SHRAPNEL SHELL MANUFACTURE SHRAPNEL SHELL MANUFACTURE A COMPREHENSIVE TREATISE ON THE FORGING, MACHINING, AND HEAT-TREATMENT OF SHELLS, AND THE MANUFACTURE OF CARTRIDGE CASES AND FUSES FOR SHRAPNEL USED IN FIELD AND MOUNTAIN ARTILLERY, GIVING COMPLETE DIRECTION FOR TOOL EQUIPMENT AND METHODS OF SETTING UP MACHINES, TOGETHER WITH GOVERNMENT SPECIFICATIONS FOR THIS CLASS OF MUNITIONS By DOUGLAS T. HAMILTON ASSOCIATE EDITOR OF MACHINERY AUTHOR OF "ADVANCED GRINDING PRACTICE," "AUTOMATIC SCREW MACHINE PRACTICE," "MACHINE FORGING," ETC. FIRST EDITION NEW YORK THE INDUSTRIAL PRESS 1915 COPYRIGHT, 1915 BY THE INDUSTRIAL PRESS NEW YORK PREFACE The design of shrapnel and the machining of its compo- nent parts are matters which, at the present time, are of world-wide interest to manufacturers, engineers, toolmak- ers, and mechanics in general. Shrapnel is used in enor- mous quantities in the great European war, and American machine tool builders have been called upon to provide machines and tool equipment of the latest and most effi- cient design to meet the demands made upon the manufac- turers of shrapnel. Many shops are running full force, day and night, and are months behind with their orders. The great importance of shrapnel manufacture, at the pres- ent time, is, therefore, unquestioned. A small percentage of shrapnel shells are now made from bar stock, but most shrapnel bodies are made from forgings, formed hollow in hydraulic presses or in forging machines. The forging processes, which are of extraordi- nary interest, especially to those who know something of the difficulties attending them, are, however, not finishing processes. Whether made from the bar or forged hollow, all shrapnel shells must be very accurately finished by ma- chining. This book has been brought out to meet the demands for a treatise dealing comprehensively with the construction, forging and machining operations, and the tool equipment used for making the shell, fuse parts, and brass cases. In this book are included not only the unusually complete ar- ticles on shrapnel manufacture contained in the April, 1915, number of MACHINERY, of which 5000 extra copies were printed and 5000 additional reprints made, all of which have been sold, but it also includes all other material that has been published at various times in MACHINERY relating to shrapnel manufacture, together with a great deal of material obtained by the Editors especially for this book; and, in addition to this, it contains abstracts of the official specifications, together with line-engravings of the details of Russian, British, and American shrapnel shell bodies, fuses, and cartridge cases. Hence, it is believed that the book will prove the most valuable addition to the literature on the manufacture of munitions that has been made since the beginning of the great war. D. T. H. NEW YORK, October, 1915. CONTENTS PAGES CHAPTER I. Shrapnel Shells 1-19 CHAPTER II. Forging Shrapnel Shells 20-39 CHAPTER III. Machining and Heat-treatment of Shrapnel Shells 40-74 CHAPTER IV. Machines and Tools for Shrapnel Man- ufacture 75-142 CHAPTER V. Making Fuse Parts 143-171 CHAPTER VI. Making Shrapnel Cartridge Cases 172-193 CHAPTER VII. Specifications for the Manufacture and Inspection of the Russian 3-inch Shrapnel Shell 194-212 CHAPTER VIII. Specifications for the Manufacture and Inspection of the Combination Fuse for Russian 3-inch Shrapnel Shells 213-230 CHAPTER IX. Specifications for the Manufacture and Inspection of Russian 3-inch Shrapnel and High-explosive Cartridge Cases 231-250 CHAPTER X. Specifications for British 18-pounder Quick-firing Shrapnel Shell 251-259 CHAPTER XI. PAGES Specifications for British Combination Time and Percussion Fuses 260-275 CHAPTER XII. Specifications for British 18-pounder Quick-firing Cartridge Case and Primer 276-285 CHAPTER XIII. Specifications for American Shrapnel Shells 286-292 INDEX 293-296 SHRAPNEL SHELL MANUFACTURE CHAPTER I SHRAPNEL SHELLS IN NAVAL, coast defense and artillery operations, sev- eral types of explosive shells are used; the chief ones are: the armor-piercing shell, made to pierce armor -plate be- fore exploding; shells exploded by means of a timing fuse; shells exploded by either a timing or percussion fuse ; and shells exploded by percussion only. Each different shell has some definite function to fulfill, and is designed for that purpose. For field or artillery operations, the shrapnel and lyddite are the two principal types used. Of these, shrapnel is the most prominent, because of its destructive power and its interesting mechanical construction. Early Development of Shrapnel. The shrapnel shell was invented in 1784 by Lieut. Henry Shrapnel, and was adopted by the British Government in 1808. As is shown at A in Fig. 2, the first shell was spherical in shape, and the powder or explosive charge was mixed with the bullets. Al- though this type of shell was an improvement over the grape and canister previously used, its action was not alto- gether satisfactory, as the shell, on bursting, projected the bullets in all directions and there was also a liability of pre- mature explosion. In order to overcome the defects men- tioned, Col. Boxer separated the bullets from the bursting charge by a sheet-iron diaphragm, as shown at B in Fig. 2. This shell was called a diaphragm shell to differentiate it from the first shell of this type. In the shell made by Col. Boxer, the lead bullets were hardened by the addition of antimony, and as the bursting charge was small, the shell was weakened by cutting four 2 SHRAPNEL SHELLS grooves extending from the fuse hole to the opposite side of the shell. Shells of spherical shape were first fired out of plain-bored guns, and upon the advent of the rifled gun it was necessary to add a circular base, which was made of wood and covered with sheet iron or steel to take the rifling grooves. The first shrapnel shells were made of cast iron, but a later development was to use steel and elongate the body, reducing it in diameter. The diameter of the bullets was also reduced so that a greater number could be con- tained in a slightly smaller space. The improved shrapnel was also capable of being more accurately directed. Shrapnel Shells of Present-day Design. Shrapnel shells, as used at the present time by the different governments, vary slightly in construction and general contour as well as in the constituents entering into their different mem- bers. As shown in Fig. 1, a completed shrapnel comprises a brass case carrying a detonating primer and the explosive charge for propelling the projectile out of the bore of the gun. The projectile itself comprises a forged shell that carries the lead bullets and bursting charge. Screwed into the front end is the combination timing and percussion fuse which can be set so as to explode the shell at any desired point, and from which the flame for exploding the bursting charge is conveyed through a powder timing train and a tube filled with powder pellets down through the diaphragm to the powder pocket. Of these members of a shrapnel, the shell and timing fuse present the most interesting features from a mechanical standpoint. The shell used by most governments is made from a forging, machined to the desired dimensions in hand and semi-automatic turret lathes as well as in ordinary en- gine lathes. The fuse is an extremely accurate piece of mechanism, and is largely produced from screw machine parts, some of which, however, are forged previous to ma- chining. The brass cartridge case the next member of im- portance is drawn from a brass blank by successive opera- tions in drawing presses, and is indented and headed. Fol- lowing this, several machining operations are performed on the head and primer pocket. SHRAPNEL SHELLS Types of Shrapnel Shells. Shrapnel shells are made in two distinct types, one of which is known as the common shell, and the other as the high explosive. The common shell is a base-charged shrapnel, fitted with a combination fuse, whereas the high-explosive shell is fitted with a combination Fig. 1. Types of Shrapnel Shells used by the American, Russian, German, French, and British Governments fuse and, in addition, with a high-explosive head, the head also bursting and flying into atoms upon impact. The high- explosive shell is not ruptured upon the explosion of the bursting charge in the base, but the head is forced out and SHRAPNEL SHELLS the bullets are shot out of the case with an increased velocity. In the meantime, the head continues in its flight and detonates on impact. This type of shell is not used as extensively as the common shrapnel, and, therefore, the common shrapnel shell alone will be taken up in the following. The Explosive Charge. Reference to Fig. 1 will show that as far as the construction of the shrapnel shell and case is concerned, there is very little difference in those emloyed by the various governments. Starting with the cases, it Machinery Fig. 2. Original Shell designed by Lieut. Henry Shrapnel and Col. Boxer's Improvement will be seen that these are almost identical, except for length and the arrangement of the head for carrying the detonat- ing primer. There is a marked similarity in this respect between the Russian, the British, and the German, and be- tween the American and the French. The form of the ex- plosive charge held in the brass case differs in almost every instance, but without exception smokeless powder in some form or other is used. In the American shell, nitrocellulose powder composed of multi-perforated cylindrical grains each 0.35 inch long and 0.195 inch in diameter are used. In the Russian case, smokeless powder of crystalline structure is used. In the German, smokeless (nitrocellulose) powder in long sticks and arranged in bundles is held in the case. SHRAPNEL SHELLS 5 The French use stick smokeless powder^ 1/2 millimeter (0.0195 inch) thick by 12.69 millimeters (!/2 inch) wide. Two lengths or rows of this powder are arranged in the case. The British use a smokeless powder of crystalline structure somewhat similar to the Russian, but in some cases cordite has also been used, although of late this type of powder has not been quite as commonly employed. The detonating agent or primer held in the head of the case varies in almost every type of shrapnel. Practically all primers are provided with "safety heads," so that the shrap- nel can be handled without danger of premature explosion. The object, of course, of the detonating agent or primer is to detonate or cause the sudden explosion of the explosive charge in the shell for propelling the shrapnel out of the field gun. The Shrapnel Shell. The shell itself, as previously mentioned, is made either from a forging or from bar stock. Forgings, however, are used to a greater extent than bar stock, because the forged shell is more homogeneous in its structure than the bar-stock shell, and piping a serious objection in the bar-stock shell is entirely eliminated. The shells used by the British, Russian, and German govern- ments are made almost exclusively from forgings, whereas those used by the French and American governments are made both from forgings and bar stock. When the French shell is made from bar stock, an auxiliary base is screwed into it to eliminate any danger of piping. Near the base of all shells is a groove in which a bronze or copper band is hydraulically shrunk. This is afterward machined to the desired shape and takes the rifling grooves in the gun so as to rotate the shell when it is expelled. The body of the shell itself is slightly smaller than the bore in the gun, and the rifling band, which is larger and which is compressed into the rifling grooves, rotates the projectile, thus keeping it in a straight line laterally during flight. The bursting charge, which in practically all cases is common black powder, is carried in the base of the shell and is usually enclosed in a tin cup. Located above this is the diaphragm which is used for carrying the lead bullets out of the shell when the burst- 6 SHRAPNEL SHELLS ing charge explodes and distributes them in a fan shape. In most shells, upon exploding, the nose blows out, stripping the threads that hold the members together. It will, there- fore, be seen that, in the explosion, the entire fuse, fuse base, tube, diaphragm and bullets are all ejected, the shell itself acting as a secondary cannon in the air. The number of lead bullets carried in the 3-inch shrapnel shells ranges from 210 to 360. In all cases, the lead bullets are about % inch in diameter, weigh approximately 167 grains, and are kept from moving in the shell by resin or other smoke-producing matrix. The matrix put in with the lead bullets, in addition to keeping them from rattling, is also used as a "tracer." It is of importance in firing shrap- nel that the position of the explosion be plainly seen. With large shells this is not difficult, but with shrapnel for field guns at long range certain conditions of the atmosphere make it difficult to see when the shell actually bursts. Vari- ous mixtures are used to overcome this difficulty. In some cases, fine-grained black powder is compressed in with the bullets in order to give the desired effect. In the German shrapnel, a mixture of red amorphous phosphorus and fine- grained powder which produces a dense white cloud of smoke is used, and in the Russian, a mixture of magnesium antimony sulphide is used. The range of a 3-inch shrapnel shell is about 6500 yards, and the muzzle velocity of the quick-firing field gun ranges from 1700 on the American to 1930 feet per second on the Russian field gun. The dura- tion of flight ranges from 21 to 25 seconds. Development of Timing and Percussion Fuses. The first fuses used in field ammunition were short iron or cop- per tubes filled with a slow-burning composition. These were screwed into a fuse hole provided in the shell, but there was no means for regulating the time of burning. Later about the end of the seventeenth century the fuse case was made of paper or wood so that by drilling a hole through into the composition the fuse could be made to burn for approximately the desired length of time before exploding the shell, or the fuse could be cut to the correct length to accomplish the same purpose. SHRAPNEL SHELLS 7 For a considerable time all attempts to produce a percus- sion fuse were unsuccessful. Upon the discovery of ful- minate of mercury in 1799, the chief requirement of a per- cussion fuse was obtained. About fifty years elapsed, how- ever, before a satisfactory fuse was made. The first per- cussion fuse was known as the Pettman fuse, and comprised a roughened ball covered with detonating composition that was released upon the discharge of the gun. When the shell hit the desired object, the ball struck against the inner walls of the fuse, exploded the composition and powder charge, thus bursting the shell. There are at the present time three principal types of fuses in use : First, those depending on gas pressure in the gun setting the pellet of the fuse free this is a base fuse ; second, those relying on the shock of dis- charge or the rotation of the shell to set the pellet free used in nose and base fuses; third, those depending on impact. In shrapnel shells advantage is taken of two types of fuses, one of which is the combination timing and percus- sion fuse used on common shrapnel, and the other the com- bination timing and percussion fuse of the high-explosive type used on high-explosive shrapnel. These types of fuses are again sub-divided, but only in the manner of construc- tion. The most common fuse is that known as the com- bination timing and percussion fuse of the double-banked type. This is used in practically all shrapnel fuses except the French. The advantage of the double ring of com- position shown at A and B in Fig. 3 is to give a greater length of composition and more accurate burning. Triple- banked and quadruple-banked fuses on the same principle have been designed, but at the present time have not been introduced. Operation of Combination Timing and Percussion Fuses. The manner in which the combination timing and percus- sion fuse is regulated to discharge the bursting charge in the shrapnel shell is interesting and involves extremely dif- ficult mathematical calculations. Before going into the method of setting the fuse, it would probably be advisable to describe briefly just how the fuse operates. As an ex- 8 SHRAPNEL SHELLS ample of the double-banked fuse, Fig. 3 shows that adopted by the United States government. The following descrip- tion applies to this type of fuse. Assume, first, that the timing ring is set at zero. The propelling force given to the shrapnel shell in leaving the bore of the gun is such as to sever the wire C from plunger G. Plunger G carries a concussion primer which is dis- charged by hitting firing pin D. The flame passes out Machinery Fig. 3. American Type of Combination Timing and Percussion Fuse used on Shrapnel Shells through vent E, igniting the powder pellet F and the upper end of train A, and then through the vent H. From here, the flame is transmitted to the lower timing ring B through vent / and the magazine J, and from there through the tube to the bursting charge in the base of the shrapnel shell. Assume any other setting, say 12 seconds. The vent H is now changed in position with respect to vent F leading to SHRAPNEL SHELLS the upper timing train, and the vent / leading to the powder magazine J is also changed. The flame, therefore, now passes through vent E and burns along the upper time train A in a counterclockwise direction until the vent H is reached. It then passes down to the beginning of the lower timing train and burns back in a clockwise direction to the position of vent /, from which it is transmitted by the pellet Machinery Fig. 4. Russian Type of Combination Timing and Percussion Fuse used on Shrapnel Shells of compressed powder in this vent to the powder magazine J. It should be understood that the annular grooves in the lower face of each timing train do not form complete circles, a solid portion being left between the grooves in the ends of each. This solid portion is used to obtain a setting at which the fuse cannot be exploded and is known as the "safety point." As shown in Fig. 6, it is marked S on the adjustable timing ring. 10 SHRAPNEL SHELLS The timing fuse shown in Fig. 3 is of the combination timing and percussion type, and if the wire C fails to re- lease percussion plunger G, the shell is exploded by means of a percussion fuse which comes into use when the shell strikes. The percussive mechanism consists of a primer K held in an inverted position in the center of the fuse body by a cup located beneath the percussive primer. Percus- sion plunger L works in a recess in the base of the fuse body and is kept at the bottom of the recess away from con- tact with the primer by a light spring in plunger M. The firing pin N is mounted on a f ulcrumed pin, and is normally kept in the vertical position by means of two side spring plungers. When the shell strikes, the impact causes the plunger to snap up against the primer after compressing the spring in pin M. This causes the firing of the primer K and the explosive charge passes out through a hole in the percussion plunger chamber, not shown, to the magazine / and from there down to the powder in the base of the shell. Russian Fuse. The Russian fuse shown in Fig. 4 differs only in a few minor details from the American fuse, the chief difference being in the arrangement of the percussive mechanisms. The percussive plunger for the timing ar- rangement is kept up from the firing pin by means of a spring bushing E surrounding the body of the plunger. This bushing is expanded by the plunger which is forced through it due to the force of the shrapnel in leaving the bore of the gun. The spring B in the head of the fuse assists the plunger in expanding bushing E and in dropping down onto the firing pin C. The flame from the exploded primer then travels down to the powder in the shell in practically the same way that it does in the American fuse, except that the magazine chamber is located at D and ex- plodes through the impact fuse chamber. The percussive arrangement for setting the shell off by impact is slightly different from that in the American fuse, in that the primer and firing pin are held apart by means of springs, the inertia of which is overcome when the shell strikes an object. SHRAPNEL SHELLS 11 French Fuse. With the exception of a few minor de- tails, the timing fuses used in American, Russian, British, German, Japanese, etc., shrapnel shells are the same. The French timing fuse, however, as shown by the diagram Fig. 5, operates on an entirely different principle. In this fuse, the firing for the timing train is contained in a sealed tube of pure tin and is wound spirally around the head of the fuse. Inside of the head is the ignition arrangement. To set the timing part of this fuse, it is placed in a fuse- setting machine attached to the field gun and, by forcing down a handle on this device, a piercing point is thrust through the outer cap of the fuse, penetrating to the in- t e r i o r space of the head as shown at A. Upon the discharge of the shell from the gun, the gas pressure forces firing pin B back, hit- t i n g the percussive primer C. This causes a flame which passes out through the open- ing previously punch- ed at A and ignites the "rope" powder fuse which is wound around the head of the fuse body. This t y p e o f fuse is also provided with a fuse which sets off the shell by impact should the timing fuse fail to work. The head of the fuse is covered with a cap with holes for the pierc- ing point, and the whole cap can be shifted around for a short distance and set by the corrector scale marked on the body, as shown in Fig. 1. A projection on the cap engages a recess in the fuse-setting machine and provides for this movement. Firing of Shrapnel. The accuracy with which a shrap- nel can be exploded in the air at any desired point is re- markable, considering the number of variable quantities Machinery Fig. 5. French Type of Combination Timing and Percussion Fuse 12 SHRAPNEL SHELLS that enter into the construction of the timing fuse and powder train, etc. The calculations necessary for finding the correct setting on the timing ring involve, however, the use of higher mathematics and are consequently not within the scope of this treatise. In Fig. 6, the timing ring used on the American fuse is shown. Here it will be seen that the ring is provided with twenty-one graduations corresponding to twenty-one seconds in the duration of flight of the projectile. It will also be noticed that the spacing of the graduations differs. The reason for this is found in the rela- tion of the vents, the positions of the lower timing train, the trajectory of the flying missile, and the decrease of ve- locity. Diagram Fig. 7 shows in an inter- esting manner just how a shrapnel is fired. The range is approximately o b - tained by panoram- ic sights or other means, and a test shell fired, the point of explosion noted, and the necessary corrections made. A table which has been worked out for different distances is then used. In Fig. 7 the diagram shown pertains to the American quick-firing field gun hav- ing a muzzle velocity of 1700 feet per second and the Ameri- can shrapnel of 3-inch size. It will be noted that at 2000 yards the terminal velocity of the shrapnel is 1038 feet per second and the time of flight for the projectile 4.75 seconds. In other words, the timing train to explode the shrapnel at Machinery Fig. 6. Diagram showing how Timing Ring on the American Combination Timing and Percussion Fuse is laid out o ti .*/ ^ " o ?> i s, 5*' I IIS* 5 itiis 7 11" i "s.2* I-MIE-S S^s . s| * g / ' bc;2 2 <= 0.2^:5 y / / i !/ > CO ^ f 3 53 d & J? | > f|lii|||i; / i| v 'C 2 - rt ^ be a. . 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A high-explosive shell also com- prises three principal parts, but the projectile, instead of carrying a charge of bullets and black powder, is filled with a high-explosive material, which, when detonated, bursts the body of the projectile into small pieces that are thrown off with great velocity and destructive effect. Shrapnel is used against troops in the open field, whereas high-explosive shells, which may be either of the ordinary or of the armor- piercing type, are used against fortifications, etc. Classification of Explosives. The explosives used in shrapnel and high-explosive shells may be divided into three general classes: 1. Progressive or propelling explosives known as "low" explosives. 2. Detonating or disrup- tive explosives known as "high" explosives. 3. Detona- tors known as "fulminates." The first of these includes black gun powder, smokeless powder, and black blasting powder. The second, dynamite, nitroglycerine, gun cotton, etc. The third includes chiefly fulminates and chlorates. In all classes of explosives, the effect of the explosion is dependent upon the quantity of gas and the heat developed per unit of weight and volume of the explosive, the rapidity of the reaction, and the character of the confinement, if any, of the explosive charge. Low Explosives. For certain explosives, such as smoke- less powder, the explosive action does not differ in princi- ple from the burning of a piece of wood or other combustible material. The combustion is very rapid, but is a surface action, progressing from layer to layer until the en- tire grain is consumed. Such materials are known as "low" explosives, although the power developed through the com- bustion of a unit weight may be very great. The progres- sive emission of gas from a low explosive, such as burning gun powder, produces a pushing effect upon a projectile without unduly /straining the gun, whereas the sudden conversion of an equal weight of a high explosive, such as nitroglycerine, into gas, would develop such high pressures as to rupture the gun. SHRAPNEL SHELLS 15 High Explosives. In high explosives, such as nitrogly- cerine, gun cotton, picric acid, etc., the progress of the ex- plosive reaction is not by burning from layer to layer, but, instead, consists of an initial breaking up of the molecules, giving rise to an explosive wave, which is transmitted with great velocity in all directions throughout the mass, and causes it to be converted almost instantly into a gas. The velocity of this explosive wave has been determined, for some materials, to be more than 20,000 feet, or approxi- mately four miles, per second. Detonators or Fulminates. The action of fulminates is much more powerful than either the low or high explosives described. They can be readily detonated by slight shock or by the application of heat, and are used in primers, for setting off the propelling charge in a cartridge case, and in fuses, either of the plain percussion or of the combination time and percussion types. The most common fulminate is made by dissolving mercury in strong nitric acid and then pouring the solution into alcohol. After an apparently vio- lent reaction, a mass of fine, gray crystals of fulminate of mercury is produced. The crystalline powder thus pro- duced is washed with water to free it from acid and is then mixed with glass ground to a fine powder. Because of its extreme sensitiveness to heat produced by the slightest friction, it is usually kept soaked in water or alcohol until needed. Manufacture of Black Powder. Black powder, because of its "pushing" effect when exploded, is used extensively as a base charge for shrapnel shells in expelling the bullets from the projectile. It comprises three principal elements in about the following proportions : 75 parts of saltpeter, 15 parts of charcoal, and 10 parts of sulphur. These in- gredients must be absolutely free from impurities and, in manufacturing, great care is taken in refining the saltpeter and sulphur, and in burning the charcoal, to prevent the introduction of any foreign substances. After purification, the ingredients are carefully weighed in the proper propor- tions and mixed for about 5 minutes in a revolving drum provided with mixing arms. The mixed charge is now ground 16 SHRAPNEL SHELLS for several hours, the charge being moistened occasionally with distilled water, the resulting mixture being what is called a "milk cake." It is then reduced to fine meal in a machine having Tobin bronze or gun-metal rollers, after which it is compressed under hydraulic pressure. The next operation comprises the granulating of the pow- der, which is done in a strong Tobin bronze or gun-metal framework carrying two pairs of toothed and two pairs of plain Tobin bronze or gun-metal rollers. The "cake" is cut into pieces by these rollers and falls on screens which sift it into grains of the required size. The grains are then separated from the dust in a revolving screen, and the high polish or glaze is produced by putting the powder into drums or glazing barrels, which revolve constantly for several hours. Graphite is generally used to provide the glazing effect. The powder is now dried in a stove heated by steam pipes, and is spread upon canvas trays placed on shelves. Manufacture of Smokeless Powder. Smokeless pow- der, which is used in various forms in cartridge cases, was discovered in 1846 by a German chemist Schoenbein. The chief ingredient of smokeless powder is cotton. The por- tion of cotton used is generally the short fiber. The first attempts to produce gun cotton were unsatisfactory, and several very serious explosions occurred. Many of the difficulties in its manufacture were overcome by an Aus- trian, von Lenk. Still further progress was made by a Swedish engineer, Alfred Nobel, and the improved explo- sive was patented in 1888 under the name of "ballistite." One of the principal smokeless powders is known as "cor- dite", this name being derived from the cord-like form it assumes in manufacture. The first compositions of cordite were: 58 per cent of nitroglycerine; 37 per cent of gun cotton; and 5 per cent of mineral jelly. This composition, after considerable use, was found to have a slight deterio- rating effect on the bore of the gun, and after ten years' use was modified to the following proportions : 30 per cent of nitroglycerine ; 65 per cent of gun cotton ; and 5 per cent of mineral jelly. SHRAPNEL SHELLS 17 The brand of smokeless powder used most extensively as a propelling charge in shrapnel or high-explosive shells is known as nitrocellulose, and, as is common with cordite, the base of this is cotton, as previously explained. It is manu- factured as follows: After bleaching and purifying, the cotton is run through a picker which opens up the fibers and breaks up any lumps. It is then thoroughly dried and is ready for nitration. The most generally used method of nitration is to put the cotton into a large vessel filled with a mixture of nitric and sulphuric acids. The sulphuric acid absorbs the water developed in the process of nitration, which would otherwise too greatly dilute the nitric acid. After a few minutes' immersion, the pot is rapidly rotated by power, and the acid permitted to escape. Following this, the nitrated cotton is washed for a short time and then removed from the nitrator or pot and repeatedly washed or boiled to remove all traces of free acid. As the keeping qualities of the nitrated cotton are dependent upon the thor- oughness with which it is purified, the specifications for powder for the United States army and navy require that the nitrocellulose shall be given at least five boilings at this stage of the manufacture, with a change of water after each boiling, the total time of boiling being forty hours. Following this preliminary purification, the nitrocellulose is cut up into shorter lengths, by being rapidly run between cylinders carrying revolving knives. This operation known as "pulping" is necessary because of the difficulty experienced in removing the free acid, unless the fibers are cut up into short lengths. After pulping, the nitrocellulose is given six more boil- ings, with a change of water after each, followed by ten cold water washings. The material is now known as gun cotton or pyrocellulose. Previous to adding the solvent, this must be free from water. This is generally accom- plished in a circular wringer, and in addition by compress- ing the pyrocellulose into solid blocks. Alcohol is forced through the compressed mass. Ether is then added to the pyrocellulose already impregnated with alcohol, the relative proportions being two parts, by volume, of ether to one 18 SHRAPNEL SHELLS part of alcohol. After the ether has been thoroughly in- corporated in a kneading machine, the material is placed in a hydraulic press and formed into cylindrical blocks about 10 inches in diameter and 15 inches long. It is then transferred to a finishing press where it is again forced through dies and comes out in the form of long strips or rods, which are cut into pieces of the length and widths required. It is in this finishing process that the various governments differ in their methods of manufacture. The United States Government uses a short perforated circular block, whereas the French use flat sticks about 0.0195 inch thick by % inch wide. Two lengths or rows of these sticks are arranged in the cartridge case. The cut up pieces are subjected to a drying process which removes nearly all the solvent and leaves the material in a suitable condition for use. The drying process is a lengthy one, amounting to as much as four or five months for powder in large pieces. Upon completion, the powder is blended and packed in air- tight boxes. Manufacture of High Explosives. The explosive charges used in high-explosive shells are known by various trade names, such as: emmensite, lyddite, melinite, maximite, nitrobenzole, nitronaphthaline, shimose, trinitrotoluol, tur- penite, etc. The base of such explosives as emmensite, max- imite, lyddite, melinite, and shimose, is picric acid, which is secured from coal tar, subjected to fractional distillation. The liquid which comes off when this is raised to a tem- perature of 150 degrees C. is called "light" oil, and when these light oils have been again distilled, the next fraction or "middle" oil yields phenol or carbolic acid. This sub- stance when nitrated gives off picric acid. Experiments with lyddite shells showed their behavior to be very erratic, some exploding with great effect, while others gave disap- pointing results. This was due to the fact that picric acid requires a powerful detonator to obtain the highest explosive effect. The use of such a detonator, however, is dangerous, and extensive experiments have brought forth a new high explosive known as trinitrotoluol generally termed T. N. T. Although the explosive force of trinitrotoluol is slightly SHRAPNEL SHELLS 19 less than that of picric acid, the pressure of the latter being 135,820 pounds per square inch as against 119,000 pounds for trinitrotoluol, its advantages more than compensate for the difference. Trinitrotoluol is obtained by the nitration of toluene, contained in the crude benzol distilled from coal tar and washed out from coal gas. The crude benzol contains roughly : Per cent Benzine 50 Toluene 36 Xylene 11 Other substances 3 Toluene to be used for the manufacture of trinitrotoluol should be a clear water-like liquid, free from suspended solid matter, and having a specific gravity of not less than 0.868, nor more than 0.870, at 15.5 degrees C. Trinitrotol- uol when pure has no odor and is a yellowish crystalline powder which darkens slightly with age. It cannot be exploded by flame or strong percussion, and a rifle bullet may be fired through it without any effect. When heated to 180 degrees C., it ignites and burns with a heavy black smoke; but when detonated by a fulminate of mercury detonator, it explodes with great violence, giving off a black smoke.. Shells containing this explosive, first used on the western battle front, were given such names as "coal boxes," "Jack Johnsons," "Black Marias," etc., by the allies. The Russians and Austrians use a high explosive known as ammonal in which 12 to 15 per cent of trinitrotoluol is mixed with an oxidizing compound, ammonium nitrate, a small amount of aluminum powder, and a trace of charcoal. This high explosive gives somewhat better results than plain trinitrotoluol, but has the one disadvantage of easily collecting moisture, and consequently must be made up in air-tight cartridges. The British are now using an im- proved compound of this character, which is so prepared that trouble is not experienced with the collection of moisture. CHAPTER II FORGING SHRAPNEL SHELLS WITHIN the last few months, many methods have been suggested for making shrapnel forgings, but a compara- tively small number have been put into use. Practically speaking, no two governments have adopted the same method. The Russian government uses double-acting hori- zontal hydraulic forging presses in which two operations are performed at the same time on different forgings. For instance, while the punch in one end of the machine is piercing a heated billet, the ram on the return stroke per- forms the hot drawing operation on another shell located at the opposite end of the machine. In this way a shell is completed at each cycle of the machine forward and re- turn stroke. The French government, up to a short time ago, used steam hammers for this purpose, and produced shrapnel forgings in practically the same manner as a drop- forging is made, the punch being carried in the ram of the press and the die held on the bed. This is rather a slow process and requires more than one heating to complete the forging. The German government uses a horizontal hydraulic forging press for piercing the billet and a steam driven machine for drawing the forging, which receives its motion from a rack and pinion. This method has the ad- vantage over the hydraulic press of being more economical in the consumption of power. The methods followed by different concerns in this coun- try and Canada, at the present time, differ to a large ex- tent. Some manufacturers are using a method that dates back as far as 1890, as will be described later. Others are using a more improved method developed about 1895, whereas about three concerns are using a still more im- proved method developed within the past year. Caley Method of Making Shrapnel Forgings. The first method (known as the Caley process) of making shrapnel forgings in this country had its inception about 1890 and 20 FORGING SHRAPNEL SHELLS 21 was used almost exclusively until 1895. This comprised a slug-forming and billet-piercing operation followed by a successive reduction and elongation of the forging through drawing dies The order of these operations is shown dia- grammatically in Fig. 1. The information given herewith pertains to the making of a forging for a 3-inch shrapnel shell. As shown at D, a billet of steel 3*4 inches in diame- ter and 6% inches long was cut off from a bar with a cold Machinery Fig. 1. Diagram showing Caley Process of making Shrapnel Forgings in Hydraulic Forging Presses saw, and formed into a cone shape under a vertical hy- draulic press having a capacity of 100 tons. The billet was heated in a furnace to about 1900 degrees F., dropped into the impression in the die and forced into shape by a hy- draulic plunger having a depression in the lower end which centered the blank. The result of this operation is shown at F. Machinery 22 Fig. 2. Watson-Stlllman Hydraulic Forging Press of the Vertical Type used for making Shrapnel Forgings FORGING SHRAPNEL SHELLS 23 The next step was to anneal the billet, after which it was pierced as shown at C, and at the same time slightly elongated. This operation was handled in a hydraulic press of the type shown in Fig. 2. On a 0.70 per cent carbon steel billet the pressure on the punch in the pierc- ing operation was 20,000 pounds per square inch, and the machine used was a vertical hydraulic forging press of the type referred to having a capacity of 100 tons. From the piercing operation the forging was taken direct without annealing to the horizontal hydraulic draw press, and, as is shown at H, was located on a punch and forced through a series of drawing dies which gradually reduced the shell to the correct diameter, 3Vs inches, and drew it out to the required length, about 8% inches. A point worthy of attention is the preparation of the cone-shaped billet. The smallest end was made slightly smaller than the smallest reduction die in the series. The reason for this was that if any drawing were done on the end of the shell the front corner would be drawn over and deformed, increasing the amount of machining required. The drawing dies in this case were six in number, as shown at H, and were reduced on a sliding scale of the following proportional reductions. First, 0.100 inch; second, 0.080 inch; third, 0.060 inch; fourth, 0.040 inch; fifth, 0.030 inch ; and sixth, 0.020 inch. This gave dies of the following sizes, in inches, starting with the largest in the series : 3.355, 3.275, 3.215, 3.175, 3.145, and 3.125. The shape given to the drawing edges of the dies is of prime importance. The mouth or entering side of the hole was beveled to an angle of 20 degrees leading to a liberal curve which terminated in a land 1/16 inch wide. The shape was finished off with a %-inch radius. These dies were made from chilled cast iron and were held in position as shown at H y being slipped into a pocket in the frame of the machine, as shown at /. The punches for the coning, piercing and hot drawing operations were made from spe- cial hot punching steel. The first drawing die in the series lasted the longest because the metal was hotter at this point than when it was drawn completely through the dies. As 24 FORGING SHRAPNEL SHELLS 25 a rule, the last drawing die turned out 100 shells before being worn or scored. Then it was reground to a larger size and used again. The drawing punch was lubricated occasionally with graphite. After drawing, the forging is annealed to obtain the proper physical qualities. This method of making forgings for a 3-inch shrapnel shell is capable of producing 400 in ten hours. Holinger Method of Making Shrapnel Forgings. About 1895 the following method, known as the Holinger process of making shrapnel forgings, was devised. Instead of making the billet conical in shape before piercing, this pre- liminary operation was dispensed with, and to facilitate the work, as well as to reduce the friction of the flowing metal, the arrangement of the piercing punch and die was changed. This process is shown in Figs. 3 and 4, and was accom- plished in a hydraulic press provided with two cylinders, one located at the bottom and the other at the top of the press. The operation was as follows: The die a was held in a movable frame b and the piston c acted first. The first position after the billet was dropped into the die is shown at B. Here the die a and punch d remained stationary while the piston c descended, pushing the billet through the die and over the punch. When the piston reached the end of its stroke, as shown at C, the lower cylinder began to act and the frame carrying the die was raised. This frame, as shown at D, carried a stripper plate e which removed the pierced billet from the punch and located it so that it could be picked off with a pair of tongs. A subsequent operation of hot-drawing as shown at E, Fig. 4, was required, which is similar to that described in the first method. The method just described was used chiefly for 6- and 8-inch shrapnel and projectile forgings, and at the present time is still used for 3- and 6-inch shell forgings. It requires much less power and turns out a better and more concentric forging than the method previously described. The production on 8-inch shells is about 180 in ten hours, and 250 on the 3-inch shell. FORGING SHRAPNEL SHELLS 27 Later Methods of Forging Shrapnel Shells. The in- creased demand for shrapnel within the last few months has been instrumental in bringing about a radical improve- ment in the production of forged shells. Previously, the aim was to get the internal diameter as close as possible to the finished size and to do comparatively little machining on it; in fact, this is still, in a great number of cases, one of the requirements. While at first glance this would ap- pear to be the logical way of handling the work, on further investigation it is found that the forging of the shell to the correct size is much more expensive than to leave suffi- cient metal to machine all over. In the first place, a hy- draulic machine of 100 tons capacity costs considerably more in initial outlay than a turret lathe, and in the second place it is more expensive to operate. The cheapest method of making a shrapnel forging is to rough-forge it to ap- proximately the correct shape and then finish to exact shape and diameter in turret lathes or semi-automatic chucking machines. This simplifies the forging process and also de- creases the production costs. One of the later methods of making shrapnel forgings is shown diagrammatically in Fig. 5. A billet of steel 6% inches long by 3 5/16 inches in diameter is heated to a temperature of from 1900 to 2100 degrees F., and then dropped into the impression in the die a held in a special cast-steel die-holder b. To do this, die a is drawn out from beneath the punch, punch guide c removed, and the billet dropped in. Then the guide is replaced and the die-holder slid in until it contacts with the stop d. The press is now operated, and, as shown at B, advances, piercing the billet and making the metal flow up around the walls of the punch. The punch now retreats, carrying the centralizing guide c with it. The die-holder is now drawn out from under the punch onto a bracket projecting from the bed of the press. The high-carbon steel, hardened block e then drops out of the die, as is also the case with the finished forging. This block e, of course, is heated up to a considerable extent due to the hot metal resting on it so that several blocks of this 28 FORGING SHRAPNEL SHELLS kind are provided. In the illustration, as shown at C, cen- tralizing guide c is shown attached to the punch. In actual operation this is not the case. When the punch rises, guide c is stripped from it by stripper plate / so that the guide is gripped with tongs and laid down on the bed of the press until a fresh heated billet has been placed in the die impression ready for the next piercing. The punch is made from special hot punching steel and the die from Fig. 6. Producing Shrapnel Forgings in a 750-ton Hydraulic Forging Press chilled cast iron. The production of forgings by this method for a 3-inch shrapnel shell is about 600 in ten hours. The amount of metal left for machining by this method varies from Vs to 3/16 inch on the internal and external diameters. The forging after annealing is then machined FORGING SHRAPNEL SHELLS 29 inside and out on turret lathes, or semi-automatic chucking machines. The accepted method is to first machine the in- ternal diameter and then hold the shell on an expanding arbor and machine it on the external diameter. Producing Shrapnel Forgings in Hydraulic Presses. In the foregoing description various principles of making shrapnel f orgings were described. Owing to the large num- ber of f orgings lately required, practically all types of forg- ing presses and power forging machines have been used. Fig. 6 shows how one manufacturer is solving the problem. Fig. 7. Piercing Billets for Shrapnel Forgings in a 750-ton Hydraulic Forging Press Wood' The machine used is an R. D. Wood Co., 750-ton hydraulic forging press; this performs both the billet piercing and drawing operations. The forgings turned out on this ma- chine are for the British 18-pound shell, and the billet is 3% inches in diameter by 4i/ 2 inches long. The first oper- ation, piercing the billet, is done by the punches and dies shown in Fig. 7. The billet is heated in a furnace to a temperature of 2000 degrees F., and then quickly removed FORGING SHRAPNEL SHELLS and placed in the dies. The press is now operated, pierc- ing two billets at the same time. The pierced billet is S 1 /^ inches in diameter by ?V& inches long. A complete batch of pierced billets is first put through, then the pierced billets are taken to the furnace again and heated to 2000 degrees F. The punches and dies in the cen- ter of the illustration Fig. 8 are used for finish-drawing the forging by drawing it out to 31/2 inches in diameter by 11 inches long. This method is only temporary and will be Fig. 8. Drawing Shrapnel Forgings in a "Wood' Hydraulic Forging Press 750-ton replaced shortly by three R. D. Wood four-post hydraulic presses. The piercing operation will be handled on one press of 350 tons capacity, and the drawing operations on two presses of 200 tons capacity. Making Shrapnel Forgings in Power Forging Machines. One of the latest developments in the art of producing forgings for shrapnel shells is the adaptation of the power forging machine to this work. As has been previously men- tioned, there are several methods of producing shrapnel FORGING SHRAPNEL SHELLS 31 shells, and as it has been conclusively proved that the forged shell is superior to the shell made from bar stock, it is only natural that several methods for making the f orgings would be developed. In the forging machine method, a bar slightly larger than the finished diameter of the forging is cut off, making a billet about 5V& inches long. This billet, for a 3- inch shell, weighs about 9% to 91/2 pounds. The billet is heated to a white heat in a furnace, the tem- perature being about 2000 degrees F., depending on the car- bon content and other constituents in the steel, and is then placed in the lower impression of the forging die. The Fig. 9. Examples of Shrapnel Forgings turned out on a Power Forging Machine machine used for this size of forging is a standard upset- ting and forging machine provided with a special crank- shaft. Upon being operated, the lower plunger, which is larger than the diameter of the powder pocket in the shell, advances and pierces the billet. The pierced billet is then raised to the next impression, and the machine again oper- ated. The second punch is longer than the first and smaller in diameter. The billet is forced up on this punch, which reduces it in diameter and increases its length. After the second impression the partially formed shell is then placed in the third or final die impression, where it is given two blows, being given one-half turn after the first blow to form it more perfectly. The operations just enumerated 32 FORGING SHRAPNEL SHELLS are performed in one heating of the billet, and the produc- tion of a 3-inch shell ranges from 400 to 450 in ten hours. The dies for this work are, of course, constructed upon a somewhat different principle from the ordinary forging die, because in this case it is necessary to make the metal flow up on the punches. The dies, therefore, are so con- structed that they recede as the punch advances, which tends to make the metal flow up on the punch. The prac- ticability of this method is well illustrated by the samples shown in Fig. 9. Here D is the rough forging just as it comes from the machine, with the exception that the mouth has been trimmed. C is a section of a shell made from low-carbon steel about 0.30 per cent carbon; B is a shell made from 0.50 per cent carbon, 3% per cent nickel steel. This has been rough-turned, as the illustration shows. The homogeneity of the forgings is clearly indicated. A is a forging made from low-carbon steel, finish-turned. One of the most interesting points about this method is its cost as compared with shells made from bar stock. To produce a 3-inch shell from bar stock requires about 22 pounds of material, and on metal costing 10 cents per pound, a bar shell exclusive of machining costs $2.20; to produce the same shell on a power forging machine re- quires about 9% to 9% pounds, and figuring on 10 cents per pound the cost for the material is only $1 a saving of $1.20 on each shell. Furthermore, the production of shells from bar stock on automatic machines is about twelve to fifteen per day. The number of forgings that can be turned out in the same time is 400 to 450, and the number that can be machined in this time varies from forty to fifty for two operations. It is therefore evident that the production of shells by forging is far superior to the bar method, and the forged shell is more satisfactory from every standpoint. Forging Shrapnel in a Power Press. Another interest- ing development in the forging line is shown diagrammati- cally in Fig. 10. This method comprises three operations, and is handled in a No. 80!/2 Bliss press capable of exert- ing a pressure of 1200 tons. A billet 3*4 inches in diame- FORGING SHRAPNEL SHELLS 33 ter by 3% inches long is heated in a furnace to 1976 degrees F. and then quickly placed in the die shown at A. The press is operated, and the punch in descending pierces the billet, being guided by the guide a, as shown at B, which Machinery Fig. 10. Diagram illustrating Method of piercing and drawing Shrapnel Forgings in a Bliss Power Press 34 FORGING SHRAPNEL SHELLS also acts as a stripper. The forging retains its heat to a certain extent after this operation, the temperature being about from 1380 to 1425 degrees F. This is sufficient to perform the second minor operation which, as shown at C and D, consists in forcing the heated billet into the die- block to reduce the diameter of the lower end and facilitate the succeeding operation. This reducing operation is per- formed with the same type of punch as is used in the suc- ceeding operation, and the die-block is simply laid on top of a bolster while the reducing is being done. The final forming or drawing of the forging is accom- plished as shown at E and F, the same type of press, viz., a Bliss No. 80 V power press, being used for this purpose. The pierced billet is now heated to 1976 degress F., and is then forced through the three drawing dies b, c and d, by the punch e. The first die is 3 5/16 inches in diameter and reduces the forging from 3% inches to this size. The second is 3 7/32, and the third, or last, 3Vs inches in diame- ter. The forging, after being forced through the dies, is stripped from the punch by plates /, and as it still retains a temperature of 1475 degrees F. sufficient for annealing is thrown down on the sand to cool off. The billet pierc- ing and drawing dies, shown in the illustration, were made from 50-point carbon steel, hardened. This gave fair re- sults, although chilled cast-iron dies would prove even more satisfactory. The punches were made from several differ- ent materials such as chrome-vanadium, 70-point carbon steel, and unannealed malleable casting. Of the three ma- terials, the latter gave the most satisfactory results, in that pitting was reduced to a minimum. Of course, it was nec- essary to grind the malleable casting to shape. Flow of Hot Metal When Pierced. In the manufacture of shrapnel shell forgings, the first operation is that of piercing, and to accomplish this satisfactorily, it is neces- sary to understand the action of a piercing punch on a semi-plastic billet of steel. There are certain fundamental laws governing the flow of metals under pressure and a study of these is of exceptional interest. An attempt has been made in Fig. 11 to illustrate diagrammatically some of FORGING SHRAPNEL SHELLS 35 the principles involved, and in the following discussion it should be understood that the billet is made from 50-point carbon, 60-point manganese steel, 6i/ 2 by 3 5/16 inches in diameter. At A a round-end tapered punch is shown in contact with the heated billet, and the lines show the possible flow of the metal, i. e., the material commences to "pack" at the end of the punch. In this case the walls of the die are Fig. 11. Diagram illustrating Flow of Hot Metal while being pierced straight. At B the billet is being pierced, and the result- ant effect on the flow of the metal is indicated. Here it will be seen that the pressure increases as the punch de- scends, because of the wedging action on the metal and the friction between the surfaces of the sides of the punch and die. The pressure on the end of a punch of this shape is about 20,000 pounds per square inch. By leaving the sides of the die of the same shape as at B, but making the end of the punch square instead of round 36 FORGING SHRAPNEL SHELLS and not tapered, different action is caused. When the flat punch, as shown at (7, first contacts with the metal, the pressure required is greater than at A, but as soon as the metal commences to flow as at Z), the pressure decreases. For instance, suppose the pressure required at B to pierce the billet was 100 tons ; on the same material at D, the re- quired pressure would be only 70 tons a decrease of 30 per cent. The metal, however, does not follow the sides of the punch as closely at D as at B, and this accounts in part for the reduction of power required. The action of hot flowing metal on the face of a square punch is just the reverse of what would naturally be expected. Instead of Fig. 12. Shrapnel Shell Head and Diaphragm produced in a Power Forging Machine the punch wearing away at the edge, the center first shows signs of wear as indicated at e. Seams are opened up in a radial direction caused by the hot metal attacking the softest parts in the face of the punch. Again, a different condition exists to that shown at B and D, when both the die and the punch are tapered as shown at E. Here the friction of the extruded metal on the walls of the die and sides of the punch is excessive, and it is practically impossible to produce a satisfactorily pierced billet in this manner. From a theoretical standpoint, the conditions shown at F are ideal. Here the sides of the FORGING SHRAPNEL SHELLS 37 punch are straight, the end flat, and the walls of the die taper or increase in diameter toward the bottom. In this case the friction of the flowing metal is greatly reduced because of the lessening of the wedging action. Other con- siderations, however, make this method impracticable. A still greater reduction in the pressure necessary to pierce a billet is shown at G. Here a square billet instead Fig. 13. Diagram illustrating Method of producing Shrapnel Shell Heads in a Power Forging Machine without any Waste of Stock of a round one is being pierced. In the plan view it will be noticed that the friction on the walls of the die is greatly reduced, and the pressure continues low until the extruded billet contacts all around with the surface of the die. The completed product, however, is inferior to that made from a round billet. From the previous remarks, it will be seen that a punch and die that would best meet the requirements 38 FORGING SHRAPNEL SHELLS is one having a rounded end as at B, straight sides as at D, and straight walls in the die. The most satisfactory punch and die for piercing shrapnel f orgings when all the variable conditions are considered would be as shown at H. Forging the Shrapnel Head. The shrapnel head shown at A in Fig. 12, that screws into the end of the shell and in- A LJ STOP 6 -BAR STOCK Machinery Fig. 14. Diagram illustrating Method of making Shrapnel Shell Diaphragms in a Special Type of Power Forging Machine to which the fuse body is screwed, is made from a forging of low-carbon steel for the French shell. One method of producing this, which is of unusual interest, is shown in Fig. 13. A power-driven forging machine equipped with a special set of tools is used for this purpose. A bar of steel of the same diameter as the hole in the finished forging, FORGING SHRAPNEL SHELLS 39 in this case li/a inch, is gripped in the dies as shown at A, and is upset by means of a plunger a, forming an upset on the end of the bar shown to the right. The upset bar is now placed in the second impression of the gripping dies, as shown at B. By way of explanation, it should be stated that the views of the dies shown at A, B, and C are sec- tions taken in a horizontal plane at each stage or die im- pression. Upon gripping the upset forging in the second impression in the dies, the plunger b advances and forms an annular groove in the face of the forging, at the same time increasing its width as shown at c. The forging, still integral with the bar, is now quickly removed and placed in the last impression of the dies. The diameter of the hole in these dies is larger than the bar, allowing it to slip back as the punch advances to punch the hole in the forging. When the punch moves forward it carries with it the spring-operated sleeve d, thus finish- ing the forging in one heat. This method of forging is very satisfactory, producing a homogeneous forging at the rate of 1500 in ten hours. Forging the Steel Diaphragm. The steel diaphragm shown at B in Fig. 12 is made from low-carbon steel in a special type of forging machine operated similarly to a hot-pressed nut machine. That is to say, the bar, instead of being fed in from the front, as in a regular forging ma- chine, is fed in from the side. The manner in which this is accomplished is shown in Fig. 14. A flat bar of steel 2% inches wide by % inch thick, heated to the proper tem- perature for a distance of three feet, is fed across the face of the die as at A and located by stop b. Punch c then advances and cuts out a blank of the required diameter, forcing it into the die, as shown at B. The metal is now confined between the faces of punches d and c and in die a, and is forged to the required shape. The next step is shown at C, where punch d advances and forces the formed forg- ing out of the die. The production on this diaphragm is in the neighborhood of from 8000 to 10,000 in ten hours. CHAPTER III MACHINING AND HEAT-TREATMENT OF SHRAPNEL SHELLS SHRAPNEL shells are manufactured either from bar stock or forgings. The bar-stock method, however, is not considered as satisfactory as forging because of piping, so that the greater number of shrapnel shells made at the present time are turned out from forgings. The first step, therefore, in the making of a shrapnel shell is to cut off a billet of the required length from a bar of steel of the nec- Fig. 1. Shrapnel Shells in Various Stages of Manufacture essary constituents. In the making of an 18-pound shrap- nel shell, the billet is cut off from a bar of 46-point carbon, 60-point manganese steel in machines of different types. One way of doing this, as shown in Fig. 2, is to use a New- ton cutting-off machine having an air clamp for holding the bar in place while it is being cut off. A Hunter duplex saw, as shown in the illustration, provided with high-speed steel inserted teeth, performs the cutting operation. The billet for an 18-pound shrapnel shell is 31/2 inches in diame- 40 MACHINING AND HEAT-TREATMENT 41 ter by 4^ inches long. It is then forged to shape, as has been previously explained. Assuming that the forging has been completed, the fol- lowing is a complete summary of the machining operations on the shell up to the point of assembling. In one plant where this work is being done, the shrapnel shells are put through in lots of 120, each lot being kept in three boxes, forty shells to a box. Out of every 120, one shell after heat-treatment is tested for tensile strength. The tensile strength before heat-treatment must be from 30,000 to 40,000 pounds per square inch, and from 80,000 to 90,000 Fig. 2. Cutting off Billets for making Shrapnel Forgings in a Newton Cutting-off Machine pounds per square inch after heat-treatment. For facili- tating transportation, trucks of various designs are used. One type of truck used for this purpose is shown in Fig. 3. This is built by the Chapman Double Ball Bearing Co. of Canada, Ltd., Toronto, Ontario, and has some interesting features, the chief of which are the ball-bearing swiveling head, ball-bearing wheels, and the means of releasing or raising the load with the handle in any position. This feature is valuable in using the truck in a crowded space. Trimming and Facing the Shell Forging. The first ma- chining operation on the forged shell is to cut off the rag- 42 MACHINING AND HEAT-TREATMENT ged end, which is generally from i/ 2 to li/ 2 inch longer than that required for the finished shell. This operation is performed in many different ways, but one of the most common is to place it in a Hurlbut-Rogers cutting-off machine as shown in Fig. 4. For performing the cutting- off operation, two plain forged cutting-off tools made from "Sabine" extra high-speed steel are used. The forging is located in the proper position in the chuck by a plunger or stop A, sliding in a fixture B clamped to the base of the machine. This plunger locates the shell from the bottom of the hole or powder pocket and forces the shell into the Fig. 3. Truck built by the Chapman Double Ball Bearing Co. for transferring Shrapnel Shells about the Shop chuck against the resistance of an open-wound spring. The stop is then located by a gage C that forms a member of the fixture and fitting ring D on the stop. The chuck jaws are now clamped on the work and the cutting off com- mences. As soon as the excess stock is cut off, the stop is drawn back and the pressure of the jaws on the work released; the spring in the chuck then ejects the forging. The production of an 18-pound shell from one machine is about 140 in eight hours. The next roughing operation is to face off the bottom or closed end of the forging, bringing the shell to approxi- MACHINING AND HEAT-TREATMENT 43 mately the correct length. There are also many ways of performing this operation. One method is to grip the forg- ing in a chuck, as shown in Fig. 5, in an ordinary lathe and face off the end with a high-speed steel tool held in an Armstrong tool-holder. From 14 to % inch is faced off from the end. Fig Cutting off Excess Length of Shrapnel Forging in Hurlbut-Rogers Cutting-off Machine Fig. 5. Facing off Closed End of Shell to Length Rough-turning Operations on Shrapnel Forging. Prac- tically every type of engine lathe and turret lathe as well as special machines are used for turning and boring shrap- nel forgings, and in the following chapter each method will be dealt with separately. Before doing this, however, 34 MACHINING AND HEAT-TREATMENT a complete summary of the methods of machining employed in a large plant turning out shrapnel will be described. In this plant, the first rough-turning operation is handled on a flat turret lathe, as shown in Fig. 6. For this purpose, the shell forging is held on an expanding arbor and is driven by a dog fastened to it and driven by the faceplate of the lathe. A multiple tool turner is first brought into position and takes a cut of about % inch from the diame- ter for practically the entire length of the shell. The next tool then faces off the end of the shell to length. Fig. 6. First Rough-turning Operation on Shrapnel Shell in a Flat Turret Lathe The shell forging is now ready for cutting the rifling band groove and producing the waves. This is handled in an ordinary engine lathe equipped with a special fixture, carrying grooving, waving and under-cutting tools. The shell forging, as shown in Fig. 7, is held in a chuck at one end and supported by a revolving center at the other. One part of the fixture is clamped to the bed of the lathe and the other to the carriage. The grooving and ribbing is accomplished with a tool held in holder A at the front of the lathe, whereas the two under-cutting tools are held in holders D and E at the rear of the lathe. In operation the carriage of the lathe is moved toward the chuck, carry- MACHINING AND HEAT-TREATMENT 45 ing the fixture to which are fastened cams C, F, and G. Cam C forces in the holder carrying the combination groov- ing and ribbing tool, whereas cams F and G force in the holders carrying the two under-cutting tools, these being presented at an angle to the work. The required oscilla- tions to the slide carrying the grooving and ribbing tool are secured through a face-cam B clamped to a "Whiten" chuck. The face-cam operates against the tension of spring H and gives the required oscillations to the tool- slide carrying the ribbing and grooving tool, shown at A. The third machining operation is accomplished in a flat turret lathe, as illustrated in Fig. 8. This consists in fac- Fig. 7. Cutting the Rifling Band Groove with a Special Grooving and Ribbing Attachment on an Engine Lathe ing the open end of the shell, boring the powder pocket and facing and boring the diaphragm seat, and also turning the angular surface on the external nose of the shell. First, a roughing drill is brought in to rough out the powder pocket. The turret is then indexed and a tool for turning the angle of the nose is brought into position. The machin- ing on the nose is then accomplished by operating the cross- sliding head. Then a roughing cutter is brought in to rough-bore the powder pocket. The turret is again indexed and a finishing tool is brought in to finish the powder pocket and face the diaphragm seat. This finishes the machining operations on the shell previous to heat-treatment. 46 MACHINING AND HEAT-TREATMENT Fig. 8. Third Machining Operation on Shrapnel Shell in a Flat Turret Lathe, consisting in Facing the Open End of the Shell, Boring the Powder Pocket, Facing and Boring the Diaphragm Seat, and Turning the Angular Surface on the External Nose of the Shell Fig. 9. Heat-treating Shrapnel Shells, using a Hoskins Electric Barium-chloride Bath Furnace MACHINING AND HEAT-TREATMENT 47 Heat-treating Shrapnel Shells. As was previously stat- ed, the tensile strength of a forged shrapnel shell after heat-treatment must be from 80,000 to 90,000 pounds per square inch, and in order to obtain the desired physical qualities, it is necessary that the heat-treating operations be properly conducted. Several methods of heat-treating employing different cooling solutions are used in the manu- facturing plants making shrapnel shells. One method, as Fig. 10. Testing Hardness of Shrapnel Shells with Shore Scleroscope shown in Fig. 9, is to heat the shell in a Hoskins electric furnace that contains a barium-chloride bath, heated to a temperature of about 1480 degrees F. The shells are left in this furnace for half an hour and are taken out and dipped in a bath of cotton-seed oil heated to a temperature of 113 degrees F. The temperature to which the shell is heated varies with the different constituents of the steel and practically every different batch of 120 shells requires 48 MACHINING AND HEAT-TREATMENT a slightly different temperature. The proper temperature is determined by cutting out a section of a heat-treated shell and testing it for tensile strength. The next step is to draw the temper on the open end of the shell. In this operation a muffle gas furnace heated to a temperature of about 1000 degrees F., is used. The temper is drawn for about two-thirds of the length of the shrapnel shells. Testing for Hardness and Tensile Strength. One shell from a batch of 120 is now cut open in the proximity of the powder pocket and the cut-out section sent to the gov- ernment inspectors to test it for tensile strength. Each one of the shells in the batch, in addition, is tested for hardness by a Shore scleroscope as shown in Fig. 10. Be- fore testing for hardness, the shell near the band groove is polished so as to get a true reading, then placed in a fixture, and the hammer of the scleroscope allowed to drop on it. The reading should be between 40 and 50, indicating an elastic limit of from 80,000 to 90,000 pounds per square inch. The shell must not be ruptured at the point tested when the charge in it is exploded or when the charge in the case is set off. Should the shell upset near the rifling band groove when it is propelled out of the gun, it would tear out the rifling in the bore of the gun. Experience with the scleroscope has disclosed the exist- ence of a fairly definite relation between the hardness and strength of metal. In determining the strength of metal, two stages are recognized: First, the elastic limit, deter- mined by the load required to produce a permanent set; second, the ultimate strength, determined by the load re- quired to cause rupture. The hardness indicated by the scleroscope is intimately related to the elastic limit. The elastic limit increases more rapidly than the hardness from 43 to 45, this being the minimum index of the strength value required. As an elongation of 8 per cent in 2 inches is also required, there must necessarily be an upper limit to the hardness. On the steel used for shrapnel, which is generally about 50-point carbon and 60-point manganese, the maximum hardness should not be over 60 on the scleroscope. MACHINING AND HEAT-TREATMENT 49 Tests relating to Heat-treatment of Shells. In the September, 1915, number of MACHINERY, Mr. J. M. Wilson, who has been actively engaged in heat-treating shells since the beginning of the war, and who has had to rely entirely upon his own resources in meeting and overcoming the troubles which seemed to arise on all sides, relates the results of his experiments. The British government shell specifications call for a yield point or elastic limit, after heat-treating, of not less than 36 tons per square inch, a breaking point or ultimate Machinery Fig. 11. Cross-sectional View of Shrapnel Shell showing Points A, B, and C where Tests are made, and one of the Tensile Test Samples strength not less than 56 tons per square inch, and an elongation not less than 8 per cent in % inch. Officially there is no maximum specified for either of those three physical characteristics ; but as a matter of fact any unus- ual condition which is not in conformity with recognized metallurgical practice may cause the chief government in- spector for the district in which the manufacturer is located to reject a shipment. Reference has been made to certain points in the shell which must resist the strains due to firing. The nature of these strains and condition of the steel best suited to meet them will be understood from Fig. 11, which shows a cross-section of the British 18- pound shrapnel shell. When a shell is fired from a gun, the base A is subjected to a blow, i. e., a sudden increase of pressure which almost instantly attains a maximum of from 12 to 14 tons per square inch, and imparts the initial velocity to the shell. The shell, being a body at rest, op- 50 MACHINING AND HEAT-TREATMENT poses this velocity with its own inertia, the result being that both compressive and tensile strains are set up in the shell body. The shell body assumes the conditions of a column which has a compressive load varying from noth- ing at the nose to a maximum at the base. The tensile load is due to the inertia of the bullets inside the shell. These bullets are subject to an increasing compressive load from the top down, the resultant strain being a bursting effort which attains a maximum in the region of the point B, known as the "set-up point." When the time required for the fuse to act has elapsed, the powder charge is exploded, and the contents of the shell are blown forward in the usual manner. The contents are released either by the stripping of the thread of the brass socket, or else the walls of the shell yield at the point C, opening the threads sufficiently to free the socket. At A, (the base) the shell must be perfectly sound and free from flaws such as minute cracks, etc., which may allow the flame from the firing charge to strike through with disas- trous results to the shell and gun. The metal in the base must not be too hard or it may fracture under the pressure of the explosion, and it must not be too soft or it may flatten out and spoil the rifling in the bore. At the point B there is no maximum requirement so far as tensile strength is concerned, but any abnormal strength is viewed with suspicion unless it is accompanied by a generous elongation. At B the metal is particularly liable to distension while the shell is acquiring velocity, and unless the shell is strong enough to resist the sudden bursting strain, and the amount of elongation is sufficient to cushion or absorb this strain at the instant of firing, the shell is liable to take a permanent set in the region of point B, with results mentioned above, The shell must not be too hard at the point C as it may burst, thus neutralizing the real object of a shrapnel shell which is to project the bullets forward with increased velocity at the predetermined instant, being in fact an aerial gun arranged to discharge its contents at any desired point of its flight. MACHINING AND HEAT-TREATMENT 51 Uniformity of Steel for Shrapnel. Having these re- quirements firmly established in his mind, the heat-treating expert is now confronted with a double problem: How is it possible to give steel the suitable strength ; and having done so, how is it possible to know that the desired result has been obtained, without actually making test pieces from each shell. The principal condition upon which successful heat-treating depends is uniformity of material. Carbon and manganese are the principal substances which influence the results. The exact composition of steel specified by the government is not given to any manufacturers other than steelmakers. It is, however, generally understood to be a 0.50 per cent carbon, 0.60 per cent manganese steel. Allowing five points variation in carbon and ten points variation in manganese, the requirements would be ap- proximately 0.45 to 0.55 per cent carbon and 0.50 to 0.70 per cent manganese. In one carload of forgings, one firm received shells from 23 different heats or melts, with carbon varying from 0.60 to 0.47 per cent, and manganese varying from 0.63 to 0.49 per cent, with all possible combinations and proportions between these limits. The number of forgings supplied from each heat varied from one up to 1200 so that the question of determining the best tempera- ture for each carbon content was indeed quite impracticable. Many manufacturers at the present moment may be in a similar position, and the gravity of the situation, both from a financial and a military point of view, may justify a somewhat detailed description of the method which was followed in treating shells of such varying composition. Results of Tests. It is generally known to manufac- turers that the highest tensile strength of steel is obtained by cooling it rapidly from a temperature slightly higher than the decalescent point or critical temperature. The degree of hardness resulting from this operation can be ascertained quickly, accurately, and repeatedly by means of the scleroscope. The degree of hardness thus shown is a reliable indication of the probable strength of the mate- rial; that is to say, after making due allowance for differ- ent makes of steel and varying proportions of the principal 52 MACHINING AND HEAT-TREATMENT constituents, the scleroscope readings are a reliable indica- tion of the results which may be expected when a tensile test is made of any given shell. In the opening months of the shell business, considerable reliance was placed on the accurate determination of the decalescence point. Forg- ings of varying analysis were received; the carbon being from 0.48 to 0.53 per cent, and the manganese from 0.54 to 0.69 per cent. All steels whose composition was within those limits showed a decalescence point of between 1390 and 1425 degrees F., and when quenched in water at 50 degrees F. above the decalescence point, such steels would have a scleroscope hardness number as high as 85; but when quenched in ordinary fish oil the hardness was only slightly over 50, the sample being 1 inch square and Vs TABLE I. RESULTS OF TESTS TO DETERMINE THE BEST QUENCHING MEDIUM FOR SHRAPNEL SHELLS Quenching temperature, degrees F. Quenching medium Temperature of quenching medium, degrees F. Scleroscope hardness No. 1475 Fish oil 90 50 to 55 1475 Coal oil 90 65 to 70 1475 1475 1475 1475 Cottonseed oil.. Engine oil Oil of degras . . Water 90 90 90 90 70 to 75 75 to 80 77 to 85 82 to 87 Machinery inch thick. A complete shell quenched in fish oil would show a scleroscope hardness number at the set-up point of from 38 to 40. Test pieces from such a shell failed to reach the minimum breaking strength of 56 tons by the narrow margin of 0.6 ton, and this failure brought up the ques- tion of which was the best quenching medium. A series of experiments gave the results presented in Table I; all conditions were equal in each test, and the test pieces were all made from the same forging. From the results of the tests presented in Table I, oil of degras, commercially known as "No 2 soluble quenching oil," was selected as the quenching medium and operations were commenced on forgings supplied from two separate heats. The results were all that could be desired until MACHINING AND HEAT-TREATMENT 53 forgings were received from a certain heat, which would not respond to treatment based upon the results of pre- liminary experiments. Investigation yielded the results presented in Table II. While water-treatment of the forg- ings from "Heat No. 3" gave satisfactory strengths under test, the liability of shells to crack, owing to their thin TABLE II. RESULTS OF TESTS CONDUCTED TO SECURE GENERAL DATA 01T HE AT- TREATMENT Heat No. i 2 3 Carbon per cent 45 52 50 Manganese, per cent... Decalescent point, de- grees P 0.68 1400 0.62 1425 0.47 1390 Quenching temperature, degrees F .... 1450 1475 1450 Temperature of oil, degrees P .... 160 160 120 Resultant hardness, scleroscope No 65 to 75 65 to 75 *39 Temperature of water, degrees F 75 Resultant hardness, scleroscope No Tempered until show- in g a scleroscope hardness of 48 48 55 to 60 52 Yield point tons 47 8 48 6 46 5 Breaking point, tons... Elongation, per cent... 67.9 14.5 65.4 16.9 66.2 17.4 Machinery *Note: This shell was then reheated and quenched in water with results shown. walls contracting more rapidly than the base, was a fatal objection to this method. Attention should be called to the fact that while the temperature at which quenching should be done is specified by the government at 1560 degrees F., manufacturers are not tied down to this particular tem- perature. What is required is that the manufacturers shall so treat the material that it will fulfill the requirements 54 MACHINING AND HEAT-TREATMENT already stated. If, when fulfilling these requirements, the treatment should prove detrimental to the shell in other re- spects, then it must be changed accordingly. Referring to results presented in Table II, "Heat No. 3," it will be observed that the manganese is only 0.47 per cent with carbon 0.50 per cent. Comparing "Heat No. 3" with "Heat No. 1", it is evident that an increase of 5 points carbon is more than -offset by a reduction of 21 points in the manganese. Increase of temperature seemed to offer the greatest possibilities and sample shells were drawn every 121/2 degrees up to 1675 degrees F. The greatest hardness was obtained at 1637^, scleroscope readings of from 50 to 55 being the average. This was not considered TABLE III. RESULTS OF TESTS ON SAMPLES TAKEN FROM A SHELL WITH A SCLEROSCOPE HARDNESS NUMBER OF FROM 48 TO 52 Heat No. Scleroscope reading on test piece after ma- chining Yield Point, tons Breaking point, tons Elongation, per cent 1 Outside 525350 ) Inside 555555 f 55.8 73.3 14.3 2 Outside 525450 ) Inside 555753 j" 53.8 72.4 17.4 3 Outside 575749 / Inside 606251 V 52.8 77.3 12.7 Machinery satisfactory, and the oil-circulating pump was speeded up. Scleroscope readings as high as 65 were frequently obtained at a quenching temperature of approximately 1635 degrees, and when the shell was tempered to read 48 to 52 on the scleroscope, three test pieces from one shell gave the results presented in Table III. A careful study of this data re- vealed the fact that, while a low-carbon, low-manganese steel hardens satisfactorily within a limited range of tem- perature, a medium steel has a wider range, and a high- carbon steel, a still wider range of hardening temperature. When the shipment of mixed heats previously referred to was treated, the method pursued was to take 0.50 per cent carbon and 0.50 per cent manganese as a base compo- sition which hardened at 1600 degrees F. to show 55 to 65 MACHINING AND HEAT-TREATMENT 55 hardness on the scleroscope. Then : (a) If, for every point of carbon below 50, there be present 1 or more points of manganese above 50, the steel should harden satisfactorily at 1600 degrees F. (b) If, for every point of manganese below 50, there be present 2 or more points of carbon above 50, the steel should harden satisfactorily at 1600 degrees F. (c) If both carbon and manganese be below 0.50 per 0.45 ACTUAL LIMITS OF MANGANESE, PER CENT Machinery Fig. 12. Chart showing Hardening Temperatures for Various Percentages of Carbon and Manganese in Steel used for Shrapnel Shells cent, increase the hardening temperature 12% degrees F. for each point of manganese short of 50, and 6*4 degrees F. for each point of carbon short of 50. (d) If both carbon and manganese are above 0.50 per cent, a hardness number above 55 will probably be obtained at a quenching tem- perature of 1600 degrees F., but the maximum hardness, 56 MACHINING AND HEAT-TREATMENT i. e., from 75 to 80, will be obtained at a somewhat lower temperature, the exact temperature being most easily found by starting at 1500 degrees F. and trying a couple of sam- ple shells every 25 degrees F. until a maximum hardness is obtained. Forgings containing from 0.50 to 0.55 per cent carbon and from 0.54 to 0.62 per cent manganese in any varying proportions may be hardened at 1600 degrees F. to show a hardness number of from 55 to 75 ; and when tempered to give a hardness number of from 48 to 52 they will yield the following results: yield point, 45 to 50 tons; breaking point, 65 to 70 tons ; and elongation, 14 to 20 per cent. Looking back, (c) offers a basis for charting the harden- ing points in a fairly approximate manner, to form a guide as to where the best hardness may be obtained. Such a chart is shown in Fig. 12. By following the horizontal and vertical lines from the carbon and manganese content until they intersect, a diagonal line will be found which will indicate the temperature at or about which the maxi- mum hardness will be obtained. This does not prevent the use of 1600 degrees F. as the average temperature for the majority of shells, provided they are strong enough when hardened at that temperature; but where shells do not harden satisfactorily at 1600 degrees F., the chart offers an alternative method subject to such variation as may arise due to the use of steel from different makers, etc. Probably the best practice is to make careful scleroscope readings of each piece before pulling. Care must be taken to have a uniform surface on both sides, all tool marks be- ing removed with fine emery cloth. The points tested are shown at A, B, and C in Fig. 11. After the test piece is made, the value of the hardness number increases as a result of the piece being solidly supported in the scleroscope, whereas, when the reading is made on the shell, the arched form of the wall acts as a spring, and absorbs the shock to some extent. Readings thus increase from 2 to 10 points after the test piece is finished. A careful study of the data presented in Table IV re- veals the fact that results are not always consistent. With MACHINING AND HEAT-TREATMENT 57 TABLE IV. DATA ON THE HEAT-TREATMENT AND STRENGTH TESTS OF SHRAPNEL SHELLS Car- bon, per cent Manga- nese, per cent Quen- ching temper- ature, degrees Tem- pered, sclero- scope hard- ness No. Readings of scleroscope Yield point, tons Break- ing point, tons Elong- ation, per cent 0.50 0.47 1635 51 60 57^-57 474848 48.3 69.9 16.9 Three pieces from one shell 605653 485258 45.2 70.6 19.1 63^5657 515554 51.6 74.6 16.9 0.48 0.65 1565 49 515452 485350 47.3 67.4 15.9 Three pieces from one shell 515249 535151 48.2 67.9 15.3 525550 505547 49.2 70.7 15.4 0.50 0.57 1600 50 505250 495049 46.0 64.8 19.0 0.50 0.57 1600 60 566057 545654 55.8 77.8 14.3 0.50 0.57 1600 50 596056 5559+56 60.7 82.2 12.7 0.60 0.57 1600 60 606155 606257 57.8 80.0 12.6 0.60 0.57 1600 52 575756 545653 48.2 69.7 17.5 0.50 0.57 1600 50 485250 495249 44.2 64.3 17.4 0.50 0.57 1600 50 525555 605152 44.7 65.2 14.7 Machinery an increase of carbon, one occasionally finds an increase in elongation and vice versa; and the results due to variations in manganese content are similarly unreliable. In order to secure a degree of uniformity in hardness, which will be sufficient to insure test pieces standing up successfully, it is necessary to have the shell hard inside as well as outside, and a method of doing this is referred to later. Assuming now that the shell has been tempered, it is rough-polished 58 MACHINING AND HEAT-TREATMENT *J siLLJ i MACHINING AND HEAT-TREATMENT 59 on a canvas buffing wheel around the outside of B, Fig. 11, for a width of at least 1 inch. Readings by the sclero- scope are made on a zone % inch wide, and if they are between 46 and 52 the shell may be relied upon to show good results in the tensile test. In making test pieces, it is desirable to cut the piece from a spot which reads 48 to 50 ; and in machining the test piece, care should be taken to remove an equal quantity of metal from either side of the wall so that the test piece is a true specimen of the average wall structure. Where a shell is carelessly quenched, and the test piece so machined that the surface on one side is practically the same as the inner side of the wall, the results would not be a true indication of the real average strength, and a lot of shells might possibly be rejected on account of a slight oversight in this respect. Reference has been made to the base A, Fig. 11. Forging defects show up here occasionally and in such cases the shell is at once condemned. These flaws take the form of small cracks, from the width of a hair up to 1/16 inch. They seldom can be detected until after heat-treating, and are most easily observed by polishing the base on a disk grinder. Losses in this respect vary, but might average about 0.20 per cent. The hardness of the base itself may vary from 38 to 50, which insures an ample degree of toughness and avoids all possibility of the shell cracking under fire. Heat-treating Department. Many methods of heating, quenching, annealing, and cleaning are in use by the different firms engaged in shell making. For rapidity of output, cleanliness of the resulting product, ease and econ- omy of operation, and uniformity and control of results, the lead bath seems best for hardening, and the semi-muffle furnace for annealing. In one case the use of a lead bath by a skilled operator yielded excellent results both as to economy and uniformity, but, when the output exceeds 500 shells per 12 hours, a semi-continuous furnace meets the requirements to better advantage. The lay-out of a hardening room for an output of 12,000 shells per week is given in Fig. 13. The lead baths consist of a rectan- 60 MACHINING AND HEAT-TREATMENT gular pot of suitable capacity, resting on a 4i/2-mch hearth built of common firebrick and heated by either oil or gas burners below the hearth. They are built in pairs with a common wall between, which is thick enough to provide a flue to carry off products of combustion. The quenching tanks are rectangular, water- jacketed, and provided with two quenching cradles each. These cradles are arranged to swing lengthwise in the tank, and, when the carrier hold- MacMnery Fig. 14. Special Arrangement of Scleroscope for Testing Shrapnel Shells ing the shell is lowered into the oil, a pipe is automatically extended downward into the shell and introduces cold oil in the inside of the shell, while the operator swings the cradle back and forth in the tank, thus cooling the outside of the shell at the same time. This method of quenching made it possible to harden shells which, by reason of low carbon and manganese, defied all conventional methods of dipping and swinging back and forth with tongs. The MACHINING AND HEAT-TREATMENT 61 output per man with this apparatus is largely in excess of any hand method, while the uniformity and degree of hardness is all that could be desired. The oil pump draws the oil from a depth of 6 inches below the surface and pumps it through 100 feet of 1-inch copper pipe arranged in two 50-foot coils in parallel. The cooled oil is delivered into an overhead reservoir, the over- flow being connected to both tanks equally. After quench- ing, the shells are set on draining racks, and then washed in boiling water and sal-soda, placed on another draining rack and then brushed with wire brushes previous to tempering. The tempering furnace is of rectangular form, Fig. 15. Closing in Nose of Shrapnel Shell in Hydraulic Press and consists of a long flat hearth with rails laid lengthwise on it. At each end a space is partitioned off from the body of the furnace, by means of vertical sliding doors; and a rack holding a number of shells is deposited on the rails at the front end of the hearth, the door is elevated and the rack is slid into the main chamber. After a suita- ble lapse of time another rack is introduced, and so on until the first rack is ejected at the rear end of the furnace. The shells are now hot enough to loosen all foreign matter on the surface, and a few seconds brushing with a wire brush cleans out the driving band groove, and leaves the shell 62 MACHINING AND HEAT-TREATMENT with a delicate brown oxidized finish. The shell is now spotted on three places with a canvas buff and tested for hardness. Fig. 14 shows the arrangement of the scle- roscope. The shell is supported on a single narrow V-block with hardened edges, situated immediately under the set-up point. A narrow strip supports the open end of the shell, thus giving a three-point support, while a ver- tical stop at the back of the shell maintains it in a position tangential to the radius of the swinging arm. The usual rubber bulb was soon dispensed with as being quite unsuited Fig. 16. Third Operation on Nose of Shrapnel Shell Turning, Facing, and Threading for such hard service, and a small pump cylinder substi- tuted. The piston in the cylinder is operated by a down- ward pressure of the heel on the pedal to give compression, and a spring inside the cylinder gives the necessary pull when the scleroscope hammer is to be raised by suction. After being tested the shells are ready for "nosing in." Closing-in the End of the Shell. On some makes of shells, particularly the British, the nose is closed in before performing the third series of machining operations. The closing-in is generally accomplished in a hydraulic or power MACHINING AND HEAT-TREATMENT 63 Fig. 17. Grinding Shrapnel Shells In One Operation Fn a Ford-Smith Grinding Machine carrying a Wheel about 8^ Inches Wide by 20 Inches In Diameter, rotated at 1200 Revolutions per Minute Fig. 18. Closing in Copper Band on Shrapnel Shell in a Machine provided with Six Dies, as shown in Fig. 20, back of each one of which there is a Hydraulic Cylinder , 64 MACHINING AND HEAT-TREATMENT press. Fig. 15 shows the closing-in operation being per- formed in a vertical hydraulic press capable of exerting a pressure of 800 pounds per square inch. Before closing the open end of the shell, it is heated in the lead bath, shown to the left of the illustration, which is kept at a temperature between 1450 and 1500 degrees F. The steel diaphragm, which is larger in diameter than the nose of the shell, is first thrown in. Then the shell is placed in the press, and a cone-shaped die descends, closing in the nose to the proper shape and diameter. The third machin- ing operation consists in finishing the radius on the nose, both inside and outside, and cutting the thread. This is Machinery Fig. 19. Special Type of Wheel-truing Device used on Ford-Smith Grinding Machine shown in Fig. 17 done, as shown in Fig. 16, in an ordinary engine lathe with a turret on the saddle. The boring is done with cutters held in boring-bars and the thread cut with a Geometric collapsible tap. The thread on the 18-pounder is 2.94 inches in diameter, 14-pitch, Whitworth type. Grinding Shrapnel Shells. The exterior surface of a shrapnel shell is straight for a portion of the length and then curved on the nose. While the limits required are not extremely close, it is necessary, where large production is required, to accomplish the finishing operations on the exterior of the shell in some way by which fairly close MACHINING AND HEAT-TREATMENT 65 dimensions can be secured as well as large production. Grinding has, therefore, been recommended for finishing the exterior of the shell. One method of grinding shrapnel shells, in which a wide-faced wheel is used that covers the entire ground surface, is shown in Fig. 17. This machine is built by the Ford-Smith Machine Co., Hamilton, Ont., and carries a wheel about 8*4 inches wide by 20 inches in diameter. The grinding wheel is rotated at 1200 R. P. M., and the work at 50 R. P. M. The depth of the cut is about 1/32 inch, and the time to complete one shell varies between two and three minutes. For grinding, a plug is Fig. 20. Close View showing Closing-in Dies of Banding Machine shown in Fig. 18 screwed into the open end of the shell. This is held on the tailstock center and a chuck holds and drives the shell from the other end. It is necessary, of course, that the wheel be kept the correct shape, and for this purpose an interesting type of wheel-truing device, differing considerably from that shown in Fig. 17, is now used. Referring to Fig. 19, it will be seen that this comprises a combination wheel guard and bracket, the latter being used as a base for the wheel-truing device proper. The diamond A is carried in a holder B that operates in a slide in the face of the traversing wheel- truing slide C. The diamond holder carries a cam point 66 MACHINING AND HEAT-TREATMENT D which is kept in contact with the guide or former cam E by means of a spring F. The wheel-truing slide C is tra- versed by a triple pitch screw G so as to give a rapid move- ment to the slide in order to produce what might be termed a "rough-truing" of the wheel. For change in diameter, and also for bringing the diamond in contact with the wheel, a vertical slide H is provided that is operated by handle /. In order to observe the diamond when truing the wheel, a trap door J is provided in the wheel guard, which can be dropped down into place when the actual grinding of the shell is being done. Pressing on the Rifling Band. In order to rotate the shrapnel when propelling it out of the howitzer, it is nec- essary to put on a rifling band to take the rifling grooves of the gun bore. As a rule, these rifling bands are made from copper tubing and are simply cut off in a hand screw machine or turret lathe. The next operation is to close in the rifling band on the shrapnel shell. The ring is dropped over the shell and a fixture is used to locate it in the correct relation to the groove in the circumference of the shell. Then a slight pressure is exerted on it to align it properly in the groove. It is now placed in the banding machine shown in Fig. 18. This particular machine is provided with six dies as shown in Fig. 20, and back of each one is a hydraulic cylinder operated by water pressure. Two squeezers are necessary to close the rifling band properly into the groove, the shell being given a half turn after each squeeze. There are several different machines on the market for performing this closing-in operation on the rifling band. Another machine, built by the West Tire Setter Co., Roches- ter, N. Y., is shown in Fig. 21. The principle upon which this machine operates is almost identical with that pre- viously described, but in this case oil is used as a pressure medium. It is forced into the machine by means of a belt- driven pump shown to the left of the illustration, which drives the oil from the oil tank and carries it to the center of the base of the press. An oil head is located at this point from which the pipes are run to each of the six rams MACHINING AND HEAT-TREATMENT 67 Fig. 21. Shrapnel Banding Machine built by the West Tire Setter Co., having a Capacity for Compressing two Bands per Minute Fig. 22. Assembling Bullets, Resin, and Fuse Socket in Shrapnel Shell 68 MACHINING AND HEAT-TREATMENT or cylinders. The amount of pressure required for com- pressing the copper band depends largely upon the width and thickness and the amount that the band must be spread to fill the grooves, rather than upon the diameter of the shell. The machine shown in Fig. 21 is capable of exerting a pressure of 30 tons on each cylinder or a combined pres- sure of 180 tons on all six cylinders. It has a capacity for compressing at least two bands per minute. Machining the Rifling Band. One method of machin- ing the rifling band to the correct shape is shown in Fig. Fig. 23. Finishing Rifling Band on Shrapnel Shell to Shape 23. Here a Fox lathe is used which is provided with a chuck for holding the shell and which carries in the turret a revolving center for additionally supporting it. The ma- chining is done by form tools which are of the correct shape. Before any other machining operations can be ac- complished it is necessary to put in the tin powder cup, brass fuse tube, bullets, and resin. This cup is slipped in past the steel diaphragm, then both parts are allowed to drop to the bottom and the fuse tube is screwed into the diaphragm. The required number of lead bullets, which 70 MACHINING AND HEAT-TREATMENT for the British 18-pound shrapnel is about 375 per shell, is then poured in. The bullets are held in a tank and are allowed to flow out upon the opening of a stopcock. In order to pack the bullets solidly, a compressed air ramming device forms the base upon which the shell rests while the bullets are being poured in. This is operated three or four times for the filling of each shell and arranges the bullets compactly. The resin is now poured in, as shown in the center of Fig. 22. This is carried in the tank which is heated by a gas furnace and is poured in almost level with the top of the bullets. The shell is then placed on the scale in the im- mediate foreground and weighed. One dram plus or minus is allowed as a variation, and in order to not exceed this, Fig. 25. 18-pound Shrapnel Shell showing Dimensions and Manufacturing Limits more or less resin is poured in until the correct weight is obtained. The brass fuse socket is now screwed in as shown to the left of the illustration, and upon the comple- tion of this operation the shell is ready for the fourth and last machining operation. This last operation consists in machining the brass socket on the outside diameter to con- form to the radius on the nose of the shell, and boring on the inside and threading to fit the fuse body. These oper- ations are handled in a Fox brass working lathe. Upon the completion of the machining operations the plug is screwed in, the shell stamped, cleaned, weighed, and in- spected by government inspectors. After this, the shell is given two coats of paint and a red band is painted around the nose. It is now packed in boxes holding six shells MACHINING AND HEAT-TREATMENT 71 Fig. 26. Group of Gages made by Wells Bros. Co. for gaging British Shrapnel Shells and Parts and is ready for shipment. This completes the manufac- ture of the shrapnel shell. Gaging Shrapnel Shells. The machining operations on shrapnel shells are required to be held within certain limits, and government inspectors watch these closely. Some of the principal gaging operations on the shrapnel shell body Machinery Fig. 27. Diagram showing Application of Wells Bros. Gages 72 MACHINING AND HEAT-TREATMENT Fig. 28. Collection of Wells Bros. Co.'s American Shrapnel Shell Gages are shown in Fig. 24. Fig. 25 shows the 18-pound shrapnel shell in section, and gives the principal dimensions together with the limits ; it will be seen from this illustration that the range allowable is in most cases large. The Wells Bros. Co., Greenfield, Mass., has made a large number of shrapnel gages, some of which are shown in the accompanying illus- trations. In the three upper views of Fig. 24, the Wells Bros, standard thread gage is illustrated. This is used for all diameter measurements by substituting flat gaging pins for the V-points used when gaging thread diameters. Gages for British Shrapnel Parts. Fig. 26 illustrates typical gages for gaging such parts of the British shrapnel Fig. 29. Dwight-Slate Hand-operated Marking Machine for Shrapnel Shells MACHINING AND HEAT-TREATMENT 73 as body diameters, diaphragm seat, powder pocket, fuse socket, thread diameters, and fuse parts. Fig. 27 shows the application of several different types of shrapnel shell gages. At A is the gage for the over-all length. At B is the gage used for measuring the thickness of the closed end. The outer arm of this gage can be swung away to allow the placing of the gage on the standard. At the extreme lower left- hand corner of the gaging arm is a slight shoulder on the rod and the height of this acts as the limit. C shows the application of outside diameter and thread gages. D shows three form gages for checking the shape and dimensions of the wave ribs, the diameter and shape of the undercut i n t h e band groove, and the shape of the nose of the shell. E shows the gage used for checking the thickness of the wall of the shell at different distances from the mouth. F shows the application of a powder pocket gage, and also a gage for checking the shape of the finished rifling band. Gages for American Shrapnel Shells. Fig. 28 shows a miscellaneous collection of gages used in checking the di- mensions of the American shrapnel shell. Gages, A, B, C, and D are for measuring the diameter of the diaphragm seat. E is for checking the distance from the diaphragm seat to the mouth end of the shell, and gage F is for the Fig. 30. Power-driven Dwight-Slate Mark- ing Machine for Shrapnel Shells 74 MACHINING AND HEAT-TREATMENT outside diameter of the shell. Gage G is used for the rifling band groove. Gages H and / are for the thread in the mouth of the shell, H being a "not-go" and / a "go" gage. The gage at J performs several gaging functions on the American shell. It consists of a standard having two up- right posts across which a bar is mounted. The purpose of the bar is to gage the over-all length of the shell, and its lower surface is provided with two steps giving the limits. This gage is also used for measuring the depth of the pow- der pocket, rod K and block L performing this function. Two rings are cut around the rod K registering with the top surface of the bar, the purpose being to show the accu- racy of the work. Another interesting gage is shown at M. This is for gaging the concentricity of the shell and consists of an arbor mounted so that it can be swung on a pivot. The arbor carries two collars N and O that fit in the shell. Collar P is merely a sizing plug and when the gage is in use this plug is removed. A gaging finger Q rests against the shell when it is on this arbor, and a standard type of indicator R shows the variation in concentricity when the gage, collars, and shell are rotated on the arbor. Marking Shrapnel Shells. All shrapnel shells are marked on their circumference with five or six lines of lettering, as shown in Fig. 29. This indicates the size of the shell, the series, muzzle velocity, name of the manufac- turer, date completed, etc. Two types of machines for producing the stamping, built by Noble & Westbrook, Hart- ford, Conn., are shown in Figs. 29 and 30. The machine shown in Fig. 29 is of the hand-operated type. The figure block A is held in a slide that is moved longitudinally by pulling down handle B, rolling the shell, and at the same time stamping it. The shell is located on the table in the two positions by gages C and D. The "Dwight-Slate" stamping machine shown in Fig. 30 is power-driven, and the work is held on an elevating table. The stamp is held in a slide operated by an eccentric and connecting-rod. In this machine the shell is not distorted. CHAPTER IV MACHINES AND TOOLS FOR SHRAPNEL MANUFACTURE Reed-Prentice Co. Equipment for Machining Forged Shrapnel Shells. In machining the 18-pound British shrapnel shell on the equipment furnished by the Reed- Prentice Co., Worcester, Mass., eight distinct operations are performed as follows: First, drilling a center hole in the closed end of the forging in a Prentice 16-inch ball- bearing sensitive drilling machine equipped with a special centering fixture ; second, rough-turning the outside diame- ter, grooving, squaring the closed end and rounding the corners in a Reed-Prentice 14-inch heavy type automatic lathe; third, machining the powder pocket and diaphragm seat, as well as the internal and external diameters of the nose in a 14-inch Reed extra-heavy turret lathe; fourth, under-cutting band grooves and producing wave ribs in a 14-inch Reed engine lathe; fifth, boring, reaming, thread- ing and facing the open end in a Reed 14-inch extra-heavy turret lathe; sixth, finish-turning outside diameter and radius on nose, also form-turning copper band in a Reed 14-inch heavy type automatic lathe; seventh, cutting off center projection on closed end of shell in a Reed 14-inch engine lathe; eighth, finishing brass socket to form, clean- ing inside of socket and cutting off excess length of tube in a Reed 14-inch extra-heavy turning lathe. First Operation on Rough Shell Forging. The drilling of the center hole in the closed end of the forging is a comparatively simple operation, and is performed in an in- teresting fixture held on a 16-inch Prentice ball-bearing sensitive drilling machine. This fixture, which is designed for handling the work quickly, is shown in Fig. 1, and con- sists of the base casting A clamped to the table of the drill- ing machine. The entire back part of the jig swings on the trunnion B to provide a means for quickly removing the forging C from the arbor D. A locking pin E is used for locating the fixture in its upright position for drilling. 75 76 SHRAPNEL MANUFACTURE Machinery Fig. 1. Fixtures used for holding Shrapnel Shell Forgings when drilling Center Hole in a 16-inch Prentice Ball Bearing Sensitive Drilling Machine Bushing G in the top plate F of the fixture guides the combination drill and countersink. The construction of the work-holding arbor is worthy of special attention. This arbor D has a cap H on its top end that acts as a stop for the inside of the forging, which, SHRAPNEL MANUFACTURE 77 in being placed over the arbor, is located centrally and clamped by fingers N. To operate these fingers, hand lever / is depressed, and as this is fulcrumed at the point J, it causes collar K to rise on the arbor. Yoke L forms a con- nection between the lever and the collar with which the sleeve carrying fingers N is integral. Fingers N are ful- crumed in arbor D and are thrown outward to grip the forging when sleeve M is raised. Light springs tend to keep the gripping fingers in a vertical position against Fig. 2. Tool Lay-out for performing Second Series of Operations on Reed- Prentice Heavy Type Automatic Lathe the arbor when they are not being forced outward by the inclined "surf aces on sleeve M. Handle / carries a spring pawl P that holds the sleeve M stationary while the forging is being center-drilled. Second or Rough-turning and Facing Operations. The second operation is performed on a Reed-Prentice 14-inch heavy type automatic lathe, as shown in Figs. 2 and 3. The forging A is held on an internal expanding arbor B, the driving part of which is supported by the head-center. At the closed end, the shell is steadied Dy tne 78 SHRAPNEL MANUFACTURE tail-center. The bottom of the shell rests against the end of the arbor which acts as a gage. In this setting, the external diameter of the forging is rough-turned by four tools F, mounted on the carriage G. This carriage has a travel slightly less than two inches, and an automatic throw- off is provided at the end of the cut that disengages the tools, draws them back and returns the carriage. At the rear of the carriage on this machine a facing arm is mounted on a heavy bar. Turning tools are carried on this facing arm, as shown, and when the front carriage Fig. 3. Section through Reed-Prentice Automatic Lathe, showing Tool Arrangement feeds longitudinally a cam bracket O, bolted to the carriage, is carried along with it. Clamped on this bracket is an adjustable cam N held in place by screws. Cam roll M on the facing arm contacts with cam N, causing the facing arm to rock forward as the carriage travels longitudinally. Referring to the plan view in Fig. 2, tool H, held in the arm, faces the end of the forging, tool I chamfers the cor- ner, and tool / cuts the depression for the wave ribs, leav- ing a projection in the center from which the ribs are formed. It should be understood that the tools on the SHRAPNEL MANUFACTURE 79 carriage and facing arm work together. One man can run two of these machines without trouble. Third Series of Machining Operations. The third se- ries of operations on the shrapnel forging is performed on a 14-inch Reed heavy lathe with a specially large turret, as shown in Fig. 4. This lathe is fitted with a 12-inch three-jaw chuck, bored out to 3^ inches to permit the forging to extend into it. The forging A is put in the chuck as shown at B, and the jaws grip at C. The first operation is performed with a bar D carrying a blade cutter E that rough-bores the powder pocket, and tool F that Machinery Fig. 4. Tooling Equipment for performing Third Series of Operations on 14-inch Extra-heavy Turret Lathe rough-bores the mouth. The turret is now indexed, and a boring-bar carrying a blade G roughs out the diaphragm seat, while an auxiliary tool H faces the shell to length. At the next indexing of the turret the boring-bar / that carries the finishing tool / finishes the diaphragm seat and powder chamber. Fourth Operation Under-cutting and "Waving" Band Groove. For the fourth operation, the forging is held in a 14-inch Reed engine lathe provided with an automatic attachment for under-cutting and waving the ribs for the 8 3 O^o *Q} -^ K^ s Jr* O ^ hjQ BQ JjS CO SH .3 o; 02 QJ rQ O 2 lll 3 2 ^ -g 0> ft ^j IM I 5.S ~ 0) H . a> _f> n) -J3 +3 02 .2 o'o 80 |a-g s O j-H CH *^j o .S !^ ^2 SHRAPNEL MANUFACTURE 81 B. Spring D keeps the roll E on the lower slide of the tool-holder in contact with the cam slot in cam-plate F that is fastened to carriage R. When the carriage is traversed toward the chuck, the irregular surface of cam-plate F engages the roll and forces the tool-holder forward. Side motion to produce the wave is then effected by face-cam G, mounted on the chuck and contacting with the roll H. This roll is supported on a bracket forming an auxiliary slide S that carries the waving tool C. A stiff barrel spring keeps slide S in contact with the cam G. Thus, when the machine spindle revolves, the auxiliary slide is caused to oscillate back and forth far enough to give the desired amount of wave. The under-cutting in the band groove is accomplished by tools / and / which are mounted on separate tool-slides K and L. These slides are fed in at an angle to the axis of the forging, against the action of coil springs M and N, by the cam surfaces of plate Q in which rolls and P work. Plate Q is bolted to carriage R which, in advancing toward the chuck, forces in the under-cutting tools in the manner just described. The tail-center of this machine is fitted with a quick-acting mechanism so that it may be withdrawn quickly to insert a new piece. Fifth Series of Operations. Before performing the fifth series of operations, the forging is heated and closed in on the nose. It is then handled in the following manner: A Reed 14-inch heavy lathe, equipped with an extra large turret mounted on a special wide-bridge carriage carries tools for boring, reaming, threading and final squaring of the open end, as shown in Fig. 6. The shell forging for these operations is held in a three-jaw chuck provided with special jaws. In the first position the rough-boring of the nose and the rough-facing of the extreme end is performed with tools B and C. The turret is then indexed and tools Z), and E finish-ream the hole in the nose and face the end. The tap F is next brought into position, cut- ting the thread in the nose. The turret is again indexed, bringing a special form bor- ing tool into position. Here the boring tool G is carried in 82 SHRAPNEL MANUFACTURE SHRAPNEL MANUFACTURE 83 a bar H held in a holder of the cross-sliding carriage type that is fastened to two faces of the turret. By means of cross-screw /, the boring tool H may be drawn in or out at will. This tool operates as follows: As the turret is ad- vanced, handle / is operated to let tool G enter the nose of the shell, and, upon the continued advance of the turret, arrow head M is forced in between and gripped by the fin- gers N. The turret is now backed away from the chuck, and while receding acts upon slide P through the medium Fig. 7. Reed-Prentice 14-inch Heavy Type Automatic Lathe used for performing Sixth Series of Operations of roll L and cam groove R. The plate containing cam groove R is attached to the arrow head M and consequently is held stationary while the turret is being withdrawn from the work. This backward movement of the turret is continued until the tool G is withdrawn from the work and slide S comes in contact with check-nuts on rod 0, withdrawing arrow head M from fingers N and allowing the turret to be indexed ready for the first operation on the next forging. Sixth or Finish-turning Operations. The sixth series of operations is performed on a Reed-Prentice 14-inch heavy type automatic lathe, similar to that used for the second 84 SHRAPNEL MANUFACTURE operation, and the machine is also operated in a manner similar to that previously described. The operations con- sist in finish-turning the outside diameter of the shell and turning the radius on the nose. In addition, the copper rifling band, put on previous to this operation, is turned to shape. Referring to Fig. 7, the shrapnel shell A is held by the tail-center at one end and is supported and driven from the other end by a plug screwed into it. This plug is held on the live center and is driven by an equalizing driver, coming in contact with pins in the special faceplate. Machinery Fig. 8. Tools for machining Brass Fuse Socket on 14-inch Heavy Turning Lathe Eighth Operation Two slides B and C are carried on the front of the car- riage. Slide C carries three tools D; two of these start in from the rifling band and turn in toward the nose, and the other works up toward the rifling band from the closed end. Tool E, carried in slide B, turns the curve on the nose of the shell and is controlled in its action by means of a slot in cam F in which a roller held to the slide oper- ates. At the rear of the carriage is carried a facing bar attachment, as previously described in connection with the second operation. This attachment carries three tools, as illustrated, for machining the rifling band to shape, facing the closed end and chamfering the corner. SHRAPNEL MANUFACTURE 85 Seventh and Eighth Operations. After the sixth oper- ation, the fuse tube is threaded into the diaphragm, the bullets put in, and the hot resin poured in to keep them from rattling. The brass socket is then screwed into the nose and the fuse tube soldered to it. The shell is now ready for the seventh operation which consists in cutting- off the center projection. This is accomplished in a Reed 14-inch engine lathe, provided with a faceplate chuck for holding and driving the shell at the open end, and a steady- rest for supporting it close to the point where the cutting is being done. The shell is now ready for the eighth opera- tion, which consists in machining the brass socket to shape 'aohlnery Fig. 9. Shrapnel Case made from Chrome-nickel Steel having High Tensile Strength on a Cleveland Automatic Screw Machine with Special Tool Equipment in an extra-heavy lathe as shown in Fig. 8. The tools used for machining are retained in a special holder on the carriage. Tool A, which is used for facing off the fuse tube and the brass socket, is inverted, starts at the center and is fed out toward the circumference. The external surface of the socket is machined with a circular forming tool C held on a stud D located in block B. The inward travel of this tool is limited by stop E coming in contact with the shell. Making Shrapnel Shells on the Cleveland Automatic. An unusual example of automatic machine work is that of producing the shrapnel shell shown in Fig. 9. This shell 86 SHRAPNEL MANUFACTURE is made from a bar of 3 1/16-inch chrome-nickel steel stock. The steel has a tensile strength varying from 125,000 to 135,000 pounds per square inch, and is extremely tough. Fig. 10. Order of Operations on the Shrapnel Case The work is accomplished on a 314-inch Cleveland auto- matic, and the tooling equipment, as shown in Figs. 10, 11, and 12, is interesting. While the general operation of the Cleveland automatic is well understood by many mechanics, SHRAPNEL MANUFACTURE 87 the production of this piece illustrates a number of points in the operation of this machine which are not so well known. Therefore, it is advisable to explain in detail just how this interesting job is handled. The first operation, as the job was originally laid out, was to feed the stock out to the stop A, shown in Fig. 11, which is held on the cross-slide and operated by a lever on the base of the machine. This method has been im- proved upon since the photograph shown in Fig. 11 was taken, and the time reduced from twenty-seven and one- half minutes to twenty-five minutes (see Fig. 10 for im- Fig. 11. Cleveland 3V4-inch Automatic Screw Machine set up for making a Shrapnel Case In Twenty-five Minutes proved method). The second operation is to rough-drill the large hole with an inserted bit B, step the hole for the taper reamer with cutter C and rough-turn the external diameter with cutter D held in a special turning attach- ment. This attachment envelops the shanks of all six tools in the turret in order to obtain support. The cutters in the attachment shown in Fig. 11 work in advance of the under-cutting forming tool E shown in Fig. 12, which is held on the rear cross-slide. The time required for the completion of the operations outlined is thirteen minutes. if a SHRAPNEL MANUFACTURE 89 In the third operation drill H finishes the powder pocket, and two cutters / counterbore for the tap time required three minutes. The fourth operation consists in finishing the diaphragm seat with the counterbore /, finishing the front end with inserted cutter K and breaking the corner to facilitate tapping with inserted cutter L, the time re- quired being forty-five seconds. In the fifth operation the thread is cut with a tap M held in the tap-holder N in forty- five seconds. Then the turret is indexed and for the sixth operation the hole is taper-reamed with reamer O, provided with four inserted "Novo" steel blades, in ninety seconds. The last and seventh operation consists in knurling the band with a knurl P (see Fig. 12) mounted on the front cross-slide, and cutting off the shell with a cut-off blade Q retained in a holder on the rear cross-slide time six min- utes. The total time required to produce this shrapnel case by the improved methods illustrated by the diagram in Fig. 10 is twenty-five minutes. There are several points of unusual interest in the pro- duction of this shrapnel case. One is the large amount of stock to be removed to form the hole ; the second is the long taper-reaming operation difficult work to accomplish sat- isfactorily on an automatic screw machine and the third is the long outside forming operation which must be held to a limit of 0.0005 inch on the diameter. In order to ac- complish this last operation successfully, the external diam- eter of the piece is first turned with a cutter held in a separate turning attachment, leaving only 0.010 inch on the diameter to be removed by a wide under-cutting or shaving tool E held very rigidly on the rear cross-slide. Not only must the case be exact as regards diameter, but it must not vary f om one end to the other nor at any point through- out its length. The large shaving tool held rigidly in the manner illustrated in Fig. 12 accomplishes this result sat- isfactorily. The material from which the case is made is so tough that some difficulty was met with in selecting a tool steel that would stand up for a reasonable length of time under cut. The drills and counterbores are tipped with "Novo" 90 SHRAPNEL MANUFACTURE cutters and all the forming tools, including the cut-off tool, are also made from the same steel. The only cutting tool in the entire tooling equipment not made of this steel is the tap. The bar is rotated at sixty-four revolutions per minute, giving a surface speed for the external cutting tools of approximately fifty-one surface feet per minute. Machining the British Forged Shell on Potter & John- ston Automatics. In making the British forged shell on Fig. 13. First Operation on Shrapnel Shell, performed on a No. 6A Potter & Johnston Automatic Chucking and Turning Machine the Potter & Johnston automatic chucking and turning machine, three operations complete the work. The first operation completes the outside of the shell, except for the extreme end which is covered by the gripping mechanism of the chuck. The second operation finishes the inside of the shell and at the same time finish-turns the extreme open end. After the second operation is performed the shell is "nosed," which consists in heating it in a lead C 0> t "^3 QJ rti o. n . "\ 6 A 4 6 B C i- : ?t<-2^ 40 42 45 0. Oi D 1 D 1 LJ XacMncry Fig. 51. Diagram showing Sclerpscope Hardness Test of Heat- treated Shrapnel Shell at Various Points along its Surface dependency controlled so that either one can be operated separately. A stop is provided on the back toolpost so as to turn each plug to the same diameter. The automatic throw-out for the feed of the threading tool is set from the front handle on the ratchet and pawl as regularly furnished on the "Automatic" threading lathes. Grinding Shrapnel Shells. An increasingly large num- ber of shrapnel shell manufacturers are finishing the steel shell by grinding instead of finish-turning. That is, the exterior surface of the shell is rough-turned to within from 0.030 to 0.080 inch of the finished size and is then finished to the required limits and shape by grinding, as shown in Fig. 50. It is claimed by the advocates of grinding that the finishing operations are more speedily performed in this manner and that a more accurate and concentric shell is SHRAPNEL MANUFACTURE 133 produced. They also point out the fact that portions of the shell are so hard that it is extremely difficult, if not impos- sible, to turn it in the allowable time. The varied heat-treatment given to the shell on the closed end and nose leaves it harder in some sections than others, as indicated in Fig. 51. The section E, 2y% inches from the closed end of the shell, must strike from 42 to 50 on the scleroscope, and the section A at the nose must strike be- tween 20 and 25. The section marked Z), or that part of it to the left of the line that marks the limit of the heat- treating on the closed end, has not been heat-treated at all, k~#~-H !=[$ DRIVING PIN' DRIVING PIN _f r HEADSTOCK CENTER u B c Machinery Fig. 52. Two-operation Method of grinding Shrapnel Shells on Norton Grinding Machines and partly on this account, and also because of the grad- ually diminishing thickness of the shell along this section, it strikes between 40 and 45, decreasing as the thickness of the wall diminishes, until at C the section strikes but 35. Section B, adjacent to the annealed nose of the shell, strikes about 30 on the scleroscope. On the other hand, some manufacturers are not putting the shell through this heat-treating and tempering process, and omit the annealing and machining of the nose after the nosing-in operation. This leaves the nose with considera- ble stock to remove and in such a condition as regards hard- 134 SHRAPNEL MANUFACTURE ness that the grinding machine becomes a necessity. In the face of these varying degrees of hardness of the shrap- nel shell, it will be seen that it is difficult to secure wheels of the right grain and grade to suit all of these conditions. With this information in mind, we can more intelligently take up the actual grinding of the shell. The Norton Grind- ing Co., Worcester, Mass., has been actively engaged in developing methods of grinding shrapnel shells and the fol- lowing illustrations and descriptions apply to this work. STOCK jTl __ HEADSTOCK CENTER DRIVING Pl?f ;.. J_J~" HEADSTOCK CENTER '"T < 2V 4 ^-WHEEL |pil Br-=rt DRIVING PIN J-i- HEADSTOCK CENTER Machinery Fig. 53. Three-operation Method of grinding Shrapnel Shells on Norton Grinding Machines Fig. 52 shows the two-operation method of grinding the shrapnel shell. Section A at the open end of the shell is covered by a wide-faced wheel formed to shape, that fin- ishes the radius on the nose at one in-feeding of the wheel. Sections B, C, and D are covered by a wide-faced wheel, formed to shape so as to finish these three surfaces at one in-feeding of the wheel. Section E at the closed end of the shell is finished completely by turning. SHRAPNEL MANUFACTURE 135 Some manufacturers use a three-operation method of grinding the shrapnel shell as illustrated in Fig. 53. In this case, the sections A and D are first ground with the same wheel, as American manufacturers deem it advisable to grind surface A rather than to finish it by turning. The second stage in this grinding is the finishing of the nose E with a formed wheel, and the third stage is the finish-grind- ing of the body at points B and C. Two-operation Method of Grinding Shrapnel Shells. The procedure followed in grinding shrapnel shells by the two-operation method is first to screw plugs into the open Fig. 54. Radius Wheel-truing Device for forming Grinding Wheel for grinding Shrapnel Shell Nose end of the shells, as shown in Fig. 52. The outer ends of these plugs are centered, and the projection left on the closed end of the shell with the center intact acts as a means of supporting the shell. Some of the Canadian manufac- turers vary this practice by cutting off the center projec- tion on the closed end of the shell and fitting a cap with a center hole over the closed end. Others use a ball-bearing cup center to carry the closed end. American manufac- turers, however, leave the center projection on the shell until after the grinding has been finished. In grinding the nose end of the shell, the amount of metal removed varies from 0.020 to 0.090 inch on the diameter. 136 SHRAPNEL MANUFACTURE The grinding wheel operates at from 6000 to 6250 surface feet per minute. The speed of the work is 75 revolutions per minute, or a surface speed of practically 75 feet, and the machine used is a Norton 6 by 32 plain grinder. The wheel used is generally 14 inches in diameter by 214-inch face. The wheel requires truing for every five to twenty shells, depending upon the amount of metal removed and the hardness of the shell. For truing, a simple radius fix- ture carrying a diamond is used. Fig. 54 shows this wheel- truing device clamped on the grinding machine bed. It is applied in the same manner as the usual steadyrests used Fig. 55. Norton Special Form Wheel-truing Device for truing Wheel for grinding Shrapnel Shell Body for supporting the work. The diamond is mounted in a swinging arm that is operated by a hand lever as shown. By successive cuts across the wheel, the desired shape is attained. For grinding the body either a 10 by 24 special-purpose or 10 by 36 Norton grinding machine is employed. The amount of metal removed from the body varies from 0.030 to 0.075 inch on the diameter, and the limits vary from 0.002 to 0.010 inch, depending largely on the requirements of the plant in which the work is being done. The wheel used on the body is 20 inches in diameter and is of the ring-wheel SHRAPNEL MANUFACTURE 137 Fig. 56. Besly No. 14 Ring Wheel Grinder equipped for grinding Shrapnel, but shown without Hoods and Water Attachments type. It will be noticed in Fig. 52 that the wheel for grind- ing the body is also formed to shape. The method of truing the wheel for shaping the shrapnel shell body is shown in Machinery Fig. 57. Fixture used on Besly No. 14 Ring Wheel Grinder for grinding Center End from Shrapnel Forgings Fig. 55. This attachment is clamped to the front of the grinding machine bed and at the top of the bracket is fitted a slide A operated by handwheel B. Upon the face of this 138 SHRAPNEL MANUFACTURE slide nearest the grinding wheel is pivoted an angular arm C that supports the diamond D at its lower end. Under the end of the upper arm is a spiral spring that keeps the diamond normally back from the wheel. A plate former E clamped to the bottom face of the bracket is shaped to agree with the form to be given the wheel. At the lower ex- tremity of the arm and behind the diamond is mounted a roll F that bears constantly against form E. When the diamond slide is reciprocated by turning the handwheel, the diamond is made to traverse a path conforming with the cam that guides it. By moving the wheel in toward the diamond and making successive traversings of the diamond, the wheel is given the desired shape. Fig. 58. Tools for making Base of Powder Cup For grinding the body, the wheel must be trued after every ten to twenty-five shells are ground, depending upon the amount of metal removed and the hardness of the shell. In grinding shrapnel shells, the usual method is to fit a lot of the shells with the driving plugs and carry them all through to completion before removing the plugs. Removing Center End From Shrapnel Forgings. For performing practically all the machining operations on the shell, a center projection is left on the closed end of the shell for supporting it. This, of course, must be removed before the shell is completed. One method of doing this is to use a Besly No. 14 ring-wheel grinder equipped with a SHRAPNEL MANUFACTURE 139 special fixture. A Besly grinder fitted up for this work is shown in Fig. 56, and the fixture used for holding the shell is shown in Fig. 57. The machine, as furnished, is arranged for wet grinding, but is not so fitted up in the illustration. The fixture is fastened to the geared lever feed table and is of simple design. It is provided with a backing-up stop A, the work resting in two semi-spherical groove projections on the fixture. The operator simply holds the shrapnel shell in place by hand and then feeds it in against the wheel and traverses it past in the usual manner. The time for remov- ing a %-inch diameter stub end projecting % inch from the body of the shell is less than a minute. Press Tools for Making Powder Cup. In the British shrapnel shell, the powder in the base of the shell used for Fig. 59. Tools for making Top Member of Powder Cup exploding it and ejecting the lead bullets, etc., is held in a tin-plate powder cup. This is completed in the punch press in the manner shown in Figs. 58 and 59, and comprises two parts, a base and a top. The base is made from tin plate 0.022 inch thick, whereas the top is made from 0.036 inch thick tin plate. The bottom of the cup is completed in one operation with the punch and die shown in Fig. 58, which is held in a single-action press. It is turned out from a blank 3 7/32 inches in diameter and is cut out and formed in one operation. The completed size is 2*4 inches diameter by % inch high. After cupping, the top edge is trimmed in a turret lathe. The press operations on the top, as shown in Fig. 59, are a little more complex. The first operation con- .+_> .9 s.s 010 2 + P* 43 43 (> O M 1.1" Ml fl5 A QQ 140 SHRAPNEL MANUFACTURE 141 ferent governments varies. There are 252 in the Ameri- can 15-pound shell, and 235 or 236 in the British 15-pound shell. The bullets used by the U. S. government have six flattened sides, to facilitate packing, whereas those used by foreign governments are spherical. There are several methods of making shrapnel bullets. One is to cast the bullets in iron molds, which are split in the center, so that the bullet can be removed when cast. Another is to cut off slugs from lead wire and strike these between dies in a heading machine. The bullet heading machine takes the wire from a reel, cuts it oif , forms it and trims off the resultant flash automatically. In making the American bullets, a second operation follows, consisting in flattening the sides. The Waterbury Farrel Foundry & Machine Co. furnishes unit equipments for doing this work. For the flattened bullets, the unit consists of one hydraulic wire extruding press and fourteen heading machines cap- able of giving a production of 850. bullets per minute. For the spherical bullet, the unit equipment consists of one hydraulic extruding press and eight heading machines, giv- ing a production of 950 bullets per minute. The method of casting lead bullets in ordinary molds is antiquated, and another method somewhat similar to that just described has taken its place. The first step is to pro- duce the wire from which the bullets are eventually made. This is accomplished in two ways. The first is the hot metal process and consists in pouring the molten lead into a cylinder, from which it is extruded through a die by a plunger advanced into the cylinder. By this method, it is necessary to allow the metal to settle before the press can operate. An improvement over this is utilized in presses built by a hydraulic lead press manufacturer of Brooklyn, and consists in first casting ingots of the required diameter and length and then charging the press with these instead of pouring the molten lead into the press chamber. Two presses have been designed for this process. One has a capacity of 700 tons and is charged with ingots weighing 150 pounds, whereas the other has a 900-ton capacity and is charged with 200-pound ingots. The product from these 142 SHRAPNEL MANUFACTURE two machines is 1800 pounds of lead wire from the small and 2500 pounds from the large press per hour. The wire as it is extruded from the die is wound on a reel carrying 2000 pounds of wire. There are two principal types of swaging machines used for making these lead bullets from wire. One carries a single set of dies, whereas the other carries twelve sets of tools. The operation of the latter will be described. Re- ferring to the diagram, Fig. 60, twelve reels of lead wire- not shown are arranged in tandem on stands behind the press, six reels in a row. The wire is conveyed from these reels to the dies by a feeding mechanism, being guided to the individual tools by a plate A, having twelve U-shaped impressions in its top edge. The wire now passes over a spring B which serves to lift it up slightly at each stroke of the press. The tools C and D, as shown, are provided with half -spherical depressions in their adjacent faces and are set so that they come within 1/64 inch of meeting. The dies are guided and controlled in action by a special mechan- ism, and the press in which they are carried operates at 70 revolutions per minute. This gives a rated production of 840 bullets per minute. As is clearly indicated in the illus- tration, considerable scrap is formed in making lead bullets by this process in fact the scrap is about 33 per cent of the reel of wire; also owing to the setting of the punches a slight fin is formed around the periphery of the bullet. After forming, the bullets are taken to a tumbling ma- chine where they are tumbled for one hour. No other ma- terial is put into the tumbling barrel, but the action of the bullets working on themselves satisfactorily removes all the fins. Both the swaging and tumbling operations must be carefully watched because of the necessity of having the bullets a certain weight. The allowable variation on one pound of bullets is one dram, and there are forty-one bullets to the pound. Ten pounds of lead rod make 6*/2 pounds of bullets, and the scrap resulting from the swaging opera- tion is remelted and used over again. After tumbling, the bullets are inspected and are then ready for use. CHAPTER V MAKING FUSE PARTS COMBINATION timing and percussion fuses comprise a large number of small parts made from different metals and alloys, and are produced in various ways. Some of the parts are made from brass rod or alloys of copper and aluminum, whereas others are made from hot-pressed f org- ings and are machined after being formed to shape. In the following, a brief description of several different methods of making the most important fuse parts will be Fig. 1. Tools used in forging Brass Fuse Socket illustrated and described, together with details regarding the forging tools used for the socket and plug. Forging the Fuse Socket. The fuse socket, which screws into the nose of the shrapnel shell and acts as a base for the fuse, is made from a special forgeable alloy casting containing 40 per cent copper, 58 per cent zinc, and 2 per cent lead. The first step in this process is to melt the above constituents in the usual manner and then to cast the slugs in sand molds, six to eight being gated together. These castings are made 2 11/16 inches in diameter by 11/16 inch thick, as shown in Figs. 1 and 2. There are several methods in use for forging the plugs, but the gen- eral principle is the same. In this particular case, a No. 23 143 144 MAKING FUSE PARTS Bliss press capable of exerting a pressure of 250 tons i& used. The castings are placed in the furnace where they are allowed to "soak" at a temperature varying from 1200 to 1300 degrees F., or, in other words, until they reach a dull red color. One casting at a time is then quickly re- moved and placed in the impression of the die shown to- the right in Fig. 1 and in detail in Fig. 2. The working Machinery Fig. 2. Diagram showing Construction of Tools used in forging Fuse Socket parts of these dies are made from Jessop's high-carbon tool steel and one blow of the press completes the forging, turning out about 3000 in ten hours. The tools used for this purpose are of interesting construction, as shown in Fig. 2. They comprise a lower die A machined out to the shape of the finished forging and carrying an ejector, and MAKING FUSE PARTS 145 lower former B operated by plunger C which ejects the forg- ing if it sticks in the die. The top member or punch com- prises a holder D into which the punch E is screwed. This is bored out to fit an ejector F which ejects the forging as the ram of the press ascends. Punch E and stripper or ejector F are made from high-speed steel, hardened. G shows the cast blank and H the completed forging. Forging Brass Plugs. The brass plug shown in Fig. 3 is used as a temporary cap for the shrapnel to protect it during transportation. It remains in the fuse socket until the shrapnel shell reaches the field of operations, when it is removed and replaced by the timing fuse. This member is made from a special forgeable alloy casting 2 inches in Fig. 3. Tools used for forging Brass Plug diameter by % inch thick and is cast in sand molds in a similar manner to the fuse socket. It is also composed of the same constituents as the socket and is forged in the same type of press. The construction of the tools, however, varies somewhat from that of the tools used in making the socket, as will be seen upon reference to Figs. 3 and 4. The tools for the plug comprise a lower die A carrying a combined ejector and forming die B. Inserted in this lower forming die is a secondary ejector C which is operated by plunger D. The upper member of this forging tool consists of a punch-holder E carrying forming punch F which is counterbored to receive an ejector ring G. Pass- ing down through the center of punch F is a center-punch H 146 MAKING FUSE PARTS that is made in two parts. The lower member is made of high-speed steel, hardened, whereas the upper portion is ordinary carbon steel. This center-punch is operated to eject the forging by a plunger / on the up-stroke of the press through the action of three pins J coming in contact with the flange on punch H. K shows the rough casting and L the completed forging. Machinery Fig. 4. Diagram showing Construction of Tools for forging Brass Plug Tooling for Machining Brass Socket. The New Britain automatic chucking machine, referred to in the following, consists essentially of a multiple-chuck turret with capacity for holding five or six pieces of work, acted upon simulta- neously by four or five tool-holding spindles. The sequence of operations is similar to that of a multiple-spindle screw MAKING FUSE PARTS 147 machine. A finished piece is removed and a rough blank inserted at each indexing. The machine is not idle while chucking, there being one more chuck than spindles. ADVANCE 0.022 PER REV. OF SPINDLES PRODUCTION 120 PIECES PER HOUR Machinery Fig. 5. Diagram showing First Series of Operations on Fuse Socket on the New Britain Automatic Chucking Machine The shrapnel socket which, as previously explained, is made from a brass casting and pressed into rough shape, is machined in two settings in the New Britain No. 24 chuck- 148 MAKING FUSE PARTS ing machine. This machine has four spindles, and at the first spindle position, as shown in Fig. 5, reamer A cleans out the hole in the pressed brass blank, counterbore B cleans out the inside, and tool C faces the end. At the ADVANCE 0.022 PER REV. OF SPINDLES PRODUCTION 120 PIECES PER HOUR Machinery Fig. 6. Diagram illustrating Second Series of Operations on Fuse Socket on New Britain Automatic Chucking Machine MAKING FUSE PARTS 149 ADVANCE 0.025 'PER REV. OF SPINDLE PRODUCTION 50 PIECES PER HOUR Machinery Fig. 7. First Series of Operations on Fuse Body on No. 73 Seven-spindle New Britain Automatic Chucking Machine second spindle position, reamer D finishes the central hole, counterbore E faces the bottom, and tool F chamfers the hole. 150 MAKING. FUSE PARTS The under-cutting preparatory to threading is done at the third spindle position. The operation is performed with tool G working on the cross-cutting head H. When the pressed blank is fed in and reaches stop /, it commences to push the housing H of the cross-cutting head backward. A pair of stationary fingers J operate in oblique slots in the housing H, and as the housing presses down on these fingers, the motion gives a cross movement to the under- cutting tool G and its arbor K. In this manner, the under- cutting of the piece is performed. The fourth spindle operation is simply that of tapping the threaded interior with a tap L. Second Operation on Shrapnel Socket. Fig. 6 shows the order of operations performed on the shrapnel socket at the second chucking, the work being screwed on threaded arbors. At the first spindle position, pilot A engages the central hole, while tool B turns the external diameter, tool C chamfers the corner, tool D turns the thread diameter, tool E faces the shoulder, and counterbore F finish-forms the nose of the piece. At the second position, these same surfaces are machined with finishing tools of the same design as those just described. At the third spindle position, the shoulder at the end of the threaded section is under-cut. This is done by a cross- cutting head, similar to that shown in Fig. 5 and carrying the cutter G. At the fourth spindle position, the final oper- ation threading is performed with die H. Machining Fuse Bodies. In Fig. 7 is illustrated an in- teresting tooling set-up for machining a fuse body. This is done on the No. 73 seven-spindle New Britain automatic chucking machine. The operations in this set-up are per- formed on one end only of the fuse body. Strictly speak- ing, this is a seven-spindle machine, but the first four spin- dles carry internal spindles running at high speed that co- operate with the external spindles in machining the work, making this virtually an eleven-spindle machine. At the first spindle position, the broad face and stem are machined with cutters A of hollow-mill type, and centering tool B, car- ried in the inner spindle, centers the work for drilling. MAKING FUSE PARTS 151 In the second spindle position, tools C bevel the external diameter of the flange at the same time that drill D is pro- ducing the hole in the stem. In the third spindle position, roll D supports the work against the thrust of beveling tool E, and the small drill F held in the internal spindle deepens the hole. At the fourth spindle position, the external spin- dle carries a hollow-mill G that finishes the stem diameter, and a counterbore H is carried in the internal spindle to machine the central hole. Fig. 8. Machining a Shrapnel Head on the New Britain No. 24 Automatic Chucking Machine A cross-cutting head in the fifth spindle position carries a circular tool / that machines on both sides of the section subsequently to be threaded, and while this operation is being performed the pilot J steadies the work as well as the tool-holder. In the sixth spindle position, the small hole is threaded with tap K, and the exterior is threaded with a die, tap and die being of different pitches. In the seventh spindle position, a holder carries the forming tool M for 152 MAKING FUSE PARTS cutting grooves in the face of the flange, and the same spin- dle carries a reamer N that finishes the hole in the stem. Machining Steel Shrapnel Heads. Heads for shrapnel shells made from cold-drawn steel stampings are machined ADVANCE 0.0125 PER REV. OF SPINDLE PRODUCTION 62 PIECES PER HOUR Machinery Fig. 9. First Series of Operations on Shrapnel Head on the New Britain Automatic Chucking Machine in two settings on a No. 24 New Britain automatic chucking machine of the four-spindle type, shown in Fig. 8. This piece, shown in Fig. 9 in its sequence of operations, is espe- cially difficult to machine on account of the stringy nature of the metal. The work is held for the first chucking with MAKING FUSE PARTS 153 ADVANCE 0.0125 PER REV. OF SPINDLE PRODUCTION 90 PIECES PER HOUR Machinery Fig. 10. Second Series of Operations on Shrapnel Head on the New Britain Automatic Chucking Machine the small end out, and in the first spindle position the fac- ing on the end is distributed between tools A and B, while counterbore C roughs out and chamfers the hole. In the second spindle position, tool D faces the end, and counter- bore E finishes the hole. A cross-cutting head of a type similar to that previously described is carried in the third 154 MAKING FUSE PARTS spindle position. This retains a tool F which produces an annular groove in the nose of the head, the work being sup- ported with pilot G. The fourth and last operation consists in threading the hole with the tap H. ADVANCE 0.0167 PER REV. OP SPINDLE PRODUCTION 225 PIECES PER HOUR Machinery Fig. 11. Diagram showing Tooling Set-up for machining Fuse Nose on New Britain Automatic Chucking Machine MAKING FU$E PARTS 155 ORMING TOOL 1ST OPERATION SELF-OPENING DIE NTERNAL NECKING TOOL, 2o OPERATION 3D OPERATION 2o OPERATION FIRST SERIES OF OPERATIONS 3D OPERATION SECOND SERIES OF OPERATIONS Fig. 12. Machining Brass Fuse Socket on 3^/ 4 -inch "Gridley" Automatic Turret Lathe First and Second Series of Operations Second Series of Operations on Shrapnel Heads. The set-up for the series of operations performed at the second chucking is shown in Fig. 10, the work being held 156 MAKING FUSE PARTS on threaded arbors. In the first spindle position, tools A and B face the shoulder, and counjerbore C machines a seat in the inner flange. In the second spindle position, counterbore D finishes the part roughed out by C in the previous operation, tool E faces the end, and tool F cham- fers the inner edge. In the third position, a cross-cutting attachment carrying external cutting tool G is utilized for recessing the external diameter next to the shoulder. The threading on the external diameter is accomplished with the die H in the fourth spindle position. Machining Shrapnel Fuse Noses. The time fuse nose for a shrapnel shell, which is made from a brass forging, is machined as shown in Fig. 11 on a No 33 New Britain automatic chucking machine at one setting. It this case, an extra spindle designated as No. is added to the machine for equalizing or properly locating the forging in the chuck when it is being tightened. At the first spindle position, tool A takes a cut from the external diameter, tool B cuts an annular recess in the face, and counterbore C roughs out the center portion. In the second spindle position, the same operations are performed with finishing tools. In the third spindle position, a cross-cutting head carries a recessing tool D that forms a recess back of the tapped portion. The hole is then tapped in the fourth spindle position, and in the fifth spindle position a special counterbore F takes a light finishing cut from all the surfaces previously machined. The external surfaces of the fuse nose are, machined on a turret lathe. Machining Shrapnel Fuse Parts on "Gridley" Automatics. The machining of fuse parts for the British shrapnel shell on "Gridley" single- and multiple-spindle automatics, made by the Windsor Machine Co., Windsor, Vt., forms the basis of several interesting tooling equipments. A num- ber of the parts are machined from hot-pressed brass forg- ings, so that they must be handled separately. The fuse socket, as has been previously described, is made from a brass forging and is machined complete in two operations on a 3% -inch "Gridley" automatic turret lathe of the single- spindle type. The manner in which the work is loaded in MAKING FUSE PARTS 157 ORMING TOOL SECOND SERIES OF OPERATIONS FIRST SERIES OF OPERATIONS Machinery Fig. 13. Diagram illustrating First and Second Series of Operations on Fuse Body on "Gridley" Automatic 158 MAKING FUSE PARTS the chuck and held for the first series of operations is shown at A in Fig. 12. The rough blank a is first placed over the spring fingers b, which are held in a holder clamped in the turret, but are free to rotate. When the work is pushed into the chuck, it forces back spring-ejecting stud c, which, as soon as the pressure of the chuck is released, ejects the work. As the loading device operates on the first slide of the turret, the first machining operation takes place on the second slide. This is a comparatively simple operation and consists in boring the central recess with a tool d and cham- fering with tool e. The turret is then indexed, bringing the internal necking tool / into position. This is held in a holder and is operated by the forward motion of the forming slide. Following this, tap g is brought into position to thread the recess in the socket. The operation of the tur- ret is now stopped automatically until the operator loads a new piece in the chuck. The tapping is done with the spin- dle running in the forward direction on slow speed. After the hole has been tapped, the spindle is reversed and oper- ated at a higher speed. The spindle continues to run back- ward for loading, and is still running backward, but slowed down, at the time of the second operation. It is for this reason that the boring tool d operates on the reverse side of the hole, and tool e is mounted upside down. At the third operation, the spindle is still running backward but is speeded to its highest speed while the internal necking is done with the tool on the reverse side of the hole. Second Operation on Fuse Socket. The method of hold- ing the fuse socket for performing the second operation on the 3 14 -inch "Gridley" single-spindle automatic turret lathe is shown at B in Fig. 12. The socket h, which has now been threaded, is screwed onto the body of special arbor i, fitting in sleeve j that is gripped by the spring collet. On the reduced end of arbor i is a nut which serves to clamp the work up against the face of sleeve j. The method of using this arbor is as follows: To chuck the work, sleeve j and its auxiliary members are removed from the spring collet, and the work is screwed 160 MAKING FUSE PARTS position and back to slow just before the fourth position. Machining the Fuse Body. The fuse body is made from a hot-pressed brass blank, and is machined in two chuckings in "Gridley" multiple-spindle automatics. The first series of operations is performed in a "Gridley" 1%-inch multiple-spindle automatic in the order shown to the left in Fig. 13. The work is loaded in the chuck by hand. Forming tool A now advances and rough-forms the outer diameter, whereas flat drill B and trepanning tool C combine to drill the central hole and trepan the narrow channel. At the second spindle position, tool D finish- forms and necks the outer surface, while tool E counter- bores the surfaces of the recess. Die F at the third spindle position now threads the body, and at the fourth spindle position forming tool G turns down the outer end of the thread while a floating trepanning tool H finishes the coun- terbored and trepanned surfaces. It should be mentioned here that the hot-pressing of this brass part makes it ex- tremely difficult to machine, so that the edges of the tools dull rapidly. Second Series of Operations on Fuse Body. The method of holding the fuse body while the second series of opera- tions is being performed is shown in Fig. 14. The work- spindles A of the machine are fitted with special nose-pieces B, the inner surface of which is chamfered to receive the spring collet C, which is threaded to the end of draw-back rod Z>. The work is not gripped directly by the spring collet, but is first screwed into a special bushing E, having thin walls as shown. This bushing is not split but springs sufficiently to permit it to be closed in on the work and released when the collet pressure is removed. A flange G attached to the end of the spindle nose serves as a stop for the work and a gaging point for the operations. The regular collet closing mechanism is used, but as may be seen in the left-hand end, the finger holders are reversed. When the clutch ring H is pushed forward by the chuck-closer gripping fingers / swivel and draw rod D backward through contact with flange /. When the clutch ring H is moved MAKING FUSE PARTS 161 FORMING TOOL PILOTED COUNTERBORING AND FACING TOOL Machinery Fig. 15. Diagram illustrating Set-up for machining Timing Train Rings on "Gridley" Automatic backward, the gripping fingers release rod D, relieving the pressure of the collet on bushing E and the work. Referring again to Fig. 13, the second series of operations on the fuse body is shown to the right of the illustration. At the first spindle position, forming tool / advances and forms the exterior diameters, while drill / drills the hole 162 MAKING FUSE PARTS in the end. At the second spindle position, the rear part of the work is supported by a roll back-rest, while the regular turner K takes a cut across and chamfers the shoulder. At the same time counterbore L comes in, cleans up the drilled hole and faces the bottom. At the third spindle position, the diameter M is threaded with a plain die. At the fourth spindle position, a tool N operated from the turret cuts a series of concentric grooves in the flange of the fuse body. The grooving tool is cut away to clear the forming tool O which takes a light cut over the grooved face, finishing the body as illustrated. Machining the Stationary Timing Train Ring. The machining operations on the stationary timing train ring are shown to the left in Fig. 15, and as can be seen are of a comparatively simple nature. This fuse part is made from a Tobin bronze bar in a 2% -inch "Gridley" multiple- spindle automatic. At the first spindle position, a drill held on the turret drills the hole, and a forming tool on the cross-slide forms it to shape and breaks it down for the cut-off tool. At the second spindle position, the piece is reamed, and at the third position it is faced off with an under-cutting tool. In the fourth spindle position, not shown, the finished piece is cut off, and the stock is fed out. Machining the Graduated Timing Train Ring. The machining operations on the graduated timing train ring are almost identical with the stationary ring and are shown diagrammatically to the right in Fig. 15. This part is also made from a bar of Tobin bronze in a 2%-inch "Gridley" multiple-spindle automatic. The only difference in the op- erations on this part is in the use of a combination float- ing counterbore, and facing tool provided with a roller pilot. Machining the Closing Cap and Bottom Closing Screw. The closing cap and bottom closing screw for the shrap- nel timing fuse are made from brass rod with a compara- tively simple tool set-up as shown in Fig. 16. The machine used is a 1%-inch "Gridley" multiple-spindle automatic. The machining operations on the closing cap are shown to the left in the illustration, and consist in drilling, counter- boring, forming, threading, and cutting off. The opera- MAKING FUSE PARTS 163 COUNTERBORE \ FORMING TOOL FLAT FORMING TOOL. CUTTING-OFF TOOL CUTTING-OFF 'TOOL Machinery Fig. 16. Diagram illustrating Set-ups for machining Closing Cap and Bottom Closing Screw on "Gridley" 1%-inch Multiple-spindle Automatic 164 MAKING FUSE PARTS tions on the bottom closing screw, shown to the right of this illustration, are counterboring, forming, recessing, threading, and cutting off. FEED STOCK TO STOP */ DRILL BOTTOM HOLE REAM AND "BOTTOM" HOLES CUT-OFFTOOL ON BACK SLIDE Machinery Fig. 17. Method of machining Fuse Hammer on a No. 2 Model G Brown & Sharpe Automatic Screw Machine equipped with -an Eight-hole Turret Making Fuse Parts on Brown & Sharpe Automatic and Hand Screw Machines. A brief description of two of the many interesting set-ups on Brown & Sharpe automatic and hand screw machines for making timing fuse parts MAKING FUSE PARTS 165 is given in the following 1 . Timing fuse parts are made from several different materials. The screws and other small members as a rule are made from brass rod, whereas the parts such as the capsules, primer cups, etc., are made from sheet brass. Other members, such as the fuse body FORM AND CUT-OFF ERTICAL SLIDE TOOL Machinery Fig. 18. Diagram illustrating Method of Machining a Fuse Nut on a No. 6 Brown & Sharpe Hand Screw Machine or stem, are made from different alloys and metals such as copper, copper aluminum, aluminum, etc. Set-up for Making Fuse Hammers. The method of making a fuse hammer on a No. 2 Model G Brown & Sharpe automatic screw machine provided with a special eight-hole turret is shown diagrammatically in Fig. 17. This part is 166 MAKING FUSE PARTS made from %-inch round brass rod and is finished com- plete in the screw machine. First, the stock is fed out to the stop in the turret. Second, the end is centered and faced with tools held in tool-holder A. The body is then formed with a circular tool B working from the front cross- slide ; at the same time the turret is revolved, bringing tap drill C into operation. The forming tool is working at the same time as the drills. The turret is again revolved and drill D for finishing the middle hole is brought in and com- pletes its operation. At the next index of the turret, drill E finishes the bottom hole. The turret is now indexed and a recessing tool-holder carrying tool F advances and is brought into operation to recess the work by a pusher on the cross-slide. The turret is again indexed and a reamer G is advanced to bottom and ream the holes. Upon the next index of the turret, tap H threads the work, which is finally cut off with circular tool /. The stock is rotated at 973 R. P. M. forward and backward for drilling and turn- ing, and at 421 R. P. M. forward for threading. The stock is cut off rotating backward. The surface speed for the forming tools is 220 feet per minute and 31 feet per minute for the tap. Tool Set-up for Making Fuse Nut. The fuse nut on the Russian timing fuse is made from 1 %-inch round brass rod in a No. 6 wire-feed Brown & Sharpe hand-screw machine as shown in Fig. 18. First the stock is fed out to length, being gaged by a stop in a vertical slide, which is held in the turret. The turret is then indexed and drill A drills the large hole. The turret is now revolved and the combination drill B is advanced. The turret is again re- volved and counterbore C faces and counterbores the work. Upon the next index of the turret, a vertical slide tool-holder carrying recessing tool D is advanced. This tool-holder is operated by a handle attached to the holder. The turret is again indexed and tap E threads the work. After this the turret is indexed and the work is recessed with a tool-holder F carrying two cutters which balance each other in cutting. The seventh operation is performed from both the front and rear cross-slides with tools G and H. The eighth oper- MAKING FUSE PARTS 167 ation is cutting off. This is performed with a special verti- cal slide tool-holder held in the turret and operated by a handle. The stock for these operations is rotated at 352 R. P. M., giving a surface speed for the forming tools of 180 feet per minute and 66 feet per minute for the tap. Making Fuse Parts on Hand Screw Machines. The de- mand for shrapnel fuse parts has been so great that time has not been taken in all cases to tool up automatic screw machines before production has been started. In order to get parts out quickly while automatic machines are being tooled up, hand screw machines have been made use of. Fig. 19. Machining Fuse Parts on F. E. Wells & Son's Hand Screw Machine These machines are also used to a large extent on small orders and to help out production in general. Fig. 19 shows an F. E. Wells & Son Co. hand-screw machine work- ing on shrapnel fuse parts. The capacity of this machine is for %-inch diameter rod and it will tap or drill % inch diameter. Shrapnel fuse parts are produced on this ma- chine at the rate of from 25 to 100 pieces per hour. Drilling Percussion Primers for Fuses. The percussion primer, used in the American combination fuse shown in Fig. 3, Chapter I, is made in a Brown & Sharpe automatic screw machine from brass rod in two operations. Follow- 168 MAKING FUSE PARTS ing the screw machine operations, four holes about 1/32 inch in diameter are drilled through this bushing, employ- ing a special "snap index" jig in a high-speed ball-bearing drilling machine made by the Leland-Gifford Co. of Wor- cester, Mass. (See Fig. 20.) The extremely small size of this part makes it difficult to handle, so the jig was designed Fig. 20. Drilling Percussion Primers on a Leland-Gifford Ball Bearing Sensitive Drilling Machine with a special loading arm to facilitate rapid handling. The jig consists of a platform base bolted to the table of the drilling machine. Upon this is the index ring, which is turned by handles / and indexed for the four drilling posi- tions by spring plunger /. The center of rotation is in the center of the four holes in the part. B is the loading MAKING FUSE PARTS 169 lever, with a nest A at the end into which the work is slip- ped. This lever swings on stud C. The work is located in the swinging arm B when it is in the position shown in the illustration, with the arm B resting against stop D. The arm is then swung under the drill until it reaches stop E. It is maintained in this position by spring plunger H that bears against lever F, fulcrumed on stud G. The side of this lever bears against the work and holds it firmly Fig. 21. Drilling Fuse Plugs on "Avey" Drilling Machine while the drilling is proceeding. The drill is guided by four bushings in plate L, mounted on the index ring. The operation consists in rotating the index ring to the four stations for drilling the respective holes. By means of this quick-indexing ring, and the high speed at which the Leland- Gifford drilling machine runs, it is possible to drill as many as 6000 pieces, or 24,000 holes in ten hours. 170 MAKING FUSE PARTS Drilling Timing Fuse Plugs. An application of a regu- lar No. % "Avey" drilling machine, built by the Cincinnati Pulley Machinery Co., Cincinnati, Ohio, to the drilling of brass timing fuse plugs is shown in Fig. 21. The require- ments are to drill three No. 55 (0.052 inch) holes through the dome of the plug ; a number of pieces are shown on the table of the machine. These three holes practically run to- gether at the inside of the dome, making it necessary to drill one hole at a time. The fixture used for this purpose is of unique construction. The body A is made of an aluminum cast- ing, whereas the operating mechanism is of hardened tool steel. The drill spin- dle is operated by a foot treadle, connec- tion being secured through rod B, pass- ing down through the fixture and fast- ened to the spindle sleeve by the L- shaped piece and yoke C. The work E i^ij -_ Q C rm/ial work-spindle located inside the fixture that is indexed one-third revolution through the medium of rod B upon the raising of the drill spindle sleeve. The work holding-down and ejecting mechanism is supported in aluminum bracket F. Attached to this bracket is a supporting arm for the lower crank of Fig. 22. Graduating Timing Fuse Rings on Dwight-Slate Marking Machine MAKING FUSE PARTS 171 lever G, which holds a segment gear. Bracket D carries the drill bushing. After drilling the third hole, the operator depresses lever G, rotating the segment gear meshing in rack teeth in rod H, which lifts the latter up to eject the work and at the same time through a connection, not shown, raises the holding-down rod. The ejector, not shown, which is spring controlled, returns to a neutral position immediately upon the ejection of the work, while the holding-down rod is still raised. The work, after being discharged, falls into a chute and is carried to the rear of the machine. The operation of this fixture is rapid, the production being from 9000 to 10,000 pieces in ten hours. Graduating Fuse Timing Ring. As has been previously stated, the adjustable ring on the timing fuse is graduated in seconds, starting at zero and running to twenty-one sec- onds. As shown in Fig. 22, the graduating of this timing ring is performed in the Dwight-Slate marking machine built by Noble & Westbrook, Hartford, Conn. The main arbor of the machine carries the stamping roll A and is turned by the handle shown. The timing ring to be grad- uated and marked is held at B. The two gears C prevent the stamp from "creeping" ahead or slipping on the work. The work-holding arbor, as shown, is held in a bracket and is raised to the stamp roll by pressure on the foot treadle. Two operations are required for stamping and graduating the timing ring. The first is marking the graduations and the second is putting on the figures. CHAPTER VI MAKING SHRAPNEL CARTRIDGE CASES THE brass cartridge case that contains the powder charge for propelling the shrapnel shell from the bore of the quick-firing gun is drawn up from a blank of sheet brass. The number of operations necessary to complete the case depends on its size and the method of handling. Some shell manufacturers prefer to do more or less drawing at one operation, but in all cases the sequence of operations is practically the same. The material used for shrapnel cartridge cases generally consists of a composition of 2 parts copper and 1 part zinc. This alloy has been found to possess the best physical qualities, that is, great tensile strength and a high percentage of elongation when properly annealed. The drawing operations through which the cart- ridge case passes increase the hardness, and the ductility of the metal is restored by annealing. The annealing temper- ature in most cases is from 1150 to 1200 degrees F. On reaching this temperature, the work is either cooled off in water or allowed to cool off gradually, as the speed of cool- ing does not affect its physical qualities. In the following, two methods of handling the various operations will be de- scribed. Method of Making Cartridge Cases. Figs. 1 and 2 show the sequence of operations blanking, cupping, re- drawing, indenting, trimming, heading, and tapering, as advocated by the Waterbury Farrel Foundry & Machine Co., Waterbury, Conn., for making cartridge cases for 18- pound shrapnel. The first operation consists in cutting out a blank from %-inch sheet brass 6% inches in diameter. The next operation is cupping. This is handled in a short- stroke geared straight-sided press. Before re-drawing, the cup is annealed, and the third operation, which is handled in a longer stroke press, is then performed. Annealing fol- lows this operation, and then the fourth drawing or second re-drawing operation is performed. This consists in re- 172 CARTRIDGE CASES 173 Mr * 20 OPERATION-CUP k 1J4 11 ^ 3o OPERATION 1sT DRAW 4TH OPERATION-20 DRAW STH OPERATION- 1iT INDENTING 4" -+-K' % 6TH OPERATION 2o INDENTING &' H 4- >i 7TH OPERATION-3D DRAW M v *"4 k= y^. 51 I I STH OPERATION 4TH DRAW 10TH OPERATION CUT Off ENO DF CASE &TM OPERATION-DTH DRAW Fig. 1. Operations in making an "18-pound' Cartridge Case 174 CARTRIDGE CASES ducing the fillets slightly at the corners, decreasing the diameter of the cup to 4% inches and increasing its length to 4% inches. The dimensions given here are approximate. Indenting Operations. --The fifth operation or first in- denting operation, which consists in indenting the bottom, is handled in a press similar to that used for the cupping and re-drawing operations. This shortens the length of the case by % inch and forces the indentation about half way through the thickness of the stock. The second in- denting is then accomplished. This again shortens the case by an additional 14 inch and squares up the corners. The case, without annealing, is now passed through the third re-drawing, or seventh, operation, reducing its diame- ter to 4 inches and increasing its length to 5i/ 2 inches. It is annealed after this operation, and is then drawn to a shape 8 inches in length by 3% inches in diameter, and the wall decreased in thickness to 1/16 inch. The case is then annealed and passes through the fifth re-drawing operation. The machine used for handling the third, fourth and fifth re-draws is a long-stroke straight-sided rack-and-pinion press. After the fifth re-drawing, or ninth, operation, the case is trimmed and about two inches cut off the end. This leaves the case in better condition for the succeeding oper- ations. The trimming machine is of the horizontal type. Final Re-drawing Operations. The sixth re-drawing, or eleventh, operation is performed in a horizontal drawing press of the hydraulic type provided with automatic revers- ing valves. This operation increases the length of the case to 13*4 inches and reduces its diameter to 33/4 inches. After this operation, the case is annealed and then 1% inch is trimmed off the open end. The thirteenth and fourteenth operations consist in heading the case. These are practi- cally of the same nature, and combine to form the head of the case as shown in the illustration. The heading opera- tions each reduce the length of the case 1/4 inch, and are performed in a 1000-ton hydraulic heading press operated by a geared compound power pump and having a working pressure of 5600 pounds per square inch on the ram. After heading, the case is annealed and the fifteenth operation, CARTRIDGE CASES 175 ,12rn OPERATION TRIM CASE 12-INCH LONO T k %- ?! 11TH OPERATION-6TH DRAW -Jt IR-ru ODCDATI/Mu 1 ** TAO M OPERATION-18T TAPERING 17TH OPERATION TIM OFF V4" ,13TH AND UTH OPERATIONS- HEADING 16TH OPERATlON-2o TAPERING Fig. 2. Operations in making an "18-pound' Cartridge Case 176 CARTRIDGE CASES which consists of tapering, is performed. The first taper- ing, or fifteenth, operation reduces the mouth of the case to 3 9/16 inches in diameter and gradually tapers it for a distance of 5% inches half the length. The case is then annealed, pickled and washed, and a second tapering opera- tion is performed. This reduces the mouth of the case to 3% inches and tapers it completely to the head. The case is not annealed after the last tapering operation, but 1/4 inch is trimmed off the end. The various operations through which a cartridge case passes in drawing and forming to the correct length having been described, attention will now be given to the type of tools used for this purpose. These tools have been designed and built by the Ferracute Machine Co., Bridgeton, N. J., and are used with its presses for making cases for 3-inch projectiles. Cupping and First Series of Re-drawing Tools. The cutting out of the blank is frequently omitted because the specified thickness and size can be furnished by the mill. Before cupping, the dies and blanks are well greased, as this assists in drawing. Olive oil or soapy water is used, de- pending on the stage at which the drawing operations have arrived. The first cupping operation is accomplished with a punch and die as shown at A in Fig. 3. This operation is accomplished in a Ferracute 100-ton ram press equipped with a dial feed. The die consists of a hardened ring of tempered steel having an interior shape similar to a trun- cated cone. The punch is slightly tapered on the lower end and has an air vent hole drilled up through it to facilitate the drawing and produce a cup free from wrinkles. The second operation, or first re-drawing operation, is shown at B. Here the type of die used differs somewhat from that shown at A, in that the drawing angle is 15 in- stead of 45 degrees. The cup, after this operation, is re- duced in diameter to 3.877 inches and is 2% inches long. After the first cupping operation, the case is annealed. The second re-drawing operation is accomplished as shown at C. The die in this case is the same as at B, as is also the punch, except for an increase in the taper and change CARTRIDGE CASES 177 I_OL | CO _oj' ! OT.'T '~5 5TH DRAW HORIZONTAL SCREW PRESS Machinery Fig. 3. Tools for drawing a 3-inch Shrapnel Cartridge Case Ferracute Machine Co.'s Method in shape on the end. The object of this, of course, is to keep the case thick at the head but reduce the walls further up along the section. The case, after this operation, is also drawn out to a length sufficient to necessitate using a strip- 178 CARTRIDGE CASES ping device for removing it from the punch. This is accom- plished by six spring-operated stripper pins as shown, which slip over the top edge of the case as it is forced through the die, stripping it from the punch. The cup now passes through the third annealing operation and is ready for the third re-draw, shown at D. The press used for performing this operation is similar to that described, and the die and punch is similar in construction to that shown at C. Final Re-drawing Operations. For the final re-drawing operations, horizontal double-ended screw presses instead of the horizontal hydraulic presses formerly used are em- ployed. Horizontal presses are used because the length to which the cartridge case is drawn after the third re-draw is such that it exceeds the stroke of the vertical presses. The cartridge case, after each drawing operation, is an- nealed; E in Fig. 3 shows the fourth re-drawing tools, which are handled in a horizontal screw press. The die used is similar in shape to that shown at D, but the holder in which it is held differs, of course, owing to the difference in the type of press used. The stripping arrangement for removing the case from the punch is also of a different type. In this case five spring-operated stripper pins are held in a holder which is free to oscillate within certain limits in the block in which it is retained. The reason for having this oscillating stripper is that it accommodates itself to the irregular shape on the end of the case and gives practically a constant pressure all around the circumference of the case, assisting in removing it from the punch. The case is now annealed and is finish-drawn as shown at F. Here the same type of die, stripper arrangement, etc., is used as that shown at E. The case in the fifth re-drawing opera- tion is 14% inches long by 3.186 inches outside diameter. Annealing and Washing Cartridge Cases. As was pre- viously stated, the cartridge case, after practically every re-drawing operation, is annealed, being subjected to a tem- perature of about 1150 to 1200 degrees F. and then allowed to cool off or dipped in water which, of course, forms a scale on the surface of the case. This must be removed before any subsequent operations can take place. Several differ- CARTRIDGE CASES 179 ent solutions are used for this purpose, but a common one comprises the following : Sulphuric acid diluted with water to a strength of 1 to 4. This pickling solution is held in lead-lined wooden troughs and the case is allowed to remain in the bath varying from eight to fifteen minutes, accord- ing to the strength of the solution. The cases are then washed in lead-lined wooden troughs through which a stream of water is circulated to remove all traces of the acid. Testing Hardness of Cartridge Cases. The hardness of a cartridge case must conform to a certain standard. When too soft, a permanent set will occur from the pressure of Machinery Fig. 4. Fixture for testing Hardness of Cartridge Cases with Shore Scleroscope the firing charge and the case will stick in the breech of the gun. When the hardness is too high for a given com- position of brass, it is too brittle and will split, or the head may blow off. There is, therefore, a certain hardness which must be adhered to as closely as possible. Some manufacturers hold the standard to within 20 to 25 on the body walls and reject cases striking 15 as being too soft, and 30 to 35 as being too hard. Owing to the thinness of the walls of the case, it is im- possible to take a reading without rigidly supporting it, and for this purpose the Shore Instrument & Mfg. Co., 180 CARTRIDGE CASES 551-557 West 22nd St., New York City, has devised a spe- cial fixture as indicated in Fig. 4. This comprises a bracket A held in an ordinary vise, to which is fastened an anvil plug B, as indicated. In order to hold the case tightly against the anvil plug, a spring C, fastened to the bracket A, is also fastened to a yoke D surrounding the case. A rod attached to the yoke and to a foot treadle furnishes a means of drawing the yoke down to hold the case in contact with the plug. The anvil plug provides the weight or inertia to Fig. 5. Special Shrapnel Case Trimming, Facing, and Chamfering Machine resist the impact of the drop-hammer of the scleroscope, but in order to be sure that there is proper contact of the case with the plug a rubber cushion E is provided between the pressure ring or yoke and the brass case. Machining Shrapnel Cartridge Cases. The Bullard Ma- chine Tool Co., Bridgeport, Conn., has designed and built a number of special machines for performing the machin- ing work on the head and mouth ends of brass cartridge CARTRIDGE CASES 181 6TH OPERATION Machinery Fig. 6. Sequence of Operations performed on Cartridge Case in Machine shown in Fig. 5 cases. This machine, as will be seen from Fig. 5, is of the hand turret machine type, designed to work on the case from both ends. In this machine the brass case is chucked in the center of an extremely large spindle, and worked on from the head end with four sets of turret tools and two sets of cross-slide tools, while the mouth end is bored and 182 CARTRIDGE CASES trimmed with tools held on a carriage located on the back facing bar. The drive for the work chuck spindle is over a 16-inch pulley with a 3-inch belt. The pull of the belt is not taken directly on the spindle, but on a special pulley bearing 7% inches in diameter and 5 inches in width. The spindle itself is supported in bearings 9 inches in length and 5% inches in diameter. As previously mentioned, the spindle is hollow so that any type of shrapnel cartridge case up to 414 inches in diameter and from 10 to 18 inches in length can be machined. Fig. 7. Set-up showing First Operation on Cartridge Case Head From the construction of the machine in Fig. 5 it will be seen that the front end of the spindle carries a large three-jaw chuck of special design. These jaws catch the cartridge case just under the head and revolve it for ma- chining. The case is supported internally by a tubular arbor which also acts as a stop and is attached to a rod extending to the rear bracket where it is backed up by a spring. The front end of this tubular support or stop is provided with a thrust ball bearing so that the case can be loaded in the chuck while the spindle is running. When the chuck operating lever is manipulated to close the chuck jaws on the work, it first draws back the rod mentioned CARTRIDGE CASES 183 through the medium of a tie-rod and the rear bracket to a positive stop, and then closes the jaws on the work. The cartridge case is put in and removed from the chuck with Fig. Set-up showing Fourth Operation on Cartridge Case Head Fig. 9. Set-up showing Operations on Mouth End of Case the turret indexed between stations to give the required space. The back boring and trimming head is held on a hollow spindle through the center of which the rod passes. This 184 CARTRIDGE CASES spindle is provided with rack teeth on its top surface which engage with a pinion located in the extension bracket and operated by a handle. The forward position of the boring and trimming head is governed by a stop-collar. Fig. 10. Set-up showing Sixth Operation on Head End of Case Fig. 11. Set-up showing Seventh Operation on Head End of Case Sequence of Machining Operations on Cartridge Case. -The sequence of machining operations performed on the o> X O SI ^H ,i_j < .2 & O 4-i -t-> e .a S^JI|S 1^ o^|^ 03 111 a a S O .3? S O <> .g ^^2.5 S >. * 1 * ' "' 5 ^p g^ 3 ^ - , . a s ho f-t :I3 a) v> S JL H- o .22 ^ O bo o .^ ill I'SjJiJll CD b>^ O2 tj_j Li ** K Illllll O , ^ ^ -M 02^ 186 CARTRIDGE CASES The following operations are now performed on the mouth or open end of the cartridge case as shown in Figs. 6 and 9, with the spindle running at the same speed 500 R. P. M. as that used for the first series of operations. Two tools H and / are used. Tool H bores the mouth of the case for a distance of 1 inch, whereas tool / trims off the open end of the case and rounds the edges. The mouth of the case at the rear end of the spindle is supported by a hardened 4TH OPERATION FRONT CROSS-SLIDE BLOCK 2ND OPERATION Machinery Fig. 13. Diagram illustrating Machining Operations on French Cartridge Case on Potter & Johnston Machine bushing to prevent it springing away from the action of the boring tool. The boring and trimming tools are mounted in a special head J, Fig. 9, that is operated back and forth by a handle K through the medium of a rack and pinion. The forward movement of this head, as previously explained, is controlled by means of an adjusta- ble collar L screwed onto spindle M. CARTRIDGE CASES 187 The work-spindle is now slowed down and the following operations, shown in Figs. 6, 10, and 11, are performed on the head end of the case. The sixth operation is to finish- counterbore and ream the primer pocket with tool O held FIRST OPERATION THIRD OPERATION RECESSING TOOL SIDE ELEVATION CAM ON CROSS-SLIDE """ FOR OPERATING VERTICAL SLIDE TOOL Fig. 14. Tooling Set-up for Machining 18-pound Cartridge Case in an adjustable holder, whereas the seventh operation is threading the primer pocket with collapsible tap P. The chuck lever in Fig. 5 is now manipulated, first, releasing the grip of the chuck jaws on the case and, second, advanc- 188 CARTRIDGE CASES ing the rod to eject the case sufficiently to enable it to be easily removed from the chuck. The spindle is changed to the highest speed after the next case is put in. In changing the work, it is not necessary to stop the spindle. Machining Shrapnel Cartridge Cases on Potter & Johnston Automatics. The cartridge case is made from sheet brass as previously stated. It is practically formed to shape in drawing and heading machines, but to secure the desired accuracy on the head and primer pocket these surfaces are Fig. 15. Tool Set-up for Machining 18-pound Cartridge Case machined. The method of holding the French 75-milli- meter case on a No. 5A Potter & Johnston automatic chuck- ing and turning machine for machining the head and primer pocket is shown in Fig. 12. Here it will be seen that the cartridge case butts up against a stop B and fits over the tapered plug C, which steadies it. It is held in place by an ordinary draw-in collet D. This is operated by means of a lever E, fulcrumed to a bracket on the rear end of the machine and operating a sliding clutch collar. The chuck CARTRIDGE CASES 189 is operated through fingers which draw back the sliding sleeve to which it is attached. These fingers operate against a spring at the rear of the spindle which serve to open the collet. The machining operations on the French shrapnel cart- ridge case are handled in the manner illustrated in Fig. 13. The first operation is to rough-drill the hole in the head. The turret is then indexed, bringing in a roughing reamer which reams the hole previously drilled, whereas the front cross-slide carries tool B that faces the head and a circular tool C that rough-forms the external diameters of the head. Upon the next indexing of the turret, the tool D counter- bores the powder pocket and the circular forming tool E finish-forms and rough-chamfers the head. The last oper- ation consists in finishing the primer pocket with a taper reamer F. Machining the British Shrapnel Cartridge Case. The brass cartridge case for the British shrapnel is more difficult to machine than the French case, as refer- ence to Figs. 14 and 15 will clearly show. The machining operations are accomplished on a No. 5A Potter & Johnston automatic chucking and turning machine having a five- sided turret. The first operation is to drill the primer pocket hole with a three-step drill A. The turret is now indexed and the surfaces previously roughed out are fin- ished with inserted-blade counterbore B. At the same time, the head of the case is faced with a relieving tool C held on the cross-slide and rough-formed with circular tool D. The turret, in being indexed to the third position, brings vertical recessing tool E into operation. This carries two cutters, one of which recesses the primer pocket at the point where the thread is to terminate, whereas the other removes the burr and faces the inner boss. In the fourth operation, the smallest diameter of the primer pocket is reamed and the largest diameter of the hole chamfered by tools held in bar F. The rear cross-slide is advanced at the same time, carrying the circular tool G that finish-forms the head. The final operation threading is performed with the "Geometric" collapsible tap H. Q 190 III 5 ZO i O -4-3 ; SS .2^5 c O^ ^ >> II P PQ ^ M 2 00 O OO O O GO O O Tt< GO 00 OO GO T* CO ^^ ^l ^H TH CO CO WWW 8 e 3 g 3 o -o A* 3 g gg o o o TH -tS -M 8~ e" e~ o> .2 ^> O be II I- s l M l^l *! SftSI - . w - d J 3 a S to o t^ to GO > CO TH 1~> il CO 00 t- t- co' co* bJO rt S ^ 'ra :R *Q ^&.S S fftll ^.&l s , P.3^C !R'Pw g.a* H ^ M>ef "w "H illlllllllff 111 1 |||fi||i| w s| lii '-SJtJJgjIJe^ g|s? 2 ^H 'O -t- 3 03 . C3 bO j3 rrj bC bC S !* ijliliMtii ii^iii-iiiiit CO O O i-t 00 OSO-r-i JH4 =$' U0.14L0.134 2JTHDS. PER INCH R. H' ^T^ T^DS. PER INCH R. H. BODY ALUMINUM HOLES DIA. X 0.05 DEEP 2.36 L2.34 Machinery Fig. 2. Body of Russian Combination Time and Percussion Fuse (Vickers Type) obstacle. At this instant the lower percussion arrangement, releasing itself from the grip of the lugs of the counter safety catch and compressing the counter safety spring, approaches the needle, which punctures the detonating cap ; the flame from the latter together with the flame from the powder of the chamber bushing are transmitted to the bursting charge in the shrapnel shell. When the fuse is set for "grape shot," the transmitting openings in the time rings and the ignition openings in the flange of the stem 228 RUSSIAN COMBINATION FUSE are brought so close to one another that the bursting of the shrapnel must take place on the average not farther than 42 feet in front of the muzzle of the gun. Russian Combination Time and Percussion Fuse Vickers Type. Since the outbreak of the present war, various fuses have been used on Russian shrapnel shells. One of the principal of these fuses is the Vickers type of combi- nation time and percussion fuse shown assembled in Fig. 1, and in detail in Figs. 2, 3, 4, and 5. While the original Russian fuse shown in Fig. 4, Chapter I, and described in the preceding pages, has, up to the present war, been the only fuse used in this shell, it has largely been replaced by ^ a H0.20 TOP RING ALUMINUM 0.1 02 0.035 .152 BOTTOM RING ALUMINUM Machinery Fig. 3. Top and Bottom Time Rings on Russian Combination Time and Percussion Fuse (Vickers Type) other fuses, because of the difficulties experienced in manu- facturing it. The Vickers type of fuse is somewhat easier to manufacture and, therefore, has been used to some extent on Russian shrapnel shells. Another fuse that is now be- ing adapted to the Russian shrapnel shell is the American combination time and percussion fuse, Fig. 3, Chapter I, which is also of the same type as the British fuse described in Chapter XI. The chief difference in design between the , ,. I1.4L1.39 122L0.12-*) \^ I* -H 1.618 1 24THDS.PERINCHR.H. __ 14 THDS.PER I NCH R.H. CAP. TABLET BOTTOM RING, TABLET TOP RIN INTERPOSED BETWEEN VEGETABLE PAPER VEGETABLE PAPER CAP AND LINEN WASHER BODY CLOTH THICKNESS H 0.045 L 0.035 WASHER, BOTTOM RING, VEGETABLE PAPeR WASHER, BOTTOM RING, CLOTH THICKNESS H 0.0*5 L 0.035 DISK. ESCAPE HOLE. TABLET, FLASH HOLE vFf-ETArn e PAPER IN TOP RING, 2 PER FUSE DISK ' ESCAPE HOLE . SILK PAPER ALUMINUM 2 PER FUSE STIRRUP SPRING, TIME RD-ROLLED SHEET BRASS Fig. 4. Details of Russian Combination Fuse (Vickers Type) 229 230 RUSSIAN COMBINATION FUSE WIRE 0.04 DIA. (APPROX.) 4 STRANDS 0.018 DIA. END OF WIRE SECURED IN FLANGE OF FUSE BODY LENGTH OF WIRE-ABOUT 15..5 A -H 0.575 L 0.567 5\ FERRULE BRASS STRIP SECURING WIRE COTTON TAPE CEMENTED TO COVER DISK, SCREW PLUG PERCUSSION DISK i TIME PELLET, DETONATOR, PAPER CARD-BOARD Machinery Fig. 5. Details of Russian Combination Time and Percussion Fuse (Vickers Type) standard Russian and the Vickers type of combination time and percussion fuse is in the percussion and concussion ar- rangements. It will be noticed in Figs. 1 to 5, inclusive, that the details of the Vickers fuse are much simpler to manu- facture. There is also an absence of the numerous springs in the original Russian fuse. CHAPTER IX SPECIFICATIONS FOR THE MANUFACTURE AND IN- SPECTION OF RUSSIAN 3-INCH SHRAPNEL AND HIGH-EXPLOSIVE CARTRIDGE CASES The following specifications are abstracted from the offi- cial specifications for the Russian brass cartridge cases for 3-inch shrapnel and high-explosive shells, and contain all the essential information relating to the requirements in the manufacture and inspection of these cartridge cases. Clause 1 . The Rights and Duties of the Inspector. The inspector's duty consists not only in acceptance of the cart- ridge cases manufactured, but also in looking after the methods used in the manufacture of the cartridge cases, and the brass used for them. In order to do this, the in- spector must have the right of access to any work and tests referring to the cartridge cases ; he must have the right to enter any shop during any time of the day or night, where the manufacture of the cartridge cases ordered may take place, i. e., the casting and rolling of the brass, drawing, annealing, finishing, etc. If the firm with whom the order for the cartridge cases is placed does not cast brass, but obtains it from other works, the inspector has the right to visit these latter works in order to ascertain the quality of the casting (and quali- ties of copper and zinc) , method of cutting the top and bot- tom parts of castings, method of rolling, etc. The inspector's expenses with reference to his journey to the brass works in such case must be borne by the firm with which the order for the cartridge cases has been placed. The minimum number of the necessary journeys must be determined be- fore the placing of the order. The firm, which is manufacturing the cartridge cases, must have a testing machine for the mechanical tests of the metal used for the cartridge cases; it must also possess a microphotographical laboratory for the brass (the power of the microscope must be at least 100). The firm must 231 232 RUSSIAN CARTRIDGE CASE furnish the inspector with the results of all the chemical, microscopical, thermal, mechanical and any other tests car- ried out on the brass used for the manufacture of cartridge cases, as well as on cartridge cases themselves. In addi- tion to this, the inspector must be given the right to use all the firm's testing plant for the above-mentioned tests. The inspector must carry out the specified tests mentioned in the following for the acceptance of the cartridge cases. Independently of the above, if the inspector thinks it necessary, for the purpose of ascertaining the qualities and evenness of the material used for the cartridge cases, as well as the cartridge cases themselves, to carry out in addi- WEIGHT OF CASE WITHOUT PRIMER NCES DRAM 2 9 H. 12.776" L. 12.736- H.15.168"L. 15.148 Machinery 1 Russian 3-inch Cartridge Case tion some other trials, the firm must provide him with all necessary assistance. The firm must place at the sole disposal of the inspector sufficiently large dry and heated accommodations for carry- ing out his inspection, provided with cupboards for his gages; scales must also be provided; the place must be lighted by electricity, and all necessary power for the in- spection must be provided ; gages ; and a microscope of from 40 to 50 power. All gages used for the gaging of cartridge cases must be checked by the inspector before the beginning of the in- spection, as well as during the inspection. Before submit- ting the cartridge cases manufactured to the inspector, the RUSSIAN CARTRIDGE CASE 233 works must submit them to their own examiners. These examiners must work according to the rules given them by the works, and prepared in conjunction with the inspector. The firm must provide their examiners with a separate set of gages manufactured similarly to those supplied to the inspector. The inspector has the right to inform the management of the works of all defects noticed by him in the manufac- ture of the cartridge cases, as well as of those defects which occur in the cartridge cases submitted for acceptance. Fi- nally, he has the right to suggest some improvements in the manufacture of the cartridge cases ; it is left to the discre- tion of the management of the works to make use of the above suggestions, if it is found advisable by them to do so, but the inspector has no right whatever to interfere with the orders issued by the management of the works. Clause 2. Test Consignment. Before beginning the manufacture of the order, the works must submit a test consignment. The cartridge cases for test consignment must be manufactured to the approved drawings, and made of brass according to these specifications. During the manu- facture of the cartridge cases, it is required: 1. That the annealing of the cartridge cases shall be regulated to prevent any over-heating of the metal. 2. That after the cartridge case is properly formed, the upper half of the case shall be definitely annealed at a temperature not less than 400 degrees C. 3. That the mechanical quality of the metal in the manu- factured cartridge case shall be in accordance with these specifications. The method of manufacturing the cartridge cases, as well as the regulation of the annealing before drawing, is left to the discretion of the works. The test consignment must be inspected and gaged by the inspector, and then sent for firing tests. The inspector must measure, on all cartridge cases in the test consignment, the diameter of the case near the bottom next to the flange, at a distance of !/2 an d l*/2 inch from the flange. After firing the first round, all cartridge cases must be inspected and measured on the same diameters on which 234 RUSSIAN CARTRIDGE CASE they were measured before firing. The cartridge cases showing the maximum increase of diameter are to be re- sized after each round, together with those that are doubt- ful with regard to strength, if such re-sizing is allowed by these specifications. The cartridge cases spoiled during re-sizing must be replaced by new ones from the same con- signment, but these new cases must be fired the same num- ber of rounds as the old spoilt cases. The consignment will be accepted: 1. If all cartridge cases after firing are extracted with- out any difficulty. 2. If no case shows longitudinal or transverse cracks (or any other cracks). The cartridge cases which are supplied together with shell must be checked and examined in order to ascertain whether the shells are sufficiently secured in the case. The test consignment of cartridges must be manufac- tured at the expense of the works, but the tests are carried out at the expense of the government. In the case of an unsatisfactory test of the first consign- ment, the works have the right to submit a second test consignment. In the case of unsatisfactory results of the tests of the second consignment, the military administra- tion has the right to cancel the contract. The inspector has to weigh all cartridge cases of the test consignment, ascertaining thus the mean weight. In addi- tion, the inspector must carry out the following test on the cartridge cases of the test consignment: 1. Chemical composition of brass. 2. Mechanical and microphotographical qualities of metal in the manufactured cartridge cases. 3. The temperature of the last annealing, i. e., the tem- perature of annealing before last drawing, temperature be- fore compressing, and temperature of the final annealing of the finished cartridge case. The temperatures of annealing must be ascertained by pyrometers. For this purpose such pyrometers as Ferry may be used, in which the temperature is ascertained by the color of the object heated. RUSSIAN CARTRIDGE CASE 235 The methods of manufacture of the order of cartridge cases must be similar to those used for the manufacture of test consignment. In case of any alterations in the method of manufacture, the works must inform the inspector to that effect, and he must report the matter to the military administration with his opinion on the value of such altera- tion in manufacture. It is left to the discretion of the mili- tary administration to allow such alteration or to demand from the works the delivery of a new test consignment. A firm which has already manufactured cartridge cases of certain type may be released from the delivery of a test consignment, provided the methods of manufacture have not been altered. Clause 3. The Acceptance of the Brass. The brass used in the manufacture of cartridge cases must be of the following composition : Copper from 67 to 72 per cent. Zinc from 33 to 28 per cent. The proportion of other metals must not exceed 0.5 per cent, except tin, which must not exceed 0.3 per cent. During the manufacture of cartridge cases in the same consignment, the variation of copper in the brass must not exceed + 1 per cent, or 0.5 per cent compared with the usual composition used by the works which composition must be given to the inspector before the manufacture of the test consignment. The method of manufacture of brass is left to the discretion of the works. The only require- ments are as follows: 1. The cast ingots must be annealed before first rolling. 2. All rolling must be carried out in the same direction, thus allowing the top end of the casting always to be distin- guishable. The top or bottom portion of the castings must not be used for the manufacture of cartridge cases. They must be cut from the ingots by the works manufacturing the brass, or the blanks for the cartridge cases must be cut at a certain distance from both ends of the ingots. On receipt of the brass ingots, the works manufacturing the cartridge cases must inform the inspector to that effect, giving him 236 RUSSIAN CARTRIDGE CASE the chemical analysis and the composition of the casting. The consignment of the brass must be sufficient for the manufacture from it of the whole consignment of the cart- ridge cases. At the works which manufacture the brass, test bars must be cast from the same furnace and from material of the same quality, melted in a similar manner, and stamped with the same number as the castings. This number must be stamped at the bottom of the cartridge case. The brass used for tests must be submitted to the inspec- tor in bars, and the cutting of the test disks from the bars must be carried out under the inspector's supervision. A few bars are to be used for the microscopical analysis. The bars of each consignment must be stamped with a number, which number must be stamped afterwards on the blanks during all the drawings. This number must also be stamped on the bottom of the case, as mentioned. These numbers must be put by the inspector in the report together with chemical analysis of metal, composition of casting, number of rods delivered, time of delivery, name of brass foundry by which the brass has been supplied (if the manufactur- ers do not manufacture brass themselves), and the num- ber of test disks cut. For each consignment of cartridge cases manufactured from brass bearing a certain number, at least one chemical analysis must be made. The brass not answering to the requirements of the chemical analysis will be returned to the manufacturer for re-casting. To insure that the amount cut off from the top and bot- tom of the rods is sufficient, the inspector must ascertain from the first consignment the number of cartridges man- ufactured, with defects inside as well as outside, from (1) disks cut from upper end of rod, (2) disks cut from roller end of rod, and (3) disks cut from the remaining part of rod. The percentage of cartridge cases with defects, in the above-mentioned three groups, must not differ materially from each other. The above-mentioned tests must be car- ried out from time to time during the manufacture of the cartridge cases. RUSSIAN CARTRIDGE CASE 237 The following methods can be used to ascertain that the ends of any rod are cut off sufficiently: 1. At the center of the rod, cut a piece from the top of the upper blank; the transverse surface of the piece must be polished and etched with a weak solution of nitric acid ; if the piece cut off from the top end was not sufficient, the test piece will show, in the middle, more or less solid black lines, inside of which, under the microscope, it will be pos- sible to see small microscopical flaws and foreign substances. 2. The transverse test piece cut in the above-mentioned manner must be broken in a testing machine; if the top portion was not sufficiently cut off, the middle of the piece will show ruptures in the metal. Clause 4. The Arrangement of the Cartridge Cases in Lots. The cartridge cases for delivery must be arranged in lots. It is desirable that the cartridge cases in each lot should be manufactured from one casting of brass metal. If the lots are compiled from the cartridge cases of differ- ent castings, it will be necessary to select cartridge cases for the control test from all the castings, and the cases left over from the lots already tested and accepted may be placed in the new lots without repeated tests. The dimensions of punch and die for the last drawing must be verified from time to time. The control of the an- nealing must be carried out by means of a pyrometer. The cartridge cases in each lot must be inspected as follows : 1. Outside inspection. 2. Inspection of dimensions and weight. 3. Mechanical test of the metal. 4. Firing test. Clause 5. Outside Inspection. The cartridge cases, before submission for inspection, must be cleaned inside and outside with sawdust and sand, or with brushes. The fol- lowing defects usually occur in the cases. 1. Cracks. Longitudinal cracks chiefly occur at a dis- tance of two or three inches from the flange, and, gener- ally speaking, form two parallel lines very slightly notice- able on the inner surface. Transversal cracks, slightly no- ticeable, generally occur above the flange at the bottom ; they are always on the outside surface and very seldom pene- trate through. Cases with such defects must be rejected. 238 RUSSIAN CARTRIDGE CASE 2. Ruptures. These defects usually are on the outer or inner surface of the cases and show that something is wrong with the metal ; cartridge cases with ruptures are re- jected without further consideration. Slight ruptures found in the corner of the socket for the primer do not af- fect the strength of the case and are, therefore, allowed. 3. Flaws and Fissures. Cases submitted to the inspector after being filed and cleaned on the inner surface are re- jected. Cases with flaws and fissures on the inside sur- face must be submitted to the inspector separately from the others and the filing of them must be carried out under the inspector's supervision. The inspector has to determine to what extent the flaws are vital. Special attention must be paid to the flaws on the rim and on the tapered portion. 4. Scratches. These are usually due to the punch, or to dirt which may have been in the punch. Small scratches do not vitally affect the strength of the cases. Oases with deep scratches are rejected, especially if on the inner side of the case a very noticeable mark is seen, extending to the lower part of the case. 5. Scars. Small scars which make the surface of the case dull are allowed. Large scars on the surface giving the appearance of a grained surface indicate too high a tem- perature in annealing, and cases with such scars must be rejected. 6. Dents. Dents, if rectified, are allowed on cases if they are not important ; they are not allowed on the conical portion or at the end of the case. 7. Goffering. Goffering on the inner surface of the case is usually due to the uneven drawing of the metal in the case of very rigid material ; it is due to defects in the uni- formity of the material. Goffering does not appreciably affect the strength of the cases, and therefore cannot gener- ally be taken as a reason for rejection. A large amount of goffered cases shows that there are some abnormal con- ditions in the manufacturing of the brass or the cases them- selves. In such cases the inspector must point this out to the works, and if the works will not take measures to re- move these defects the goffered cases must be rejected. RUSSIAN CARTRIDGE CASE 239 8. Folds. Folds of metal are sometimes noticed inside the case at the bottom and show bad manufacture. Cases with such defects are rejected. 9. Other Small Defects. Dents at the bottom, inside, and other small defects are allowed at the discretion of the inspector. Clause 6. Gaging. Cases which pass satisfactory out- side inspection must be gaged by means of gages for maxi- mum and minimum allowances. The dimensions gaged are as follows: 1. All outside diameters of the cases must be gaged with ring gages or half ring gages. 2. The inner diameter of the end of the case is gaged with calipers. 3. All outside dimensions of the bottom of the case are as follows : (a) Diameters of flanges by half ring gages. (b) Thickness of flanges with snap gages. (c) Concentricity of the bottom of the case by ring gage. 4. The thickness of the bottom by special gage. 5. Concentricity of the hole for the primer, by special gage. 6. All dimensions of the hole for the primer must be gaged with a set of corresponding gages. 7. The flatness of the surface, the absence of cuts and hammering of the metal around the hole for the primer with a straightedge. 8. The outline and the length by a special gage. 9. The thickness of the walls is gaged by means of a snap gage with cut corresponding to the thickness of the cartridge case at the end, by a small special gage with pointer for ascertaining the thickness of the walls as well as the depth of the cleaning away in places near the end of the case, and by a special gage with pointer for ascer- taining the thickness of the walls along the whole length of the case. For the purpose of ascertaining that the outline of the cases is correct, the inspector has the right to select 0.2 per 240 RUSSIAN CARTRIDGE CASE cent of the cases from the lot, choosing preferably from the rejected cases; special attention must be paid to the differ- ence in thickness of the walls at the lower end of the cases. To ascertain the similarity in weight, all cases must be ,weighed ; the difference from mean weight must not exceed the limits fixed for each caliber of the cases. If during the preliminary examination of the cases more than 15 per cent are found defective, as regards the metal or dimensions, the inspector has the right to stop the further examination of the cases submitted, and to ask the firm to re-submit them again. If, after re-submitting, and during the second examination of the cases, more than 5 per cent are found unsatisfactory, the whole lot will be rejected. Clause 7. Mechanical Tests. In the following para- graphs are given special conditions for the acceptance of cartridge cases for the guns of different calibers. As a general rule, the mechanical qualities of the metal used for cartridge cases must comply with the following conditions : 1. The rigidity of the bottom and the lower end of the cases must be sufficient to insure the proper extraction of the cases. 2. The rigidity of the end of the cartridge must insure the proper grip of the shell, and for the howitzer cases must not show any dents on the metal. 3. The rigidity of the metal along the whole length of the case must change evenly, without sudden changes. During the manufacture of the cases, care should be taken to work the metal as near as possible to the lower limits of the rigidity of the metal, as any extra rigidity affects the strength of the case during firing and in storage. The mechanical qualities of the cases must, as far as pos- sible, be alike; they are tested (a) by a breaking test of the metal used for the cases ; (b) by ascertaining that the shell is fixed properly in the case (a casting may be used for this purpose manufactured to the dimensions and the weight of the proper shell) ; (c) microscopical analysis of the metal; and (d) any other methods at the discretion of the inspector, as, for instance, by ascertaining the hardness of the metal, compression of the mouth of the case, etc. RUSSIAN CARTRIDGE CASE 241 For the tensile test the inspector selects from each lot about five cases rejected on account of the dimensions ; these are cut in halves for the purpose of ascertaining the thick- ness of the walls. The number of cases used for mechanical tests may be increased by the inspector if it is required by the quality of the material. From each case selected for the mechanical test, three rings must be cut, one inch wide ; one next to the flange, iy% inch above it; one from the mid- dle of the mouth; and one immediately under the conical portion, if such portion exists ; otherwise from the middle of the case. The rings cut in the above manner must be cut longitudinally and straightened by delicate hammering with a wooden mallet or by rolling between wooden rollers. From each strip obtained in such manner two test pieces must be cut with a distance between marks of 1.97 inch (50 milli- meters). The width of the test pieces must be the same. Ten division marks must be made on the test pieces, each division being 0.197 inch (5 millimeters). During the mechanical test, the following data must be ascertained: Breaking stress, total elongation, and local elongation be- tween all division marks. Clause 8. Firing Proof. After the examination of the whole consignment, the inspector selects some cases for proof by firing. The inspector chooses for the firing trials those cases which he considers the least satisfactory. The works have the right to re-examine the cases selected by the inspector for firing, and remove any case selected by the inspector ; but, in such an instance, all cases with similar de- fects are to be rejected, and the inspector replaces the cases removed by the firm. The works have not the right to re- move the cases selected in the above manner more than twice for each consignment. The firing proof of the cases must be carried out at any place selected by the artillery administra- tion, where the cases must be delivered by the works. The firing proof must be carried out in a similar manner to the test consignment, and the submitted consignment is accepted : 1. If all cartridge cases after firing are extracted with- out any difficulty. 242 RUSSIAN CARTRIDGE CASE 2. If no case shows longitudinal, transversal or any other cracks, or ruptures of metal. If during the firing trials one case shows a crack or is difficult to extract, the works have the right to review the consignment and submit for the firing trials a second set chosen by the inspector. In such instances, the works have no right to remove any case selected by the inspector for secondary proof ; the number of cases selected for secondary proof as well as the number of proof rounds fired may be increased. For the acceptance of the consignment, all cases must give satisfactory results in the second firing test. If the two consecutive firing proofs will give unsatisfactory results, the artillery administration has the right to cancel the contract. The firing proof is carried out at the expense of the government, and the cases normally used are counted as part of the consignment. The fired cases, after re-sizing, annealing and inspection, are submitted by the works to the inspector, and afterwards they must be packed in separate boxes. The cases required for secondary proof must be at the expense of the manufacturer. Clause 9. Varnishing. In case of satisfactory results of firing proof, the works varnish the cases inside as well as outside. The varnish must be used evenly. When scratched with a wooden point or with the finger nail, the varnished surface must not show any impression; when scratched with a metallic point the varnish must not crum- ple, and must not show any cross cracks. The varnish on the cases must not alter its appearance if placed for twenty- four hours in water, and after removal from the water and again dry, it must adhere so firmly as not to be removable under pressure of the finger. The specific gravity of the varnish must be from 0.9 to 0.94. Brass strips covered with the varnish must not show any oxidizing action. After the heating of the varnished strips during 24 hours in the water bath at a temperature of 167 degrees F., the varnish, when heated, must not peel off. For the purpose of ascertaining the character of the reaction of the varnish, 10 cubic centimeters (0.61 cubic RUSSIAN CARTRIDGE CASE 243 inches) of solvent must be distilled from 100 cubic centi- meters (6.1 cubic inches) of the varnish, and the solvent obtained in this manner, when mixed with a weak solution of litmus, must not give an acid reaction. Clause 10. Stamping. The cases must be stamped as follows: On the top, the number of the consignment of brass ; at the left, number of the consignment of the cases and the year of manufacture; on the right, the firm's in- itials ; at the bottom, the inspector's stamp, which must be placed after the inspection, and the stamp which means ac- cepted and which must be placed after the firing proof. The letters and figures must not exceed Vs inch in height. Clause 11. Packing. The cases, after being wrapped in paper, are covered with straw caps and packed in strong wooden boxes. These must be dovetailed from pine or fir wood, with rope handles and iron bands. The lids must be fixed with screws. The works have to pack the cases to the satisfaction of the inspector. To ascertain the accuracy of packing, the inspector turns over one of the boxes chosen, and after that the case must not show any dents or any noticeable damage to the varnish on the cases. Fifty cases are packed in each box. The boxes must have the following marking: Accepted Cases: Fired Cases: Caliber of Cases Caliber of Cases Name of Works Name of Works Year of Manufacture Year of Manufacture Number of Cases in Lot Number of Cases in Lot Number of Consignment Fired, but Good for Use Number of Consignment Condition for Acceptance of Cartridge Cases for 3-inch Field Guns. The test consignment must consist of fifty cartridge cases. The proof must be carried out from the gun with pressure of about 15.75 tons per square inch (2400 atmospheres). Ten cases are selected from those showing the maximum increase of diameter and are used for re- charging; they must be re-annealed after each round; all doubtful cases must be added to the above-mentioned cases. Each of these cases must stand eight rounds. 244 RUSSIAN CARTRIDGE CASE The gaging must be carried out as follows : Dimensions in Inches Normal Reject 1. Diameter of the case near bottom, gaged with half ring gages 3.294 3.286 2. Diameter of flange, gaged with half ring gages 3.547 3.539 3. The outside diameter of the end, gaged with half ring gages, and with gage inserted in the case 3.004 3.000 4. The inner diameter of the case 2.923 2.9?7 5. The thickness of the flange 0.142 0.134 6. The thickness of the bottom, gaged with special gage . 0.157 $+0030 "j 0.010 7. The concentricity of the hole for the primer must be gaged with special gage. 8. The concentricity of the flange with reference to the body must be gaged with half ring gage, the dimensions of which must be as follows: (a) Maximum diameter of flange. (b) Maximum diameter of the case at bottom. (c) Maximum thickness of the flange. 9. The outline and the length of the case must be checked by special chamber gage. The allowance for length must be 0.010 inch. 10. The gaging of the hole for the primer is carried out by the fol- lowing gages: (a) Screw gages, normal and reject. (b) Normal gage which is used for the gaging of the whole diameter and the depth of the hole for the primer, normal and reject. (c) Reject gage for the flange of the primer. (d) Reject gage for the thread. (e) Reject gage for the plain surface of the hole. (f) Normal and reject gages for the thickness of the hole for the flange of the primer. (g) Normal and reject gage for the depth of the plain portion of the hole, (k) Gage for the ignition hole. 11. Normal and reject gage for the height of the boss for the primer. 12. Gages, compasses and special gages for the thickness of the walls and for the depth of filing of the inner as well as the outer surfaces. 13. Straightedge for gaging the bottom surface of the case. The difference in the weight of cases from mean weight must not exceed 3 ounces. The test pieces subjected to the tensile test must show the following breaking stress: (a) At the ends, 48,000 to 57,000 pounds per square inch, with local elongation not less than 60 per cent. (b) Next to the flange, from 64,000 to 85,000 pounds per square inch. (c) Next to the conical portion, not less than 52,500 pounds per square inch. RUSSIAN CARTRIDGE CASE 245 Firing Trial. : For the firing trials, thirty cartridge cases must be selected. These cases must be measured and must pass a similar test to that of the test consignment, with the following exceptions. 1. Only five cases are taken for re-proving, including cases showing the maximum expansion, and those doubtful with reference to their strength. 2. The cases are to be fired five times. During the firing of the secondary proofs, as well as dur- ing the firing of the cases selected from the lots entirely consisting of the defective cases, the number of cases as well as the number of re-tests may be increased to the num- ber fixed for the test consignment. Specifications for Primers. The charge primer consists of brass body, detonator, bush, brass anvil, a charge of gun powder (not polished with graphite) , a disk of saltpe- ter-soaked tissue paper, four powder cakes, disk of salt- peter-soaked muslin, disk of parchment, and a brass disk bored in the center and coated outside with thick shellac varnish mixed with cinnabar. Detonator. The detonator consists of a small copper cap containing a charge of 0.275 grain of the detonator composition, covered by a thin paper parchment disk and compressed with a pressure of 125 pounds. The thickness of the parchment is between 0.002 and 0.0025 inch. The sur- face of the parchment facing the composition is coated by a thin layer of fluid shellac varnish composed as follows: 15.12 gallons of 95 per cent alcohol and 20 pounds of shellac. The detonator composition contains 50 per cent fulminate of mercury, 20 per cent chlorate of potassium and 30 per cent glass ground to dust and sifted through a sieve No. 100 (100 meshes to 1 inch). To this mixture is added 0.25 per cent of tragacanth gum and a trace of gum arabic. The com- position is placed in the cap while moist. After compres- sion the detonator is dried for ten days at a temperature of 88 degrees F., and twenty days at 111 degrees F. Then the exterior surface of the parchment disks is coated with a thick varnish composed of 0.891 gallon of 95 per cent alco- hol, 2.75 pounds of shellac, and 0.5 pound of resin. The 246 RUSSIAN CARTRIDGE CASE varnished detonators are dried at room temperature for five or six days, and then undergo a final examination, in which the defective caps will be rejected. The caps, when ready, must have even wedges, no rents, cracks, dents or such like defects, and the parchment disks must be placed concentric with the edges of the caps. Out of a lot representing a day's output (about from 10,000 to 15,000) of detonators, twenty-five are set aside without selection, for testing under a drop weight of 13.65 ounces, falling from a height of 3.94 inches. These must not show a single failure. If a day's output of detonators does not answer that condition, it undergoes, after a sup- plementary drying, a second test in double quantity. Any lot of detonators that does not stand this test will be re- jected and burnt out. The tissue paper and muslin disks are soaked with a 10 per cent solution of saltpeter. The powder cakes are com- pressed gun powder, not polished with graphite, and have a diameter of 0.748 inch, a height of about 0.120 inch, and weigh from 21.95 to 23.32 grains each. Charging Primers. The charging of primers is preceded by the examination of their bodies and other parts. The charging is done in the following order : The detonator is placed in the bush which is screwed onto the end into its seat and then nipped in two places in order to prevent its becoming unscrewed. The anvil is then screwed into its seat, so as to press tightly on the detonator composition, without, however, cutting the parchment disk. To inspect the proper screwing in of the anvils, 30 primers are set aside out of every 300, and from those the anvils are screwed out and the detonators examined. The parchment disks must bear clear marks of the anvils, without being cut through. In properly fitted primers the anvils are prevented from becoming unscrewed by nipping them in two places. A charge of from 10.286 to 10.972 grains of powder is placed in the groove between the hose and the internal surface of the body of the primer. This charge must fill the groove to the brim. The powder is now covered with the disk of RUSSIAN CARTRIDGE CASE 247 tissue paper soaked in saltpeter. On the top of it will be placed four powder cakes, which will be covered first with a disk of saltpeter-soaked muslin, then with a parchment disk and lastly with a brass disk bored in the center, after which the upper edge of the primer is closed in, this opera- tion being carried out in three stages. After the first press- ing, a proper position is given to the disks inside the primer ; after the third (final) pressing the primer is to be gaged. The upper side of the brass and parchment disks is var- nished with thick shellac mixed with cinnabar. After having been dried in the shop for 24 hours, the primers are packed in cardboard boxes. Two such boxes, (50 primers in each) are sealed hermetically in zinc boxes. The proper hermetic soldering of some boxes chosen at random will be tested. Eight zinc boxes are packed in one wooden box, which will thus contain 400 primers. Inspection of Primers. Bodies and other details will be manufactured of brass, the composition of which will be left to the discretion of the works, but on the express con- dition that the primers will comply with all requirements stipulated. The best results have been obtained when the metal contained from 67 to 74 per cent of copper, and from 33 to 26 per cent of zinc. Before beginning the manufacture of the order, the works with which the order will be placed must deliver a test consignment consisting of 100 primers. The test consignment of primers after being charged must be sub- jected to a firing trial. The conditions of this trial are similar to those used for the trials of the complete order. The order must be submitted in lots of 25,000 each. The gaging of dimensions at the works manufacturing the primers must be carried out after each separate opera- tion of manufacture, for which approved gages and control gages must be used. All the gages must be manufactured by the works, with which the order for the primers is placed, with the exception of the gage nut used for the gag- ing of the outer thread and the check screw for same. The last mentioned gages must be handed over to the primer works by the proper authorities. 248 RUSSIAN CARTRIDGE CASE The primers, before being charged, will be assembled at the works which manufacture them, i. e., bushes and anvils are screwed in, and the primers are delivered to the explo- sive works in such condition. After the completion of the manufacture of a lot of 25,000 primers, 1000 of them, chosen at random during the manufacture, will be sent to the ex- plosive works for inspection, for testing the rigidity of the metal, and for preliminary tests of the metal by firing. If, during the trial for the rigidity of the metal carried out by the compression of 50 primers chosen at random, more than 5 per cent show ruptures, the complete lot of 1000 primers will be returned to the manufacturers. In the case of satisfactory results of firing trials, the remaining 24,000 primers will be delivered to the works intrusted with the charging. If, after partial examination of a lot (not less than 1000 primers), more than 10 per cent of primers will be rejected in accordance with the following two paragraphs, the further inspection will be stopped at the charging works, and the whole lot will be returned for resorting. When inspecting primers, the following defects are not allowed : ruptures, blow-holes, fissures, flaws, sandy surface, dirt, oil, dust, shavings, dents on the bottom surface of the flange, dents at the bottom of the charge chamber, and con- siderable crumbling of threads (more than one-fourth of a thread) . The examination of the bottom surface for even- ness must be carried out by spinning the primers on a pol- ished steel plate. The primers which will not spin must be rejected. The primer chambers must be varnished. The anvils must not show any flaws and fissures at their striking edge and at the threads. The striking edge must not be sharp, to prevent the cutting through of the parchment disks of the detonator; generally speaking, the anvil and the bush must also answer all the requirements of the preceding paragraph. Gaging. One hundred primers complete from each lot must be gaged. Special attention must be paid to the fol- lowing points : RUSSIAN CARTRIDGE CASE 249 (a) All primers to be screwed into gage without being specially loose. (b) The thickness and the outer diameter of the primer head must not exceed the specified maximum dimensions, thus securing the proper fit of the primer flange in its seat in the cartridge case. (c) The height of the boss inside the primer must be strictly in accordance with the allowance given. (d) The inner thread of the boss must be strictly in accordance with the gage. (e) The seat for the detonator and the hole in the bush must be correct and in accordance with the gage. (f) The thickness of the bottom of primer (0.067 to 0.077 inch) must be in accordance with the gage. The anvils and bushes must screw and unscrew easily, without being loose and must be interchangeable. After charging, all primers will be inspected with regard to their height, and gaged outside. In case of unsatisfactory results in gaging (rejected primers exceeding 3 per cent) an addi- tional 100 primers must be chosen for the same purpose, and in case the results are the same, the whole lot will be re- turned to the works manufacturing the primers for re- sorting. Firing Trials. Fifty primers out of 1000 delivered from a lot of 25,000, after being charged, are tested with refer- ence to the quality of the metal, by firing with increased charge at a pressure of 2400 atmospheres (15.75 tons per square inch). These primers, after the test, should not show any breakage (after being unscrewed) through cracks and flaws, the presence of which would mean that the gas escaped through the base of the primers. The escape of gases leaving a residue between the side surfaces of the primer flanges and their seating is allowed on not more than 30 per cent of the primers subjected to firing test from new 'cartridge cases; in the case of using fired cart- ridge cases, no attention must be paid to the presence of the above-mentioned residue. Non-through cracks are allowed on not more than 2 per cent of tested primers; in the case of a larger percentage, 250 RUSSIAN CARTRIDGE CASE but not exceeding 4 per cent, the whole lot must be resorted and retested. The recurrence of 2 per cent of non-through cracks in the second test may not be taken as a reason for the rejection of the whole lot; 50 primers must be used for the second test. In the case of the absence of above-men- tioned defects, only those primers will be considered satis- factory which, after firing, can be removed from the cart- ridge case by hand or by an ordinary spanner. The serviceableness of the primers is determined by firing 50 primers chosen at random from the complete lot of 25,000 charged primers. The conditions just laid down hold good for this trial also. In addition to this, no com- plete misfire must occur; not more than two primers may misfire once each, with lock in proper order. (Before firing, the tension of the main spring and the protrusion of the firing pin must be verified.) A second test may be carried out if during the preliminary test defects occur. The sec- ond test must be carried out on double the number of primers taken at random, i. e., on 100 primers. During second test the same conditions as laid down for the first test hold good. Primers passing successfully the first or second firing tests are accepted for the service. A lot of charged rejected primers must be destroyed and the metal scrapped. In addition to the firing tests, the following test must be carried out by the works intrusted with the charg- ing of primers to determine the correctness of charging: 1. One per cent of a day's output must be tested under a drop weight of five pounds falling from a height of 0.39 inch with flat firing pin 0.25 inch in diameter ; during this test no primer must detonate. Primers having passed this test and not showing any noticeable mark on the base must be recharged and added to the lot. 2. When testing 0.5 per cent of each day's output under a drop weight of five pounds, falling from a height of 5.9 inches, with firing pin of an approved pattern, no primer must fail to explode. CHAPTER X SPECIFICATIONS FOR BRITISH 18-POUNDER QUICK-FIRING SHRAPNEL SHELL The following paragraphs, abstracted from the official specifications, give all the information contained in these specifications relating to the manufacture and inspection of the British 18-pounder, quick-firing shrapnel shell. Body. The body of the shell is made of cast or forged steel of the best quality for the purpose, turned or ground to the form and dimensions, and having the edge of the base rounded. If made of cast steel, the casting must be clean, of uniform transverse thickness, free from flaws,, blow-holes, and other defects. The use of chaplets is pro- hibited. If made of forged steel, the body must be forged hollow, and free from forging marks and flaws. Should the shells be subjected to heat-treatment, this must be carried out in batches consisting of shells of the same cast. An undercut groove, with two projecting waved ribs, will be turned on the body. Three chisel cuts may be made across the waved ribs in the groove for the driving band, at an angle to the longitudinal axis of the projectile to allow the air in the channels between the ribs to escape when the band is being pressed on. The top is threaded to receive the socket, and a groove for the fuse cover provided. The steel body alone must weigh 6 pounds 5 ounces 12 drams, plus or minus 2 ounces. Driving Band. The driving band is made from a ring of drawn or electro-deposited copper, pressed into, and in contact with, the bottom and undercut of the groove in the shell all around, and accurately turned to the form required. The weight must be 4 ounces 12 drams, plus or minus 2 ounces. Socket. The socket is made of composition metal, known as Class "C," threaded externally below the shoulder to fit the body, and internally to receive the fuse, the bottom being bored to receive the top of the central tube. The 251 252 BRITISH SHRAPNEL SHELL junction of the socket and central tube is soldered to pre- vent the resin getting into the tube and socket. A hole is to be bored in the side, threaded and fitted with a steel fixing screw. The weight must be 8 ounces 8 drams. Central Tube. The central tube may be made of brass, copper, delta metal, or gun metal. The lower end is to have REMOVE SHARP INNER E OF SCREW HOLE SOLDER JUNCTION BETWEEN SOCKET AND CENTRAL TUBE TUBE TO BE FLUSH WITH BOTTOM OF FUSE SOCKET RESIN Machinery Fig. 1. Construction of British 18-pounder Quick-firing Shrapnel Shell a shoulder to rest on, and to be threaded to enter the steel disk, the bottom being reduced in diameter to fit the neck of the cup. Weight, 2 ounces 12 drams. Steel Disk. A steel disk, of the form shown in Fig. 2, will rest on the shoulder in the bottom of the body, a hole BRITISH SHRAPNEL SHELL 253 being bored and threaded through the center of the disk to receive the central tube. Weight, 9 ounces 8 drams. Tin Cup. The cup in the base of the shell to contain the bursting charge will be made of tinned plate to the form and dimensions shown in Fig. 2, the parts being soldered together. Weight, 1 ounce 12 drams. Gages. Contractors may send their gages at any time to the chief inspector, Woolwich Arsenal, London, England, to be checked and compared with the standard gages. Screw Threads The screw threads must, unless other- wise stated, be of "the British standard fine screw thread, and conform to the chief inspector's standard gages. Preliminary Examination of Contractor's Work. The bodies, after completion of machining, will be submitted at the contractor's works, to an inspector, for preliminary ex- amination. Bodies made of cast steel must also be submitted for a hydraulic test under a pressure of 100 pounds per square inch. Any shell which shows the slightest leak, or fails to satisfy the conditions, will be rejected. Assembling. The tin cup, steel disk, and central tube are to be placed in position and the shell filled with mixed metal bullets, 41 per pound (composed of seven parts of lead and one of antimony), the interstices between the bullets being filled with resin, which must be perfectly pure, and filtered when in a liquid state through a sieve having 32 meshes per inch. The socket is then screwed onto the body as tightly as possible, the threads having been previously coated with Pettman's cement or red lead. Marking and Plugs. The shells are to be marked on the side, above the driving band. Plugs for the protection of the fuse holes in transit will be supplied, free of charge, on demand, by the ordnance officer to whom delivery is to be made. Delivery. (a). The shells will be covered with a thin coating of vaseline or other similar anti-corrosive grease, which must be of such a nature as not to interfere with the gaging, and they will then be delivered unpainted, for in- spection and proof. The shells must be perfectly cleaned out, empty, complete in every respect, and dry internally. 254 BRITISH SHRAPNEL SHELL (b). Such marking as may be necessary to identify the steelmaker's cast number, and, in case of heat-treatment, the batch number, must be maintained by the contractor upon every shell throughout manufacture, (c) . The shell must be delivered in lots for purposes of proof. A lot for this purpose will consist, as far as possible, of shells of the same cast, and, when heat-treatment is employed, of shells of the same batch number, and must not contain more than 121 shells, (d). When the number of shells in a cast or batch is less than 100, two casts or batches may be grouped together for this purpose. Main Examination after Delivery. (a). Any shell of a lot which fails to pass the chief inspector's gages, or fails to satisfy the chief inspector of its serviceability, will be re- jected, (b). If at any time during the examination it is found that defects of any nature, other than errors of ma- chining, which involve rejection of defective shells, amount to 5 per cent of the number of the shells in the lot, the "lot" will be rejected, (c). One or more shells selected from the lot will be taken to pieces, and the body broken, if nec- essary, to ascertain that the details of manufacture and component parts are correct, and that the material is sound. Should they be incorrect, or the material unsound, in any particular, the lot will be rejected. The driving band will be cut out, and should it appear not to have been pressed thoroughly home into the undercut and groove throughout, the lot will be rejected, (d). If, at any time during the examination of a lot, it is found that 5 per cent of the shells in the lot depart from the approved design, further exami- nation of the lot will be suspended. The whole of the lot must be re-examined by the firm and those shells which are incorrect eliminated. Those shells in which the departure can be rectified may be brought to the approved design by the firm. The lot may then be re-submitted. Tests. At least 1 per cent of the shells of every cast will be subjected to tensile tests. Test pieces will be cut from the shell blank, or from the finished shell at the option of the chief inspector, and must be capable of standing the following minimum tests : BRITISH SHRAPNEL SHELL 255 Tenacity, Tons per Square Inch Elongation in a Test Piece 2 Inches in Length, or such Piece as can be cut from the Shell, provided that Length Yield Point Breaking Stress j/ Area 36 56 8 per cent If any one or more of the conditions in this clause are not complied with, the lot, or lots, of shell affected, will be re- jected, and must not be re-submitted. The contractor will supply, free of charge, the necessary "Class C" metal for testing, if requested by the chief inspector to do so. The pieces ishould not be less than 7 inches in length, nor less than 1 inch in diameter, and will be required to stand the following test: Tenacity, Tons per Square Inch Elongation in a Test Piece 2 Inches long and 0.564 Inch in Diameter Yield Point Breaking Stress 6 12 10 per cent Proof. (a). A percentage of the shell will be fired for recovery from an 18-pounder Q. F. gun, with such a charge as will give a chamber pressure not less than 15 tons per square inch. Should the shell so fired set up above the high diameter of body, or break up in the gun, or should any portion of the driving band separate from the shell before first graze or impact, or should the recovered shell show that the shock of discharge had distorted the disk support- ing the bullets, or cause such alteration of the internal parts as would interfere with the correct action of the shell, or should any of the components be incorrect, the lot will be rejected, provided always that the pressure did not exceed the specification proof pressure by 0.5 ton. If the pressure did exceed this limit, a second proof must be taken at the government's expense before the lot is rejected. The pres- 256 BRITISH SHRAPNEL SHELL 0.2^ |*- -*, u-,,-0.225" BODY. FORGED STEEL i-H U?* 1 0.401*- ENLARGED SECTION SHOWING g"g COPPER DRIVING BAND g o o S - - FUSE SOCKET, BRASS H 0.345 If X, 3.65'.T0.01^ .. ., ^ i I ' ^ 3.300.01- tf H.0.225 |r> | LO_ i -X^l,^ 1 ZOT.P^H. hMiKr;o"C''/\ si BRITISH! (WHIT.)~ FIXING SCREW, STEEL COPPER DRIVING BAND ELECTROLYTIC COPPER Machinery Fig. 2. Details of British 18-pcunder Shrapnel Shell BRITISH SHRAPNEL SHELL 257 sure of the round, if not taken, will be assumed to be that of the last round fired with the same charge in which pres- sure was taken. Further, should the shell be reported un- steady in flight, and be found on recovery to be without its driving band, or with the driving band loose or slipped in its seating, then the driving band of a similar number of shells to that taken for firing proof may be cut out to ascertain whether they have been properly pressed on; if they have not been pressed down to the satisfaction of the chief inspector, the lot will be rejected. If found correct, such shells will be rebanded by the contractor free of charge. (b). The shells fired for proof may, after recovery, be broken to ascertain the soundness of their material. Should any of the material be unsound in any respect, the lot will be rejected. Re-submission. (a). A rejected lot must not be re- submitted unless the rejection is due to failure of the driv- ing band, or to rectifiable gaging defects, (b). Shells put out at any period of inspection for remediable defects may be re-submitted for further examination after the de- fects have been rectified. It is to be understood that the examination of such shells at that time will be incomplete, and that they are liable to rejection after rectification, (c) . If the contractor wishes to re-invoice a lot rejected for fail- ure of driving bands, he must remove the shells and re-band them before they are again submitted, (d). Rejected shells will, if considered necessary, be marked with a small rejection mark, so that they can be readily identified if re- delivered. Replacement of Proof. The contractor will be required to replace, free of charge, all shells expended in proof and examination, which, whether fired or otherwise tested, will be the property of the government. Packing. All packages are to be so marked that the goods contained therein may be readily identified with the invoice. Unless it is specified in the contract that the pack- ing cases or other packing material are to become the prop- erty of the war department, they will remain the property of the contractor, who is responsible for their removal. 258 BRITISH SHRAPNEL SHELL Should they not be removed within two months of the ac- ceptance at the stores, they will be disposed of, and under such circumstances the contractor will not be entitled to make any claim for compensation. The packing cases must be marked "Returnable" or "Non-returnable." Inspection. The shells may be inspected at any time during manufacture by, and after delivery will be subject to testing by, and to the final approval of, the chief inspec- tor, Royal Arsenal, Woolwich, England, or an officer deputed by him. In cases of defects occurring in manufacture which necessitate repairs, the contractor shall bring the same to the notice of the inspecting officer, and shall obtain from him written authority to proceed with such repairs as may entail patching, burning, electric welding, or other similar processes. WEIGHT OF 18-POUNDER SHRAPNEL SHELL PARTS Weights (avoirdupois) Part Pounds Ounces Drama Driving band 4 12 C 2 Z ' Metal socket 8 8 Steel disk . ... 9 8 Brass tube 2 12 Tin cup 1 12 Bullets, about 327 of pound alloyed metal, 41 per 7 14 13 1 / 2 Resin . 13 11 Total weight empty (unpainted)* 16 13 Sy 2 -+-11 drams Bursting charge ... 2 8 Paint 5y 2 Fuse ... 1 7 10 Total weight . 18 8-^5 drams * To regulate weight of shell, a few buckshot may be used. Plug for Fuse Hole. The plug is to be made of a cop- per alloy, and to the form and dimensions shown on the drawing, threaded externally on the body, and a square re- cess, tapered, is to be formed in the top. The screw threads must, unless otherwise stated, be of the British standard fine screw thread, and conform to the standard gages of the chief inspector, Royal Arsenal, Woolwich, Eng- land. Contractors may send their screw gages to the chief inspector, to be compared with the standard gages. BRITISH SHRAPNEL SHELL 259 Any plug of a delivery which fails to pass the inspecting officers' gages, or shows flaws or sponginess on the surface, or fails to satisfy the chief inspector, Woolwich, as to its serviceability, will be rejected. If at any time during the examination it is found that defects of any nature, other than errors of machining, which involve rejection of the defective plugs, amount to 5 per cent of the number of plugs in the delivery, the whole order will be rejected. If at any time during the examination of a delivery it is found that 5 per cent of the plugs in the delivery will depart from the approved design, further examination of the plugs will be suspended; the whole of the delivery must be re-examined by the firm, and those plugs which are incorrect to design eliminated. Those plugs in which the departure can be rec- tified may be brought to the approved design by the firm. The delivery may then be re-submitted for examination. The contractor will be required to replace free of charge all plugs expended in test and examination, which will become the property of the government. CHAPTER XI SPECIFICATIONS FOR BRITISH COMBINATION TIME AND PERCUSSION FUSES The following specifications, abstracted from the official requirements relating to British "Mark I" (No. 85) combi- nation time and percussion fuses, give the general infor- mation required in the manufacturing and inspection of these fuses. These specifications, in conjunction with the very complete illustrations, Figs. 1 to 6, inclusive, of the de- sign and details of the British fuse, give all the essential data required. Components. The fuse consists of the following parts: Body, top and bottom composition rings ; cap with set-screw ; base plug with screw plug; time detonator pellet in two parts ; percussion pellet with sleeve and firing pin ; detona- tors; four spiral springs; brass and steel pins; onion skin paper; unbleached muslin; felt cloth and brass washers; brass and tin-foil disks ; suspending ring for time pellet ; and onion skin paper patches. Metals. The body and composition rings are to be made of bronze or metal known as "Class B ;" the time detonator pellet and percussion pellet to be erf hard-rolled brass; the percussion firing pin pivot, of steel, phosphorized or blued ; the time and percussion firing pins, of bronze or "Class B" metal; all other parts of the fuse, except where otherwise stated, of metal "Class C," or hard-rolled brass. The con- tractor must supply the necessary metal for testing, free of charge. Metals designated by "classes" are copper alloys, the compositions of which are left to the discretion of the mak- ers providing the metals conform to the above tests. Before proceeding to manufacture, the material must be submitted to the inspecting officer for mechanical test. When practicable, test pieces should not be less than 7 inches in length nor less than 1 inch in diameter, and will be re- quired to stand the following minimum tests: 260 BRITISH COMBINATION FUSE 261 Metal Tenacity, Tons per Square Inch Elongation in Per Cent in such a Test Piece as can be fur- nished, provided that Length Yield Point Breaking Stress I/ Area Bronze . . .... 13.5 12 6 6 27 20 12 12 20 30 10 10 Class "B" Class "C" Hard-rolled Brass . . . Body. The body is to be turned all over, and threaded externally at the upper and lower ends, a bevel being formed at the junction of the stem and the flange. The stem is to be bored, and a hole drilled at the bottom of the bore to receive the time firing pin. The upper surface of the flange is to be grooved. The interior is to be bored out to form a chamber for the reception of the percussion arrange- ment and threaded for the base plug; a hole is to be bored and threaded at the bottom of the bore to receive the per- cussion detonator holder. An annular recess is to be made for the magazine. Communicating holes are to be drilled as follows : (a) At an angle to the top surface of the flange. (b) Vertically from the magazine recess. (c) Horizontally at the top of the detonator recess. (d) At an angle to join (b) and (c). (e) At an angle from outside to bottom of recess in stem. Holes (c) and (d) are to be closed by plugs driven in and secured by punch stabs. Two slots are to be cut in the flange as shown in Fig. 2, and an elongated hole made to receive a stop pin, which is to be secured by a small pin, driven in. A setting mark is to be cut on the edge of the flange. Top Composition Ring. The ring is to be turned all over, and bored to fit the stem of the body. A groove is to be formed in the under side for the composition, and a re- cess made as shown in Fig. 2, three holes being drilled from the upper surface into the recess. A hole is to be drilled 262 BRITISH COMBINATION FUSE through the ring between the ends of the composition chan- nel, and recessed. A recess is to be formed in the bore, from which a flash hole is to be drilled at an angle commun- icating with one end of the composition channel, a vertical escape hole being made from the top surface to the flash hole. An indicating mark is to be made on the outside of 13) Machinery Fig. 1. British "Mark I" (No. 85) Combination Time and Percussion Fuse Modified Form of American 21 -second Fuse the ring. Two holes are to be bored between the ring and the stem of the body, into which pins are to be inserted to retain the ring in position. The ring is to be made 0.020 inch thicker than the dimension given on the drawing, and faced off to thickness after powder is pressed into the groove. Bottom Composition Ring. The ring is to be turned all BRITISH COMBINATION FUSE 263 over and bored to fit the stem of the body, the upper surface being grooved. A groove is to be formed in the under side for the composition, and an annular recess made, three holes being drilled from the upper face into the recess. A hole is to be drilled in the ring from the under side between the ends of the composition channel. An escape hole is to be drilled, at an angle, from the end of the composition channel to the annular recess, and a recess made to receive the clos- ing disk. A hole communicating with the groove and the es- cape hole is to be drilled at an angle to the top surface to receive a powder pellet. A hole is to be drilled and recessed for a setting pin, which is to be secured by a small pin driven in. The ring is to be graduated from "0" to "21.2 ;" each division, after the first, is to be sub-divided into five parts. A line to denote safety position is to be marked. The marking is to be blackened with japan black thinned with spirits of turpentine, except the mark denoting the safety point, which is to be colored red. Cap with Set-screw. The cap is to be machined all over, and recessed internally to receive the time detonator pellet. The lower part of the recess is to be threaded to screw over the stem of the body. Two slots are to be made in the cap to receive a key, and a hole is to be drilled through the side and tapped to take a brass set-screw. A groove is to be made near the top, which is to be partially closed by spinning over the edge. Four escape holes are to be drilled at an angle from the recess on the under side, into the groove. Base Plug. The base plug is to be threaded externally to fit the bottom of the body. Two holes are to be drilled in the under side to facilitate assembling, and a central recess formed with a seating to receive a brass washer with a muslin disk. Six holes are to be drilled at an angle from the upper surface into the lower recess, and a hole drilled and tapped in the bottom to take a screw plug. This plug is to be threaded externally to fit into the bottom of the base plug. Time Pellet and Detonator. The pellet is to consist of two parts, which are to be turned and bored, the parts be- 264 BRITISH COMBINATION FUSE ing screwed together to secure the detonator. A screw- driver slot is to be made in the top surface, and a seating Fig. 2. Details of British Combination Fuse formed on the outer surface for the suspension ring. The detonator is to be turned all over and recessed, four fire holes being drilled through into the recess. The recess BRITISH COMBINATION FUSE 265 is to be coated with non-acid paint and charged with 0.45 grain of the following composition (giving parts by weight) : Glass 50 Fulminate of Mercury 40 Chlorate of Potash 20 Sulphide of Antimony 30 Shellac (dry) 2.8 The ingredients are to be thoroughly pulverized, except- ing the fulminate, mixed dry, and then covered with alco- hol. The fulminate will then be added and the whole thor- oughly mixed. The composition is to be covered with a brass disk secured by shellac. The recess in the plug is to be coated with a composition of shellac and rosaniline and filled with 11/2 grain of shrapnel powder compressed with a total pressure of 60 pounds. The detonator is to be in- serted in the holder, and secured in place by the screw plug, the two being locked together by a small brass pin. Percussion Pellet. The percussion pellet is to be ma- chined all over, two holes being bored in the upper surface and a slot cut to receive the firing pin. Two holes are to be drilled at right angles to the slot and parallel to the flat surfaces, one to receive the pivot for the firing pin and the other for the centrifugal bolts. The sleeve is to be ma- chined all over, and is to be a driving fit on the pellet. Two spiral springs and two small pellets, and a pivot pin for the firing pin, are to be provided. All parts, except the pivot pin, are to be tinned all over. The parts are to be assem- bled, and a hole drilled into the sleeve and pellet, and a small brass pin driven in. Percussion Detonator and Holder. The percussion de- tonator is to be turned and recessed on both sides, two flash holes being drilled between the two recesses. The smaller recess is to be charged with 0.45 grain of the following composition (the figures giving parts by weight) : Chlorate of Potash 43.19 Sulphide of Antimony 21.5 Sulphur 7.5 Glass 10.5 Shellac . 1.7 266 BRITISH COMBINATION FUSE 0.32 0.001,, 0.0015 [< K- /NOTE: TIME T aMiaowJ U_ || ^MiSS6 _ T J i jJLwesR ..IF - - 0.002 0.1010.003 I GROOVE POWDER, SEE SPEC. DRILL 0. 073 iFTER ASSEMBLING SECTION A-A THROUGH LOCATING HOLE POLISH AND LACQUER THIS SURFACE TIME AND PERCUSSIO TOP RING O v^ ^ >j I f M"J I 30- ^""^ 30^_ A lK0.22>i| 36 THDS. _^^^_2^/ , afi-VALd I X-*-STO. i*l j COAT WITH COMPOSITION OF ROSANILINE BOTTOM CLOSING SCREW BRASS 0.064 DIA., 0.10 DEEP, DRILL AFTER OCATE AND DRIl AFTER ASSEMBLING CONCUSSION PLUNGER CUP BOTTOM CLOSING SCREW PLUG ONE BRASS ^__g 8 -H CONCUSSION PLUNGER CU ONE BRASS Fig. 3. Details of British Combination Fuse BRITISH COMBINATION FUSE 267 The ingredients are to be thoroughly pulverized and mixed dry. Alcohol will be added to dissolve the shellac. The detonator will be formed by pressing the mixture, while in a plastic state, into the recess. On the evaporation of the alcohol the composition should adhere strongly to the metal. A brass disk, 34 in Fig. 5, is to be secured over the composition with shellac. The larger recess is to be varnished with a composition of shellac and rosaniline, and 4 grains of shrapnel powder compressed into it with a pres- sure of 127 pounds and covered with a disk of tin foil, shel- lacked on. The holder is to be threaded externally to fit in the body, and recessed to receive the detonator, a central hole and two key-holes being made. Pellets. The powder pellets are to be made to the shapes shown in Fig. 5. Pellets 33 and 35 are to be made from compressed unglazed black powder, with clearance holes as shown ; pellets 32 and 36 are to have the clearance holes filled with 0.05 and 0.02 grains, respectively, of gun- cotton. Percussion Springs. The springs used in the percus- sion plunger must be made to the form and size shown in Fig. 5, and tinned. The percussion safety pin spring (21) is to be made from 0.012 inch diameter brass wire, tinned, and wound so as to give a free height of 0.150 inch 0.030 inch, and at such a spacing as to give 44 coils per inch. The percussion restraining spring (30) is to be made from 0.015 inch diameter brass wire, tinned, and wound so as to give a free height of 0.500 inch 0.050 inch, and at such a spacing as to give 36 coils per inch. This spring is to have a maximum resistance of 1.65 and a minimum of 1.5 ounce at an assembled height of 0.370 inch. Suspending Ring. The suspending ring for time deton- ator pellet is to be made of brass wire. The ring is to be of such strength that when tested with steel counterparts of the stem and pellet, the latter is forced through the ring with a deadweight load of from 69 to 77 pounds. Cloth Washers. The cloth washers are to be made from waterproofed felt cloth, with holes cut in them. The body and graduated time train washers 16 and 17, respectively, 268 BRITISH COMBINATION FUSE SPUN OVER AMD TRIMME 0. 166 0.002 -~t |\ 0. 166 O.OOS ^MfeSVMa" BOTTOM CLOSING SCREW DISK ONE-UNBLEACHED MUSLIN SHEETING SHELLACED BOTTOM CLOSING SCREW WASHER SHEET BRASS SHELLACED ON BOTTOM OF GROOVE COVER CLOSING SCREW DISK | ONE -ONION SKIN PAPER H SHELLAC AFTER GROOVE PERCUSSION PRIMER CLOSING DISK ONE TINFOIL 0.875- , , : K0.2>J0.14<- p| N _oNE BRASS 0.064 DIA. 0.15 LONG 1.152 0.003 H DRIVEN IN CONCUSSION PRIMER DISK ONE-SHEET BRASS SHELLAC ON PRIMER TIME AND PERCUSSION BOTTOM RING Machinery Fig. 4. Details of British Combination Fuse BRITISH COMBINATION FUSE 269 which are shown in Fig. 5, are to be subjected to a pressure of approximately 10,000 pounds per square inch after as- sembling, before closing cap is screwed on and adjusted. Lacquering and Polishing. The exterior surfaces of the fuse are to be polished and lacquered with a lacquer consisting of 1 pound of seedlac, 8 ounces of turmeric, and 8 pounds (1 gallon) of methylated spirits. The groove in the top and bottom composition rings, the magazine recess in the body, the powder channels and groove in the base plug, and the powder chambers of time detonator and per- cussion detonator holder, are to be lacquered with a lacquer consisting of 10 grains of rosaniline, li/ 2 pound of pow- dered shellac, and 1 quart of methylated spirits. Screw Threads. The screw threads must, unless other- wise stated on the drawing, be of the British standard fine screw thread, and conform to the standard gages of the government inspector. For fuses not made in England, the British standard threads will not be insisted upon, ex- cept for the large thread on the body. Time Arrangement The grooves on the under side of the composition rings are to be charged with 56 grains of No. 22 meal powder compressed at 68,000 pounds per square inch ; the rings are then to be faced off, and the holes at the ends of the channels drilled. The onion skin paper wash- ers are to be secured to the surfaces by shellac. Perforated pellets of black powder are to be inserted in the flash hole in the top ring, escape hole and flash hole in bottom ring, and flash hole in the body, the pellets for escape hole in bot- tom ring and flash hole having the perforation filled with loose guncotton. The space at the end of the channel in the bottom ring is to be filled with loose meal powder. An onion skin paper patch is to be secured over the flash hole in top ring, and the escape hole in bottom ring closed by a brass disk secured by two center punch holes, and coated with shellac. The cloth washers are to be secured! on the upper faces of the body and the lower time ring with fish glue, and subjected to a pressure of 10,000 pounds per square inch. 270 BRITISH COMBINATION FUSE -*>. i<-ao8 0.003, CONCUSSION RESISTANCE RING BOTTOM RING WASHER ONION SKIN 0.0015 THICK, , U_ 0.72 0.001 _>1 STAMP WITH Jj LETTERS AND FIGURES, >^ ~*0.156$!>.Q02\ TOP RING WASHER ONION SKIN 0.00 1 5 THICK, 0.54 t O.QQ2 i FTER ASSEMBLING TO PERCUSSION PLUNGER PERCUSSION PLUNGER HOUSING ONE - BRASS -TINNED 0.165 0.002 LOCATE AND DRILL AFT ASSEMBLING TO PERCUSSION PLUNGER HOUSING PERCUSSION PLUNGER PERCUSSIO^N RESTRAINING PERCUSSION FIRING PIN FULCRUM PERCUSSION SPRING HOUSING ONE-STEEL DRILL ROD SAFETY PIN TWO-BRASS TINNED ^,0 TWO- BRASS-TIN NED .uii^ ss&tsfjs AjajLs&s! ,.m' 36 COILS PER INCH T PERCUSStON RESTRAINING SPRING TWO-BRASS WIRE-TINNED PERCUSSION PRIMER ONE-BRASS TIME TRAIN RING PELLET ONE-COMPRESSED UNGLAZED BLACK POWDER PERCUSSION PRIMER DISK ONE-SHEET BRASS ONE-COMPRESSED UNGLAZEC BLACK POWDER USED IN GRAD. TIME TRAIN RING Machin Fig. 5. Details of British Combination Fuse BRITISH COMBINATION FUSE 271 Assembling and Closing. The different parts of the fuse are to be put together as in the assembly view, Fig. 1. The cap is to be screwed down so that a turning moment of 325 25 inch-ounces will just turn the ring, the cap being secured by means of a set-screw. The bench or table upon which the tensioning apparatus is fixed is to be jarred by tapping with a mallet to assist the turning of the ring. The base plug is to be screwed into the body, and the magazine filled with fine-grain powder through the filling hole. The bottom of the fuse is to be coated with shellac varnish. Delivery. The fuses are to be delivered in lots of 2000, an additional 40 being supplied free, for purposes of proof. In the event of further proof being required, the fuses will be taken from the lot. Proof. The fuses selected for proof will be tested as follows : (a) Ten will have the percussion arrangement removed, and will be tested to determine the mean time of burning at rest. The time train will be set at the highest gradua- tion mark. The mean time of burning, set full when cor- rected for barometer, will be 22.9 seconds 0.4 second. The constant to be used, when correcting for barometer, is 0.023 of the mean time of burning, for every inch the barometer reads above or below 30 inches, being plus when above and minus when below. The difference between the shortest and longest time of burning is not to be more than 0.5 second. If the lot fails to pass this test, a further proof will be taken; the fuse must burn within the limits speci- fied above, otherwise the lot will be rejected. Should the detonator fail to ignite the time ring, a second proof will be taken ; should a similar failure occur at second proof, or should there be more than one such failure at first proof, the lot will be rejected. (b) Twenty fuses will be fired, at the same elevation, in any of the following guns, with full charges, and the time of burning noted. The requirements as to the result of the firing with the fuses set at different graduations are as given in detail in the following : 272 BRITISH COMBINATION FUSE 1. The mean difference from the mean time of burning of the 20 fuses is not to exceed : ( if set full 0.14 second In 18-pounder guns j if set 16 . n second T 10 , ( if set full 0.2 second In 13-pounder guns j if set 14. . . .0.13 second The difference between the longest and shortest fuse is not to exceed : if set full 0.75 second or omitting one fuse. . . .0.6 second if set 16 0.6 second or omitting one fuse. . . .0.5 second if set full 0.9 second or omitting one fuse .... 0.7 second if set 14 0.7 second or omitting one fuse. . . .0.5 second In 18-pounder guns In 13-pounder guns 2. If there is one blind fuse, a second proof will be taken. If there is a blind at second proof, or more than one such failure at first proof, the lot will be rejected. (c) Five fuses from a lot will be tested, in shrapnel shells, by firing them set at "0" from a gun with a muzzle velocity of 1500 to 1800 feet per second. The fuses should burst the shells at from 5 to 50 yards from the muzzle of the gun. Should there be a burst in the gun, the lot will be rejected. Should any fuse fail to act within 50 yards, second proof will be taken; should a similar failure occur in the second proof, or should there be more than one such failure at first proof, the lot will be rejected. (d) Five fuses from a lot will be tested in common shells by firing them over sand, at such an elevation that the angle of descent will not be more than 4 degrees. When one only of a set of fuses so fired fails to burst on first graze the lot will be accepted without further proof; if there be more than one failure to burst on graze in the second proof, the lot will be rejected. The fuses must burst at the point of impact. For percussion proof the time ring is to be set on the bridge. BRITISH COMBINATION FUSE 273 (e) A premature explosion due to the fuse in any of the foregoing proofs will cause the rejection of the lot. (f) Should any other gun be introduced for proof of this fuse, which differs from the above guns in either muzzle velocity or twist of rifling at muzzle, the above con- ditions will be subject to modification. (g) If, in the proof of any delivery, defects are found involving the serviceability of fuses, additional proof may be taken from any other delivery not finally closed, to ascer- [< 2.28 :0 - 02 ---9.9 0.03 SOLDERING STRIP ONE-SHEET BRASS CENTERING BOX SOFT SOLDER COMPOSITION :-3 PARTS LEAD, 3 PARTS TIN, 1 PART BISMUTH 1 *% . _ /* ? 'CJT^fe 9^ SOLDERING STRIP '4 R fe k x-*i Fig. 6. Details of British Combination Fuse Cover and Case tain if the defect is general. Should the fuses fail at this further proof, the delivery will be rejected without refer- ence to the original proof. The total proof of any delivery shall not exceed 5 per cent of the lot. The contractor will be required to replace all fuses expended in further proof or examination free of charge, which, whether fired or other- wise tested, will become the property of the government. Inspection. (a) The components of the fuses, during manufacture and assembling, and the completed fuses after delivery, will be subject to examination and gaging by, and 274 BRITISH COMBINATION FUSE to the final approval of, the chief inspector or an officer deputed by him. Any component or fuse, which is not finished to the satisfaction of the chief inspector, or his rep- resentative, or which has any flaw or imperfection, will be rejected. (b) If, at any time during examination, it is found that defects of any nature which involve rejection of the defec- GBADUATION TABLE FOR TIME-RING ON BRITISH COMBINATION TIME AND PERCUSSION FUSE CROSS PAINTED RED 0.02 WIDE, 0.01 DEEP GROOVES Graduation Angle Deg. Min Graduation Angle Deg. Min. Oto5 Otol Ito2 2 to 3 3 to 4 4 to 5 5 to 6 6 to 7 7 to 8 8 to 11 each 11 to 12 26 16 15 15 16 14 14 14 13 13 13 45 15 30 30 40 35 15 55 35 12 to 13 13 to 14 14 to 15 15 to 16 16 to 17 17 to 18 18 to 19 19 to 20 20 to 21 21 to 21. 2 13 13 12 12 12 11 13 14 16 3 10 50 30 30 10 30 20 30 tive components, or fuses, amount to 5 per cent of the num- ber in the lot, the lot will be rejected. (c) If, at any time during examination of the lot, it is found that 5 per cent of fuses in the lot depart from the approved design, further examination will be suspended. The whole of the lot must be re-examined by the contractor and those fuses which are incorrect to design eliminated. Those fuses in which the departure can be rectified may be changed to the approved design by the contractor. The lot may then be re-submitted for examination. BRITISH COMBINATION FUSE 275 Tests for Safety in Transportation. From each lot, 20 time and 20 percussion plungers are to be tested to ascer- tain the correctness of their weights and static resistances. Lots of plungers not correct within the tolerence allowed will be rejected. At the commencement of manufacture, 6 time and 6 percussion plungers from each lot will be sub- jected to a drop test against a steel block 11.5 inches in diameter, 4.5 inches thick, resting on a concrete pier, to determine the limit in heights at which the same will arm when carried in standard dropping pieces. One of the pieces weighs 15 pounds and has the form of a 3-inch shell ; the two other pieces are lighter and smaller. No concus- sion plunger is to begin to arm when falling in the lighter piece from a height of 4 feet 6 inches; all shall fully arm in the shell with 14 feet 8 inches drop. No percussion plunger is to begin to arm in the special piece falling with 6 feet 2 inches drop; all shall fully arm in the shell with a 17 feet 6 inches drop. Jumbling and Jolting Test. Ten fuses will be placed, one at a time, in a wooden box approximately 16 inches by 11 inches by 5 inches inside dimensions, revolving at thirty revolutions per minute, about one of its diagonals, for four hours. The fuses will then be placed in an adjustable fuse- holder on the end of a hinged lever 16 inches long, which, by the motion of a cam, is raised 4 inches, thirty-five times per minute, and allowed to drop on an iron anvil. The fuses are thus dropped for an hour, point downward, base downward, and side downward, respectively. The primer shields must not be marked, and the time trains, powder pel- lets, etc., must be intact. CHAPTER XII SPECIFICATIONS FOR BRITISH 18-POUNDER QUICK- FIRING CARTRIDGE CASE AND PRIMER The following specifications of the British 18-pounder quick-firing cartridge case and primer govern the manu- facture and inspection of these cases and primers. They are abstracted from the official specifications and give the most important information required by the manufacturer and inspector. Construction. The cartridge may be either solid drawn brass or built up, the nature of the alloy and the thickness and distribution of the metal being left to the contractor, except that the dimensions must agree with those in Fig. 1. The maximum weight is to be 3 pounds 1 ounce. If elec- trolytic copper is used, it must be melted and run into ingots before use. In manufacture the number of drawings and the number of annealings must not be less than six. Should any folds or rings exist in the metal of the base, they must not be removed; any marks of cutting or turn- ing of the metal of the inside of the base will cause the re- jection of the cartridge. In the center of the base a hole is to be bored and threaded to receive the primer. The cart- ridges are to be marked on the base with the numeral and the contractor's initials or recognized trade mark. Screw Threads. The screw threads must, unless other- wise stated, be of the standard Whitworth thread, be cut full, and conform to the government inspector's standard gages. Contractors may send their gages at any time to the chief inspector to be checked and compared with the standard gages. General Conditions. The contractor is to supply, with the first delivery, a full-sized tracing, on tracing cloth, of the cartridge he is delivering. The contractor will also supply, free of charge, samples of the metal from which the cases are to be made, if requested by the chief inspector to do so. The samples should not be less than 6 by 2 inches. 276 BRITISH CARTRIDGE CASE 277 Cases in stock, that is, cases made before the date of the contract, must not be submitted for acceptance under a given contract. The cartridges should be delivered in lots of not less than 400. If less than 400 are delivered, the number of rounds to be fired in proof will be the same as if the delivery were the full 400. If, on examination of twenty per cent of a lot, it is found that departures from approved design, or defects of any nature, which involve rejection of the cases, average twenty-five per cent of the number examined, the whole of the lot will rejected. Proof. (a) Not less than one-half per cent will be fired in proof. At least one cartridge from each 400 de- livered will be fired three times, one round being with a proof charge, and the cartridge being (if necessary) re- formed after each round. In each remaining cartridge, one proof and one service round will be fired. (b) The cartridge must load and extract easily, and must not split or develop any flaw or crack on firing. (c) The cartridge may be sectioned after firing; the section must show no cracks. (d) The maximum pressure is not to be more than 19 tons per square inch. (e) If, in the proof of any delivery, defects appear which involve the serviceability of the article, additional proof may be taken from any other delivery not finally closed, to ascertain if the defect is general or not. Should the cases fail at this further proof, the delivery will be re- jected without reference to the original proof. The total proof of any delivery shall not exceed five per cent of the number delivered. Replacement of Proof. The contractor will be required to replace all cartridges expended in proof free of charge, and when the order is approaching completion, he will be informed by the inspector how many are required to com- plete the number on the order, exclusive of the cartridges so expended, which, whether fired or otherwise tested, will become the property of the government. 278 BRITISH CARTRIDGE CASE Packing. All packages will be so marked that the goods contained therein may be readily identified with the in- voice. Unless specified herein that the packing cases or other packing material will become the property of the war department, they will remain the property of the contrac- tor, who is responsible for their removal. Should they not be removed within two months of the acceptance of the cart- ridge cases, they will be disposed of, and in such circum- stances the contractor will not be entitled to make any claim ^ ~ I MIN. CAPACITY TO BASEJ 11 i OF PROJECTILE = 9+.8 Clj.lN. ' 8.25 -| Machinery 11 -i.o- PARALLEL Fig. 1. British 18-pounder Quick-firing Cartridge Case, giving Complete Dimensions, and Bore of Quick-firing Field Gun for compensation. The packing cases must be marked "Re- turnable" or "Non-returnable." Spontaneous Cracking. Any cartridge found to be cracked before or after filling, but before firing, is to be replaced by the contractor if such crack is discovered within six months of the date of acceptance of the cartridge in question, which date is stamped on it. The cartridges may be inspected during manufacture by, and after delivery will be subjected to testing by, and to the BRITISH CARTRIDGE CASE 279 final approval of, the chief inspector, Royal Arsenal, Wool- wich, England, or an officer deputed by him. Primer. The primer is to consist of the following parts (see Fig. 2) : body A; closing disk B; anvil C; plug D; cap E; tin foil F; ball G; paper disk H; gun powder /; and Pettman cement. The body is to be made of composition metal known as Class "A" or "B." All other metal parts of the primer, except where otherwise specified, are to be made of brass. The brass is not to contain more than 0.3 per cent of lead, nor to have more than one per cent of total metallic impurities. The Class "A" or "B" metal is to be in accordance with the following requirements: It must be perfectly straight, uniform in diameter, and free from cracks or flaws, and must be capable of standing the following minimum tests: Tenacity, Tons per Square Inch Elongation in Per Cent in such a Test Piece as can be furnished, provided that Length I/ 7 Area Yield Point Breaking Stress Class "A", 20 Class "B", 12 Class "A", 30 Class "B", 20 Class "A", 20 per cent Class "B", 30 per cent Pieces of the metals it is proposed to use in the manu- facture must be submitted free of charge by the contractor, for testing, when requested by the chief inspector. Body. The exterior of the body is to be turned and threaded and a flange formed. Two slots are to be cut in the head for the key. The interior is to be bored, cupped, and threaded. The exterior of the body is to be lacquered with a lacquer consisting of : Seedlac 1 pound. Turmeric 8 ounces. Spirit, Methylated 8 pounds. Screw, Plugs and Copper Ball. A plug having one end turned to form an anvil, which is to be free from burrs, is 280 BRITISH CARTRIDGE CASE -PAPER DISK SECURED WITH PETTMAN CEMENT OUTSIDE TO BE COATED WITH A THIN LAYER PAPER DISK SECURED WITH PETTMAN CEMENT COATED WITH PETTMAN CEMENT UNDER TURNOVER IF SAWED, NOT TO EXCEED 0.011 CLOSING DISK-BRASS ANVIL- BRASS Machinery Fig. 2. Primer for British Quick-firing Shrapnel and High-explosive Shell Cartridge Cases BRITISH CARTRIDGE CASE 281 to be threaded to suit the body. The interior is to be turned out to receive the soft copper ball, and three fire holes bored. A plug is also to be threaded to suit the body, having an an- nular recess turned on the inner side, and three fire holes bored. Cap. The cap is to be made of copper and the interior is to be varnished with varnish composed of : Finest orange shellac .... 2 pounds 2 ounces. Spirit, Methylated 8 pounds. The specific gravity of the varnish is to be 0.885. It is then to be charged with 1.2 grain of the following compo- sition (figures give parts by weight) : Sulphide of antimony 18 Chlorate of potash 12 Ground glass 1 Meal powder 1 Sulphur 1 The composition is to be pressed into the cap with a pressure of 800 pounds. A tin-foil disk, lacquered on one side, is then to be placed on the composition with the lac- quered side outwards, and placed under a pressure of 400 pounds. It is then to be varnished with a varnish com- posed of: Finest orange shellac .... 2 pounds 2 ounces. Seedlac 1 pound. Turmeric 8 ounces. Spirit, Methylated 16 pounds. The specific gravity of this varnish is to be 0.865. The lacquer for the tin-foil disk before insertion is com- posed of : Seedlac 2 pounds. Turmeric 1 pound. Spirit, Methylated 16 pounds. The specific gravity of this lacquer is 0.85. The cap is to be externally coated with Pettman cement before inserting in the body, and then a fillet of Pettman 282 BRITISH CARTRIDGE CASE cement is formed between the body and cap; Pettman cement is made from the following ingredients: Gum shellac 7 pounds 8 ounces. Spirit, Methylated 8 pounds. Tar, Stockholm 5 pounds. Red, Venetian 20 pounds 12 ounces Gun Powder. The primer is to be filled with R. F. G. 2 powder, the screw plug being first screwed in and fixed by three small punch blows, and the fire holes covered by a disk of paper secured with Pettman cement. Closing Disk. A brass disk having a paper disk se- cured to it on the inner side by Pettman cement is to be placed on the top of the powder, and a ring of Pettman cement painted round the edge of the disk where the metal will be burred over onto it. After the primer is burred over, the whole of the exterior of the disk will also be coated with a thin layer of the cement. Marking and Delivery. The primers will be marked with the numeral, serial number, contractor's initials or recognized trade-mark, and date of manufacture. The primers will be delivered in lots of 1000, an additional 20 being supplied for proof with each 1000, or any less num- ber supplied. In the event of further proof being required, the primers will be taken from the lot. Proof. A percentage of the primers will be selected in- discriminately for proof. (a) The primer when screwed into a steel block must fire correctly with a 1-pound weight falling 25 inches, and ignite a puff consisting of 4 drams of R. F. G. ? powder enclosed in one thickness of shalloon, in a 12-inch vent with special receiver, or when proved in any gun for which approved, it must ignite the charge without hang-fire. (b) A miss-fire, hang-fire, pierced cap, or serious escape of gas through or around the primer will cause rejection. (c) The falling weight is to have a point of the same shape as the service striker. (d) Should the firing proof or examination of any de- livery bring to notice any defect or defects which, in the BRITISH CARTRIDGE CASE 283 [< eor 284 BRITISH CARTRIDGE CASE opinion of the chief inspector, affect the serviceability of the primers, the delivery in question may be rejected, or further proof taken at his discretion, not only from the particular delivery, but from any others made by the con- tractor which may be under inspection, to ascertain whether the defect is general. Should any primers fail at these fur- ther proofs, the delivery or deliveries will be rejected with- out reference to any previous proof. If, on examination of twenty per cent of a lot, it is found that departures from approved design or defects of any nature which involve rejection of the defective primers average 25 per cent of the number examined, the whole of the lot will be rejected. The contractor will be required to replace free of charge all primers expended in proof and examination, which, whether fired or otherwise tested, will become the property of the government. Specifications for Cartridge Clip. The general dimen- sions for the cartridge clip are given in Fig. 3. The clip is made from hard-rolled sheet brass in one piece. Four projecting arms are to be formed; the ends of each are bent over as indicated. The clip is sand-blasted, and lacquered with a lacquer composed of: Vegetable black 1 pound. Seedlac 1% pound. Turpentine (1 quart) 2 pounds. Methylated spirits (6 quarts) ... .12 pounds. One arm is coated with paint consisting of: Vermillion, dry 2 ounces. Shellac, dry 1 ounce. White hard varnish % ounce. Spirits, Methylated l!/2 ounce. Loop. The loop is to consist of 13 inches of "webbing, cotton, 1/2 inch," threaded through the clip and sewed. Three yards of webbing, selected from the bulk, are to be submitted to the chief inspector before being used. The webbing submitted will be cut into lengths of 11 inches and the ends of each length securely fixed in the clamps of a BRITISH CARTRIDGE CASE 285 testing machine, the clamps being 7 inches apart. The strain will be gradually increased until the sample breaks. The breaking strain must not be less than 200 pounds. Delivery. The clips will be delivered in lots of 1000. If, on examination of 20 per cent of a lot, it is found that departures from approved design, or defects of any nature, which involve rejection of the clips average 25 per cent of the number examined, the whole of the lot will be rejected. CHAPTER XIII SPECIFICATIONS FOR AMERICAN SHRAPNEL SHELLS The American shrapnel shells comprise the following parts : forged shell body, copper driving band, head, washer, tubes, bullets, matrix, head filler, diaphragm, base charge, and fuse. In some cases a Semple tracer is used, and, when this is the case, the base of the shrapnel must be machined to accommodate it. Shell. The shell is to be made of forged alloy steel or bar stock having the properties outlined in Table I. The forgings must be annealed so that they can be machined with reasonable ease. The maximum elastic limit for the 2.95-inch and 3-inch shell forgings must not exceed 115,000 pounds per square inch, and in case of the 3.8-inch, 4.7-inch, and 6-inch must not exceed 110,000 pounds per square inch. All shrapnel shells must be subjected to an exterior hy- draulic pressure of 20,000 pounds per square inch up to the rotating band, and to an interior hydraulic pressure of 1000 pounds per square inch. A certain number from each 1000 shells are also subjected to- a ballistic test by firing com- pleted shrapnels from a gun with a maximum pressure of 37,000 pounds, except for the 6-inch, which will be fired under a pressure of 22,500 pounds per square inch. The shell is to be finished outside and inside except at points otherwise indicated, where it is to be left in the rough-forged state. The inside of the shell is to be coated with non-acid paint, except where machined, and the pow- der chamber is to be given a heavy coat. Great care should be taken to remove all burrs, scale, and sharp corners. The outline of the shell after the first operation, when made from bar stock, is shown by dotted lines in Fig. 1. The base of the shell is to be machined as illustrated to the right at A in Fig. 1, when a Semple tracer is used. Copper Driving Band. The copper driving band is to be cut from tubing of pure electrolytic copper, and machined to the dimensions shown. It is to be heated and expanded 286 AMERICAN SHRAPNEL SHELL 287 PRESS METAL OF FUSE INTO MATRIX RESIN AND MONO-NITRONAPTHALENE rW^-Si >< 0.45-~>t*-0.35- MODIFICATION OF REAR END OF PROJECTILE FOR USE IN 3 INCH HOWITZER 0.87 TUBE (A ONE SEAMLESS DRAWN BRASS, TUBING 0.05 THICK. COAT INSIDE WITH SHELLAC LOCKING PIN TWO STEEL FINISH 0.005 DRIVE AND PEEN AFTER ASSEMBLING HEAD TO CASE Fig. 1. Assembly and Details of American Shrapnel Shell 288 AMERICAN SHRAPNEL SHELL to 2.985 inch inside diameter for the 3-inch shell and is to be shrunk into the seat, then forced into the scores by passing through a die and afterwards turned to size. Washer and Head. The washer for the 3-inch shell- is to be made from steel 0.031 inch thick and formed to shape by punching. The head is to be made from cold- drawn steel, finished all over, and coated inside with a non- acid paint. The crimping wall is to be turned down over FUSE HOLE PLUG DIE CAST WHITE METAL NON-CORROSIVE 0.010 FUSE HOLE PLUG WROUGHT IRON OR BRONZE 0.010 0.03K DIAPHRAGM FORGED STEEL 0.005 .Machinery Fig. 2. Details of American Shrapnel Shell the washer after machining, and a hole drilled after the head is assembled to the shell. Five notches equally spaced are to be cut around the head, and a crimping groove cut for putting on the fuse protecting cap. Tube. The tube is to be made from seamless drawn brass tubing, and is to be coated inside with shellac. An additional short tube is to be inserted at the nose or mouth of this tube, next to the fuse; this latter is to be made from seamless drawn copper, and is to be forced into the tube under pressure and crimped over. AMERICAN SHRAPNEL SHELL 289 Bullets. The bullets used in the shrapnel are to be made from 12.5 per cent antimony to 87.5 per cent lead, and are to be flattened with six faces as shown in the illus- tration ; 252 bullets are used in the 3-inch shrapnel. Matrix and Head Filler. The matrix is to consist of resin and mono-nitronaphthalene, poured into the shell, as will be described in connection with loading. The head is to be filled with melted resin, poured in. Diaphragm. The diaphragm is to be made of forged steel to the dimension shown. It is to be drilled and coun- terbored, and great care should be taken to remove all burrs, sharp corners, and scale. The bottom of the diaphragm is also to be given a heavy coat of non-acid paint. TABLE I. PHYSICAL PROPERTIES OF STEEL FOR VARIOUS SIZES OF SHRAPNEL SHELLS Caliber, Inches Tensile Strength, Pounds Per Square Inch Elastic Limit, Pounds Per Square Inch Elongation in 2 Inches, Per Cent Contraction, Per Cent 2.95 120,000 90,000 16 45 3.0 120,000 90,000 16 45 3.8 110,000 80,000 15 40 4.7 110,000 80,000 15 40 6.0 110,000 80,000 15 40 Fuse-hole Plug. There are two types of fuse-hole plugs ; one is to be made from die-cast white metal, of non-corro- sive properties, and machined to dimensions given in draw- ing, and the other of wrought iron or bronze. The weight of the wrought-iron plug for the 3-inch shell is to be 0.97 pound, and the weight of the bronze plug, 1.03 pound. Either type of fuse-hole plug may be used. Locking Pin. Two steel locking pins are required which must be finished to limits of =t 0.005 inch, driven in and peened over after the head is assembled in the shell. Directions for Loading American 3-inch Shrapnel Shell. In loading, make sure that the diaphragm seats firmly on the shoulder in the shell, then pour in 0.25 ounce of pow- dered resin to seal the joints, and shake down well to fill all cracks. The powdered resin becomes plastic when the 290 AMERICAN SHRAPNEL SHELL >l O OOO 1 O i O 1-1 IO OS 00 O CO* OS O 00 t- O CQ CO CO ^ O 11 ^2 CQ.r-i 1C O O5 CO CO CO '^ ^O CO