Cold Chisels. These are usually made from octagon-bar 
 steel, hardened at the cutting ends. The two forms most used are 
 the flat chisel A, and the cape chisel B, shown in Fig. 206. The 
 blade of B is much narrower than that of A. Other forms, as the 
 half-round and V-cornered, are very useful. 
 
 357. Files. The many kinds of files are classed according to 
 (1) length; (2) form of teeth, and (3) shape of cross section of 
 the body of the file. 
 
 The usual forms of teeth are classified as shown in Fig. 207. 
 There are finer-toothed files than the " smooth," the most used of 
 which is the "dead smooth." 
 
THE MACHINE SHOP 
 
 325 
 
 In cross-section, the usual shapes are (a) rectangular, including 
 mill, flat, pillar, square and warding ; (b) round or partly round, 
 
 RASP. 
 
 Coarse. 
 
 DOUBLE CUT. 
 
 Coarse. 
 
 SINGLE CUT. 
 
 Coarse. 
 
 Bastard. 
 
 Bastard. 
 
 Bastard. 
 
 %M&$ 
 
 
 Second Cut. 
 
 Second Cut. 
 
 Second Cut. 
 
 Smooth. Smooth. Smooth. 
 
 FIG. 207. Styles of File Teeth. 
 
 inc-uding half-round, crossing, tumbler, pit-saw, cabinet cross-cut 
 and round; and (c) triangular, including three-square, and knife- 
 edge. Some rectangular files are smooth on one or both edges, and 
 
326 
 
 MECHANICAL PROCESSES 
 
 mill or flat files may have slightly rounded edges. Fig. 208 shows 
 the cross-section shape of files most used. These are : 
 
 (1) 
 
 (6) 
 
 (3) 
 
 Bound. 
 
 (7) Half-round. 
 
 (8) Three-square. 
 Knife-edge. 
 Cabinet. 
 
 Flat. 
 Mill. 
 Pillar. 
 
 (4) Warding. (9) 
 
 (5) Square. (10) 
 
 In length (measured from the heel, or where the tang begins) 
 files may be blunt or tapered, and the usual lengths of machine-shop 
 files vary from 3 to 20 inches. Smaller sizes of files for special uses 
 are known as needle files. 
 
 Another type of file has recently come to the notice of machin- 
 ists. This is a single-cut file with the cuts arranged in arcs across 
 the length of the file. 
 
 m 
 
 m 
 
 3 4 5 6 7 Q 
 
 FIG. 208. Cross Sections of Files. 
 
 358. Taps and Dies. Thread cutting is more accurately and 
 economically done by machine, but necessity frequently arises for 
 cutting threads by hand. Taps and dies for hand work are made 
 in many forms and sizes, of various standards of threads. They 
 are usually made for cutting right-handed threads, as left-handed 
 threads are used only for some particular requirement. 
 
 Fig. 209 shows a common type of machinists' hand taps for 
 threading nuts. No. 1 is a taper tap, which may be used to ream 
 out a hole and start the cutting of threads gradually, distributing 
 the wear along the tap. No. 2 is a plug tap used for quicker cutting 
 than No. 1. No. 3 is a bottoming tap used after No. 2 for cutting 
 threads to the bottom of a hole. 
 
 A convenient form of die for bolt threading by hand is that 
 shown in Fig. 210. This consists of a holder, made up of several 
 parts, and four cutters. An extra set of cutters, or " chasers/ 7 is 
 shown beside the die. These cutters may be adjusted to suit ,rods 
 
THE MACHINE SHOP 
 
 327 
 
 FIG. 209. Taps. 
 
 FIG. 210. Threading Dies. 
 
328 
 
 MECHANICAL PROCESSES 
 
 varying about 1/32-inch in diameter and may be readily removed 
 for renewing. Fig. 211 shows a die-stock A used for holding and 
 turning the die, and an adjustable tap wrench B for turning the 
 taps of Figs, 209. 
 
 FIG. 211. Die Stock and Tap Wrench. 
 
 All taps and dies are marked with the diameter of bolt and nut 
 the} 7 will cut, the number of threads per inch, and the class or 
 standard to which the thread belongs. 
 
 
 FIG. 212. Forms of Wrenches. 
 
 359. Wrenches.' Hand wrenches for tightening or loosening 
 nuts are of several forms, some of which are shown in Fig. 212. 
 The wrenches shown are designated as follows : 
 
 (1) Monkey wrench (adjustable). 
 
 (2) Pocket wrench (adjustable). 
 
 (3) Spanner wrench. 
 
THE MACHINE SHOP 329 
 
 (4) Socket wrench. 
 
 (5) Double-end,, straight, open, hexagon wrench. 
 
 (6) Double-end, " S," open, square wrench. 
 
 (7) Double-end, angle, open, hexagon wrench. 
 
 (8) Single-end, closed wrench. 
 
 360. Scrapers. To bring perfect contact between two metal 
 surfaces, each is coated with a fine film of red lead and oil, and the 
 surfaces are then rubbed together. Upon separating them, the 
 high spots may be plainly seen, and are removed by hand scraping. 
 The scrapers used are very hard pieces of steel, not unlike files 
 without teeth, as shown in Fig. 213. The faces are ground true 
 to form, either flat or curved, and the ends are ground blunt, 
 
 FIG. 213. Scrapers. 
 
 except that the end of D is at more or less an acute angle to the 
 surface. This grinding makes sharp edges at the end of the 
 scraper and the scraping is done with these edges. 
 
 Bearings are scraped to fit journals by this method, and plane 
 surfaces which move upon each other or must form a close joint 
 for steam or other pressure connections, are brought to close con- 
 tact by the same method. Scraping is always done for such fitting 
 after the parts have been finished as accurately as can be done by 
 machining, so that the amount of scraping needed will be reduced 
 to a minimum. 
 
 Modern machines for grinding plane and curved surfaces are so 
 perfected as to make hand-scraping unnecessary. 
 
 361. Surface Plates. For testing the accuracy of a surface 
 which must be exactly plane, one of the surface plates, shown in 
 
330 MECHANICAL PROCESSES 
 
 Fig. 214, is used. These plates are sold in pairs so that one may 
 be a test of accuracy of the other. When a plane surface is to be 
 tested, one of the plates is smeared with a thin coat of oil colored 
 slightly with red lead. This coating is spread evenly by rubbing 
 both plates together and then the surface to be tried is rubbed over 
 the oiled surface of one of the plates. High spots will be revealed 
 by the oil coating, and these are scraped down. 
 
 The making of surface plates requires that each of three plates 
 shall be scraped to fit the other two to insure plane surfaces. 
 
 362. Abrasive Materials. These are used for polishing metal 
 surfaces by grinding away the marks left by the file or by machine- 
 cutting tools. They are frequently seen in the forms known as 
 emery, carborundum, and crocus cloths. These are made up of 
 a cloth of considerable strength, covered on one side with fine 
 
 FIG. 214. Surface Plates. 
 
 particles of the abrasive material, held by a coating of glue. These 
 cloths are numbered according to the coarseness of the grains glued 
 thereon. Crocus cloth is covered with red oxide of iron, and is 
 used for fine polishing. 
 
 Powdered grinding materials are also frequently used mixed 
 with oil for grinding between two metal surfaces in contact. 
 
 363. Portable Tools. There is frequent necessity for drilling 
 and other cutting on work which cannot be moved to a machine. 
 There have been devised many types of small portable machines, 
 usually designated as portable tools, which can be readily trans- 
 ported to large work for effective use in drilling, chipping, grind- 
 ing away rough places, and cutting-off. 
 
 For machine-shop use the list of portable tools generally con- 
 sists of the following viz. : 
 
 (1) Various types of portable drills driven by electric or pneu- 
 matic power or by hand. The ratchet drill for hand drilling is 
 the simplest and lightest of these types. 
 
THE MACHINE SHOP 
 
 331 
 
 (2) Portable boring bar, motor driven, for boring the stern 
 bearings of ships before launching. 
 
 (3) Valve re-seating machine, hand or electrically driven, for 
 truing up the seats of valves which have become leaky in use. 
 This is done without removing the valve body from its pipe line. 
 
 (4) Pneumatic hammers for driving a cold chisel for 
 many kinds of surface or edge chipping and for cutting 
 a narrow path across a piece of metal in cutting it off. 
 
 (5) Pneumatic and electric grinders. These are es- 
 sentially small grinding wheels mounted on a suitable 
 shaft so supported that the machine can be held in the 
 hands and the revolving wheel pressed against the spot 
 to be ground. 
 
 (6) The oxy-acetylene blowpipe. This is used to 
 direct its flame along a path on a metal plate, burning 
 its way through the plate. It is used for many cutting 
 operations in bridge, boiler, ship and other work, and is 
 very useful as a portable cutting apparatus, though it of 
 course leaves rough edges at the sides of the path burned 
 through by the flame. 
 
 (7) Very useful also in various shops are lifting jacks 
 and the differential pulley. 
 
 Jacks are made for lifting either by screw or hydraulic 
 power. They exert great force and can be operated 
 usually by one man. A hydraulic jack which will lift 
 50 tons a distance of 18 inches weighs about 325 pounds 
 and can be carried by two men. Dilute alcohol is much 
 used in the hydraulic jack because it does not freeze, but 
 it lacks the desired quality as a lubricant. 
 
 The differential pulley, shown in Fig. 215, may be 
 operated by one man to lift weights ranging considerably 
 beyond a ton, according to its capacity. It consists of a double- 
 sheaved wheel, or block, at the top and a single-sheaved wheel below. 
 An endless chain is rove over these sheaves. The distance between 
 the two wheels is increased or decreased by pulling one side or the 
 other of the loose part, or bight, B of the chain. The lifting power 
 is due to the fact that the two sheaves of the upper wheel are of 
 slightly different diameters. 
 
 PIG. 215. 
 
 Differential 
 
 Pulley. 
 
332 
 
 MECHANICAL PROCESSES 
 
 364. Pipe Fitting. This is the term used to designate tho work 
 of putting together various lengths of piping and their connecting 
 parts. This work is associated with the machine shop, where the 
 required lengths of piping are usually cut and threaded. The con- 
 necting parts are known as fittings. They are made in certain 
 standard forms as a branch of re-manufacturing, and are kept in 
 quantities among the supplies of the machine-shop store-room. 
 
 FIG. 216. Example of Pipe Fitting. 
 
 The piping, used so extensively for conveying steam, water and gas, 
 in many requirements other than those of engineering, is described 
 in the chapter on the re-manufacture of metals. The standardiza- 
 tion of the sizes and threads of fittings to agree with standard sizes 
 and threads of piping makes it possible to use together the fittings 
 and piping of all manufacturers. However, difficulty is occa- 
 sionally found in pipe-fitting work due to the fact that the slightly 
 tapered threads on both pipe and fittings are cut too deep or too 
 shallow. 
 
THE MACHINE SHOP 
 
 333 
 
 Refer- 
 ence 
 No. 
 
 Fitting. 
 
 Size. 
 
 Style. 
 
 j 
 
 Globe valve 
 
 V 
 
 
 9 
 
 
 si.tr 
 
 
 y 
 
 
 w 
 
 
 4 
 
 
 3 4" 
 
 
 5 
 
 
 a/, n 
 
 
 g 
 
 
 s/.rr 
 
 
 ij> 
 
 
 1" 
 
 
 3 
 
 
 3 4" 
 
 
 9 
 
 
 1" 
 
 
 10 
 
 
 V 
 
 
 11 
 
 do 
 
 3 /k" 
 
 
 12 
 
 Toe 
 
 8 /i" 
 
 Malleable beaded 
 
 13 
 
 do 
 
 Sj.fr 
 
 Malleable plain 
 
 14 
 
 do ... 
 
 Lf.ll 
 
 Malleable beaded 
 
 15 
 
 
 B ii""Vl" 
 
 Do 
 
 if? 
 
 
 3 .^vVvl'' 
 
 Do 
 
 
 
 %rr 
 
 
 18 
 
 Cross 
 
 3 a" 
 
 Malleable beaded 
 
 19 
 
 
 3,,'r 
 
 
 
 
 Elbow 
 
 i" 
 
 Malleable plain 
 
 91 
 
 do 
 
 %^/ 
 
 Do 
 
 99 
 
 Reducin ir elbow 
 
 3 /j/'\i" 
 
 Cast iron 
 
 93 
 
 Side-outlet elbow 
 
 i" 
 
 Malleable plain 
 
 91 
 
 Street elbow . 
 
 3 /i" 
 
 
 95 
 
 45 elbow 
 
 a,// 
 
 Do 
 
 9fl 
 
 
 1" 
 
 Cast iron 
 
 97 
 
 Sleeve couplin r 
 
 \H 
 
 
 28 
 
 
 W\\" 
 
 Malleable, plain. 
 
 99 
 
 do 
 
 3 /l"\l" 
 
 Do. 
 
 30 
 
 
 I.// 
 
 Do. 
 
 QI 
 
 
 ^>"X 3 /i" 
 
 
 3 
 
 (J O 
 
 3 /t"xl" 
 
 
 33 
 
 
 ^o" 
 
 
 34 
 
 
 3 /l" 
 
 Malleable, beaded 
 
 35 
 
 
 1" 
 
 
 36 
 
 
 1" 
 
 
 37 
 
 Cap .. 
 
 W 
 
 
 38 
 
 do 
 
 3 4" 
 
 
 39 
 
 do 
 
 i ^ 
 
 
 40 
 
 Plug 
 
 3 /t" 
 
 
 41 
 
 do 
 
 %^/ 
 
 
 4 
 
 .do 
 
 3 Zi" 
 
 
 
 
 
 
 22 
 
334 MECHANICAL PROCESSES 
 
 Pipe threads are usually right handed, though left-hand threads 
 are used for special purposes. The pipe ends are always threaded 
 on the outside and most of the fittings are threaded to screw on the 
 pipe end, although some fittings are made with outside threads to 
 be screwed into other fittings. In connecting pipe and fittings, the 
 threads are swabbed with a mixture of oil and graphite to make a 
 tight joint which may be taken apart any time afterward. 
 
 365. Fittings. Fig. 216 is a specimen of pipe-fitting work 
 made up to show the use of various types of fittings. The kind, 
 size, and style of each fitting is given in the preceding list. 
 
 Fittings are usually made of brass, cast iron, or malleableized 
 cast iron. The malleableized cast-iron fittings are known as 
 malleable fittings and are adapted to high pressures. They are 
 made in two styles known as beaded, with a rolled rim at the open- 
 ing of the fitting; and plain, without this rim. 
 
 Cast-iron fittings are much more bulky than the malleable fit- 
 tings and are used for pressures not over about 150 pounds as they 
 are not elastic, although they may not burst under many times 
 that pressure. Brass fittings (known as composition fittings) are 
 used for their ornamental appearance. 
 
 Iron fittings are either Hack or galvanized. 
 
 Pipe fittings of large size or for use under high pressures are 
 made with flanged instead of screwed ends. Special fittings are 
 made for hydraulic pipe connections. 
 
 366. Tools Used in Pipe Fitting. The hand tools ordinarily 
 used in pipe work are shown in Fig. 217. The pipe vise holds pipe 
 for cutting, threading and fitting parts together. The tongs and 
 wrenches grip the pipe for holding or turning. Dies, made with 
 standard threads, are held in the die stock when in use. Each size 
 of pipe die has a bushing which fits in the stock behind the die to 
 steady the stock on the pipe end. 
 
 367. Bolts, Nuts and Machine Screws. These articles are prod- 
 ucts of the re-manufacture of metals. Those for general use are 
 made according to adopted standards of shape and size. 
 
 A machine screw is a small bolt with a slot in the head to be 
 turned by a screw driver. Machine screws are made in diameters 
 
THE MACHINE SHOP 
 
 335 
 
 designated by gage numbers, and varying over a range from about 
 1/16 to 1/2 inches in diameter. Machine screws with nuts are 
 called stove bolts. 
 
 FIG. 217. Pipe-Fitting Tools. 
 
 Bolts are standardized in the following items, viz. 
 
 (1) Length. 
 
 (2) Diameter. 
 
 (3) Threads per inch for a given diameter. 
 
 (4) Shape and dimensions of head. 
 
336 
 
 MECHANICAL PROCESSES 
 
 Nuts are standardized in shape and dimensions. A nut is 
 usually larger than the head of its bolts as it is essential that the 
 side of the nut through its smallest part should be large enough to 
 give it the strength needed. 
 
 A CD 
 
 FIG. 218. Standard Bolts. 
 
 Fig. 218 shows the usual types of standard machine bolts. 
 These are designated as follows, viz. : 
 
 A. Machine bolt,, square head and nut. 
 
 B. Machine bolt., hexagon head and nut. 
 
 C. Machine bolt, round or fillister head. 
 
 D. Carriage bolt. 
 
 E. Stud bolt. 
 
 F. Stud bolt with collar. 
 
 G. Tap bolt or cap screw (the same as A, B, or (7), without nut 
 and with longer thread. 
 
 O CD 
 
 / 2 3 * 
 
 FIG. 219. Forms of Machine-Screw Heads. 
 
 Fig. 219 shows the usual forms of machine-screw heads. 
 They are designated as follows: 
 
 1. Flat or countersunk. 3. Oval countersunk. 
 
 2. Eound or button. 4. Fillister. 
 
THE MACHINE SHOP 337 
 
 Among the special forms of bolts may be mentioned the fol- 
 lowing, viz. : 
 
 (1) The body-bound bolt, also called the tight-fitting bolt, is 
 one which is turned in a lathe to fit closely a bored hole. Bolts 
 of this kind are much used in holding together parts of machinery 
 to prevent the slightest change of position of one part on another. 
 
 (2) The set screw is used to screw through the hub of a wheel 
 and press against the shaft to hold the wheel in place. It has 
 many other similar uses. It resembles a tap bolt, and is either 
 pointed or cupped at the end to take good hold against the shaft. 
 
 (3) The expansion bolt is used for bolting brackets and fixtures 
 to a stone, brick or cement wall. The bolt has an expanding nut 
 which is placed in a hole dug in the wall. When the bolt is 
 screwed in tightly, it expands the nut and makes it press tightly 
 in the hole. 
 
 The length of a bolt does not include the head, except in the 
 case of bolts with countersunk heads. It is generally understood 
 that bolts have standard right-hand threads, and if bolts with left- 
 hand, double or other than standard threads are desired they must 
 be specified. 
 
 To prevent nuts jarring loose and unscrewing, various nut lock- 
 ing devices are used. 
 
CHAPTER XII. 
 THE BOILEU SHOP. 
 
 368. Work of the Boiler Shop. The work of building a boiler 
 is partly that of shaping flat steel plates into cylindrical and 
 flanged forms, and partly that of assembling with these forms cer- 
 tain products of other shops, as tubes, corrugated furnaces, stay 
 bolts, etc. The whole assemblage composing the boiler proper is 
 fastened together by rivets, screwed stays, and expanded tube 
 ends; and when ready for use the boiler is supplied with such 
 fixtures as the uptake and the smoke pipe, which are built in the 
 boiler shop, and with such fittings as steam gage, stop valve, safety 
 valve, etc., furnished by other shops. 
 
 369. Types of Boilers. Their Manufacture. The many types of 
 boilers may be classed under two general divisions, viz. : 
 
 (1) Shell or fire-tube boilers. 
 
 (2) Pipe or water-tube boilers. 
 
 The shell boiler is made in several forms, of which the loco- 
 motive and the cylindrical or Scotch marine types are familiar 
 examples. In general design the shell boiler is in the form of a 
 cylindrical shell which is a reservoir for the water and steam. At- 
 tached to the shell, and more or less surrounded by it are (1) a 
 fire box, or one or more cylindrical steel furnaces and their com- 
 bustion chambers, and (2) a nest of tubes opening from the fire 
 box or combustion chambers into the smoke pipe. 
 
 The water-tube boiler consists of an assemblage of straight or 
 bent tubes, the ends of which open into water and steam reservoirs 
 usually designated respectively as headers and drums. The water 
 and steam are contained in these tubes, headers and drums, and the 
 boiler is surrounded by a sheet-steel casing which confines the fire 
 and smoke within its limits. A space for the furnace is provided 
 under the tubes and the flame and hot gases pass among the tubes 
 to reach the smoke pipe. 
 
 The shell boiler held supremacy for many decades as a steam 
 generator after the steam engine came into use, but demand for 
 
THE BOILER SHOP 
 
 the economy of higher steam pressures has gradually brought into 
 use many types of the water-tube boiler, which is particularly 
 adapted to standing high pressures. This change has taken away 
 much work from the shop for building shell boilers. The building 
 of water-tube boilers consists in a great measure of the assembling 
 of the products of other shops and plants, and of the making 
 of certain parts by the cold or hot pressing of mild steel plates to 
 special forms, leaving very little work to be done, for this type of 
 boiler, by the methods and machines used in the building of shell 
 boilers. 
 
 The many patented types of water-tube boilers have brought 
 about the building of these boilers as special work, and many 
 of the processes of forming the headers and other parts of a 
 particular type of boiler are unique and ingenious methods of hot 
 and cold pressing and of welding by aid of electric, furnace, and 
 gas blow-pipe heat. 
 
 In some patented boilers the parts are made up more or less of cast 
 steel, or even of cast iron for pressures not over about 100 pounds. 
 
 Many shell boilers for high and low pressures are still built for 
 marine, locomotive, and stationary uses, also the larger drums and 
 some other parts of water-tube boilers are built in the shop 
 equipped for shell-boiler work, hence the boiler shop and its equip- 
 ment continue to be an essential part of a general manufacturing 
 plant. 
 
 The improvement in recent years of boiler steel enables shell 
 boilers to be built for higher pressures than formerly. 
 
 370. Boiler Material. The material used for plates, rivets, 
 braces, and all other parts on which the structural strength of a 
 high-grade boiler depends are made of a low-carbon open-hearth 
 steel in which is allowable only very small quantities of phosphorus 
 and sulphur. Nickel is often alloyed with this steel to improve its 
 tensile and elastic strength. 
 
 The elastic strength, rather than the tensile strength of the 
 material, is of first importance, as the permanent safety of the 
 boiler depends upon all stresses remaining within the elastic limit. 
 A good margin between the elastic and the final strength of the 
 material provides a ductility or elongation which will many times 
 save actual and disastrous disruption under pressure by allowing 
 
340 
 
 MECHANICAL PROCESSES 
 
 the material to bulge out or otherwise stretch greatly before it 
 breaks. 
 
 Specifications for high-grade boiler plate require an elastic 
 strength of about % the tensile strength, a tensile strength of about 
 70,000 pounds, and an elongation, when pulled apart, of about 
 25% in a test bar 8 inches long. Rivets, bolts, and material for 
 boiler braces are required to exceed slightly the requirements speci- 
 fied for plates. Plates which are to be flanged for parts of the 
 boiler structure must be ductile to a high degree, and specifications 
 usually require the test piece to show a slightly greater per cent 
 of elongation and allow slightly less tensile and elastic strength 
 than for other plates. 
 
 Top Center 
 
 FIG. 220. 
 
 371. Preliminary Diagram for Laying Out Work. The dimen- 
 sions and all details of a boiler to be built must be shown on suit- 
 able drawings for the guidance of the master boilermaker in laying 
 out and directing the work of building the boiler. Supposing a 
 cylindrical shell boiler is to be built, the drawings supplied must 
 give at least a longitudinal and a transverse cross section of the 
 boiler, besides views of the side and one or both end elevations, 
 and sufficient enlarged views of single or combined parts to show 
 the details of their construction. 
 
 From the drawings he proceeds to mark out to full or half size 
 on a smooth laying-out board provided for the purpose, the front 
 end of the boiler. The beginning of this work is shown in Fig. 
 
THE BOILER SHOP 
 
 341 
 
 220. Through the center, 0, of the boiler, draw the horizontal and 
 vertical lines as guides for laying down all parts of the boiler head 
 and the openings therein. This board serves, also to show on a 
 large scale the relative positions of interior parts of the boiler, 
 particularly the positions of the plates composing the combustion 
 chambers. 
 
 The shell of the boiler is composed of two or more rings or 
 courses of plates, each course consisting of one or more plates, as 
 
 FIG. 221. Double-End Cylindrical Boiler. 
 
 shown in Fig. 221. The plates in each course are butted end to 
 end, and are fastened together by butt straps on both sides of the 
 plates. An outer butt strap is marked in the figure. Two adjacent 
 courses are joined together by overlapping the ends as shown, and 
 the ends of the shell overlap the heads. 
 
 Eeferring to Fig. 220, the full-line circles represent the ends of 
 the inner and outer course plates, and the dotted lines represent 
 the neutral circles of these plates by which their curvatures are 
 figured from the flat plates from which they are made. The lines 
 through the center divide the diagram into quadrants, deter- 
 mining four points of reference for laying out the shell. 
 
342 MECHANICAL PROCESSES 
 
 372. Diagram for Laying out Shell Plates. The shell is de- 
 veloped on a flat surface, the position of each plate joint is marked 
 with reference to the top, bottom, and side center lines, which are 
 the first lines placed on this diagram, and the amount of lap for the 
 plates of each adjacent course is marked. All details of rivet and 
 other holes are transferred to this diagram, which is used for 
 marking each shell plate and their butt straps. Each end of each 
 plate is numbered when it is measured up, to insure placing it in 
 its proper location. 
 
 The developing of the shell is virtually cutting it along one of 
 its cylindrical elements and unrolling it until it lies flat. This 
 development is made as if the outer courses unrolled without 
 stretching the circumference of their neutral circle, but the inner 
 course neutral circle is supposed to be stretched until it equals the 
 length of the outer course circle in the flat diagram. 
 
 In marking off rivet holes around the girth of the shell, care 
 must be taken to space them so that they will be at equal distances 
 apart around the circle. 
 
 The distance between centers of adjacent rivet holes is called the 
 pitch of the rivets. 
 
 373. Preparation of Plates for Laying Out. Boiler plates are 
 ordered from the rolling mill as flat plates. Their dimensions are 
 determined from the drawing of the boiler, and the plates ordered 
 should be near their finished dimensions, leaving a margin of about 
 once the thickness of the. plate to be trimmed off around the edges. 
 The trimming of this margin by chipping or planing removes the 
 strained metal along the edges caused by shearing the plate at the 
 mill. 
 
 A few days before a plate is needed for laying out, it is selected 
 from stock and pickled to loosen scale and to expose the clean 
 surface of the steel. Pickling is done by immersing the plate on 
 edge for about 24 hours in a wooden vat containing about 5% of 
 hydrochloric acid in fresh water. When lifted out the plate is 
 scrubbed and rinsed with clean water made slightly alkaline with 
 lime to remove all acid. 
 
 A careful record of each plate, giving dimensions, weight, and 
 data of its manufacture and tests, is furnished the master boiler- 
 
THE BOILER SHOP 343 
 
 maker. This record enables the selection of the particular plate 
 intended for a certain place in the boiler. 
 
 Laying out consists of transferring to the clean surface of a 
 plate the dimensions and lines shown by the laying-out diagrams 
 and the original drawings. The location of lines and boundaries 
 is marked on a plate by scribed lines and by center-punch marks. 
 
 374. Operations for Shaping Plates. The operations for shaping 
 boiler plates are as follows : 
 
 (1) Planing plate edges. 
 
 (2) Rolling plates to cylindrical form. 
 
 (3) Flanging. 
 
 (4) Drilling holes for rivets, stay bolts, tubes, etc. 
 
 These operations prepare the plates for assembling, although a 
 few rivet holes are drilled immediately after the plates are marked, 
 
 FIG. 222. 
 
 
 
 for the purpose of handling them. These holes are drilled slightly 
 smaller than the finished size and their worn edges are reamed out 
 when ready for riveting. 
 
 375. Planing Plate Edges. Edges of shell plates are planed to 
 the finished dimensions before the plates are rolled. When the 
 boiler head is made up of more than one plate, the straight edges 
 of these plates are planed, but the edges 10 be flanged are not 
 planed. Flanged edges are chipped smooth by pneumatic chippers, 
 or a circular-flanged plate forming a boiler or steam-drum head 
 may have its flanged edge turned smooth in a large lathe. 
 
 Shell-plate ends which butt together must be planed at the 
 correct angle to fit at both outer and inner edges when rolled to 
 shape, as shown at a, Fig. 222. All free edges, as those marked & 
 on the butt straps, are planed or chipped to a bevel for caulking, 
 the usual angle of which is shown in the section of a plate edge of 
 thickness t. 
 
344 
 
 MECHANICAL PROCESSES 
 
 Fig. 223 shows a plate-edge planer. The plate rests flat, and 
 the edge to be planed is clamped by the screw jacks J against the 
 bedplate B of the machine. The clamping beam C is held rigidly 
 by the housings H. Two saddles, 8 and T, which travel along the 
 
 FIG. 223. Plate-Edge Planer, 
 
 bedplate, carry the cutting tools. The saddle 8 carries two tools 
 and cuts in both directions of its travel. The saddle T carries but 
 one tool which may be fed vertically during its horizontal motion. 
 The saddles are used separately. The bar K is an automatic revers- 
 ing bar for reversing the motion of the two-way cutting saddle. 
 
 FIG. 224. Plate-Bending Rolls. 
 
 376. Plate-Bending Rolls. This name is given to the machine 
 shown in Fig. 224 to distinguish it from the plate straightening 
 rolls. The machine consists of three solid-forged rolls supported 
 parallel in heavy bearings. The lower rolls are driven by gearing 
 
THE BOILER SHOP 345 
 
 and the upper roll revolves from contact with the plate rolled. The 
 upper roll may be raised or lowered to suit the thickness of the plate 
 and the curvature to which it is rolled. In case a sheet is rolled 
 into a complete cylinder, it is removed by lifting one end of the 
 upper roll and sliding the cylinder out. To do this, the yoke K 
 is screwed down against the extension bar B until the other end of 
 the roll and its bearing are lifted out of the way. 
 
 Plates are rolled cold, and are run back and forth until the cur- 
 vature gradually increases to that of a template made as a guide. 
 
 The rolls cannot bend a plate for a short distance from each end, 
 as shown by the diagram in Fig. 225. Suppose the plate to be 
 
 FIG. 225. 
 
 moving in the direction of the arrow p. That part of the plate 
 between its contact points with the rolls B and C is not bent, as 
 bending takes place only after the plate passes the first contact 
 point K with the roll B. When the plate reaches such a position 
 that the end J has passed over the crest of the roll C and begins to 
 drop, practically no further bending will take place between the end 
 and the point K. In shop practice, this difficulty is obviated by plac- 
 ing a bar of half-round iron at M and rolling it against the plate. 
 
 The lower rolls have one or more longitudinal notches, as at GG, to 
 grip the edge of the plate when started in the rolls, or to flange 
 the ends of narrow strips of plating when needed. 
 
 Plate-bending rolls are also made to operate in a vertical posi- 
 tion, and are known as vertical-bending rolls. 
 
346 
 
 MECHANICAL PROCESSES 
 
 377. Marking a Flange. In boiler making and in sheet-metal 
 work generally, a flange is a margin of metal along the edge of a 
 plate turned at a greater or less angle out of the plane of the plate. 
 
 Fig. 226 shows a cross section of a flanged circular plate with 
 the dimensions which would be given by a drawing. The lettering 
 has been added for purposes of explanation. AB is the center line 
 of the drawing, M is a point at the end of the curve of the flange, 
 t is the thickness of the plate, and r is the radius of the inner 
 
 FIG. 226. 
 
 curvature of the flange. The distance r+t is called the "draw" 
 of the flange. 
 
 The marking of the flat plate, shown in Fig. 227, consists of 
 locating the point M so that it will be 24 inches* from the center 
 line AB when the flange is turned. From C as a center describe 
 
 on the plate a circle with a radius of 24+ i inches. This circle 
 
 is marked with a series of center-punch marks, as at M', as a guide 
 to the workman in turning the flange, and these punch marks must 
 be turned into the position occupied by M in the upper figure. The 
 
 FIG. 227. Marking a Plate for Flanging. 
 
 plate must have sufficient diameter to allow for the flange width 
 MN of 3% inches, plus a small amount for chipping to a smooth- 
 beveled caulking-edge. The distance -^i- is arbitrarily added in 
 
 shop practice to the radius prescribed by the drawing as an allow- 
 ance for the change of position of the punch marks when the flange 
 is turned. 
 
 378. Methods of Flanging. Flanges may be turned (1) by 
 beating down the plate edge with hand mauls, while the plate is 
 
THE BOILER SHOP 
 
 347 
 
 suitably held on a former or between two heavy bars, or (2) by the 
 hydraulic flanging machine. Plates are usually heated to a bright 
 red along the edge to be flanged. Several heats may be necessary 
 to flange the edge of a large plate, as only 3 or -1 feet can be heated 
 along the edge at one time and flanged before undue cooling. 
 
 Flanged plates must always be annealed after flanging is com- 
 pleted as the flanging heats are local and they set up internal 
 
 FIG. 228. Flanging Clamp. 
 
 stresses in the metal. Large plates partly or wholly flanged may 
 crack if left to cool over night unannealed, hence it is well to 
 keep plates hot, or at least warm, until final annealing can be done. 
 379. Equipment for Flanging by Hand. Fig. 228 shows a 
 flanging clamp for holding plates for straight flanging. Angle 
 bars of various curvatures over their angles are furnished for plac- 
 ing over the lower clamp to give the desired curvature to the 
 
 FIG. 229. Flanging Former. 
 
 flange. When the plate is clamped, the flange is beaten down and 
 finished to shape by hard-wood mauls and other hand tools. 
 
 Fig. 229 shows a cast-iron former F made for flanging special 
 shapes. The sheet to be flanged must be held down either by bolts 
 which can be quickly adjusted or by some other means such as the 
 bar B, hook H and iron block K. The hook can be quickly hooked 
 
348 MECHANICAL PROCESSES 
 
 under the edge of the former, and the block is pressed securely on 
 the plate. 
 
 Heavy hickory mauls are used to beat the flange down, and long- 
 handled flatters and fullers are used to shape the flange exactly 
 after it is turned by the mauls. Sledges must be used with caution 
 if at all, as they scar the flange and may endanger its strength or 
 at least may cause a bad joint between the scar and the plate on 
 which it laps. 
 
 FIG. 230. Hydraulic Flanging Press. 
 
 380. The Hydraulic Flanging Press. This machine is shown in 
 Fig. 230. It consists of a heavy cast-iron body carrying four 
 hydraulic cylinders, and a suitable table on which work is held 
 steady while being flanged. 
 
 The plunger head on the rod A of the outer vertical cylinder 
 clamps the sheet to be flanged by pressing it against the former- 
 block K. The head on the rod B is then forced down against the 
 edge of the plate, turning it down against the right-hand edge of 
 the former-block. The flat end F on the rod (7, which is controlled 
 
THE BOILER SHOP 349 
 
 by the horizontal cylinder partly in view, is then forced against 
 the flange to smooth it. The triangular block G serves as a guide 
 to keep B in place as it descends. 
 
 The horizontal cylinder on top of the press is rigged merely to 
 lift the heads carried by the vertical cylinders. The pressure in 
 the cylinders A, B and C is admitted from the hydraulic accumu- 
 lator and released by means of the hand levers on the side of the 
 press. The upper cylinder is under constant pressure and acts 
 similar to a spring. 
 
 When the edge of a circular plate is to be flanged, a heavy cast- 
 iron pivot is bolted to the center of the plate and is dropped into a 
 
 fl 
 
 FIG. 231. Former for Hydraulic Flanging. 
 
 socket on an extension piece bolted to the table of the press. In 
 this way the turning of a flange truly circular is assured. 
 
 When necessary to flange the edges of a circular or an elliptical 
 hole in a plate, the hollow former-block R of Fig. 231 is bolted to 
 the table and the cross head Q is attached to both vertical cylinder 
 rods by the projections K and M. This cross head carries the 
 hollow flanging block P. By means of these fittings the flange 
 entirely around the hole is pressed at one motion. 
 
 The degree of heating a plate edge must be carefully judged so 
 that the metal will be pliable, yet not soft enough to be torn away 
 by the downward pull of the flanging head. 
 
 381. The Hydraulic Accumulator. The great pressures used in 
 
 hydraulic machines are supplied from intensifies on the principle 
 
 of that shown with the forging press in a previous chapter, or 
 
 from accumulators. Water in an accumulator cylinder is subjected 
 
 23 
 
350 
 
 MECHANICAL PROCESSES 
 
 to a pressure of at least several hundred pounds per square inch 
 by means, of weights loaded upon the cylinder as shown in Fig. 232. 
 The description and operation of the accumulator here shown 
 are given as follows, viz. : A heavy base B rests on a concrete 
 foundation and supports the accumulator. This base carries a 
 vertical steel rod E t called the ram, and short vertical supports 8 
 
 FIG. 232. Hydraulic Accumulator. 
 
 on which the cylinder rests when not in operation. A bronze 
 sleeve D, about !/o or % of an inch thick, is shrunk over the lower 
 end of the ram. The ram has a hole along its axis as shown, com- 
 municating at H with the inside of the heavy cast-steel cylinder C. 
 The upper end of the ram, which acts as a guide for the cylinder in 
 its variable up and down travel, is steadied by the roof trusses of 
 the building in which the equipment is installed. 
 
THE BOILER SHOP 
 
 351 
 
 Water is forced by hydraulic pumps (steam-driven pumps with 
 very small water plungers) through the pipe G and the opening H 
 into the space W between the rod and the cylinder. The un- 
 balanced pressure on the end of the bronze sleeve D is increased by 
 the pumps until it is sufficient to raise the cylinder and the weights 
 which it carries. These annular cast-iron weights determine the 
 degree of pressure in the cylinder. If less pressure is desired, one 
 or more of the weights is lifted and suspended above the accumu- 
 lator. 
 
 This pressure is used by transmitting it to the controlling valves 
 of a hydraulic press through a pipe connected at K. 
 
 FIG. 233. Flange-Heating Furnace. 
 
 Suitable automatic controls are rigged on the accumulator to 
 stop the pumps when the cylinder has raised its full height, and to 
 prevent a sudden drop of the cylinder in case a pipe should sud- 
 denly break. 
 
 382. Flange-Heating Furnace. Fig. 233 shows a hearth or fur- 
 nace, partly in cross section, for heating the edge of a plate for 
 flanging. It is a brick-walled basin re-inforced around the sides 
 with jron plates and covered with perforated plate sections as 
 shown. 
 
 The furnace is operated as follows : Supposing a curved edge of 
 n large plate is to be flanged, draw a chalk line BO about 5 feet 
 long, representing the curve of the flange. The perforations along 
 
352 MECHANICAL PROCESSES 
 
 this line and those within 3 inches on each side of it are left open 
 as shown, but the remainder, over the entire surface of the plates, 
 are stopped by dropping boiler rivets into them. Finely broken 
 soft coal free from sulphur and clinker is dampened and packed 
 in a layer about 8 or 10 inches deep over the rivet-covered per- 
 forations, leaving the open perforations about BC uncovered. A 
 fire of high-grade soft coal or preferably coke, is built along BC 
 over the open perforations, and the air blast is turned into the 
 hollow space beneath the plates. The air is free to escape only 
 through the fire along BC, hence the fire is easily confined to this 
 space. When a plate edge is placed over this strip of fire, it is 
 covered by several blocks of wood and old pieces of sheet iron 
 which confine the heat and facilitate heating the plate. 
 
 When a plate is flanged along two edges meeting at a corner, 
 the corner flanging must be done at nearly a welding heat. The 
 corner is rounded off before flanging to remove the excess of metal. 
 
 383. Straightening and Annealing of Flanged Plates. The work 
 of flanging usually warps a plate more or less, though the work of 
 straightening can frequently be done before it goes to the annealing 
 furnace. Flanged plates are placed in a large coal or oil-burning 
 furnace, heated red, and drawn out on a level floor of cast-iron slabs 
 to be straightened by mauls and flatters. 
 
 Annealing also takes place in a large furnace. The annealing 
 heat is best gaged by a pyrometer, and it is the best practice to allow 
 plates to cool gradually in the furnace by shutting off the fuel supply. 
 
 After annealing, flanged plates are then ready for marking with 
 the location of rivet, tube and stay-bolt holes, which could not be 
 marked before flanging, as a slight distortion of the plate would 
 warp these marks out of position. 
 
 384. Drilling Holes in Boiler Plates. Eivet and other holes in 
 boiler plates must be drilled and not punched. Holes must be 
 carefully located on the plates from the layout diagrams. Plates 
 which are not to be heated for flanging or other purpose, as in the 
 case of shell plates, may have the holes drilled as soon as they are 
 laid out. It is well to bear in mind that, in plate edges which 
 lap, rivet holes are drilled in one plate according to the lay-out 
 
THE BOILER SHOP 353 
 
 diagram, and these holes serve as guides for drilling the lapping 
 edge of the other plate. When two plates are thus drilled in con- 
 tact, they must always be taken apart afterward and the metal 
 chips and burr (rough edge of the hole) removed, otherwise the 
 joint would not be tight after riveting together. 
 
 The principal drilling machines of the boiler shop are multiple 
 and portable drills. The multiple drill (also called the gang drill) 
 is a vertical-drilling machine with several drill spindles mounted 
 at adjustable intervals along a straight carrying bar. Portable 
 drills are either pneumatic or electric driven, and are much used 
 for drilling holes in plates after the parts of the boiler are assembled 
 and temporarily held together by a few bolts. Portable drills save 
 shifting the position of heavy boiler parts for drilling. The ratchet 
 drill, for drilling by hand, is useful in confined spaces, but its 
 work is slow. 
 
 Holes for boiler tubes, usually about 3 inches in diameter, are 
 drilled in the tube sheets by a tube-hole cutter, which cuts a disc 
 of metal from the hole instead of cutting this metal out in fine 
 chips. 
 
 385. Assembling the Parts of a Boiler. After the plates com- 
 posing a boiler have been trimmed to finished dimensions, rolled to 
 the required curvatures, flanged, and have had enough rivet and 
 other holes drilled for bolting them together temporarily, the next 
 step is to assemble them into correct relative position. The plates 
 of the shell are first assembled in rings or courses, and the several 
 courses are then assembled end to end; the combustion chambers 
 and corrugated furnaces, which are placed inside a cylindrical 
 boiler, are assembled complete in themselves, and when they are 
 placed inside the shell, the boiler heads are placed in the ends of 
 the shell. 
 
 As each group of plates is assembled, rivet holes are drilled in 
 the lapped edges at the seams, the plates are taken apart, cleaned, 
 re-assembled and finally riveted permanently together. 
 
 The combustion chambers are held rigidly in place in the boiler 
 by suitable stay bolts which fasten them to the shell, or fasten 
 adjacent chambers to each other. (See Fig. 221.) The tubes join the 
 combustion chamber to the boiler head and serve to increase the 
 
354 
 
 MECHANICAL PROCESSES 
 
 rigidity of the combustion chamber while fulfilling their purpose of 
 conducting gases of combustion from the furnace to the smoke pipe. 
 Tubes are placed after all other parts are assembled and riveted, and 
 after the screw stays are placed. 
 
 FIG. 234. Hydraulic Riveting Machine. 
 
 386. Riveting. Eiveting is done by (1) hydraulic riveting 
 machines, both stationary and portable; by (2) portable pneumatic 
 riveters, and by (3) hand hammers. Portable hydraulic riveters 
 are massive and must be carried and held in place for their work 
 by a crane. 
 
THE BOILER SHOP 355 
 
 Fig. 234 shows a type of powerful stationary hydraulic riveter. 
 This is used to rivet the shell plates together and to rivet one head 
 in the shell. The shell is suspended, with its axis vertical, by 
 chains attached to a crane which is a part of the equipment of this 
 machine. The riveting dies, closed together in the view, are opened 
 to allow work to be suspended in the gap between the two arms of 
 the machine, the arm on the right projecting up inside the shell. 
 The die is placed as high on the right arm as possible to allow it to 
 be used in riveting boiler heads and other flanged work. The 
 hydraulic cylinder is so arranged that three different pressures, 
 50, 100 and 150 tons, may be exerted on rivets of various sizes. 
 The men who operate the machine stand on a platform, not shown, 
 built near the top of the arms. Heated rivets are passed up from 
 a small furnace at the base of the machine. 
 
 JB 
 
 FIG. 235. 
 
 Portable pneumatic riveters are much used for bridge, ship and 
 boiler work. They are held in the hands of the workman and may 
 be operated in confined spaces too small even for driving rivets with 
 hammers. These machines are supplied by air at a pressure of 
 about 60 pounds per square inch, led through a hose from an air 
 compressor. Eivets are held in place while driving by a man or boy 
 who presses a sledge hammer or other mass of iron, suitably sup- 
 ported, against the rivet head. Pneumatic holders-on are also used 
 for this purpose. 
 
 Careless or fraudulent work in laying off and drilling rivet holes 
 will bring about a lack of coincidence of two holes as shown at B in 
 Fig. 235. If the relative displacement is slight, it may be remedied 
 by careful re-drilling or by reaming. A bad practice is to drive a 
 tapered steel pin into the hole to enlarge it (called "drifting"), 
 and then to put in a small-bodied rivet to cover up the defect. 
 
356 MECHANICAL PROCESSES 
 
 387. Rivet-Heating Furnace. Bivets are heated preparatory for 
 driving in a forge, or more efficiently in a small oil-burning furnace, 
 a type of which is shown in Fig. 236. This consists of a small sheet- 
 steel box, lined with fire brick, mounted on its fuel tank. Through the 
 small hole in the end of the furnace an atomizer sprays oil into the 
 flame which is maintained by the burning of this spray. The 
 atomizer, or burner, is connected to its fuel tank and to a com- 
 
 FIG. 236. Rivet Heater. 
 
 pressed air tank which supplies furnaces with air at a moderate 
 pressure. 
 
 388. Methods of Holding Boiler Tubes in Place. Fig. 237 shows 
 the method of holding tubes in a shell boiler. The ends of an 
 ordinary tube are expanded to fit tightly against the sides of the 
 holes in the tube sheets. The stay tubes, heavier than ordinary 
 tubes, are screwed into the tube sheets. Stay tubes are spaced at 
 intervals among the ordinary tubes to brace the tube sheets rigidly. 
 
THE BOILER SHOP 
 
 357 
 
 It is frequently the practice to flare or bead over the tube ends to 
 insure tight joints. 
 
 Tubes of water-tube boilers are usually expanded into their 
 headers. Very few water-tube boilers have screw tubes. 
 
 J* 
 
 FIG. 237. Method of Fastening Boiler Tubes. 
 
 Fig. 238 shows a tube expander for expanding tube ends. This 
 consists of a sleeve S carrying three hard-steel rollers R in loose 
 bearings, a cap C, and a tapered-steel pin P. The sleeve is placed 
 in the end of the tube far enough to bring the edge of the cap 
 
 FIG. 238. Tube Expander. 
 
 against the tube sheet. The steel pin is driven in fairly tight, 
 and is revolved by a small steel rod placed through one of the holes 
 at the end. The pin presses against the inner edges of the rollers 
 R, and as the pin revolves it turns the rollers around against the 
 
358 MECHANICAL PROCESSES 
 
 inside of the tube, expanding the end tightly against the hole in 
 the sheet. 
 
 Beading is done by a beading tool, shown in Fig. 239. This 
 tool may be struck by a hammer or operated by a pneumatic holder 
 such as is used in chipping or riveting. 
 
 FIG. 239. Beading Tool. 
 
 389. Chipping and Caulking. After the riveting of a boiler is 
 completed, the various lapped seams are made tight by caulking 
 the beveled edges of the sheets. A flanged joint is usually made, 
 as shown in Fig. 240, with the lap of the end D on the outer face 
 of the flange and not on the inner face B except for a particular 
 reason. 
 
 This arrangement enables the beveled edge of each sheet to be 
 set down against the adjacent surface tightly, as shown at KK. 
 
 FIG. 240. Example of Caulking. 
 
 This operation of caulking is preceded by cutting the edge of the 
 plate to a uniform bevel. Flat-plate edges may be beveled by 
 planing, though edges of curved flange plates are beveled by chip- 
 ping with the cold chisel driven by the hammer or better by the 
 pneumatic holder. Chipping may be done before or after the joint is 
 riveted, and, if done after riveting, great care must be taken to avoid 
 gashing the surface of the adjacent plate. 
 
 A caulking tool is virtually a cold chisel with a blunt end. Two 
 styles of caulking-tool ends are shown at E and 8 in Fig. 240. 
 
THE BOILER SHOP 359 
 
 390. Corrugated Furnaces. The locomotive type of boiler has a 
 square fire box at one end, but the cylindrical type of marine-shell 
 boiler is fitted with one or more corrugated furnaces such as is 
 shown in Fig. 221. These furnaces are divided along the center 
 by the grate bars, and they are corrugated to enable them to resist 
 the collapsing pressure of the water which surrounds them in the 
 boiler. Each furnace is usually about 40 inches in diameter and 
 7 feet long. 
 
 These furnaces are made in the United States only by The Con- 
 tinental Iron Works of Brooklyn, New York. Briefly, the process 
 of making a furnace is as follows : A mild steel plate from the 
 rolling mill is bent into a cylinder in the bending rolls. The two 
 edges are lap-welded by passing the lap, at a welding heat, between 
 two disc rollers pressed against the seam by hydraulic pressure. 
 After welding, the cylinder is heated to a bright red heat in a 
 furnace. It is then lifted by the crane and carried to the corru- 
 gating machine, the vertical rolls of which are suitably shaped to 
 press the corrugations gradually on the cylinder as it revolves 
 repeatedly between the rolls. After the corrugations are pressed, 
 the end is heated and flanged to the shape required, and the whole 
 furnace is then annealed. 
 
 These furnaces are always made to order. 
 
 391. Other Equipment for the Boiler Shop. Besides the equip- 
 ment so far named for this shop, the shop should have 
 
 (1) Power shears for shearing heavy steel plates up to about 
 1% inches thick. 
 
 (2) Power punch for punching holes in plates up to about li/> 
 inches thick. This punch is not used for punching rivet holes un- 
 less they are afterward enlarged by drilling. 
 
 (3) Hand shears and punch, either in two machines or com- 
 bined in one machine, for shearing and punching holes in plates 
 of %-inch thickness or less. 
 
 (4) Hand pump of simple design for testing new boilers under 
 hydrostatic pressure. 
 
 (5) Cranes and other lifting appliances such as are installed in 
 the machine shop. 
 
360 
 
 MECHANICAL PROCESSES 
 
 FIG. 241, Vertical Power Punch. 
 
 FIG. 242. Vertical Power Shears. 
 
THE BOILER SHOP 361 
 
 392. Power Shears and Punch. One type of these machines is 
 shown in Figs. 241 and 242. Plates are held flat for shearing or 
 punching in chain slings carried on the hook of the crane. Two 
 men usually hold the plate to guide it under the machine at the 
 direction of a third man who sets the machine in motion by means 
 of a conveniently placed foot or hand-lever. 
 
 Punch and shears are often in one double machine, or, by a 
 change of equipment, a punch may be changed for shearing, or 
 vice versa. 
 
 FIG. 243. Hand Shears and Punch. 
 
 That part of a plate operated on by punch or shears is necessarily 
 strained to a point of disruption. Metal on each side of a shearing 
 line or around a punched hole is strained more or less according to 
 its proximity to the line of disruption, and some of this metal is 
 strained beyond its elastic limit, and hence is less strong than it 
 was before. For this reason, when boiler plates are punched or 
 sheared, a punched hole must be drilled larger, and the sheared edge 
 must be planed or chipped away sufficient to remove the metal 
 strained beyond the elastic limit. 
 
 393. Hand Shears and Punch. Fig. 243 shows a convenient 
 form of this machine. It may be bolted to a heavy bench or set on 
 
362 MECHANICAL PROCESSES 
 
 a portable stand. Small punches are frequently fitted to be operated 
 by hydraulic pressure. 
 
 394. Shapes of Rivets. Fig. 244 shows the usual shapes of 
 
 / 2 y 
 
 FIG. 244. Types of Rivel Heads. 
 
 rivets for ship, bridge, boiler and tank work. They are designated 
 as follows : 
 
 (1) Pan head. (3) Countersunk. 
 
 (2) Button or round head. (4) Cone or boiler head. 
 
 Rivet lengths do not include the head, except in the case of the 
 countersunk rivet. 
 
CHAPTER XIII. 
 OTHER SHOPS SPECIAL PROCESSES. 
 
 395. Sheet Metal Work -This is a subsidiary work in large 
 building plants. It consists of making tanks, casings, large copper 
 pipes, fenders, wheel guards, smoke and other conduits, and re- 
 ceptacles for oils and other materials. The heavier sheet-metal 
 work is done in the boiler shop, where it is shaped by the equipment 
 of that shop. The lighter sheet-metal work is shaped by hand ap- 
 pliances in the copper shop or sometimes in a separate sheet-metal 
 shop. 
 
 Sheet metals are fastened together by riveting, soldering, or 
 brazing. Seams in wrought iron or mild steel sheet work of moder- 
 ate thickness may be readily and effectively welded by the oxy- 
 acetylene blowpipe. Wiping a joint in plumbing work and sweat- 
 ing-on are forms of soldering. 
 
 By far the greater part of sheet-metal work is done in re-manu- 
 facturing processes such as were described in Chapter Y. In plants 
 which do this kind of work, large quantities of a particular article 
 are made at minimum expense, and only special articles of certain 
 shapes needed in small quantities are shaped by the expensive 
 manual operations of the sheet-metal shop in a general building 
 plant. 
 
 396. The Copper Shop. Materials Used. There is usually con- 
 siderable copper-pipe work to be done in a ship or engine-building 
 plant. This is the principal work of the copper shop. 
 
 Copper is much used for small and medium-sized steam pipes 
 which are subjected to moderate pressures, and for pipes to convey 
 salt water and other liquids. This material is easily worked, is 
 non-corrosive for all ordinary uses, and is particularly adopted for 
 pipes which must have many crooks and bends to fit in confined 
 spaces. Copper pipes often suffer in marine use from galvanic 
 action, and tinning is much resorted to for protecting them. 
 
 The larger sizes of pipes are made of sheets of medium-hard 
 rolled copper bent to cylindrical shape and brazed along the scarfed 
 
364 MECHANICAL PROCESSES 
 
 edges. Copper pipe up to 8 inches in diameter is made from seam- 
 less-drawn copper tubing supplied from the tube mill. An assort- 
 ment of this tubing is carried in stock in the copper shop. 
 
 Sheet copper comes from the rolling mill either thoroughly an- 
 nealed as dead soft sheets dull in color, or of many degrees of 
 hardness and springiness due to the pressure exerted by the rolls 
 and to greater or less annealing after rolling. Planished sheet copper 
 has a bright polished surface as a result of rolling without subsequent 
 annealing. 
 
 FIG. 245. Bench Shears. 
 
 The stock of material in the copper shop also includes more or 
 less sheet brass of different thicknesses, degrees of hardness due to 
 rolling, and of a composition suitable for shaping by bending and 
 hammering cold. 
 
 397. Copper Shop Equipment. This shop is equipped with 
 various hand appliances for cutting, bending, hammering and rivet- 
 ing tubes and sheet metals; with small furnaces for brazing and 
 annealing; and with apparatus for soldering. 
 
 FIG. 246. Snips. 
 
 The shop equipment also includes, as does that of most other 
 shops, squares, measuring rules, files, vises, compasses, cold chisels, 
 metal saw, hand punches, wood mallets and scribers. 
 
 398. Cutting, Bending and Riveting Tools. The principal tools 
 for these uses are as follows : 
 
 (1) Bench shears. These are used for heavier cutting and are 
 supported while in use by placing the bend of the lower handle in 
 a square hole in the bench. See Fig. 245. 
 
 (2) Snips, or hand shears. Fig, 246. 
 
 (3) Forming machine. This is a small set of bending rolls used 
 for bending sheets into cylindrical form as described in boiler-shop 
 
OTHER SHOPS SPECIAL PROCESSES 
 
 365 
 
 work. These rolls are seldom longer than 3 feet, hence for bending 
 longer sheets, a bending block is used, the end view of which is 
 shown in Fig. 247. The solid iron mandrel B bends the sheet and 
 the projecting edges are then beaten over it with wood mallets. 
 
 FIG. 247. Bending Block. 
 
 (4) Tinners' stakes. These tools are anvils for sheet-metal 
 workers. Fig. 248 shows a few of the many designs. They are 
 supported in a square hole in the bench. 
 
 (5) Mandrels. These are long round bars of iron. One end is 
 clamped down against the back edge of the bench top and the other 
 
 FIG. 248. Tinners' Stakes. 
 
 end projects out horizontally two or more feet beyond the bench 
 for use as an anvil in shaping work. 
 
 (6) Expanders. These are very similar to a boiler-tube expander. 
 
 They are used to expand a copper pipe slightly for about 3 inches 
 
 from the end for fitting two pipes together in a cup joint. An 
 
 efficient expander may be easily made of a sleeve coupling (pipe- 
 
 24 
 
366 
 
 MECHANICAL PROCESSES 
 
 fitting) screwed on the end of a short piece of iron pipe. This 
 coupling is driven into the end of the pipe to be expanded. 
 
 (7) Drift set. This tool is shown in Fig. 249, No. 3, and is 
 used to set the metal of the fillet d, Fig. 256, against the inner pipe 
 to make a close-fitting joint preparatory to brazing the joint. 
 
 (8) Collar lifters. These tools (Nos. 1 and 2, Fig. 249) are 
 used to enlarge a small hole drilled through the wall of a copper 
 
 FIG. 249. Coppersmith Tools. 
 
 pipe as an opening for a, branch outlet. Their use is shown in Fig. 
 257. 
 
 (9) Burring machine. This machine is placed on the bench 
 and operated by a crank. Its small disc rollers or " faces " turn a 
 burr or flange on the end of a thin hollow cylinder, as a can end, 
 and on the edge of a disc of metal to form a bottom. 
 
 ||i'"Mi' -| 
 FIG. 250. Rivet Set. 
 
 (10) Beading machine. This is another small portable bench 
 machine. It rolls different designs of corrugations around the body 
 of a pipe near the open end. These corrugations, are usually seen 
 as fancy rings on stove pipes or sheet-metal utensils, and they serve 
 the purpose of stiffening the walls of the pipe. 
 
 (11) Rivet, set. This set is used as shown in Fig. 250. The 
 edges of two sheets of metal & and c are placed over the rivet as 
 
OTHER SHOPS SPECIAL PROCESSES 
 
 367 
 
 shown. The set D is so placed that when struck with a hammer the 
 rivet will punch a hole through the metal. The set is then shifted 
 to place the small cone-head depression over the rivet end, and a 
 hlow of the hammer sets the end down to the form of the de- 
 pression. 
 
 (12) Pipe bender. This machine is made in many forms by 
 different makers. Fig. 251 shows a diagram of a machine adapted 
 
 FIG. 251. Pipe-Bending Machine. 
 
 to cold bending of wrought iron or other pipes up to 2-inch diam- 
 eter when using steam or compressed air. A hydraulic machine 
 can bend larger pipes. A die B is carried on the end of a piston 
 rod C, and another die D rests solidly on the frame of the machine. 
 The pipe is slowly bent as B travels toward D. The grooves in 
 B and D must exactly fit the size of pipe to be bent to keep the pipe 
 from flattening out of round as it bends. 
 
 23*?- 
 FIG. 252. Coppersmith Hammers. 
 
 399. Coppersmith Hammers. Fig. 252 shows the hammers made 
 especially for coppersmiths' use. Their designations and uses are 
 as follows: 
 
 (1) Eaising hammer. Used to cup flat work. 
 
 (2) Planishing hammer. This has polished faces and is used 
 to smooth the marks and wrinkles formed on pipes and other work 
 during the operation of making them by hand. 
 
368 MECHANICAL PROCESSES 
 
 (3) Collar hammer. Used to chamfer the edge of a sheet for 
 making a lap joint, or for bell mouthing the end of a pipe. 
 
 (4) Spanking hammer. Used to smooth the surface of a straight 
 pipe as it rests over a mandrel. 
 
 400. Brazing, This is a process much used for uniting copper, 
 brass or iron in a solid metallic joint of considerable strength, 
 though the strength of the joint is not equal to that of the solid 
 metal. The brazing material used, known as hard solder, spelter, 
 or brazing metal, is variable in its. composition. It may contain 
 copper, zinc, tin, and silver, according to the melting point required 
 and to the required strength of joint. The usual composition for 
 brazing brass and copper is about 60% copper and 40% zinc. This 
 alloy is melted together, and, after cooling it is heated to redness 
 and broken into small lumps in a heavy mortar or on the anvil. 
 
 The essentials in brazing are (1) the metals to be brazed must 
 be filed or scraped to a clean metallic surface and must be pro- 
 tected from becoming re-coated with oxide during the process by 
 means of a flux, and (2) the metals to be joined together must 
 have higher points of fusion than that of the brazing metal. 
 
 Brazing is accomplished by applying a considerable degree of 
 heat to the parts to be brazed. This heat melts the brazing metal 
 and allows it to run into the joint. The two parts to be brazed 
 must be suitably held together by wires, tongs or clamps and the 
 brazing metal must be so placed on the joint that gravity will cause 
 it to flow into all parts of the joint when melted. 
 
 Borax, fused to drive off the water of crystalization and powdered 
 w r hen cold for applying it easily, is used as a flux. It may be mixed 
 with the broken-up brazing metal if desired. If water of c^stali- 
 zation is not driven off, the borax swells and bubbles, causing more or 
 less annoyance. 
 
 401. Heat for Brazing. The necessary heat for brazing is usually 
 supplied by a flat-topped forge or brazing table such as is shown in 
 Fig. 253. This forge uses gas or oil fuel forced into the flame by 
 compressed air. The air is necessary for the complete burning of 
 the fuel to avoid a soot deposit on the work. 
 
 A forge table, similar to that shown, but with air-blast connec- 
 tion as in the blacksmith's forge, is much used for charcoal or coke 
 fuel. This gives a less intense heat than gas or oil and is preferred 
 
OTHER SHOPS SPECIAL PROCESSES 369 
 
 by many workmen for lighter brazing work. A blacksmith's forge 
 with charcoal or coke fuel may be used for brazing. 
 
 A compound blowpipe with rubber-hose connections to gas and 
 compressed-air supply is used as a portable heater where work can- 
 not be brought to the furnace. 
 
 Small articles may be brazed by means of the mouth blow pipe, 
 or mav be heated in a charcoal fire without air blast. 
 
 FIG. 253. Brazing Forge. 
 
 Some compositions of brass are difficult to braze because the zinc 
 in them tends to melt out. Also they are usually very brittle when 
 hot and must be handled carefully and allowed to rest quietly* 
 and free from air drafts until cool. 
 
 402. Annealing. Copper and brass sheets are frequently shaped 
 by hammering cold, as in shaping a hemispherical or other concave 
 receptacle from a flat sheet, or in making bent copper pipes. The 
 metal becomes more or less hard and brittle by hammering, and 
 continued working would cause it to crack. At intervals during 
 
370 
 
 MECHANICAL PROCESSES 
 
 the shaping, when the metal gets hard enough to produce a metallic 
 ring, it must be annealed. This is done by heating it evenly on 
 the brazing furnace and allowing it to cool. Copper may be cooled 
 quickly by holding it in an air draft or plunging it into water, but 
 it is safest to anneal brass of properties not thoroughly known by 
 letting it cool slowly where it is free from air drafts. 
 
 403. Soldering. This process of joining metals is much used by 
 tinners and other sheet-metal workers for joints requiring but 
 moderate strength. It is a simpler and more convenient process 
 then brazing, as solder melts at a low temperature. 
 
 A soldering outfit consists of the following-named items : 
 (1) Soldering irons (more correctly called soldering coppers) 
 as shown in Fig. 254. The lower copper is for heavy work. 
 
 FIG. 254. Soldering Coppers. 
 
 (2) Heater for soldering irons. This consists either of a small 
 sheet-iron fire pot in which a fire of coke or charcoal is kept, or a 
 gasoline torch with an attached rack for supporting the coppers in 
 reach of the flame. 
 
 (3) Lead pans or cups for holding flux and acid to assist in 
 soldering. 
 
 Solder, like spelter, varies in the proportions of its constituents 
 according to the degree of hardness required, but the usual com- 
 position is 1 part lead and 1 part tin for tinners' work, or 2 parts 
 lead and 1 part tin for plumbers' work. The ingredients of solders 
 and spelters must be pure. Tinners' and plumbers' solder is 
 designated as soft solder to distinguish it from hard solder for 
 brazing. 
 
 404. Method of Soldering. Two pieces of metal to be soldered to- 
 gether must be filed or scraped to a clean metallic surface if not 
 
OTHER SHOPS SPECIAL PROCESSES 371 
 
 already bright. They are brought into the position in which they 
 are to be soldered and firmly held together. The joint is sprinkled 
 or swabbed with flux to remove grease and prevent the formation of 
 oxide. Holding a bar of solder in one hand and a heated soldering 
 copper in the other, the operator brings the copper against the bar, 
 melting a slight amount of solder which either drips on the joint or 
 sticks to the point of the copper by which it is wiped and spread 
 over the joint. The two parts to be joined must be heated by the 
 copper to the fusion point of the solder in order to make the molten 
 solder stick to them. 
 
 A stronger joint may be made by first carefully tinning the sur- 
 faces joined in soldering. 
 
 The end of a soldering copper must be kept filed to a smooth 
 point and this point is tinned with solder by rubbing it on a stick 
 of solder. In heating the copper for use, it should not be heated 
 enough to melt the solder from the point. 
 
 Soldering coppers heated by the electric current from an ordinary 
 lamp socket are very convenient, dispensing witli the use of the 
 fire-pot. 
 
 Soldering fluxes remove grease and dirt, and assist in reducing 
 or fusing the film of oxide covering the work. The usual fluxes 
 are rosin, sal ammoniac, zinc chloride, and borax. 
 
 405. Copper Pipe. This pipe is often made by the coppersmith 
 from sheet copper, but it is better and cheaper to use lengths of 
 seamless drawn pipe from the tube mill. The mill supplies pipe up to 
 8 inches, or possibly 10 inches in diameter. Larger pipes must be 
 made from sheet copper. 
 
 A great advantage in the use of pipes made of copper is the 
 safety and ease with which such pipes may be bent to suit the many 
 crooks and turns necessitated by cramped machinery spaces. Thin- 
 walled pipes (about No. 12 gage or thinner) are filled with melted 
 rosin and heavier pipes are filled with dried sand to keep them from 
 flattening when bent. A wood plug is driven in one end of the 
 pipe, the entire length is filled with rosin or sand, and another plug 
 is driven tightly in the other end. Eosin-filled pipes are bent cold 
 and sand- filled pipes are bent hot. Bending is done in the hydraulic 
 bending press, or by holding one end between two pegs or clamps 
 
37.2 
 
 MECHANICAL PROCESSES 
 
 and pulling the other end with a block and tackle. A length of 
 pipe may be slipped over each end of the pipe to be bent to assist 
 in holding and in increasing the leverage of the pulling force. 
 
 Bending causes kinks or wrinkles to form at the inner curvature 
 Dr throat of the pipe. These must be carefully hammered smooth 
 while the pipe remains filled. The copper along the outer surface 
 of curvature, or back, of the bend is necessarily thinned somewhat 
 in bending, hence the practice of selecting a pipe with walls, two or 
 more gages thicker than is otherwise required. 
 
 Large pipes, or those of any size bent to a curve of small radius, 
 are, in high-grade work, bent in two stages, {. e., the pipe is filled 
 
 FIG. 255. 
 
 Copper Pipe Joints. 
 
 FIG. 256. 
 
 and bent part way to the required radius, is emptied, annealed, 
 refilled and bent to the full extent required. 
 
 Small pipes may be bent, when filled, by means of the grooved 
 formers shown in Fig. 251. 
 
 406. Joining Lengths of Copper Pipe. One length of pipe may be 
 joined to another by composition flanges as shown in Fig. 255 or 
 in a permanently brazed cup joint as shown in Fig. 256. 
 
 The flange joint may be readily taken apart by removing the 
 bolts. Flanges are standardized in all their dimensions and in com- 
 position. Each length of pipe is permanently connected to its 
 flange by beading at the end, as at l>, into a recess in the flange, 
 and by brazing around the groove c made for holding the brazing 
 
OTHER SHOPS SPECIAL PROCESSES 373 
 
 metal after it melts. A flange is brazed on while the pipe rests 
 vertically, and frequently a ring of plastic fire clay is built around 
 the joint on the flange shoulder d to keep the brazing metal on the 
 joint while molten. 
 
 The lap of a cup joint is about equal to the diameter of the pipe. 
 The cupped portion b is expanded by an expander, the bell-mouth c 
 is flared by the collar hammer, and when the two lengths of pipe 
 are cleaned for brazing and fitted together, the fillet d is closed 
 against the inner pipe by the drift set. After brazing, the joint 
 is smoothed by filing. The flared ring c assists to stiffen the pipe. 
 
 FIG. 257. Preparing a Branch Joint Opening. 
 
 407. Brazing- a Branch in a Copper Pipe. To connect a branch to 
 a length of pipe B, Fig. 257, drill a hole about f-inch in diameter 
 in the pipe. Beginning with the small collar lifter, lift the edges 
 of the hole carefully and evenly all around by strokes of the 
 hammer on the under side of the lifter. When the hole is increased 
 an inch or more in diameter, the larger lifter may be used. Care 
 must be taken not to crack the metal by excessive expanding with- 
 out annealing, nor by too much hammering at one place. When a 
 collar is raised as shown at C, the edge is flared and a cup joint is 
 formed for brazing. 
 
 Another type of branch joint may be made by cutting a hole in 
 the pipe nearly the size of the desired outlet, lifting the edge as a 
 slight collar, and placing over the outside of this collar the end of 
 the branch. This end is suitably flared to lie snugly against the 
 
374 MECHANICAL PROCESSES 
 
 outer surface of the pipe which it joins, forming a saddle flange 
 which is brazed to the pipe. 
 
 A hole in a copper pipe may be stopped by brazing on a flush 
 patch, which lies flush with the surface of the pipe, or by brazing 
 on an exposed patch, which overlaps the outer surface of the pipe. 
 
 408. The Plate and Angle Shop. Plates and structural shapes of 
 mild steel used in ship building are cut and bent to shape in this 
 shop, the principal equipment of which consists of.: 
 
 (1) Power punches, used principally for punching rivet holes 
 in ships' plates and frames. 
 
 (2) Power shears for trimming edges of plates, and for cutting 
 lengths of angles, beams and other structural shapes. 
 
 (3) Plate-edge planer. 
 
 (4) Bending rolls. 
 
 (5) Garboard bending press (hydraulic) for bending plates cold 
 to other than cylindrical form. 
 
 (6) Beam and angle bending or straightening machine. 
 
 (7) Bending slab and heating furnace. 
 
 Machines mentioned in items 1 to 4 inclusive are very similar to 
 those for the same uses in the boiler shop. Particular shaped blades 
 are used on shears for shearing structural shapes. 
 
 Much of the work of shaping ship material is done cold, except 
 that of bending angles and other structural shapes on the bending 
 
 Closely associated with the equipment of this shop are such tools 
 as the portable hydraulic riveter, pneumatic riveters, chippers, drills 
 and countersinks, used in the work of riveting together the frames 
 and plates of the ship's hull. 
 
 409. The Bending Slab. Fig. 258 shows a level floor of heavy 
 cast-iron slabs used for bending angles and other structural shapes to 
 various curved forms for ship frames. The slabs are well sup- 
 ported on permanent foundations, and the regularly spaced square 
 holes in them are used to hold various pins and eccentric washers 
 against which the frame is bent. 
 
 To arrange for bending, a wooden template giving the required 
 curve of the frame is placed on the slabs and the curve is marked 
 thereon with chalk. Pegs and washers are placed in the square 
 holes along the chalk mark as guides against which the frame is 
 
OTHER SHOPS SPECIAL PROCESSES 375 
 
 to be bent. An angle bar or otber long piece to be bent is heated 
 to a red heat in the long furnace shown in the background. The 
 view shows the workmen in the act of dragging an angle from the 
 furnace. This is dragged out,, one end is secured between two pegs 
 at one end of the curve outlined on the slabs, and the other end is 
 dragged by suitable bars and other appliances against the guide 
 pins and there clamped until cold. Very convenient clamps or dogs 
 for this use consist of heavy round bars of iron bent into a flattened 
 
 FIG. 258. Bending Slab and Heating Furnace. 
 
 V-shape, i. e., with the two legs slightly less than 90 to each other. 
 One leg is set in a slab hole and as the other comes against the 
 work, a stroke of the hammer sets it tightly in a leaning position 
 in the hole. 
 
 410. Special Processes. A few special processes are outlined in the 
 paragraphs which follow. These are selected because of the im- 
 portance of their products or because of the application of the 
 processes themselves to many different needs. 
 
 411. Malleableizing. This is the process of rendering cast-iron 
 castings malleable, or capable of bending without breaking. Castings 
 
376 MECHANICAL PROCESSES 
 
 are not only relieved of brittleness, but a considerable degree of tough- 
 ness and ductility is imparted to them. Many small articles of iron 
 in every-day use, notably iron-pipe fittings, are far more readily 
 inade as castings and malleableized afterward, than if made of 
 wrought iron or mild steel at the beginning. This process practically 
 converts them into a mild steel by the removal of carbon, and its 
 method of application is as follows : 
 
 Iron boxes of convenient size, known as annealing pots, are 
 filled with castings, each of which is entirely surrounded by some 
 kind of iron oxide, usually mill scale, squeezer scale, or pure mag- 
 netic ore. The castings have been thoroughly cleaned of sand and 
 fins or other projections of metal before leaving the foundry, and 
 a good sprinkling with sal ammoniac will give them a coating of 
 rust, which as iron oxide, assists in malleableizing. 
 
 Each pot is closed with a thin iron cover luted with clay and 
 may be placed in any kind of a furnace in which a steady heat may 
 be maintained. In malleableizing works, several hundred post are 
 stacked in a large furnace heated with producer gas. The brick- 
 lined iron door of this furnace is closed, the contents are heated up 
 to about 1800 in 24 hours, are maintained at this heat about 48 
 hours, and then allowed to cool gradually. At the high heat main- 
 tained, the castings give up their uncombined carbon to the oxygen 
 of the iron oxide, and when removed they have lost the brittleness 
 of cast iron. 
 
 This process is not so much in general use as formerly. Many 
 castings are now displaced by drop forgings and articles of pressed 
 sheet steel. These are neater looking and of less bulk than the 
 usual run of malleable castings. Some shapes are cheapest made 
 as castings, however. 
 
 412. Case Hardening. This process is the reverse of malleableiz- 
 ing, i. e.j it adds carbon to forgings of wrought iron or mild steel to 
 make them hard for resisting wear. Many articles, .such as set 
 screws, bolts and nuts, jaws of wrenches, etc., subject to unusual 
 wear, are much increased in durability by case hardening after 
 they are machined to shape. The process is as follows . 
 
 A number of forgings, each of which is surrounded by carbon 
 substances such as ground bone and charred leather, are packed 
 in an iron box. The box lid is luted with clay and the box is heated 
 
OTHER SHOPS SPECIAL PROCESSES 
 
 377 
 
 gradually in a suitable furnace up to a temperature ranging from 
 1400 to 1700 F. This heat is maintained from 6 to 14 hours. 
 The degree of heat applied depends upon the grade of steel in the 
 forgings, and the duration of the heating depends upon the depth 
 of the hardness required. The object of the process is to increase 
 the amount of combined carbon in the forgings, as in the cementa- 
 tion process of steel making. The articles are removed from their 
 boxes when cool enough to handle and are heated up to critical 
 temperature and hardened by quenching in water or oil. 
 
 This process of hardening sometimes warps forgings slightly, a 
 fault which may be in some cases very objectionable. 
 
 FIG. 259. Form for Bending Small Pipes by Hand. 
 
 413. Pipe Bending. Mention has been made in another paragraph 
 of methods of bending copper pipes and small iron or brass pipes. 
 
 Two essentials in pipe bending are (1) to keep the pipe from 
 flattening into elliptical shape in the bend, and (2) to avoid 
 wrinkles in the concave part of the bend. These may be accom- 
 plished by bending the pipe over a grooved form shown in Fig. 
 259. The sides of the form may be extended well above the groove 
 to hold the sides of the pipe against bulging along the bend. This 
 form may be used for cold bending of pipes up to about IJ-inch 
 diameter. 
 
378 
 
 MECHANICAL PROCESSES 
 
 A more elaborate form, suited to larger piping, is shown in 
 Fig. 260. Large pipes should be heated red to facilitate bending. 
 
 A pipe may be filled with sand and plugged to assist in holding 
 its circular cross section, and, if a bending form is not available, 
 the jaws of a vise may be spread apart just far enough for the pipe 
 to be held between them during bending. This will keep the pipe 
 sides from bulging. The welded seam of a pipe should be in the 
 throat or concave part of the bend. 
 
 FIG. 260. Form for Bending Large Pipes. 
 
 414. Joining Metals. There are now in use many important 
 means of uniting metals solidly together. These have many applica- 
 tions in manufacturing and one or more of them may frequently be 
 availed of in making permanent repairs, to broken machinery or 
 equipment under emergency conditions. 
 
 Methods of joining metals include the following, some of which 
 have been described : 
 
 (1) Soldering. (6) 
 
 (2) Brazing. 
 
 (3) Welding at the forge. (7) 
 
 (4) Electric welding. (8) 
 
 (5) Thermit welding. 
 
 Closely akin to these methods is the use. of metal cements, which 
 stop cracks in castings, seams, and joints of patches held in place 
 by aid of bolts and iron straps. A leaky pipe or boiler seam may 
 often be stopped by the use of sal ammoniac and iron filings, or by 
 a mixture of Portland cement and coal tar. A patented compound 
 
 Oxy-acetylene and oxy-hy- 
 
 drogen welding. 
 Burning on. 
 Puddling. 
 
OTHER SHOPS SPECIAL PROCESSES 379 
 
 known as Smooth On is very effective for mending broken ma- 
 chinery parts and repairing leaks in boilers, tanks and castings. 
 
 Joining metals implies an actual metal to metal contact. There 
 is always an oxide or other coating over a metal surface exposed to 
 air. This must be removed before two metals can be joined, and 
 it is done principally by scraping, filing,, pickling, etc. The last 
 thin coating of oxide which forms during heating is removed by 
 action of a flux. Union between the two metals is then accom- 
 plished (1) by bringing the contact surfaces of both metals up to 
 the melting point of at least one of them, as in soldering and braz- 
 ing, which necessitates the melting of the solder or brazing metal, 
 or (2) by bringing both metals to a state of incipient fusion at the 
 points where they are to be welded and pressing them together 
 firmly. 
 
 There seems no doubt that the process of welding iron or steel 
 detracts from their strength. The weld may not break under a 
 tensile test, but the metal on one side of the weld may break instead. 
 The high heating necessary for welding changes the grain size of 
 iron and steel, making it coarse and thus weaker than before. This 
 condition can be remedied by reheating welded bars to the critical 
 point and in this way restoring the fine grain size, or in a measure 
 by a thorough hammering while the weld is yet very hot. 
 
 415. Electric Welding. When an electric current encounters re- 
 sistance in its circuit a portion of its energy is converted into heat. 
 If an electric current flows across the junction of two rods placed 
 in mutual contact, more or less heat will be generated at this joint. 
 If the joint does not present great resistance, a weak current will 
 traverse it, and a large quantity of current will be required to 
 generate enough heat to weld the rods together. If, however, the 
 joint presents moderate resistance, due to the rod ends being more 
 or less separated by air space, or by scale, sand, or other non-con- 
 ductor, a stronger current is required to flow across the resistance, 
 and a much less quantity of current will produce a welding heat. 
 
 Application is made of these conditions in electric welding opera- 
 tions. The first-named condition, that requiring the lesser strength 
 of current is known as the resistance system, and the second con- 
 
380 MECHANICAL PROCESSES 
 
 dition, requiring strong enough current to produce an electric arc, 
 is called the arc system. In both systems the strength and quantity 
 of current for welding depends upon the size of the weld and the 
 time consumed in making it. The ordinary lighting circuit is 
 strong enough for many needs in welding. 
 
 416. The Resistance System. This system, developed by Prof. 
 Elihu Thompson, is much used to weld together wires, rods, small 
 forgings and other parts which are made separately for quick produc- 
 tion. It is used in welding links of chains, rings, wire fence* meshes, 
 wheel tires, valves and their stems., lengths of steel steam pipe and 
 their flanges, branch outlets, steam drums, etc. Different kinds 
 of metal may be welded in one piece provided their melting points 
 do not differ much. 
 
 FIG. 261. Electric Welding Clamps. 
 
 The essential features of the welding apparatus of this system 
 are shown in Fig. 261. The pieces R and 8 to be joined are held 
 firmly together in the desired relative position by heavy copper 
 clamps C and D, one of which may be moved toward the other. 
 Current travels along the circuit through C f R, 8 and D, 
 and when the two ends R and S are softened by heat, they are 
 mashed together by the pressure of the clamps, forming an ex- 
 panded burr which is later cut off. In some machines, however, 
 a swage surrounds the joint at the time of welding, avoiding the 
 burr and pressing the metal together very firmly in a lateral 
 direction. 
 
 Alternating current is required in this system of welding. It 
 heats both sides of the joint more evenly. 
 
 417. The Arc System. This system is used in repairing iron cast- 
 ings in a way which resembles soldering. A crack or cavity is filled up 
 
OTHER SHOPS SPECIAL PROCESSES 
 
 381 
 
 with drops of cast iron or cast steel which melt from a rod as 
 shown in Fig. 262. This view shows the method of filling a blow- 
 hole cavity in the end of the cast-iron mill-roll R. The upper end 
 of the roll (shown in cross section) is surrounded by a piece of 
 pressed coke & enclosed in moulding sand c held in a sheet-iron 
 casing d. Enclosing the whole upper end of the roll is a mass of 
 coke ~k surrounded by a checker-work g of fire bricks. This body of 
 coke smoulders, keeping the roll hot during welding. A rod of 
 cast iron s is clamped to the positive lead p of a direct-current con- 
 ductor, and is manipulated by the insulated handle h. The nega- 
 tive lead n of the circuit is attached to the roll at a convenient point. 
 
 FIG. .262. Arrangement for Arc Welding. 
 
 The lower end of the rod s is melted away by the arc, and is de- 
 posited in the cavity until the latter is filled. 
 
 418. The Thermit Process. The essential feature of this process 
 consists of generating, by chemical union between oxygen and alumi- 
 num, an intense local heat which produces from the reaction a 
 certain amount of molten iron. This iron, which is in the nature 
 of mild steel, may be run into a mould to form a small casting, or 
 may be run between the two parts of a broken forging or steel 
 casting to form a weld. The welding of cast iron by this process 
 is very difficult because the heat of the process burns out the un- 
 combined carbon of the casting, making it hard, brittle, and of un- 
 certain strength. 
 
 Aluminum and oxygen have a very strong chemical affinity for 
 each other. A mixture of finely ground aluminum and iron oxide 
 25 
 
382 MECHANICAL PROCESSES 
 
 in proper chemical proportion, known by the trade name Thermit, 
 will, when ignited, burn with an intense heat and release molten 
 iron which may be used as stated. The chemical reaction is ex- 
 pressed by Fe 2 3 + 2Al = Al 2 3 + 2Fe. More iron than comes from 
 the oxide may be supplied by placing iron punchings in the mixture 
 before it is ignited, and the heat of the reaction will melt this iron 
 and mix it with that formed from the iron oxide. 
 
 Ignition 'is accomplished by an ignition powder consisting of 
 barium oxide mixed with powdered aluminum. A small quantity 
 of this placed on top of a thermit charge and ignited with a match, 
 will start the burning of the thermit. 
 
 This process is advantageously used in welding broken locomotive 
 frames, spokes of heavy cast-steel wheels, ships' stern posts, rudder 
 posts, propeller struts and breaks in other large forgings or steel 
 castings, without removing them from their places. Its heat is also 
 used in welding together lengths of heavy wrought iron or steel 
 pipe. Lengths of street railway rails which are prevented by street 
 paving from subsequent bending under expansion due to the sun's 
 heat are smoothly and economically welded by this method. It is 
 particularly suited to large work and is not economical for small 
 work. 
 
 419. Making a Thermit Weld. The simplicity of the equipment 
 for thermit welding or casting makes it particularly valuable for work 
 far removed from shop facilities. A quantity of thermit is placed 
 in a conical, covered crucible as shown at A in Fig. 263. This 
 micible is made of sheet iron, magnesite lined, and the opening in 
 the lower end is stopped by a pin resembling a long nail over which 
 is placed a small disc of asbestos, a disc of iron and a little loose, 
 refractory sand. 
 
 The ragged ends of the two broken parts to be welded are drilled 
 or otherwise cut so that when in correct position there is a space 
 of about -J inch between them. They are then clamped rigidly and 
 the break is surrounded by a close-fitting mould made up of fire 
 bricks and baked sand shapes of the required forms to afford open- 
 ings as shown at B (Fig. 263) and to allow a collar of metal to be 
 formed partially around the break in addition to the metal which 
 fills it. All cracks in the mould must be carefully luted with fire 
 clay to prevent the loss of metal through them. 
 
OTHER SHOPS SPECIAL PROCESSES 
 
 383 
 
 The crucible is now suspended so that the opening is a few inches 
 above the pouring gate. This completes the preparations. 
 
 The first step toward the actual welding operation consists of 
 heating the ends of the broken parts to a red heat by directing 
 the flame of a gasolene compressed-air torch through the heat- 
 ing gate of the mould. When this is done, quickly stop this 
 gate with a dry sand core made for that use, and apply a match 
 or burning splinter to the ignition powder on top of the crucible 
 charge. The reaction which follows evolves heat and smoke 
 but is not explosive. It ceases after a moment, leaving the crucible 
 full of very hot molten mild steel which is tapped into the mould 
 by a sharp upward knock on tlie pin end in the bottom of the 
 
 /f/se/r 
 
 Oaf* 
 
 Gate 
 
 FIG. 263. Moulds Crucible. Thermit Welding. 
 
 crucible. A small quantity of slag (A1 2 3 ) formed by the reaction 
 floats on the metal. 
 
 A mould may be made about a break by filling the break and the 
 space for the metal collar with wax, around which is built an ordi- 
 nary sand mould provided with the same openings shown in B, Fig. 
 263. This mould is contained in a sheet-iron box and the sand 
 must be thoroughly dried. The wax is melted out when the torch 
 is applied for heating before running the steel into the mould. 
 
 Thermit steel must run into a mould under the break and rise 
 until the first metal, which chills in heating the mould, flows out 
 over the top of the riser hole. This insures the thorough softening 
 and joining of the broken parts with the molten steel which unites 
 them. 
 
384 MECHANICAL PROCESSES 
 
 After the weld has cooled,, the mould is removed, the joint is 
 smoothed up, and it is then annealed by maintaining a coke or 
 charcoal fire all around it for 5 or 6 hours and allowing it to cool 
 slowly. 
 
 420. Blow Pipe Welding. The flame of a combustible gas may be 
 so regulated in its shape and intensity by a properly constructed 
 burner that it can be effectively used for local heating such as is 
 needed in welding. In the compound blow pipe, a type of which is 
 shown in Fig. 264, oxygen is admitted to one tube of the burner and 
 a combustible gas is admitted to the other tube. These two gases pass 
 along the channels 1 and 2, mix in the small receptacle 3, and finally 
 pass from the nozzle at 4 where they enter the flame. 
 
 Oxygen is supplied from a steel cylinder in which it is stored 
 under a pressure of 100 atmospheres or more, passing through a 
 
 FIG. 264. Compound Blow Pipe. 
 
 reducing valve which lowers the pressure to 30 pounds or less per 
 square inch in the burner. 
 
 Hydrogen and acetylene gas are much used as the combustible gas. 
 They may also be stored in steel cylinders as a convenient means of 
 transporting them from the factories which make them, but acety- 
 lene gas is so easily produced that it is frequently made where it is 
 used. Great care must be taken to avoid an explosion in using or 
 handling any kind of inflammable gas. Acetylene is stored in steel 
 cylinders with acetone, a liquid which absorbs a large volume of the 
 gas under heavy pressure, thus avoiding the danger of this par- 
 ticular gas when compressed. In its simple process of production 
 that of admitting water to calcium carbide in a closed vessel its 
 explosive tendency is not always realized. A spark of flame coming 
 in contact with the gas will cause an explosion in force and volume 
 depending upon the amount of gas and oxygen or air in mutual 
 contact. 
 
OTHER SHOPS SPECIAL PROCESSES 385 
 
 As the mixture of oxygen and gas flows from the blow pipe, it 
 burns in a flame which is regulated to suit the work to be done. 
 The supply of each gas is so controlled by a small valve that the 
 relative amounts and pressures of the two may be regulated as 
 needed. The gas mixture should issue from the blow-pipe nozzle 
 rapidly enough to keep the flame from following the mixture back 
 into the pipe, and on the other hand the flame should not receive 
 too strong a blast by too rapid a flow of gas. The quantity of 
 oxygen must be kept down enough to avoid an oxidizing flame in 
 welding. 
 
 Slightly different forms of blow pipes, determined by experiment, 
 are necessary for burning gases under different pressures and differ- 
 ent intensities of flame, according to the requirements outlined in 
 the preceding statements, 
 
 . f 
 
 FIG. 265. Methods of Welding Plate Edges. 
 
 421. Method of Making a Blow Pipe Weld. The ease with which 
 an oxy-acetylene or an oxy-hydrogen outfit may be set up where 
 needed, and the small size of the blow pipe and its flexible rubber- 
 hose connections, make such an outfit very practical and convenient 
 for use on work which demands local heating. 
 
 In making a weld, two sheets of metal are butted edge to edge 
 in a clean, close-fitting joint as shown at A, Fig. 265. Two blow- 
 pipe flames are held at a and & on opposite sides of the plates, 
 directly opposite each other, and a short length along the seam is 
 heated to welding heat. With one of the pieces properly supported 
 to hold it firmly in place, the other may be struck with a hammer to 
 bring about the weld through the closer contact due to the blow. 
 
 Another method of welding is shown at 5, Fig. 265. A sheet of 
 metal rolled to cylindrical form presents its edges in V-shape as 
 at c. These edges are temporarily held together by bolts and straps. 
 
386 MECHANICAL PROCESSES 
 
 A blow-pipe flame is directed into the joint to bring it to welding 
 heat, and at the same time a heavy wire of pure Xorway iron is 
 held so that the flame melts its end. The drops of fused metal 
 from the wire run into and fill the joint, resembling the process of 
 soldering, until the entire notch is filled with solid metal. The joint 
 should be hammered while hot to restore the grain size of the fused 
 metal and increase its strength. The joint needs no particular 
 cleaning nor any flux before welding is begun. 
 
 A thicker sheet of metal may be cut at the edges to form a joint 
 as at d, and is welded along the upper notch and then rolled half- 
 way around and welded along the lower notch. 
 
 A poor joint will result if the operator allows drops of metal to 
 fall upon a part of the seam not heated to welding temperature. 
 
 422. Application of Blow-Pipe Welding. This method is much 
 used to join the edges of wrought iron or steel plates up to an inch or 
 more in thickness. Heavy plates conduct away the heat so rapidly 
 that it may not be possible for the burner to raise the seam to welding 
 temperature. Steel castings may also be wielded, and cracks or blow 
 holes may be filled with drops of molten iron. Brass castings may 
 be repaired by melting into a crack, cavity or blow hole, drops of 
 brass from a rod of the same composition as the casting. 
 
 The difficulty of welding iron is in proportion to the amount of 
 carbon it contains, and, while some operators claim ability to weld 
 or mend cast iron, it is difficult to do so. A cast-iron bar may be 
 fused at the end into drops which will weld to a properly heated 
 cast-iron surface, but the iron will not be homogeneous and it may 
 be too brittle for strength and too hard for machining. 
 
 Aluminum may be welded, under blow-pipe heat, by use of a flux 
 which removes the oxide, although this metal cannot be soldered or 
 brazed, at least by usual means. 
 
 Steel pipes and flanges may be welded together, and lengths or 
 branches welded in one piece. 
 
 A particular application of gas welding is that used in welding 
 the longitudinal seam of a boiler drum made of one sheet of metal. 
 The drum is mounted on a machine especially built to handle it 
 readily and quickly. The machine carries two specially constructed 
 
OTHER SHOPS SPECIAL PROCESSES 387 
 
 burners which travel along on opposite sides of the lapped plate 
 edges, heating them to welding heat. The burners are followed by 
 rollers which exert great enough pressure to make the weld and to 
 press the seam 'down to the thickness of the plate. Water gas and 
 air are used in the burners. The strength of such a welded joint is 
 about 90 or 95% that of the solid plate, although the ordinary oxy- 
 acetylene-welded joint is not over about 80 or 85% of the plate 
 strength. 
 
 423. Blow-Pipe Cutting of Metals. A remarkable method of cut- 
 ting metals has been developed in the use of the oxy-hydrogen and 
 oxy-acetylene burners. 
 
 To a blow pipe used for heating is attached an additional tube 
 through which a jet of oxygen is blown from a supply tank. The 
 blow-pipe flame heats the metal to be cut, and when so heated, the 
 small jet of oxygen directed against it burns a narrow cut along any 
 path over which the flame may be directed. So readily do oxygen 
 and red-hot metals unite, that such a burner is used to cut plates of 
 metals, including steel armor, up to 9 inches thick. The width of 
 the cut is not over J inch and the metal on each side of the cut is 
 unchanged in grain size or otherwise. Tubes, shafts, and structural 
 shapes may be easily and quickly cut by this means, although there 
 is difficulty in cutting cast iron due apparently to the carbon it 
 contains. Eivet heads are quickly cut off without marring the 
 riveted plates, and any tangled mass of iron or steel wreckage, old 
 boilers, or the hull of a ship may be easily cut to pieces by this 
 method. In cutting a hole of several inches diameter in a steel 
 plate, a small hole is first drilled to give the burner a start, 
 
 Hydrogen is more effective for this cutting than is acetylene, as 
 the former makes a hotter flame. For light cutting, a blow pipe 
 may be used which has no extra oxygen tube attached. The 
 flame is given an excess of oxygen from the regular tube, making it 
 an oxidizing flame. 
 
 424. Burning On. This is a method employed for mending a 
 cracked, broken, or honey-combed casting of cast-iron or brass. Many 
 costly castings which would otherwise have to be discarded may be 
 made sound by this process, although defects in some cases are too ex- 
 tensive, or are not well located for practical repairing. 
 
388 
 
 MECHANICAL PROCESSES 
 
 The application of the method is illustrated in Fig. 266. The 
 view A shows the casting to be repaired and B shows the same cast- 
 ing bedded in sand and otherwise prepared for the work. Let it 
 be supposed that the portion b of the upper flange of A is cracked 
 or filled with blow holes. The defect is chipped out to present a 
 slit or cavity which shows sound metal. Supporting the casting 
 firmly on the foundry floor, surround the defective part with a 
 mould made of baked sand cores and fire bricks wedged and clamped 
 in place. The joints between bricks and cores are carefully plastered 
 with clay. It is essential to leave either a small hole c leading from 
 the bottom of the mould., or one at d leading from the highest point 
 at which the metal is to stand in the mould. Both openings may be 
 
 A 
 
 FIG. 266. Mending a Casting. 
 
 provided if desired, and each leads into a sand basin which holds 
 metal as it flows from the mould. After assembling and securing 
 the mould around the defect, the casting must be heated by means 
 of a gasolene torch or blow pipe. This heating may be slowly done 
 by using a charcoal fire, and sometimes the position of the defect 
 is such that heating must be done before the mould parts are placed. 
 When the casting is nearly or quite red hot, a ladle of molten metal 
 of the same composition as the casting is held over the opening g 
 in the upper core, and a steady stream is poured into the mould, 
 keeping it filled. The first metal poured in serves merely to heat 
 and soften the metal around the defect, and is allowed to flow out. 
 The stream of molten metal is continued until it has about melted 
 the metal adjacent to the defect. A small iron rod is used to deter- 
 
OTHER SHOPS SPECIAL PROCESSES 
 
 389 
 
 mine this condition. The lower open c is then stopped with a shovel 
 full of dry earth, and the mould is left full of metal. The casting is 
 covered with a few pieces of sheet iron and allowed to cool slowly. 
 When cool, the defect will be found filled with solid metal which can 
 be trimmed to the contour of the casting. 
 
 Cast iron may be brazed by means of spelter as described for 
 brazing copper. It is essential (1) that the broken parts be 
 thoroughly free of scale, dirt and grease; (2) that they be clamped 
 in their correct relative position; (3) that heating be done evenly 
 in a clean fire, and (4) that the spelter be applied along every part 
 of the break. 
 
 425. Puddling. This is a method of repairing small broken cast- 
 ings similar to burning on. A mould of clay or plaster of Paris is 
 formed about the broken parts of a small casting as shown at 6, 
 
 f$$$|^ 
 
 FIG. 267. Uniting a Broken Casting. 
 
 Fig. 267. When dry, the mould holds the casting firmly. Both 
 are supported in a box of sand, and the fracture is heated with an 
 oxy-hydrogen or an oxy-acetylene blow pipe. At the same time a 
 rod of metal is held in the flame so that the end melts and joins 
 the highly heated ends of the casting. These ends are kept prac- 
 tically molten until enough metal has melted from the rod to join 
 them together. 
 
 After the casting has cooled, the superfluous metal is ground 
 away. This method of mending castings burns out the carbon of 
 cast iron and makes the joint harder and more brittle than the iron 
 of the casting. 
 
 426. Classification of Welding Methods, Those methods which 
 accomplish the union of two pieces of metal directly by fusion of one 
 to the other, without the intervention of another metal at the 
 joint, are classed as autogenous methods. Those which accomplish 
 union between two metals by means of an intermediate metal, as in 
 soldering and brazing, are classed as heterogeneous methods. 
 
390 MECHANICAL PROCESSES 
 
 427. Grinding". The popular idea of grinding is its use in shaping 
 more or less roughly the edges of cutting tools and in removing 
 fins and other small projections from forgings and castings as a 
 step toward making them smooth. 
 
 Developments in recent years in the production of grinding 
 wheels of many shapes and degrees of hardness and the fitting of 
 these wheels to high-grade machines for controlling their motions, 
 have brought into practical use methods of grinding which pro- 
 duce smooth and true surfaces of a degree of accuracy not attainable 
 by any other known means. 
 
 Work is now roughed out on the lathe, planer, milling machine 
 and other machine tools and is finished to any desired degree of 
 accuracy better, cheaper and quicker by grinding machines than 
 by other means. This applies to the ordinary as well as to the 
 finest finishing, and it applies also to metals of all degrees of 
 hardness. 
 
 428. Grinding Machines. Machines for accurate grinding are 
 usually built on the general lines of either a lathe or a milling 
 machine. In these machines, the grinding wheel takes the place of 
 the cutting tool, and it is so mounted that it can be revolved at high 
 speeds suited to the work. 
 
 The grinding lathe holds work between centers, or in special 
 chucks, and the wheel may be fed along the lathe bed as it revolves 
 in light contact with the cylindrical work to be ground. This 
 machine is used for grinding engine valve stems, piston rods, and 
 any similar cylindrical work. Crank shafts of automobile or other 
 small engines are finished from the rough forging in this machine. 
 
 The milling machine form of grinder may be either a plain or 
 a universal machine. Work may be placed on its movable table for 
 flat grinding, or the usual lathe center attachments may be used 
 to support work for internal and external cylindrical or other 
 curved-surface grinding. In these machines, the rapidly revolving 
 grinding wheel takes place of the milling cutter. These machines 
 are used for grinding drills, milling cutters, cams, parts of many 
 articles made in quantity such as guns, pistols, tools, and an end- 
 less variety of small castings and forgings requiring machine 
 finishing. 
 
 The spindle which carries a grinding wheel and the bearings in 
 
OTHER SHOPS SPECIAL PROCESSES 391 
 
 which it rests are made with the greatest accuracy possible and are 
 fitted to allow no play whatever between spindle and bearing. 
 Grinding may be either wet or dry, but wet grinding is the more 
 accurate as it prevents inaccuracy due to change in temperature of 
 the piece operated on. The machine must be amply protected from 
 water and grit in wet grinding or from dry grit in dry grinding. 
 
 429. Grinding Wheels. Experience has shown that the kind of 
 wheel, its periphery speed, the extent of contact between the wheel 
 and the work, and the rate of feed of the wheel over the work are 
 essential factors in successful grinding. 
 
 The kind of wheel depends upon three factors, viz., (1) the 
 grinding material of which the wheel is made; (2) the size of 
 grains of this material, and (3) the strength of the cement bond 
 holding the grains together. Wheels are made of emery, one of the 
 many forms of aluminum oxide found in nature; corundum, an 
 artificially made aluminum oxide much purer than emery; and 
 carborundum, a compound of silicon and carbon. Corundum and 
 carborundum are products of the electric furnace. These materials 
 are crushed to powder, and the grains are separated according to 
 their sizes. A wheel is made up by mixing grains of a certain size 
 with a bonding material. Hydraulic cement is much used for 
 bonding high-grade wheels. The wet mixture of cement and grind- 
 ing material is moulded to shape and burned into a bonded mass 
 in a furnace at high temperature. In operation, the wheel cuts 
 by contact of the sharp hard particles against the material operated 
 on, and as these particles become dull, they gradually crumble away 
 from the bonding material and give place to sharper particles. The 
 softness or hardness of a wheel depends upon the strength of the 
 bonding cement. 
 
 Makers of wheels and of grinding machines supply full informa- 
 tion of the proper kind, size and speed of wheel for each class of 
 use. 
 
 Wheel surfaces are trued by a diamond-pointed tool held against 
 the wheel as it revolves. 
 
 430. Lapping. This is a method of grinding external and internal 
 cylindrical surfaces to a finer degree of accuracy (-nrhnr i ncn ) 
 than can be obtained with certainty in the use of a grinding wheel. 
 It is under more certain control and is employed to finish wheel- 
 
392 
 
 MECHANICAL PROCESSES 
 
 ground work when the highest attainable degree of accuracy is 
 required. 
 
 The process consists of revolving the work in a grinding lathe 
 while it is lightly held in a lead-lined clamp on which is smeared 
 a thin coating of oil and very fine grains of grinding material. 
 For internal grinding, a lead-covered iron plug, or a plug with lead 
 ribs cast in longitudinal grooves, is used to carry the grinding 
 material. The hard grains of grinding material become unbedded 
 in the soft lead and their grinding action is guided by the contact 
 of the lead itself with the surface to be ground. 
 
 J__ III 
 
 I . I 
 
 / \ , / \ , / 
 
 ^'M'ER g 
 
 i . i 
 
 i.ii 
 
 FIG. 268. Armor Plate Hardening. 
 
 431. Armor-Plate Making. An armor plate should be hard enough 
 on the outer surface to prevent penetration by a shell and tough 
 enough under the hard surface to resist breaking or cracking. 
 Armor plate is commonly made of nickel-steel with which is alloyed 
 chromium, tungsten, or vanadium. Nickel increases toughness 
 and the other metal increases hardness. 
 
 Armor steel is made from high-grade ore by either the acid or 
 the basic open-hearth process. The reduction of phosphorus in the 
 steel is highly essential, hence the basic process is employed in 
 America. The ingot is cast in a very large cast-iron mould lined 
 inside with a layer of hard-baked loam. It is forged to shape under 
 
OTHER SHOPS SPECIAL PROCESSES 393 
 
 a powerful hydraulic forging press, is planed to dimensions, and is 
 then subjected to the hardening process. 
 
 Fig. 268 shows the diagram of two plates prepared for hardening. 
 A heavy steel car is covered with layers of fire brick to protect it 
 from intense heat, and on this is built the structure shown. The 
 flues 1, 2, 3, 4 allow the passage of hot gases under the lower plate. 
 Between the two plates is a layer of powdered charcoal. The car 
 supporting this structure is rolled into a regenerative furnace and 
 is walled in. It is then heated up gradually and kept above a red 
 heat for several days. The carbon penetrates the steel, as in the 
 cementation process, and the degree of penetration depends upon 
 the degree of heat and upon the length of time the heat is main- 
 tained. It is estimated that the process occupies five days for heat- 
 ing and cooling and one day for each inch of penetration of the 
 carbon. As carbon is absorbed, the angle iron frame gives down 
 under the weight of the upper plate and allows this plate to remain 
 it contact with the carbon. 
 
 The plates are hardened after removing and cleaning. This is 
 done by reheating and spraying the carburized surfaces with jets 
 of cold water. This hardness penetrates only about 2 inches or less, 
 but the surface is so hard that it cannot be cut or drilled. 
 
 The processes of armor making are guarded with much secrecy 
 by the few manufacturers who are engaged in this work. 
 
APPENDIX 
 
 432. Table of Brasses and Bronzes. The following table gives a 
 list of the brasses and bronzes in common use. Their compositions as 
 here given are more or less varied by manufacturers. 
 
 The skill of melters, and their personal experience,, lead them to 
 good results on alloys with mixtures not exactly the same in relative 
 amounts. 
 
396 
 
 APPENDIX 
 
 a 
 
 
 sqi 
 
 snaoqd 
 
 o 
 
 
 . 
 
 
 0^3 g 
 
 u 
 
 ou; Z 
 
 8 S 
 
 Muntz Metal. 
 Cast Naval B 
 
 1 =3 
 
APPENDIX 
 
 397 
 
 433. Degrees of Hardness of Steel Tools. The amount of carbon 
 in various well-known tools and implements made of hardened steel 
 is shown approximately by the following list: 
 
 .6 to .7 per cent. 
 
 .7 to .8 per cent. 
 
 .8 to .9 per cent. 
 
 .9 to 1.0 per cent. 
 
 Screw drivers. 
 
 Smiths' hammers. 
 
 Wrenches. 
 
 Machinists' 
 
 
 
 
 hammers. 
 
 Anvil tools. 
 
 Punches for metals. 
 
 Circular saws. 
 
 
 
 
 
 Hand saws. 
 
 Gun barrels. 
 
 Hand picks. 
 
 Lathe centers. 
 
 
 
 
 
 Cold chisels. 
 
 Chisels for hot 
 
 Wood augers. 
 
 Anvil facing. 
 
 
 metals. 
 
 
 
 Steel springs 
 
 
 
 Vise jaws. 
 
 for Vehicles. 
 
 
 
 Drop-forgingdies. 
 
 
 1.1 to 1.2 per cent. 
 
 1.20 to 1.26 per cent. 
 
 1.26 to 1.30 per cent. 
 
 1.30 to 1.50 per cent. 
 
 Rock drills. 
 
 Pocket knives. 
 
 Ball bearings. 
 
 Saws for cut- 
 
 
 
 
 ting steel. 
 
 Threading taps 
 
 Wood chisels. 
 
 Strong magnets. 
 
 
 and dies. 
 
 
 
 Tools for cutting 
 
 
 Hatchets, axes. 
 
 Files. 
 
 hard metals. 
 
 Lathe tools. 
 
 
 
 
 
 Twist drills. 
 
 Wire-drawing 
 
 Metal scrapers. 
 
 Steel springs 
 
 
 dies. 
 
 
 for power. 
 
 Pipe cutters. 
 
 
 
 
 
 Glass-cutters. 
 
 
 
 Milling cutters. 
 
 
 
 
 Cutters for wood- 
 
 
 
 
 working machines. 
 
 
 
 Degree of 
 Hardness. 
 
 Per cent 
 of carbon. 
 
 Very hard 1.50 
 
 Hard 1.25 
 
 Medium hard 1.00 
 
 Tough 80 
 
 Tenacious 65 
 
 Very elastic 30 
 
 434. File Making. To illustrate many of the essential opera- 
 tions in making tools, a description of file making is here given. 
 This description applies to a flat tapered file of rectangular cross 
 section. The steel used is a superior grade of high-carbon crucible 
 26 
 
398 APPENDIX 
 
 steel, received from the manufacturers in bars about 12 feet long 
 and of the same cross section as the file. The steps are as follows : 
 
 (1) Forging. A bar is cut into blanks of the length required. 
 Each blank is heated, the tang or handle end is forged by a rapidly 
 working machine hammer, and the taper end is forged by hand. 
 
 (2) Annealing. As the blanks cool, they become somewhat 
 hardened and must be softened by annealing. Several forged blanks 
 are packed in a bulky cast-iron box, and its lid is placed on and 
 luted with clay. Small blanks lose some carbon in heating for 
 forging, and this is restored by packing carbon around the blanks 
 to be annealed. The cast-iron boxes and contents are heated gradu- 
 ally in a furnace to red heat and allowed to cool slowly, occupying 
 two or three days. 
 
 (3) Straightening. When annealed, the blanks are inspected by 
 a man who straightens crooked blanks by tapping with a hammer. 
 
 (4) Grinding and Draw filing. Straightened blanks are ground 
 on large grind stones to remove scale and expose a clean metal sur- 
 face. Some blanks are so ground as to remove entirely any de- 
 carburized surface due to heating before forging. The grinding 
 is in some cases supplemented by filing the blanks to make them 
 level across their length, as the stones cannot grind a true flat 
 surface. 
 
 (5) Cutting. The teeth are then cut on the blanks in a machine. 
 A blank lies flat on the lead-covered machine table and is fed in the 
 direction of its length under a wide chisel which is held by the 
 machine and made to oscillate rapidly in a vertical direction or in 
 a direction slightly inclined to the vertical. This chisel strikes the 
 blank and cuts a gash entirely across its width. A double-cut file 
 is run under this chisel twice before the opposite side of the blank 
 is cut. A rasp file is cut by a small chisel resembling a punch 
 which strikes the blank at an angle and raises teeth from its sur- 
 face. If the blank is bent in cutting the teeth, it is straightened 
 by a lead hammer. This is seldom necessary. 
 
 (6) Dipping. After cutting, the files are usually stamped with 
 the name of the makers, and are then prepared for hardening by 
 dipping into a mixture which forms a film over the surface and 
 prevents oxidation of the tooth points as the file is passed from the 
 heating to the hardening bath. If necessary, this dipping is pre- 
 ceded by a bath of strong alkali to remove grease. 
 
APPENDIX 
 
 399 
 
 (7) Heating and Hardening. Each pile is then heated gradually 
 by dipping it into a molten-lead bath kept at a uniform high-tem- 
 perature by oil burners. It is hardened and tempered in one opera- 
 tion by quenching in salt water. 
 
 (8) Cleaning. After hardening, each file is cleaned by scrub- 
 bing, and is further relieved of dirt and clinging particles of metal 
 by subjecting it for a moment to a blast of fine sand and water. 
 This renders the teeth clean and sharp. 
 
 (9) Softening Tangs. The tang ends (handle ends) are then 
 softened by heating in lead and cooling in oil. This keeps the tang 
 from breaking when in use. 
 
 (10) Final Inspection Testing. Each file is now carefully ex- 
 amined for defects in manufacture, and if perfect, is oiled to pre- 
 vent rusting. It is then struck on an anvil to detect from the 
 sound any possible flaw, and is tried in filing a piece of metal of 
 standard hardness to discover if it has the right hardness. If these 
 tests are passed, the file is brushed and sent to the packing and 
 shipping department. 
 
 435. Wire Gage Table. The following table is given to show a 
 comparison of the various wire gage systems : 
 
 
 Actual Dimensions in Fractions of an Inch. 
 
 Wire 
 
 
 
 
 4" 
 
 5 
 
 Gage 
 Units. 
 
 American or 
 Brown <fe 
 Sharpe. 
 
 Birmingham 
 Wire Gage 
 or 
 Stubb's Iron. 
 
 Stubb's Steel 
 Wire. 
 
 U. S. Standard 
 for Steel and 
 Iron Plates. 
 
 British 
 Imperial 
 Standard 
 Wire Gage. 
 (S. W. G.) 
 
 0000 
 
 .4600 
 
 .454 
 
 
 .406 
 
 .400 
 
 000 
 
 .40964 
 
 .425 
 
 .... 
 
 .375 
 
 .372 
 
 00 
 
 .3648 
 
 .38 
 
 .... 
 
 .344 
 
 .348 
 
 
 
 .32486 
 
 .34 
 
 
 .313 
 
 .324 
 
 I 
 
 .2893 
 
 .30 
 
 .227 
 
 .281 
 
 .300 
 
 2 
 
 .25763 
 
 .284 
 
 .219 
 
 .266 
 
 .276 
 
 3 
 
 .22942 
 
 .259 
 
 .212 
 
 .250 
 
 .252 
 
 4 
 
 .20431 
 
 .238 
 
 .207 
 
 .234 
 
 .232 
 
 5 
 
 .18194 
 
 .22 
 
 .204 
 
 .219 
 
 .212 
 
 10 
 
 .10189 
 
 .134 
 
 .191 
 
 .141 
 
 .128 
 
 20 
 
 .03196 
 
 .035 
 
 .161 
 
 .0375 
 
 .036 
 
 30 
 
 .01002 
 
 .012 
 
 .127 
 
 .0125 
 
 .0124 
 
 40 
 
 .00314 
 
 .... 
 
 .097 
 
 
 
 .0048 
 
 50 
 
 
 
 
 .069 
 
 
 .001 
 
 
 Intermediate sizes above No. 5 are not here given. 
 
400 APPENDIX 
 
 436. Wire Dies. Wire dies are usually made of chilled white 
 cast iron, hard-carbon steel, and alloy steel. The very smallest 
 sizes of dies are made of diamonds because drawing soon enlarges 
 a very small hole in a steel die. 
 
 Sometimes a coil of wire is found in the market which is not of 
 the same size throughout. This may be due to running the draw- 
 ing block too fast, which stretches the wire in soft places after it 
 has passed through the die, or it may be due to the wearing of the 
 die. When it is essential that a coil of wire be of the same diameter 
 at both ends, it is drawn nearly to gage in a roughing die and is 
 finished in another die which has little work to do. 
 
 As diamond is the hardest substance known, it requires special 
 means and considerable time to get a hole in a diamond die. An 
 uncut gem, somewhat flat and round, is mounted in a piece of soft 
 metal and is firmly secured in a small machine much resembling an 
 ordinary sewing machine. The oscillating arm of this machine 
 carries a small hard steel point, just as a needle is carried in a sew- 
 ing machine, and the arm is adjusted to make this point strike the 
 diamond surface just at the end of the oscillation. The point 
 strikes the diamond several hundred times a minute and a cutting 
 action is obtained by covering the gem with diamond dust held in 
 place by oil. The steel point is revolved as it oscillates, and it is 
 so worn at the end of 10 or 15 minutes that it is replaced by 
 another point. It requires a week or more to cut a very small hole 
 in the diamond. Steel points are ground round by holding them 
 against a diamond chuck revolved rapidly by a small lathe. 
 
 437. Dimensions of Standard Iron Pipes. The following table 
 shows the standard dimensions of iron pipe, including standard 
 threads for ends of the; pipe. These standard sizes are made in 
 wrought iron, mild steel, and brass as commercial products. 
 
 In ordering iron pipe it is necessary to designate only the size 
 of pipe required as given in the first column of the table, without 
 any mention of thickness. 
 
APPENDIX 
 
 401 
 
 
 Actual 
 
 
 
 
 Actual 
 
 
 
 Size 
 
 Outside 
 
 Thickness 
 
 Threads 
 
 Size 
 
 Outside 
 
 Thickness 
 
 Threads 
 
 Inches. 
 
 Diameter 
 
 Inches. 
 
 per Inch. 
 
 Inches. 
 
 Diameter 
 
 Inches. 
 
 per Inch. 
 
 
 Inches. 
 
 
 
 
 Inches. 
 
 
 
 X 
 
 .405 
 
 .068 
 
 27 
 
 3K 
 
 4.0 
 
 .226 
 
 8 
 
 \/ 
 
 .54 
 
 .088 
 
 18 
 
 4 
 
 4.5 
 
 .237 
 
 8 
 
 % 
 
 .675 
 
 .091 
 
 18 
 
 4K 
 
 5.0 
 
 .246 
 
 8 
 
 y* 
 
 .84 
 
 .109 
 
 14 
 
 5 
 
 5.563 
 
 .259 
 
 8 
 
 % 
 
 1.05 
 
 .113 
 
 14 
 
 6 
 
 6.625 
 
 .280 
 
 8 
 
 i 
 
 1.815 
 
 .134 
 
 ll/^ 
 
 7 
 
 7.625 
 
 .301 
 
 8 
 
 \% 
 
 1.66 
 
 .140 
 
 UK 
 
 8 
 
 8.625 
 
 .322 
 
 8 
 
 \% 
 
 1.9 
 
 .145 
 
 HM 
 
 9 
 
 9 . 625 
 
 .344 
 
 8 
 
 2 
 
 2.375 
 
 .154 
 
 UK 
 
 10 
 
 10.75 
 
 .366 
 
 8 
 
 2K 
 
 2 . 875 
 
 .204 
 
 8 
 
 11 
 
 11.75 
 
 .375 
 
 8 
 
 3 
 
 3.5 
 
 .217 
 
 8 
 
 12 
 
 12.75 
 
 .375 
 
 8 
 
 438. Methods of Threading Bolts. Bolts are usually threaded by 
 being held firmly in a machine which runs a briskly revolving thread- 
 ing die along the body of the bolt as far as the thread is to extend. 
 These dies are kept deluged with oil while they work, though the 
 work is so severe that they wear out rapidly. 
 
 A very effective thread for the cheaper-made bolts is either cold 
 or hot pressed on the bolt by a machine, the essential principle of 
 which is shown in Fig. 269. The bolt B is placed between the flat 
 
 i_ : 
 
 I -jzz* 
 
 f=/afr 
 FIG. 269. Dies for Rolling Threads on Bolt Ends. 
 
 dies C and D which are made to move in the direction of the arrows 
 and are held firmly at a given distance aj>art by bearing against the 
 parallel faces of the guides F and G. Each die moves forward and 
 back once, traveling a distance in one direction equal to at least 
 the circumference of the bolt. 
 
 The side view of the die plate shows how it is cut to impress 
 threads on the bolt. The notch N is cut in the face of the die to 
 the depth of the threads. 
 
402 APPENDIX 
 
 439. Illustration of Automatic Screw Machine Work. Fig. 270 
 shows the steps in the work of cutting the small helical gear 
 wheel shown at W in Fig. 92, Chap. VI. This is done in six 
 operations, requiring a total of 80 seconds of time. A dimen- 
 sion drawing of the wheel is shown at the bottom of the illustration. 
 Operation IV, that of cutting the spiral teeth, is. done by a very 
 ingenious tool made up of several moving parts, all automatically 
 operated, and designed at the works of The Brown & Sharpe Mfg. 
 Co., Providence, R. I. 
 
 440. Shop Location and Equipment. In locating and equipping 
 a manufacturing plant the following-named factors are of im- 
 portance : 
 
 (1) The cost of obtaining raw materials at their source of 
 supply, their quality and the available quantity. 
 
 (2) Cost of transporting raw materials to the plant and finished 
 products to market. 
 
 (3) Cost of fuel for manufacturing. 
 
 (4) Cost and available supply of labor needed. 
 
 (5) All buildings should be well lighted, dry and comfortable 
 and convenient for workmen. 
 
 (6) The power house (boilers, engines, and electric generators) 
 should be located convenient for receiving fuel and for distributing 
 power to the shops needing it. 
 
 (7) The buildings should be so located with reference to one 
 another as to afford a short and ready means of transferring work 
 from one shop to another in regular course of construction. 
 
 (8) Appliances for lifting and carrying heavy work readily in 
 the shops should be installed, and the machines in each shop should 
 be placed to reduce necessary handling of heavy work to a mini- 
 mum. 
 
 From the receiving of raw materials at a plant until they leave 
 as finished products, they are handled many times. It saves time, 
 labor, and cost to reduce this handling to a minimum, and careful 
 study should be made with the view of eliminating all unnecessary 
 handling. Much unnecessary handling and many needless move- 
 ments of workmen are many times overlooked because they are a 
 part of custom or habit. These points are given careful attention 
 in progressive shops. 
 
APPENDIX 
 
 403 
 
 FIG. 270. Specimen Operation of Automatic Screw Machine. 
 
404 
 
 APPENDIX 
 
 441. Allowance for Forcing and Shrinkage Fits. A table is here 
 given, showing the usual allowance or difference, in fractions of an 
 inch, between a shaft and the hole in which it fits, for forcing 
 and shrinkage fits. 
 
 Shrinkage fits. 
 
 Forcing fits. 
 
 Diameter in 
 inches. 
 
 Allowance (or 
 difference in di- 
 ameters). 
 
 Diameter in 
 inches. 
 
 Minimum 
 allowance. 
 
 Maximum 
 allowance. 
 
 2 
 
 .0025 
 
 2 
 
 .003 
 
 .005 
 
 8 
 
 .0090 
 
 8 
 
 .009 
 
 .011 
 
 16 
 
 .0175 
 
 16 
 
 .014 
 
 .017 
 
 40 
 
 .0400 
 
 
 
 
 65 
 
 .0700 
 
 
 
 
 442. IT. S. Standard Screw Threads. 
 
 Diameter of 
 screw. 
 
 Threads per 
 inch. 
 
 Diameter at 
 root of thread. 
 
 Diameter of 
 screw. 
 
 Threads per 
 inch. 
 
 Diameter at 
 root of thread. 
 
 \ 
 
 20 
 
 .185 
 
 2 
 
 4V2 
 
 1.7113 
 
 s g 
 
 18 
 
 .2403 
 
 21/4 
 
 4^ 
 
 1.9613 
 
 k 
 
 16 
 
 .2936 
 
 2i/ 2 
 
 4 
 
 2.1752 
 
 7 
 
 14 
 
 .3447 
 
 2% 
 
 4 
 
 2.4252 
 
 3/ 2 
 
 13 
 
 .4001 
 
 3 
 
 Sifc 
 
 2.6288 
 
 9 
 
 12 
 
 .4542 
 
 3V4 
 
 31/2 
 
 2.8788 
 
 % 
 
 11 
 
 .5069 
 
 
 
 3V4 
 
 3.1003 
 
 3 /4 
 
 10 
 
 .6201 
 
 3% 
 
 3 
 
 3.3170 
 
 7 /3 
 
 9 
 
 .7307 
 
 4 
 
 3 
 
 3.5670 
 
 1 
 
 8 
 
 .8376 
 
 4V 4 
 
 27/ 8 
 
 3.7982 
 
 Hfe 
 
 7 
 
 .9394 
 
 4V2 
 
 2% 
 
 4.0276 
 
 1*4 
 
 7 
 
 1.0644 
 
 434 
 
 2% 
 
 4.2551 
 
 1% 
 
 6 
 
 1.1585 
 
 5 
 
 2^ 
 
 4.4804 
 
 H/2 
 
 6 
 
 1.2835 
 
 514 
 
 % 
 
 4.7304 
 
 1% 
 
 5V2 
 
 1.3888 
 
 5V 2 
 
 2% 
 
 4.9530 
 
 1% 
 
 5 
 
 1.4902 
 
 5% 
 
 2% 
 
 5.2030 
 
 1% 
 
 5 
 
 1.6152 
 
 6 
 
 2*4 
 
 5.4226 
 
 443. Hydraulic Data. 
 
 TABLE OF GALLONS. 
 
 
 Cu. ins. in a 
 gallon. 
 
 Wt. of gal., 
 pounds 
 avoirdupois. 
 
 Gallons in 
 a cu. ft. 
 
 One cu. ft. of water at 
 its maximum density, 
 39.1 Fahr., weighs 
 62.425 Ibs. avoirdupois. 
 
 United States.... 
 Imperial 
 
 231 
 
 277.274 
 
 8.33 
 10.00 
 
 7.480 
 6.242 
 
APPENDIX 405 
 
 One Imperial gallon = 1.2 U. S. gallons. 
 
 One U. S. gallon = 0.833 Imperial gallon. 
 
 268.8 U. S. gallons of water = 1 ton. 
 
 35.88 cubic feet of water = 1 ton. 
 
 1 cubic inch of water = .03613 pound. 
 
 Cubic feet of water x 62.425 = pounds. 
 
 Cubic inches of water x .03613 = pounds. 
 
 U. S. gallons x .13368 cubic feet. 
 
 Cubic inches x .004329 = U. S. gallons. 
 
 Cubic feet x 7.48 = U. S. gallons. 
 
 Cubic inches x .0005787 = cubic feet. 
 
 Pressure of a water column in 
 
 pounds per square inch height of column in feet x .4335. 
 
 Pressure of a water column in 
 
 pounds per square foot = height of column in feet x 62.425. 
 
 One cu. ft. sea water at 62 Fahr. .= 64 pounds. 
 One cu. in. sea water = 0.037037 pounds. 
 
INDEX 
 
 A PAGE. 
 
 Abrasive materials 330 
 
 Absorption point 150 
 
 Accuracy of surface grinding, 390 
 
 Accurate cutting of holes 322 
 
 Acetylene gas for welding .... 384 
 
 Acid ores 40-41 
 
 Acid process of steel making. . 89 
 Adjustments of machine bear- 
 ings 283 
 
 Alcohol as fuel 64 
 
 Alcohol, sources 63 
 
 Allowance for forcing or 
 
 shrinkage fits 404 
 
 Allowance for shrinkage, pat- 
 tern making 218 
 
 Alloy of magnesium 20 
 
 Alloys 17 
 
 Alloys, peculiarities of 17-18 
 
 Alloys, requirements of pre- 
 paring 18 
 
 Alloys, table of 395-396 
 
 Alloys, used for machinery 
 
 parts 395-396 
 
 Alloys, well known designa- 
 tions of 18 
 
 Alloy steels 113-114 
 
 Alloy steels, uses of 113-114 
 
 Alloy steel tools, hardening of, 270 
 
 Alumina 51, 57 
 
 Aluminum bronze 19 
 
 Aluminum, fusing point of . . 24 
 Aluminum, production of. ... 57 
 Aluminum, properties of .... 24 
 
 Aluminum, sources of 57 
 
 Aluminum, strength of 24 
 
 Aluminum, uses of 23 
 
 PAGE 
 
 Aluminum, welding and sold- 
 ering 386 
 
 Annealing 15, 151-152 
 
 Annealing in blacksmith shop, 270 
 Annealing of boiler plates . . . 352 
 Annealing of brass and copper 
 
 work 369-370 
 
 Annealing of sheet brass .... 155 
 Annealing of sheet copper . . . 154 
 Annealing of sheet iron .... 161 
 Annealing of steel castings, 
 
 152, 258 
 Annealing of steel forgings.. 152 
 
 Anti-friction metal 20 
 
 Antimony 24 
 
 Anvil for blacksmithing .... 262 
 
 Anvil tools 264 
 
 Appliances for steam hammer 
 
 forging 271-273 
 
 Architectural shapes 130, 157 
 
 Armor plate, cutting of 387 
 
 Armor plate, manufacture of, 392 
 
 Ash and refuse in fuel 59 
 
 Autogeneous welding 389 
 
 Automatic screw machine. .196-197 
 Automatic screw machine, work 
 
 of 198, 402, 403 
 
 Automobile forgings 192-195 
 
 B 
 
 Band saw 211 
 
 Basic ores 40-41 
 
 Basic process of steel making, 89 
 
 Bauxite 51-52, 57 
 
 Beading boiler tubes 358 
 
 Bearing, meaning of 323 
 
408 
 
 INDEX 
 
 PAGE 
 
 Bearings, adjustment of 283 
 
 Bench equipment, machine 
 
 shop 323 
 
 Bench work, machine shop.. 323 
 
 Bending slab 374-375 
 
 Bessemer converter 92 
 
 Bessemer converter, operation 
 
 of 93 
 
 Bessemer process 89, 91-92 
 
 Bessemer process, features of, 96 
 
 Bessemer steel, uses of 96 
 
 Beton 25 
 
 Billet 124 
 
 Billet mill 135 
 
 Billets for forgings 261 
 
 Blacksmith anvil 262 
 
 Blacksmith forge 262 
 
 Blacksmith tools 263-264 ' 
 
 Blast furnace 37-40 
 
 Blast furnace, fusion zone . . 45 
 Blast furnace, modifications of, 40 
 Blast furnace, operation of 42-45 
 
 Blast main 39 
 
 Blast stoves 45-48 
 
 Blister copper 54 
 
 Blister steel 90 
 
 Blooming mill 128, 131-133 
 
 Blooms and billets 124-125 
 
 Blooms and billets, reheating 
 
 of 139-142 
 
 Blooms for forgings 261 
 
 Blooms, wrought iron 83 
 
 " Blowing in " a blast-furnace, 42 
 " Blowing out " a blast-furnace, 45 
 
 Blow pipe 384-385 
 
 Blow pipe cutting of metals. . 387 
 
 Blow pipe welding 384-386 
 
 Boiler building, assembling 
 
 parts 353 
 
 Boiler drums, welding of, 386-387 
 Boiler, laying out parts . . 340-341 
 
 Boiler material 339 
 
 Boiler plates, annealing 352 
 
 Boiler plates, bending 344-345 
 
 PAGE 
 
 Boiler plates, cleaning 342 
 
 Boiler plates, drilling holes.. 352 
 Boiler plates, flanging. 347-349, 351 
 
 Boiler plates, laying out 342 
 
 Boiler plates, planing edges, 
 
 343-344 
 
 Boiler plates, shaping 343 
 
 Boiler riveting 354-355 
 
 Boiler rivets " 196, 362 
 
 Boiler shop equipment 359 
 
 Boiler steel 340 
 
 Boiler tube expander 357 
 
 Boiler tubes, making of ... 171-176 
 Boiler tubes, means of fasten- 
 ing 357 
 
 Boilers, types of 338 
 
 Bolt making 195-196 
 
 Bolts, methods of threading ..401 
 Bolts, types and sizes ....334-336 
 
 Boring 300, 314-316 
 
 Boring bar 294-295, 331 
 
 Boring deep holes 322 
 
 Boring machine (for wood) . . 213 
 Boring machines (metal) 313-316 
 
 Boshes 39 
 
 Brass 18-19, 396 
 
 Brass, annealing sheets of . . 155 
 
 Brass, extruded 155-157 
 
 Brass, furnace for melting, 250-251 
 Brass, general methods o f 
 
 shaping 125 
 
 Brass, rolling of sheets 155 
 
 Brass, table giving composi- 
 tion 395-396 
 
 Brazing 368-369 
 
 Brazing cast iron 389 
 
 Brazing forge 369 
 
 Brazing-metal 368 
 
 Breaking down forgings 191 
 
 Breaking down ingots 125 
 
 Briquettes 63 
 
 British Thermal Unit (B. T. 
 
 U.) 59 
 
 Brittleness , 15 
 
INDEX 
 
 409 
 
 PAGE 
 
 Brittleness of unannealed steel, 152 
 
 Bronze 18, 19-20 
 
 Bronze, general methods of 
 
 shaping 125 
 
 Bronze, rolling of sheets 155 
 
 Bronze, table giving composi- 
 tion 396 
 
 Building and repairing, shops 
 
 for 199-200 
 
 Burned steel 151 
 
 Burning on 387-389 
 
 B. W. G. (wire gage) 166 
 
 B & S. (wire gage) 166 
 
 Calcination of iron ores 69 
 
 Calcination of ores 36 
 
 Calipers 281, 284, 285, 286-287 
 
 Carbon in iron and steel . .70, 74-75 
 
 Carbon in steel tools 397 
 
 Carborundum 330, 391 
 
 Cartridge cases, pressing of . . 186 
 
 Case hardening 376-377 
 
 Casting pit 103-105 
 
 Castings, defects in 251-252 
 
 Castings, remedies for defects, 252 
 Castings, repair of, 380-381, 386-389 
 Castings, steel. (See Steel 
 
 castings.) 
 Castings, Thermit process of 
 
 making 381 
 
 Cast iron 70 
 
 Cast iron, brazing of 389 
 
 Cast iron, carbon in 74 
 
 Cast iron, expansion in cool- 
 ing 250 
 
 Cast iron, fusing point 77 
 
 Cast iron, properties of 77 
 
 Caulking boiler work 358 
 
 Caulking, tools for 358 
 
 Cement 24-25 
 
 Cement, Portland. (See also 
 
 Portland Cement.) 24 
 
 Cement, quick-setting 25 
 
 PAGE 
 
 Cements, causes of setting 29 
 
 Cements for metals 378-379 
 
 Cementation process 90 
 
 Cementation process, discov- 
 ery of 88 
 
 Center punch 281 
 
 Centering work for lathe .... 296 
 Change in shape of new cast- 
 ings 321 
 
 Changes in properties of metals 15 
 Changes in steel due to heat- 
 ing 150 
 
 Chaplets 242 
 
 Charcoal 60 
 
 Charcoal iron 71 
 
 Chasers for screw threads. . . . 300 
 
 Chemical laboratory 200 
 
 Chill moulds 242-243 
 
 Chrome steel 114 
 
 Chromite 51 
 
 Chuck, drill 303 
 
 Chuck, lathe 292-293 
 
 Chuck, planer 306 
 
 Chuck and porter bar 148-149 
 
 Chuck stub 148 
 
 Circular saw, setting teeth . . 214 
 
 Circular saw table 206 
 
 Classification of forces 16 
 
 Clay 51 
 
 Coal 60 
 
 Coal, desirability of 59 
 
 Coal, powdered 62 
 
 Coal screenings 63 
 
 Coating for wire 167 
 
 Cogging mill 131, 132-133 
 
 Coke and coke-making 61-62 
 
 Coke furnace 61 
 
 Cold-blast iron 71 
 
 Cold chisels 324 
 
 Cold pressing of sheet metals 
 
 185-189 
 Cold pressing of sheet metals, 
 
 examples 187, 188, 189 
 
 Cold rolled steel . . 144 
 
410 
 
 INDEX 
 
 PAGE 
 
 Cold-short iron 76 
 
 Cold shuts in ingots and cast- 
 ings 119, 252 
 
 Colors for judging hardness of 
 
 tools 269 
 
 Combined carbon in iron . . . .74, 77 
 
 Combustion 58 
 
 Composition (alloy) 18 
 
 Compression 16 
 
 Concentration of iron ores 68 
 
 Concrete 25 
 
 Concrete, method of using ..28-29 
 Concrete, proportions of mix- 
 tures 28 
 
 Concrete, re-enforced 27 
 
 Concrete, water proof qualities 29 
 
 Conductivity 15 
 
 Continuous mill 132 
 
 Converter, Bessemer 92 
 
 Converter, for copper 53 
 
 Converter, Tropenas 257 
 
 Cope 219, 230 
 
 Copper, annealing of 21 
 
 Copper converter 53 
 
 Copper, fusing point of 21 
 
 Copper, general methods of 
 
 shaping 125 
 
 Copper, how disposed of from 
 
 smelter 123 
 
 Copper, impurity allowable in 
 
 sheet 153 
 
 Copper, impurities in 21 
 
 Copper, native 35 
 
 Copper pipe and pipe joints, 
 
 371-373 
 Copper pipe, shaping of . . 365- 
 
 368, 371-372, 377-378 
 
 Copper, production of 52-55 
 
 Copper, properties of 21 
 
 Copper refining 54-55 
 
 Copper, rolling into sheets . . 153 
 
 Copper shop equipment 364 
 
 Copper, sources of 52 
 
 Copper, strength of 21 
 
 Copper, uses of 20 
 
 PAGE 
 Core boxes and core prints. . . . 222 
 
 Cores for moulds 241 
 
 Corrugated iron 160 
 
 Corundum 391 
 
 Countersink 303 
 
 Cracks in forgings 323 
 
 Critical points 150 
 
 Crocus cloth 330 
 
 Crop ends of steel 118, 148 
 
 Crucible process 107-108 
 
 Crucibles 109 
 
 Crucibles, method of charging, 111 
 
 Crucible steel 90 
 
 Crucible steel, expense of .... 107 
 Crucible steel furnace ....109-111 
 Crucible steel, materials of . . 108 
 Crucible steel, properties of . 112 
 
 Crude petroleum 63 
 
 Cupola 247 
 
 Cupola, operation of 248 
 
 Cuts in woodworking 216 
 
 Cutting holes with blowpipe. 387 
 Cutting metals with blowpipe, 387 
 Cutting of metals, speeds for. 276 
 Cutting of screw threads. .297-300 
 
 Cutting speed of tools 321 
 
 Cylinders for gas storage 185 
 
 D 
 
 Defective castings, remedies 
 
 for 252 
 
 Defects in castings ..251-252, 259 
 
 Defects in steel ingots 118-119 
 
 Defects in rolled metals 143 
 
 Defects in seamless tubes 181 
 
 Degree of heat for forging, 266, 274 
 Degrees of hardness from car- 
 bon 397 
 
 Degrees of hardness in steel 
 
 tools 397 
 
 Degrees of refinement in ma- 
 chining 276, 282-283 
 
 Density 15 
 
 Diamond cutting for wire dies, 400 
 Dies, for cutting threads, 326-328 
 
INDEX 
 
 411 
 
 PAGE 
 
 Differential pulley 331 
 
 Direct metal 71 
 
 Discard in steel ingots 118 
 
 Dividers 281 
 
 Dolomite 51 
 
 Dote, in lumber 33 
 
 Draft of patterns 219 
 
 Drag (moulding) 219, 230 
 
 Drawing-blocks (wire mak- 
 ing) 165 
 
 Drawing or drafting room, 200-201 
 
 Drawing out (forging) 266 
 
 Drawings for shop use 201 
 
 Drawings, methods of repre- 
 senting by 201-202 
 
 Drawings, orthographic and 
 
 isometric 202, 203 
 
 Drawings, purpose of 200 
 
 Drawing wire .164-166 
 
 Drawing wire, dies for 400 
 
 Drilling holes, methods of ... 300 
 Drilling machines, types of . . 300 
 Drilling machines, for boiler 
 
 shop 353 
 
 Drills, types of 303 
 
 Driving fit 283 
 
 Drop forging automobile parts, 
 
 192-193 
 Drop forging, dies for, 191-192-193 
 
 Drop forging hammer 190-191 
 
 Drop forging, largest 195 
 
 Drop forging operations ..191-193 
 
 Drop forgings 189 
 
 Drop forgings, specimens, 194-195 
 
 Drop forgings, utility of 261 
 
 Dry process of smelting 36 
 
 Ductility 15 
 
 Duplex process 106 
 
 Durability of wood 34 
 
 B 
 
 Effects of hammering and roll- 
 ing metals 144 
 
 Effects of hydraulic forging 
 press 145 
 
 PAGE 
 
 Effects of rolling metals 142 
 
 Effects of steam hammer, 145, 274 
 
 Elastic limit 16 
 
 Elasticity 15 
 
 Electric current for welding, 380 
 
 Electric steel furnace 122 
 
 Electric welding 379-381 
 
 Electricity in Metallurgy 57 
 
 Electrolysis in copper refining, 
 
 54, 55 
 
 Elongation 16 
 
 Emery 330, 391 
 
 Engineering materials ...... 14 
 
 Equipment for bench work . . 323 
 
 Erecting shop 200-275 
 
 Essential features of patterns, 218 
 Essential factors in hardening 
 
 steel 152 
 
 Essentials in machine shop 
 
 work 276 
 
 Example of making small 
 
 mould 239-240 
 
 Examples of patterns 220-221 
 
 Examples of work, automatic 
 
 screw cutting machine 198 
 
 Extruded brass and bronze, 
 
 155-156 
 Extruded shapes 157 
 
 F 
 
 Face plate 292 
 
 Factors in hardening steel . . . 152 
 
 Fatigue of metals 15-16 
 
 Ferro-manganese 77 
 
 Ferro-silicon 75 
 
 Fettling 81 
 
 Files, manufacture of 397-399 
 
 Files, varieties of 324-326 
 
 Fillets 222-223, 322 
 
 Fins 138, 143 
 
 Fire bricks 52 
 
 Fire clay 51, 234 
 
 Fitting by forcing 404 
 
 Fitting by shrinking 404 
 
 Fittings for pipes 332-334 
 
412 
 
 INDEX 
 
 PAGE 
 
 Fixed carbon in coal 60 
 
 Flange heating furnace 351 
 
 Flanging mild steel plates, 347-348 
 
 Fluid compressed steel 119-122 
 
 Fluxes for soldering 371 
 
 Flux for brazing 368 
 
 Flux for smelting 41-42 
 
 Flux for welding 267 
 
 Fluxing mixture for galvaniz- 
 ing 162 
 
 Forces, classification of 16 
 
 Forcing fit 283 
 
 Forcing presses 320 
 
 Forge equipment for hand 
 
 work 261-262 
 
 Forge, essentials for heating, 265 
 
 Forge for brazing 369 
 
 Forge shop 260 
 
 Forge shop equipment 271 
 
 Forging appliances for steam 
 
 hammer 271-273 
 
 Forgings, drop. (See Drop 
 forgings.) 
 
 Forgings, large 145 
 
 Forgings, materials for 261 
 
 Forgings, measuring stock for, 267 
 
 Forging terms 266 
 
 Forms of newly produced 
 
 metals 123 
 
 Forms of screw threads 299 
 
 Foundries, iron, steel, and 
 
 brass 228, 253 
 
 Foundry cupola 247 
 
 Foundry cupola, operation of, 248 
 
 Foundry equipment 231 
 
 Foundry iron 249 
 
 Fuel, ash and refuse in 59 
 
 Fuel, components of 59 
 
 Fuel, essentials for burning . . 58 
 Fuel for blacksmith forges . . 265 
 
 Fuel for producer gas 67 
 
 Fuel, heating value of 59 
 
 Fuels, classes of 59 
 
 Fuels, liquid 63-64 
 
 PAGE 
 
 Fuels, objections in metal- 
 lurgy 58 
 
 Fuel, uses 58 
 
 Fuller bar 272 
 
 Furnace, annealing 152, 258 
 
 Furnace, blast 37 
 
 Furnace, electric, for steel... 122 
 Furnace for heating flange 
 
 work 351 
 
 Furnace for lieating rivets . . 356 
 Furnace for melting brass . . . 250 
 
 Furnace, open hearth 97-99 
 
 Furnace, open hearth, charg- 
 ing 99-100 
 
 Furnace, puddling 80-81 
 
 Furnaces for steam-hammer 
 
 work 273 
 
 Furnaces, muffle 152 
 
 Furnaces, reheating 140-142 
 
 Furnaces, reverberatory, 37, 48-50 
 
 Furnaces, smelting 37 
 
 Fusibility 15 
 
 Gage, depth 284 
 
 Gage, drill 285 
 
 Gage, fixed 285 
 
 Gage for metal thicknesses, 166-167 
 Gage for pipe and tube walls, 167 
 
 Gage, surface 282 
 
 Gage, wire and sheet metal . . 285 
 Gages, inside measuring . .284, 287 
 
 Gaging sizes of wire 166 
 
 Galvanized iron 160 
 
 Galvanizing 161-162 
 
 Gang drills 302 
 
 Gangue 35 
 
 Ganister 51 
 
 Gas carbon in coal 60 
 
 Gas fuels 64 
 
 Gas, natural 64 
 
 Gas producer 64-65 
 
 Gas storage cylinders 185 
 
 Grinding, accuracy of, 390, 391, 392 
 
INDEX 
 
 413 
 
 PAGE 
 
 Grinding accurate surfaces . . . 390 
 
 Grinding machines 390 
 
 Grinding wheels 391 
 
 H 
 
 Hammers, blacksmith 263 
 
 Hand planer 212 
 
 Hand tools, woodworking . . . 214 
 
 Handling large forgings 148 
 
 Hard solder 368 
 
 Hardening baths for steel, 159, 270 
 
 Hardening of alloy steel 270 
 
 Hardening of steel 152, 159 
 
 Hardening of steel tools 269 
 
 Hardest steel known 114 
 
 Hardness 15 
 
 Hardness of tools, judging by 
 
 colors 269 
 
 Hardwood lumber 31 
 
 Hardwood lumber grades 32 
 
 Heartwood 31-32 
 
 Hearth of smelting furnace ... 39 
 Hearth of puddling furnace . . 81 
 
 Heating in a forge 265 
 
 Heating of steel, methods 159 
 
 Heat treatment of metals 149 
 
 Heterogeneous welding 389 
 
 High carbon steel 74, 79, 91 
 
 Highest degree of surface ac- 
 curacy 390 
 
 High-speed steel 113, 114 
 
 Holders-on for riveting 355 
 
 Hole cutting by blow pipe 387 
 
 Hot blast main 39 
 
 Hot short iron 75 
 
 Hydraulic accumulator . . . 349-351 
 
 Hydraulic data 404-405 
 
 Hydraulic flanging press . .348-349 
 Hydraulic forging press ..145-148 
 Hydraulic forging press, ef- 
 fect of 145 
 
 Hydraulic lime 25 
 
 Hydraulic riveting machines .. 355 
 
 Hydraulic shears 128 
 
 Hydrogen gas for welding . . . 384 
 27 
 
 I PAGE 
 
 Illuminating gas 67 
 
 Impurities in ores 35 
 
 Impurities in steel 117-118 
 
 Impurity allowable in sheet 
 
 copper 153 
 
 Influence of quenching in hard- 
 ening tools 270 
 
 Ingot 124 
 
 Ingot moulds 114-116 
 
 Ingots, defects in 118 
 
 Ingots, heating necessary for 
 
 rolling 128, 129 
 
 Ingots, method of rolling . .128-129 
 Ingots, reducing to smaller 
 
 form 125 
 
 Ingots, reheating of 126-127 
 
 Ingots, stripping from moulds, 117 
 
 Inspecting department 200 
 
 Inspection of rolled material, 142 
 Inspection of material. (See 
 Defects.) 
 
 Iron, charcoal 71 
 
 Iron, chemically pure 73 
 
 Iron, classified methods of 
 
 shaping 124 
 
 Iron, cold blast 71 
 
 Iron for foundry use 249 
 
 Iron, general classes of 74 
 
 Iron, grey, mottled and white, 249 
 Iron, how disposed of from 
 
 smelter 123 
 
 Iron, ingredients entering mol- 
 ten 70, 74-77 
 
 Iron ores 68 
 
 Iron ores, preparation for 
 
 smelting 68-69 
 
 Iron ores, reduction 70 
 
 Iron pipe, standard dimen- 
 sions 400-401 
 
 Iron, pig, converted into steel, 123 
 Iron. (See also Steel, pig iron, 
 cast iron, wrought iron, mal- 
 leable iron.) 
 Isometric method of drawing, 202 
 
414 
 
 INDEX 
 
 J PAGE 
 
 Jacks for lifting 331 
 
 Jacks for planer work 306 
 
 Jigs 304 
 
 Joining metals, methods of . . 378 
 
 Jointer . 212 
 
 Joints for copper pipe 372-373 
 
 Joints in woodworking 216 
 
 Journal , . 323 
 
 Ladles for foundry use 249 
 
 Ladles for steel 104 
 
 Ladles shanks 112 
 
 Lapping (grinding) 391-392 
 
 Large forgings 145 
 
 Large forgings, handling of . . 148 
 
 Lathe attachments 292 
 
 Lathe boring bar 294 
 
 Lathe chucks 292-293 
 
 Lathe dog 289 
 
 Lathe mandrels 293-294 
 
 Lathes, examples of woodwork 
 
 in 208 
 
 Lathes for metal working, 207, 
 
 287-291 
 
 Lathes for wookworking, 207-210 
 Lathes, hand tools for wood- 
 working 209 
 
 Lathes, how sizes are desig- 
 nated 209 
 
 Lathe, steady rest 296 
 
 Lathes, swing of 209 
 
 Lathe tools (for metals), 291-292 
 
 Lathe work, centering 296 
 
 Laying-down board 224 
 
 Leaching 36 
 
 Lead pipe 157 
 
 Lead, properties of 23 
 
 Lead, smelting of 56 
 
 Lead, sources of 56 
 
 Lead, uses of 23 
 
 Lifting jacks 331 
 
 Lime 25 
 
 Lime, hydraulic 25 
 
 PAGE 
 
 Limestone in ores 40 
 
 Limestone, use in steelmaking, 100 
 
 Liquation 18 
 
 Liquid fuels 63-64 
 
 Loam for moulding 234 
 
 Looping mill 132 
 
 Lumber, dressed 33 
 
 Lumber, grading of 31 
 
 Lumber, hard and soft wood. . 31 
 Lumber inspection rules . . . .32-33 
 
 Lumber, log run 31 
 
 Lumber measurement 34 
 
 Lumber, methods of sawing. . 30 
 
 Lumber, quarter sawed 30-31 
 
 Lumber, shakes in 33 
 
 Lumber, standard defects ... 33 
 Lumber, standard lengths ... 32 
 Lumber, standard thicknesses, 32 
 
 M 
 
 Machining 278 
 
 Machine screws 334-336 
 
 Machines for cold pressing of 
 
 metals 186 
 
 Machines for cutting screws, 
 
 196-198 
 Machine shop equipment, 276-278 
 
 Machine shop notes 321 
 
 Machine shop practice ....275-276 
 Machine shop work, degrees 
 
 of refinement in ... .276, 282-283 
 
 Machine tools 278, 287 
 
 Magnesia in ores 40 
 
 Magnesite 51 
 
 Magnesium alloy 20 
 
 Malleability 15 
 
 Malleable Iron 78, 376 
 
 Malleable iron, processes o f 
 
 making 375-376 
 
 Mandrels for lathe work ..293-294 
 
 Manganese bronze 19 
 
 Manganese in iron 70, 76 
 
 Manganese steel 114 
 
 Manganese steel, hardening of, 153 
 
INDEX 
 
 415 
 
 TAGE 
 
 Marking a plate for flanging . . 346 
 
 Marking-off table 224, 279-280 
 
 Marking work for machining, 
 
 278-279 
 
 Materials for forgings 261 
 
 Materials for patterns 215 
 
 Materials of construction .... 14 
 
 Materials, properties of 14-15 
 
 Matte (copper smelting) 53 
 
 Measuring stock for forgings, 267 
 Melting brass for castings, 250-251 
 Melting iron for castings, 247-248 
 
 Merchant bar 131 
 
 Merchant mills 131 
 
 Metal cements 378-379 
 
 Metal-cutting saws 320 
 
 Metal scrapers 329 
 
 Metallurgy, electricity in 57 
 
 Metals, annealing of 151-152 
 
 Metals, cold pressing and shap- 
 ing 185 
 
 Metals, effect of rolling 142 
 
 Metals, extraction of 36-45 
 
 Metals, fatigue of 15-16 
 
 Metals, forms when newly pro- 
 duced 123 
 
 Metals, heat treatment of ... 149 
 
 Metals, main sources of 35 
 
 Metals, mechanical treatment 
 
 of 144 
 
 Metals, re-manufacture of .... 158 
 
 Micrometer caliper 286 
 
 Mild steel 74, 79 
 
 Mill scale 130 
 
 Milling machine 308-311 
 
 Milling machine attachments, 
 
 312-313 
 
 Milling machine cutters 313 
 
 Mineral oil 63 
 
 Mixer 71 
 
 Mortise machine 213 
 
 Mould, example of loam ..243-246 
 Mould, example of making . . 239 
 Mould, parts of 219 
 
 PAGE 
 
 Mould loft floor 200 
 
 Moulds, classes of 228 
 
 Moulds, dry sand 229 
 
 Moulds, essential features of, 231 
 Moulds for chilled castings, 
 
 242-243 
 
 Moulds for steel castings 254 
 
 Moulds for steel ingots ..114-116 
 Moulds, green sand, 228-229, 
 
 230-231 
 
 Moulds, loam 228, 229, 243-246 
 
 Moulds, open sand 228, 229-230 
 
 Moulders' tools 238-239 
 
 Moulding accessories 237 
 
 Moulding flasks 235-237 
 
 Moulding machines 241 
 
 Moulding materials 234-235 
 
 Moulding sands 233-234 
 
 Muck bar 85 
 
 Muffle furnaces 152 
 
 Multiple spindle drills 302 
 
 N 
 
 Nail making 195 
 
 Native copper 35 
 
 Natural gas 64 
 
 " Neat " cement 28 
 
 Necking tool 272 
 
 Neutral axis 17 
 
 Nickel, properties and uses.. 23 
 Nickel, sources and smelting, 56 
 
 Nickel steel 113, 261 
 
 Notes on steam hammer forg- 
 ing 274 
 
 Nowell 219, 230 
 
 Nuts ..196, 334-336 
 
 Oil tempering 153 
 
 Open hearth furnace (steel) . 97 
 Open hearth furnace, charg- 
 ing 99-100 
 
 Open hearth furnace, opera- 
 tion , ..100-102 
 
416 
 
 INDEX 
 
 PAGE 
 
 Open hearth furnace, tapping 
 
 out 102 
 
 Open hearth process 96 
 
 Open hearth steel, uses of 106 
 
 Ores 35 
 
 Ores, acid and basic 40-41 
 
 Ores, impurities in 35 
 
 Ores, iron. (See Iron ores.) 
 
 Ores, treatment of 35-36 
 
 Orthographic method of draw- 
 ing 202 
 
 Oxidizing atmosphere 50 
 
 Oxy-acetylene blow pipe 331 
 
 Oxygen for blow-pipe use 384 
 
 Parting sand 234 
 
 Pattern maker, requirements 
 
 of 205 
 
 Pattern shop 205 
 
 Pattern shop accessories 224 
 
 Pattern shop equipment 205 
 
 Pattern shop power tools 205 
 
 Patterns, drawing from 
 
 moulds 219-221 
 
 Patterns, essential features of, 218 
 
 Patterns, examples* of 220-221 
 
 Patterns, materials used for . . 215 
 Patterns, methods of marking, 223 
 
 Patterns, records of 224 
 
 Patterns, varieties of 225 
 
 Peculiarities of alloys 17-18 
 
 Pene (shape of hammers) 263 
 
 Permanent set 16 
 
 Phosphor bronze 19 
 
 Phosphorus in iron 70, 76 
 
 Phosphorus in smelting flux . 42 
 
 Pig boiling 82 
 
 Pig iron. (See also Iron.) ..70-71 
 Pig iron, grades of, how pro- 
 duced 73 
 
 Pig iron, grey, mottled and 
 
 white 73, 249 
 
 Pig iron, inspection of frac- 
 ture . 73 
 
 PAGE 
 
 Pig iron, substances contained 
 
 in 70 
 
 Pig iron, tests for purchase . . 73 
 Pipe bending methods, 367, 
 
 371-372, 377-378 
 
 Pipe, butt welded 168-169 
 
 Pipe, cast iron 168 
 
 Pipe, commercial-iron 171 
 
 Pipe cutting and threading ma- 
 chine 319 
 
 Pipe, defects in welded 171 
 
 Pipe, extra strong 172 
 
 Pipe fitting 332 
 
 Pipe fittings 332-334 
 
 Pipe fitting tools 334, 335 
 
 Pipe, lap welded 169-171 
 
 Pipe, manufacture of welded . 168 
 
 Pipe, material for welded 168 
 
 Pipe, test for welded 171 
 
 Pipe threading 319 
 
 Pipe, welding of 386 
 
 Pipes. (See also Tubes.) .... 168 
 
 Piping in steel ingots 118 
 
 Pitch of rivets 342 
 
 Pitch of threads 298 
 
 Pits 143 
 
 Planer (machine shop) ...304-305 
 
 Planer, parts of .304-305 
 
 Planer tools (metal work) ... 306 
 Planer (woodworking) ...212-213 
 
 Planished iron 160, 164 
 
 Planished sheet copper 155 
 
 Plate and angle shop 374 
 
 Plate mill 137 
 
 Plates of iron, largest rolled, 137 
 
 Pneumatic tools 331 
 
 Poling process of refining cop- 
 per 54 
 
 Portable tools 330-331 
 
 Porter bar 148-149 
 
 Portland cement 24-25 
 
 Portland cement. (See also 
 Cement. See also Concrete.) 
 Portland cement, composition 
 of ..25-26 
 
INDEX 
 
 417 
 
 PAGE 
 
 Portland cement, effect of clay 
 
 and lime in 26 
 
 Portland cement, improved in 
 
 storage 26 
 
 Portland cement, manufacture 
 
 of 26-27 
 
 Portland cement, uses of 27 
 
 Power tools (machine shop) . . 287 
 Precautions in heating steel . . 142 
 
 Producer gas 64-66 
 
 Producer gas, constituents of, 
 
 66-67 
 
 Producer gas, fuel for making, 67 
 Propeller blades, planing of . 306 
 Propeller blades, moulding in 
 
 foundry 307 
 
 Properties of materials 14-15 
 
 Properties of materials, 
 
 changes in 15 
 
 Protective coating for wire . . . 167 
 
 Protractor 285 
 
 Puddle balls 83 
 
 Puddle bar 85 
 
 Puddle rolls 84 
 
 Puddling furnace 80-81 
 
 Puddling (repair of castings), 389 
 Puddling (wrought iron mak- 
 ing) 80-81 
 
 Pull-over mill 132, 154 
 
 Punch, hand 361 
 
 Punch, power 361 
 
 Q 
 
 Quarter sawed lumber 30-31 
 
 Quenching baths for hardening 
 
 steel 159, 270 
 
 Quick-setting cement 25 
 
 Radial drilling machines, 302-303 
 
 Rail mill 136 
 
 Railroad rails, making 128, 137 
 
 Ratchet drill 330 
 
 Reamers . .324 
 
 PAGE 
 
 Recalesence point 150 
 
 Red short iron 75 
 
 Reducing atmosphere 50 
 
 Reduction 36 
 
 Re-enforced concrete 27 
 
 Refractory materials 50-52 
 
 Reheating blooms, slabs and 
 
 billets 139-142 
 
 Reheating, furnaces for ..140-142 
 
 Reheating of ingots 126-127 
 
 Re-manufacture of metals . . . 158 
 Remedies for defective cast- 
 ings 252 
 
 Reverberatory furnaces 48-50 
 
 Reverbera tory furnaces, a t- 
 
 mosphere of 50 
 
 Reversible mill, 128-129, 132, 
 
 133-134 
 
 Rivet heating furnace 356 
 
 Rivet holes in boiler work ... 352 
 
 Rivet making 195-196 
 
 Rivets, cutting by blow pipe. . 387 
 
 Rivets, shapes of 362 
 
 Riveting in boiler work 354 
 
 Roasting furnace 48-50 
 
 Roasting ores 36 
 
 Roll scale 130 
 
 Rolled material, inspection of, 142 
 
 Rolling angle bars 138-139 
 
 Rolling mill parts 137-138 
 
 Rolling mills, types of 86, 131 
 
 Rolling mill, work of 125 
 
 Rules for lumber inspection . . 32 
 Russia iron 160, 164 
 
 Sands for moulding 233-234 
 
 Sap wood 31-32 
 
 Saw table (circular saw) 206 
 
 Saws for cutting metals 320 
 
 Scabs 143 
 
 Scarfing (in forging) 266 
 
 Scrapers for metals 329 
 
 Screenings of coal .... 63 
 
418 
 
 INDEX 
 
 PAGE 
 
 Screw cutting machines 196 
 
 Screw cutting machines, work 
 
 of 402, 403 
 
 Screw threads, cutting ...297-300 
 Screw threads, definitions ... 298 
 
 Screw threads, forms of 299 
 
 Screw threads, standards of. . 299 
 Screw threads, U. S. standard, 404 
 
 Scribers 281 
 
 Segregation 118 
 
 Self-hardening steel 113, 114 
 
 Sensitive drill 302 
 
 Set-screws 337 
 
 Shapes of rivets 362 
 
 Shaper 307 
 
 Shearing 16 
 
 Shears for. metal cutting .... 361 
 
 Shear steel 90 
 
 Sheet bar* mill 137 
 
 Sheet bars 131, 160 
 
 Sheet copper 153-155, 364 
 
 Sheet iron and its manufac- 
 ture 160-161 
 
 Sheet metal, tools for 364-367 
 
 Sheet metal work 363 
 
 Sheet mills 131, 154 
 
 Shop drawings 201 
 
 Shop location and equipment, 402 
 Shops of a building and repair 
 
 plant 199 
 
 Shop work, consecutive order 
 
 of 202 
 
 Shrinkage allowances 218 
 
 Shrinkage cracks in steel cast- 
 ings 255 
 
 Shrinkage fit 283 
 
 Shrinkage rule 218 
 
 Siemens process (steel making) 89 
 
 Siemens-Martin process 89 
 
 Silica, acid material in ores . . 40 
 Silica, refractory material . . 51 
 Silicate of aluminum in ores. . 40 
 Silicate of aluminum, refrac- 
 tory material 51 
 
 PAGE 
 
 Silicon in iron 70, 75 
 
 Silicon pig 75 
 
 Sizes of standard iron pipe, 400-401 
 
 Skelp 168 
 
 Skelp mill 137 
 
 Slabbing mill 131 
 
 Slabs (rolled steel) 125 
 
 Slabs, reheating of 139 
 
 Slag, blast furnace 42 
 
 Sliding fit 283 
 
 Slotting machine 317 
 
 Slotting machine tools 318 
 
 Smelting 36 
 
 Smelting charge, making up. . 42 
 
 Smelting, furnaces for 37 
 
 Smelting iron 70 
 
 Smooth cutting of metals .... 321 
 
 Snakes 143, 181 
 
 Snapping bar 272 
 
 Soaking pit 125-127 
 
 Soft wood lumber 31 
 
 Solder 370 
 
 Soldering 370-371 
 
 Soldering fluxes 371 
 
 Special steels 113 
 
 Speed for cutting metals 276 
 
 Spelter 22, 56, 368 
 
 Spiegel-eisen 77 
 
 Spinning lathe 187 
 
 Spinning, shaping metals by, 
 
 185, 187 
 Spring swage (steam-hammer 
 
 work) 273 
 
 Springing work while machin- 
 ing 321 
 
 Squeezer , 83-84 
 
 Steady rest 296 
 
 Steam hammer 271 
 
 Steam hammer appliances, 271-273 
 Steam hammer, effects of, 145, 274 
 Steam hammer, forging notes, 274 
 
 Steel alloys 113-114 
 
 Steel alloys, hardening of, 153, 270 
 Steel, best effect in annealing, 152 
 
INDEX 
 
 419 
 
 PAGE 
 
 Steel, burned 151 
 
 Steel, carbon in 74 
 
 Steel casting at steel works. . 124 
 
 Steel castings 253 
 
 Steel castings, annealing, 152, 258 
 Steel castings, avoiding shrink- 
 age cracks 255 
 
 Steel castings, defects in 259 
 
 Steel castings, material for . . 256 
 Steel castings, moulds for. . . . 254 
 Steel castings, reshaping b y 
 
 forging 261 
 
 Steel castings, temperature of 
 
 pouring 258 
 
 Steel castings, welding of ... 386 
 Steel, changes due to heating, 150 
 Steel, classified methods of 
 
 shaping 124 
 
 Steel, cold rolled 144 
 
 Steel, crystals affected by heat- 
 ing 151 
 
 Steel cylinders for gas storage, 185 
 Steel, effects of alloying ma- 
 terials on heating 151 
 
 Steel, effects of rolling 142 
 
 Steel, fluid compressed 119-121 
 
 Steel for boilers 340 
 
 Steel forgings, annealing 152 
 
 Steel> forms of newly produced, 123 
 
 Steel foundry 253 
 
 Steel furnace, electric 122 
 
 Steel, grades of, how classed, 78-79 
 
 Steel, hardest known 114 
 
 Steel, heating and hardening 
 
 of 159 
 
 Steel, hardening of 152 
 
 Steel, history of 88 
 
 Steel, impurities in 117-118 
 
 Steel ingots, defects in 118-119 
 
 Steel ingots, moulds for ..114-116 
 
 Steel ingots, record of 144 
 
 Steel, ladle for 104 
 
 Steel made bad by treatment, 142 
 Steel making, Bessemer pro- 
 ' cess . ..91-93 
 
 PAGE 
 
 Steel making, cementation pro- 
 cess 90 
 
 Steel making, crucible p r o- 
 
 cess 107 
 
 Steel making, duplex process, 106 
 Steel making, open hearth pro- 
 cess 96-97 
 
 Steel making, origin of basic 
 
 process 89 
 
 Steel making, outline of pro- 
 cesses 91 
 
 Steel making processes, dates 
 
 of 88, 89 
 
 Steel making, Talbot process, 
 
 105-106 
 Steel moulds, essentials of . . 254 
 
 Steel moulds, surfaces of 254 
 
 Steel, necessary heat for shap- 
 ing 151 
 
 Steel, oil tempering 150 
 
 Steel, pouring of 94-96, 105 
 
 Steel, precautions in reheating, 142 
 
 Steel, properties of 78-79 
 
 Steel, simple test for 79 
 
 Steel, size of crystals 78 
 
 Steel tools, hardness of 397 
 
 Steel, uses of open hearth 106 
 
 Steel. (See also Mild steel, al- 
 loy steel, high carbon steel.) 
 
 Stoves, blast furnace 45-48 
 
 Straight-edge 281 
 
 Strength of welded joints, 379, 387 
 Stripping ingots from moulds, 117 
 
 Structural mill 134 
 
 Structural shapes, cutting by 
 
 blow pipe 387 
 
 Structural shapes, extruded.. 157 
 
 Structural shapes, rolled 130 
 
 Sulphur in iron 70, 75 
 
 Surface cracks in forgings . . . 323 
 
 Surface gage 282 
 
 Surface plates 329-330 
 
 Swage block 265 
 
 Swaging 266 
 
420 
 
 INDEX 
 
 T PAGE 
 
 Talbot process of steel making, 
 
 105-106 
 Tangential cuts of lumber ..30-31 
 
 Taps and dies 326-328 
 
 Temperature for forging, 266, 274 
 Temperature for pouring steel 
 
 castings 258 
 
 Tempering steel tools 269 
 
 Tensile strength 16 
 
 Tension 16 
 
 Terne plates 164 
 
 Testing room 200 
 
 Thermit process, features of. . 381 
 
 Thermit process, uses of 382 
 
 Thermit welding 382-384 
 
 Thread cutting by hand ..326-328 
 Threads. (See Screw threads.) 
 
 Threading bolts 401 
 
 Three-high mill 132, 135 
 
 Tilting crucible steel 113 
 
 Timbers, sawing of 30 
 
 Tin (metal) 22-23,123 
 
 Tin (metal) sources of 56 
 
 Tin (tin plate) 160 
 
 Tin plate, manufacture of, 162-164 
 
 Tin plate, qualities of 164 
 
 Tin plate, standard size 163 
 
 Tinning 162 
 
 Tinsmith tools 364-366 
 
 Tool making 158-159 
 
 Tools, essential features of. . 159 
 Tools for blacksmithing ..261-265 
 Tools for bench work on 
 
 metals 323 
 
 Tools for caulking boiler 
 
 seams 358 
 
 Tools for hand lathe 209 
 
 Tools for lathe 291-292 
 
 Tools for marking-off table, 
 
 280-282 
 
 Tools for measuring 283-286 
 
 Tools for moulding 238-239 
 
 Tools for pipe fitting 334, 335 
 
 Tools for planer 306 
 
 PAGE 
 Tools for slotting machine ... 318 
 
 Tools, hardness of 397 
 
 Tools, materials of 158-159 
 
 Tools, power for machine shop, 287 
 
 Torsion 16 
 
 Tropenas converter for steel, 257 
 
 Tube expander, boiler 357 
 
 Tube-piercing mills 173, 180 
 
 Tubes. (See also Pipes.) .... 168 
 
 Tubes, brass and copper 180 
 
 Tubes, cold drawn 177-179 
 
 Tubes, defects in seamless . . 181 
 
 Tubes, hot drawn 182-185 
 
 Tubes, hot drawn, example of 
 
 size 185 
 
 Tubes, making of seamless, 172-184 
 
 Tubes, seamless 172 
 
 Tubes, small 181 
 
 Tubes, thin-walled 181 
 
 Tubes, welded and seamless . . 168 
 Tungsten steel, hardening of, 153 
 
 Tuyeres, blast furnace 39 
 
 Types of screw threads 299 
 
 U 
 Uncombined carbon in iron . . 77 
 
 Universal rolling mill 132, 134 
 
 Upsetting (forging) 266 
 
 Uses of alloy steels 113-114 
 
 Uses of Bessemer steel 96 
 
 Uses of crucible steel 107 
 
 Uses of open hearth steel.... 106 
 
 Valve re-seating machine 331 
 
 Vertical boring and turning 
 
 mill 315 
 
 Vertical drilling machine .... 301 
 
 W 
 
 Wane (lumber defect) 33 
 
 Warping of wood 223 
 
 Water gas 67 
 
INDEX 
 
 421 
 
 PAGE 
 
 Water gas, use in welding . . . 387 
 
 Welds, types of 268 
 
 Welding by blow pipe 384-386 
 
 Welding by hand 267 
 
 Welding by Thermit process, 
 
 381-384 
 
 Welding, electric 379-381 
 
 Welding methods classified . . 389 
 
 Welding of steel pipes 386 
 
 Welding, reducing strength of 
 
 iron 379 
 
 Wet processes of extracting 
 
 metals 36 
 
 Wheels for grinding 391 
 
 Whitworth compressed steel, 
 
 119-122 
 
 Wire-bar (or billets) 164 
 
 Wire, coating for protection of, 167 
 
 Wire dies 165, 400 
 
 Wire drawing bench 165 
 
 Wire for springs 167 
 
 Wire gage units 166, 399 
 
 Wire, hard 167 
 
 Wire, manufacture of 164-166 
 
 Wire, material for 166 
 
 Wire, method of coating 167 
 
 Wire ribbon 167 
 
 Wire, smallest drawn 167 
 
 Wire, soft 168 
 
 Wire, tempering of 167 
 
 Wood .as fuel . 60 
 
 PAGE 
 
 Wood, durability of 34 
 
 Wood, heart and sap 31-32 
 
 Wood trimmer 215 
 
 Wood used for patterns 215 
 
 Wood, uses in machinery 29 
 
 Woodworking, cuts and joints 
 
 in 216 
 
 Working fit 283 
 
 Wreckage, cutting up by blow 
 
 pipe 387 
 
 Wrenches, types of 328 
 
 Wrought iron, advantages of, 78 
 
 Wrought iron, carbon in 74 
 
 Wrought iron, disadvantages 
 
 of 78 
 
 Wrought iron, history of 79 
 
 Wrought iron, manufacture 
 
 of, 79-88 
 
 Wrought iron, methods of pro- 
 ducing 80 
 
 Wrought iron, properties of, 77-78 
 Wrought iron, simple test for, 79 
 
 Zinc, impurities in 22 
 
 Zinc, manufacture of ...55-56, 123 
 
 Zinc pot, for galvanizing .... 162 
 
 Zinc, properties of 22 
 
 Zinc protectors 21 
 
 Zinc, sources of 55 
 
 Zinc, uses of .... 21 
 
14 DAY USE 
 
 RETURN TO DESK FROM WHICH BORROWED 
 LOAN DEPT. 
 
 This book is due on the last date stamped below, or 
 
 on the date to which renewed. 
 Renewed books are subject to immediate recall. 
 
 T flirfSfi* 
 
 
 v> A 
 
 " ^ 'bb - PM 
 
 REC'D LL> 
 
 LOAN DEPT. 
 
 NOV 519R7 
 
 
 
 
 
 
 ADD 25 19631m 
 
 
 H"f\ ff'v 
 
 (U-U^^ 
 
 
 <^w~ 
 
 
 pr*^ 
 
 
 
 
 
 
 
 
 
 
 LD 21A-50m-8,')57 
 (C8481slO)476B 
 
 General Library 
 
 University of California 
 
 Berkeley 
 
u, 
 
 r " 
 
 302099 
 
 
 UNIVERSITY OF CALIFORNIA LIBRARY