STACK JFFEGTIVE METHODS IN lECHANIGAL DRAWING EVANS EFFECTIVE METHODS IN MECHANICAL DRAWING THE GEOMETRY OF DRAFTING AND KINKS AND SHORT CUTS By FREDERICK H. EVANS, M. E. Assistant Professor of Manual Arts, Bradley Polytechnic Institute, Feoria, Hi. Formerly Draftsman for the Ironton Engine Co., Ironton, O., the Link Belt Machinery Co. and Sargent and Lundy, Chicago. THE MANUAL ARTS PRESS PEORIA, ILLINOIS COPYRIGHT, 1913, FREDERICK H. EVANS. FOREWORD. In the text that follows are presented geometrical problems that have risen in the author's work in machine drafting, covering a period of over ten years, and the solutions given are the best solutions arrived at after many hours of study. The problems are presented in their own language in the drawing board language of conventional lines. Mathematical formulae are reduced to a minimum. Kinks and short cuts demonstrate the use of paper as a tool in such a way as to render the mechanical work of solving the problems in this subject much more accurate, less difficult, and, we hope, more interesting. In making working drawings of bevel gears (especially when the axes are not at right angles) the draftsman finds himself facing a difficult task in computation. A method is here given that has been tested and found to be the simplest, shortest, and most accurate known to the author. This book is essentially a reprint of selected sections of "The Drafting Room Series", a larger work by the same author. 2O65968 GEOMETRICAL CONSTRUCTION. 1. Machine parts are largely made up of solids bounded by plane and cylindrical surfaces. The reason for this is that these surfaces are the easiest to construct and measure. The chief uses of the planer, shaper, and milling machine are to construct plane surfaces, while the drill press, boring mill, and lathe are to construct cylindrical surfaces. An object, the surfaces of which are planes, has sharp corners. Sharp corners are avoided in machine construction, being either rounded off or filled in. The rounded corners are generally represented on drawings by circular arcs which are tangent to straight lines. If an object is bounded by surfaces other than planes the surfaces must be tangent to each other in order to avoid sharp corners. For these reasons, methods of passing circles and lines tangent to each other are important to draftsmen. The essential steps in drawing a circular arc tangent to two lines are as follows: (See Plate 2.) Determining the radius. Locating the center, Locating the starting point of the arc, Locating the stopping point of the arc. The starting and stopping points are points of tangency. Tangent problems involving straight lines and circular arcs are solved by an application of the following general rules: 1. (a) If a circular arc is tangent to a given straight line, its center must lie on a line parallel to the given line and at a distance from it equal to the radius of the circle. (See "Another Way" Plate 2.) (b) The point of tangency must be at the foot of the perpendicular dropped from the center of the arc to the line. 6 THE GEOMETRY OF DRAFTING 2. (a) If a circular arc is tangent to a given circle, its center must lie on one of two circles concentric with the given circle; its radius being equal to either the radius of the given circle plus the radius of the arc, or, the radius of the given circle minus the radius of the arc. (b) The point of tangency must be at the intersection of the line joining the two centers, with the given circle. Solutions to a number of typical problems are here given. If the student is to enable himself to solve problems that he meets in practice, he must not follow these solutions blindly but must grasp the underlying principles and see the reasons why. These are not only possible solutions. The merit of a geometrical solution consists in its fewness of steps and its avoidance of multiplication of errors. Compare the two methods on Plate 9. Problems. Make drawings of the problems on the succeed- ing pages, following the steps as given. THE GEOMETRY OF DRAFTING 8 3 i ra 1 1 \o ^ ^ // r e /- , 1 s I t PLATE 1. THE GEOMETRY OF DRAFTING GIVEN. REQUIRED: A drawing of The figure to scale. 4- - r> IN DFfAWlN6 ARCS ANOTHER WAY: PLATE 2. THE GEOMETRY OF DRAFTING 6/VEN- REQUIRED: A drawing of the figure to BLOCKING Our L OCA TING LOCA TING POINTS CENTERS or JANGENCY AND 0FfAWIN6 3MALL ARCS. FINISH PLATE 3. 10 THE GEOMETRY OF DRAFTING GIVEN - Slip 4-5Trianglt to position Hold 30*60 in This posi- tion Draw 1 Slip 45 and draw 2, 5lip 45~anddraw 3. REQUIRED Hnish H 8cV lines with T square and triangle's, and the oblique lines by the SET TRIANGLE METHOD shown PLATE 4. THE GEOMETRY OF DRAFTING PLATE 5. 12 THE GEOMETRY OF DRAFTING GIVEN : A drawing of the figure to A 5. BLOCKING Our, FINDING AND TANGENT POINTS, AND DRAWING ARC. PLATE 6. THE GEOMETRY OF DRAFTING 13 LOCATING CENTERS LOCATING TANONT POINTS AND DRAWING SMALL ARC 5 PLATE 7. 14 THE GEOMETRY OF DRAFTING GlVCN. REQUIRED: A drawing of thf fiqure fo zcale. BLOCKING OUT AH o LOCATING CENTERS. LOCATING TANGENT POIHTS DRAWING <5MALL ARCS. PLATE 8. THE GEOMETRY OF DRAFTING 15 GIVEN PLATE 9. 16 THE GEOMETRY OF DRAFTING GEOMETRICAL CONSTRUCTION CIRCLES A HP TANGENTS SYMBOLS Given Points o Given Lines Given Radii : - Required Points o Required Lines Required Radii o *- Construction Points o Construction Lines Construction Radii o - 3. 6. PLATE 10. THE GEOMETRY OF DRAFTING 17 7. GEOMETRICAL CONSTRUCTION CIRCLES ANP TANGENTS 4 t 10. THE GEOMETRY OF DRAFTING GEOMETRICAL CONSTRUCTION CIRCLES AND TANGENTS 19. ^0. PLATE 12. THE GEOMETRY OF DRAFTING 19 NOTE: DRAW TO SCALE PLATES 13 AND 14. AFTER MAKING A DRAWING OF PLATE 16 USE IT TO DRAW A MACHINE SLIDE, FOLLOWING THE DIRECTIONS GIVEN ON PLATE 18, ASSUMING VALUES FOR C 1 AND C 2 - 20 THE GEOMETRY OF DRAFTING PLATE 13. THE GEOMETRY OF DRAFTING 21 PLATE 14. 22 THE GEOMETRY OF DRAFTING I ' I /1F----- fH tJUsa. V? lp-1 PLATE 15. THE GEOMETRY OF DRAFTING 23 PLATE 16. 24 THE GEOMETRY OF DRAFTING PLATE 17. THE GEOMETRY OF DRAFTING 25 8 g 2" i i S -3 o g 'S S iV iv; ^ w IM "^ *w bi'S e '2 O, S O 13 T3 4"-> c r'.tJ .M C 4S ^2 *^ ^ M * 53 O 4) *^co o c i 03 re *Q o t-i j_i I-H *T3 *O ?i *i 3* ^ **"* Co^ C c 2 "^ en's <> C s & & 3 3 1 *s ! i *! S * *s S x x ? ' a o^'S w ^^^-S^.SsE^'w&co n Sj sJ' bfl bJO 4> t^ H ,22 -*- 1 S c ^ S r* r* c C C t->4)oo C ^ u O O 52 i5 -t-'-^'ai-t-' 1 - 1 "^ .^ re re i-i ^ ** . 4> cu t-i a, Tn 4 *' ^ " o re .;; Is ^cn 1 ^ co-'-' DM p^ --^ J^ *-i * -i *^7 ^H u j^ v | ~ H . r/i JL* ^^ * CU . CT* ^^Zt DO CO 3 -- x ai _c! r; :' :' a J? ..;:j . ^ cOCwuC N ]-; L^ vj {/} ''O c/3 MH bJO txD b/) bJO ^ QJ C ^ re D "|/5 4) ^ O *2 C C C C QD^JJJ-M pi 6 B 9 O O g ^5 .S '? ^ ^ '? '-3 ^ g '" . S 2 S 3 "3 " HH.s._i'73 i ~ i re re re re u *fi! O bfli-" -> to H-fitS^*- 1 - u ^ CucuOcxajco" 5 ^ 3 ^" 3 W to *i M - 2 aJ - c ,co '^co'oF -* ^ ,. -" -S'^ o u c-^-,- -}-: 1_ ^_ rH ^l CO ,n ^ . "-> rrl Jj ^ O 1-1 s^- 3 creCuC'f c c^ -.-Jc 4-~;H t ^-' ^cSloreoboj-^co-ogS^wSw ^co c c 2 asC^RiS^jS-.S ** CO -M Bo' 2 -s 0* & & && a o & g ^ SfC -2-^c x ^H ai^oi^C-^i-iw ^3 C M-l'i3M-l'ij < *- | S l * -I " O +--XooOcao'^ "^^oS^X > SC u .^UyOyU^jO diuw '^ CX| 6o'a-2 to x Q a, ad, adn reO. reHh-O^ ^^w^Q g S ^?^a ^rJJ-Cte 6 Co S S c C ^ X t_. *5 *x. o coco.s.s *j|>4->r H re'O 26 KINKS AND SHORT CUTS KINKS AND SHORT CUTS. 2. The French or Irregular Curve. The French curve is used as a ruler for drawing non-circular curves. When a curve is determined by a number of points, a smooth freehand curve should first be drawn lightly in pencil thru the points. The French curve is then fit to a part of the curve by trial and FIG. 1. a line drawn as far as the French curve follows the general direction of the curve. The French curve is then moved to another position so that it fits farther along the curve and also follows the part of the curve just drawn for a short distance. This operation is repeated until the curve is completed. The heavy line a, c, b, e, d, f, g, Fig. 1, is being inked. Position 1 of the curve is drawn in light lines and shows only KINKS AND SHORT CUTS 27 a part of the curve. Position 2 in heavy lines shows the entire curve, and position 3 in light lines shows only a part. In position 1 ab is drawn, in position 2 cd, and, in position 3 ef. 3. Fig. 2 shows an instrument designed by the author. Its outlines consist of tangent circular arcs of different radii. The small blackened areas at A, B, C, D, etc., are holes cut thru the instrument. The corners of these holes are centers of the arcs a, b, c, d, etc. Its operation is as follows: FIG. 2. Use the instrument as a French curve to pencil the curve to be inked, marking the ends of the arcs (1, 2, 3, etc.) passed over by the pencil, and also their respective centers (A, B, C, etc). After penciling the result is as Fig. 3. The centers and tangent points being given, the curve can now be inked with 28 KINKS AND SHORT CUTS the compass. A trial will convince the experienced that this is a saver of blots and a preventive of their accompanying losses of time and temper. This instrument may be made out of cardboard, and by following the solution of Prob. 27, Plate 12, its outline may be made to approximate any curve. 4. Templets of Standard Parts. The templet method is a means of reduplicating small drawings. The drawing to be reduplicated is made and trans- fered to another piece of paper by pricking thru the essential parts. Fig. 4 shows a templet devised by the author. From this a bolt head or nut can be laid out by pricking thru the holes surrounded by the small circles. The process is as fol- lows: The pricker point is placed at A, s Fig. 5. If it is a bolt head to be drawn, the notch H of the templet is slipped against the point; if a nut, H is used. The holes are pricked thru as FIG. 3. the notch below shown. Lay out lines and arcs are drawn. Fig. 6. The finished head. Fig. 7. A templet when made should be filed away for future use. 5. A Master Templet. Where there are a number of sizes of standard parts a master templet can be made from which different sizes can be laid off direct or from which individual templets can be made. Fig. 8 shows such a templet of a nut. o o o o S"~ ^V O U. J. 5t'd. Unch o /^"=^ HE 40 3? fH NUT IJf FIG. 4. KINKS AND SHORT CUTS 29 In making this templet, the smallest and the largest standard size nut was accurately laid out to scale from a table of dimensions. Lines were then drawn connecting the principal points of each. To lay out a nut of any other size, the process is as follows : From A and B on the line AC lay off the bolt diameter of the required nut and draw the lines FG and DE. DE marks I FIG. 5. FIG. 6. FIG. 7. the top of the nut, and the intersections of FG with the lines connecting the corner layout points of the largest and smallest sizes, locates the corner layout points for this particular one. FIG A vertical line dropped to the line K from the intersection of FG with the line H locates the center of a small arc. The center of the large arc can be found by the intersection of a 45 line, drawn from an outside corner, with the center line. By laying off the proper height this same templet may be used for a bolt head. 30 KINKS AND SHORT CUTS 6. Section Lining. In section lining or "cross hatching" the spacing is generally done by eye. Where a great deal of hatching is done it saves the eyes to use a mechanical device to do the spacing. There are a number of section liners on the market, but most of them have other objectionable features besides the price. FIG. 9. Fig. 9 shows a common and simple device for mechanical spacing. It consists of a piece of wood or celluloid that will not quite fill up the space inside of a triangle. With the middle finger of the left hand on the piece of wood, and the index finger on the triangle, one is slipped while the other is held, thus "walking" in steps of equal length. If a piece of wood is not available, should the draftsman be so fortunate as to possess a few coins, he can make use of the same principle and get the right spacing by some such combination as shown in Fig. 10. KINKS AND SHORT CUTS 31 7. Fig. 11 shows an adjustable three-piece section liner. It can easily be whittled out of hard wood. The author has used one made by himself for ten years. To set it to a given space proceed as follows : Draw two lines a and b at the proper distance apart. Set the triangle on b. Slip clamp c to the left to loosen the device, and spread d and e as far apart as the triangle will permit. Hold d fast, slip the triangle to a, move c to the right, and the liner is set. FIG. 10. 8. To Rectify an Arc. It is theoretically as well as practically impossible to lay off the exact length of an arc on a straight line, or, a straight line on an arc. However, the 32 KINKS AND SHORT CUTS degree of accuracy attainable is not limited by theoretical con- siderations, but, as in all other measurements, by the accuracy of instruments and the acuteness of sight and touch. The method generally used is that illus- trated in Fig. 12, in which TO is the given arc and TQ a tangent at T. Starting at O small spaces are stepped off with the dividers until a point P, less than one step from T, is reached, from which point the same number of steps are taken on TQ. Theoretically, by this method the error may be made less than any assignable value by making the steps sufficiently short, since the shorter the chord the nearer it approaches in length to the arc which it subtends. Practically, an error of measurement is made with each step and the resultant error is the difference between the algebraic sum of errors made in stepping off the arc, less the algebraic sum of errors made in stepping off the straight line. Hence, the probable sum total of errors in measurement varies directly with the number of steps. There are a number of approximate methods of rectifying an arc. The following is a method devised by the author: 9. The Rectifier. On a stiff piece of paper a circle of some commensurate diameter is drawn, Fig. 13. AB is drawn tangent to the circle and B is carefully located by an accurate scale so that AB equals the computed length of the semi-, circumference AC. AB and AC are divided and subdivided into the same number of parts. Tangents are drawn to the circle at each division and the proper length taken from AB and laid off on each to plot the involute CB. A templet is cut out as shown in Fig. 13. KINKS AND SHORT CUTS 33 The following explains the use of the rectifier. To rectify on PQ the arc TO.* Fig. 14. FIG. 13. FIG. 14. Place the pricker point at K, Fig. 15, and slip the notch of the templet against it. FIG. 15. Turn until R of the templet falls on the line KL. Draw AB by ruling along AB of the templet. Turn the templet about K until R falls on KO, Fig. 16, and mark where the involute intersects AB at N. Draw the line KN until it intersects TQ at Q. TQ is the arc TO rectified as required. Fig. 17 is an enlarged view of the notch K. * The same method is used when the radius of the arc is less than the radius of the templet circle. \ 34 KINKS AND SHORT CUTS 10. Plotting Trochoidal Curves. In Fig. 18, A, B, C, and D are points fixed to M. Let it be required to plot the locus of each when M is rolled on N. These loci may be drawn by plotting the loci of any two points fixed to M. Let the locus of A and D be chosen. The locus of A is the circle AA' with E as center. When A is at A' D will lie on an arc of a circle with center A' and radius equal to AD. D will also lie on the line A'C' extended where Rect. arc FC'=Rect. arc FC. Any number of positions of A and D may be thus obtained. The accuracy of this method depends on the accuracy with which the locus of C, which is an epicycloid, is plotted. An easier and more accurate method is to plot the locus of A and E as follows: With E, Fig. 19, as center, draw an arc thru A, and with A as center draw an arc thru E. angle AEK AC Lay off K and L so that = - angle EAL CE Divide AK and EL into the same number of equal parts (1, 2, 3, etc., on AK, and 1', 2', 3', etc., on EL). With 1, 2, 3, etc., as centers strike arcs thru E. With E as center strike arcs thru I', 2', 3', etc. The intersections of these arcs at a, b, c, etc., are points on the locus of E when E is a point on M, and M is rolled on N.. 11. The Trochoidal Templet. The last method above was used in plotting the trochoidal templet, Fig. 20. The points in the imaginary circle U is the locus of A fixed to M when M rolls on N. V is the imaginary circle described by E fixed to N when N rolls on M. W is the locus of E fixed to M when M rolls on N. X is the locus of A fixed to N when N rolls on M. KINKS AND SHORT CUTS 35 Any trochoidal curves of M and N may be plotted as follows : Place the trochoidal templet over the paper on which the curves are to be plotted. Make a templet similar to that shown in Fig. 21 where FG=AE. Mark on this templet the points to be plotted. FIG. 16. If M is to roll on N place the pricker point successively at 1, 2, 3, etc., of U in Fig. 20 and slip F of Fig. 21 against it while the sharp end is at the corresponding point of W. Prick thru the points on the notched templet in each position. This will mark points of the required loci on the paper underneath. In making Fig. 23 the points on U and the locus of a point on the circumference of M, Fig. 19, were pricked thru to the paper on which the drawing was to be made. A templet shown in Fig. 22 was then made to follow these points as just described, and with a soft pencil, the tooth curve on the templet was drawn in each of its positions. FIG. 17. 36 KINKS AND SHORT CUTS KINKS AND SHORT CUTS 37 38 KINKS AND SHORT CUTS FIG. 20. KINKS AND SHORT CUTS 39 Problems. 1. (a) Construct a trochoidal templet for pitch circles 6 and 8 inches diameter respectively. See Arts. 10 and 11. (b) Plot a series of trochoidal curves using a moving templet with points located as in Fig. 21. (c) Make FIG. 22. a templet of a gear tooth for the 6-inch pitch circle and find its conjugate tooth on the 8-inch circle. See Figs. 22 and 23. 2. (a) Draw Brown and Sharpe Standard involute teeth of two meshing gears. Diam. pitch=2; 12 and 16 teeth. 3. Make a layout drawing of two bevel gears. Diam. pitch=3, 30 and 38 teeth, axes intersecting at an angle of 75. Dimension by scaling. See Plate 22, Page 44. 40 KINKS AND SHORT CUTS 4. Compute the necessary dimensions of Prob. 3, using instructions on Plates 19, 20, and 21, Pages 41, 42 and 43. TIG. 23. KINKS AND SHORT CUTS 41 BEVEL GEAR FORMULAE AXES 3O QUANTITY " vj |? FORMULAE 52 Diametral Pitch \ These are defer mined by the fr L vwrfring condi- tions of the c\ gears. Number 0f Teeth in Gear 1 II II H II II ^ Addendum d= (B.8cS.$t'd) &7 Pedendum JJS7 fa a c c^l & - \U. (J^i Addendum Increase of Gearl A= ^xc Addendum Increase of Gear m=4*b PLATE 19. 42 KINKS AND SHORT CUTS BEVEL GEARS CALCULATED DIMENSIONS PLATE 20. KINKS AND SHORT CUTS 43 BEVEL GEARS CALCULATED DIMENSIONS 6 ear 2 Number of Teeth in Gear 1 =b Number of Teeth in GearB =B Ang/e of Axes =/3 Number of Teeth in the & Imaginary 6ear 2. ~tan@ For other quantities substitute in PLATE 19 PLATE 21 44 KINKS AND SHORT CUTS BEVEL OBTAINING THE MACHINED DIMENSIONS BY LAYOUT REQUIRED: A layout for cutting the teeth of two bevel gears of 3 Pitch, 12 and 18 Teeth respective- ly, / Face, Axes perpendicular Dedendum Addendum^*, Pitch Diam. Pitch P/am. = Compare with PLATE. PLATE 22. Books on the Manual Arts PROBLEMS IN MECHANICAL DRAWING. By Charles A. Bennett. With drawings made by Fred D. Crawshaw. This book consists of 80 plates and a few explanatory notes, and is bound loose leaf, in board covers with brass fasteners. Its purpose is to furnish teachers of classes beginning mechanical drawing with a large number of simple, practical problems. These have been selected with reference to the formation of good habits in technique, the interest of the pupils, and the subjects generally included in a grammar and first-year high school course. Each problem given is unsolved and therefore in proper form to hand to the pupil for solution. Price, $1.00. MECHANICAL DRAFTING. By H. W. Miller. A new departure among textbooks on mechanical drawing. It is intended to supplement the work of the instructor in such a way as to reduce lecture work to a minimum. It is written about a flexible course but may be used equally well with any course. The book abounds in illustrations, both line drawings and half-tones, It shows a wise selection of material, a keen insight into the work of the draftsman and a thoro knowledge of the principles and methods of teaching. Above all it is a practical treatment of subject matter and a students' text easily adaptable to varied schools and conditions. Contains 219 pages and 225 illustrations and is bound in black flexible leather, pocket book size. Price, $1.50. DESCRIPTIVE GEOMETRY. By H. W. Miller. A successful textbook that is at once clear and terse in expression, complete in treatment and logical in arrangement. It treats of Point, Line and Plane, Inter- sections and Developments, Shades and Shadows and Linear Perspective. It con- tains about 1,000 graphic problems and is bound in leather, pocket book size. Price, $1.50. THE WASH METHOD OF HANDLING WATER- COLOUR. By Frank Forrest Frederick. A brief, clear, comprehensive text printed in sepia and illustrated with wash drawings and a water-color painting by the author. Price, 50 cents. SIMPLIFIED MECHANICAL PERSPECTIVE. By Frank Forrest Frederick. A book of simple problems covering the essentials of mechanical perspective. It is planned for pupils of high school age who have already received some elementary training in mechanical drawing. It is simple, direct and practical. Price, 75 cents. HANDWORK IN WOOD. By William Noyes. A handbook for teachers and a textbook for normal school and college students. A comprehensive and scholarly treatise, covering logging, sawmilling, seasoning and measuring, hand tools, wood fastenings, equipment and care of the shop, the common joints, types of wood structures, principles of joinery, and wood finishing. 304 illustrations excellent pen drawings and many photographs. Price, $2.00. WOOD AND FOREST. By William Noyes. Chotograpns ana micropnotograpns 01 sections. Domains a general oionography 01 ooks and articles on wood and forest. Profusely illustrated with photographs from the United States forest service and with pen and ink drawings by Anna Gausmann Noyes and photographs by the author. 309 pages. Price, $3.00. Published by the Manual Arts Press - - Peoria, 111. THE DRAFTING ROOM SERIES By FREDERICK H. EVANS, M. E. Assiitant Professor of Manual Arts Bradley Polytechnic Institute, Peoria, Illinois A MODERN AND EXTREMELY PRACTICAL TREAT- MENT OF COMMERCIAL DRAFTING IN CARD INDEX FORM P*HIS unique work is the result of a new analysis of the processes of com- * mercial drafting by a practical draftsman, engineer and teacher. The book points out the quickest, most exact and most practical method of work to obtain the desired results. Altho essentially a textbook containing problems, explanations, information and necessary data, it is an inspiration to collect from time to time additional material for ready reference and constant use. The scope of the book ranges from tools and their uses to gears and moving parts. In the selection of prob- lems the author has refrained from choosing merely difficult and time-consuming problems and has presented problems selected because they definitely present certain principles. The aim has been to develop skill not thru repetition but thru understanding; not so much results, as methods and processes. In all, it is a textbook worthy in form, in content and in adaptability to be considered for adoption by every teacher of machine drawing. It is divided into three parts. The first part, READING MACHINE DRAWINGS, is intended for beginners' use. It is designed to teach reading of drawings, and requires the use of only an ordinary lead pencil and a pad of cross-lined paper. It consists of a 20-page pamphlet and 17 cards. The second part, MACHINE DRAFTING, contains practical informa- tion on the common instruments, materials and tools of the draftsman and is a treatment at length of the practical work of the designer, detailer, checker and tracer, and a discussion of drafting room records, systems, etc. It contains a general treatment of "The Drafting Room", '"Detailing", "Checking", PEORIA, ILL. THE DRAFTING ROOM SERIES By FREDERICK H. EVANS, M. E. Assistant Professor of Manual Arts Bradley Polytechnic Institute, Peoria, Illinois A SUCCESSFUL TEXTBOOK FOR VOCATIONAL SCHOOL, EVENING SCHOOL, TECHNICAL SCHOOL, AND ENGINEERING STUDENTS THE DRAFTING ROOM SERIES--THE LID IS DESIGNED TO BE USED AS AN EASEL TO HOLD THE CARDS WHEN I.N USE "Tracing", "The Geometry of Drafting" and "Kinks and Short Cuts". It presents problems in drawing, detailing, assembling, checking, tracing, etc., and contains 9 pages of sketches and notes on the fundamental mechanical prin- ciples and their common applications in machinery. It consists of a 48-page pamphlet and 44 cards. The third part, INTERFERENCE OF MOVING PARTS AND TOOTH GEARS, contains an entirely new presentation of gears, avoiding technical language and difficult formulae, yet going to the bottom of the matter with perfect clearness. The subjects treated of are "Interference of Moving Parts", "Transmission of Motion by Moving Contact", "Tooth Gears" and the "General Principles of Conjugate Curves". It presents problems in calcu- lation, laying out, dimensioning, working drawings and detailing of gears. This part consists of a 40-page pamphlet and 21 cards. The series complete consists of three pamphlets and fifty-four cards, no duplicates, all of standard filing card size, 5"x8", assembled in a strong cloth- covered filing box. The box is well made and bears the name of the series in gilt on the cover. PRICE, COMPLETE, $2.00 Part I Reading Machine Drawings, price 75c, without box, 50c. Part II Machine Drafting-, price $1.25: without box, $1.00. Part III Interfertnce of Moving- Parti and Tooth Gears, price 90c, without box, 65c. THE MANUAL ARTS PRESS PEORIA, ILL. Books on the Manual Arts ESSENTIALS OF WOODWORKING. By Ira S. Griffith. A textbook written especially for the use of grammar and high school students. A clear and comprehensive treatment of woodworking tools, materials, and processes, to supplement, but not to take the place of the instruction given by the teacher. The book does not contain a course of models; it may be used with any course. It is illustrated with photographs and numerous pen drawings. Price, $1.00. CORRELATED COURSES IN WOODWORK AND MECHANICAL DRAWING. By Ira S. Griffith. This book is designed to meet the every-day need of the teacher of woodworking and mechanical drawing for reliable information concerning organization of courses, subject matter, and methods of teaching. It covers classification and arrangement of tool operations for grades 7, 8, 9 and 10, shop organization, allotment of time, design, shop excursions, stock bills, cost of material, records, shop conduct, the lesson, maintenance, equipment, and lesson outlines for grammar and high schools. It is based on sound pedagogy, thoro technical knowledge and successful teaching experience. It is practical. Price, $1.50. PROJECTS FOR BEGINNING WOODWORK AND MECHANICAL DRAWING. By Ira S. Griffith. A work book for the use of students in grammar grade classes. It consists of working drawings and working directions. The projects are such as have proven of exceptional service where woodworking and mechanical drawing are taught in a thoro, systematic manner in the seventh and eighth grades. The aim has been to provide successful rather than unique problems. The 50 projects in the book have been selected and organized with the constant aim of securing the highest educational results. The book is especially suited for use in connection with "Essentials of Woodworking" by the same author. Price, 75 cents. ADVANCED PROJECTS IN WOODWORK. By Ira S. Griffith. This book is similar to "Projects for Beginning Woodwork and Mechanical Drawing", but is suited to high school needs. It consists of fifty plates of problems and accompanying notes. It is essentially a collection of problems in furniture PROBLEMS IN FURNITURE MAKING. By Fred D. Crawshaw. This book, revised and enlarged, consists of 43 plates of working drawings suitable for use in grammar and high schools, and 36 pages of text, including chapters on design, construction and finishes, and notes on the problems. Price, $1.00. PROBLEMS IN WOOD-TURNING. By Fred D. Crawshaw. In the first place this is a book of problems 25 plates covering spindle, face- plate, and chuck turning. In the second place it is a textbook on the science and art of wood-turning illustrated by fifty pen sketches. It gives the mathematical basis for the cuts used in turning. In the third place it is a helpful discussion of the principles of design as applied to objects turned in wood. It is a clear, practical and suggestive book on wood-turning. Price, 80 cents. Board covers, $1.00. WOOD PATTERN-MAKING. By Horace T. Purfield. This book was written expressly for use as a textbook for high school, trade school, technical school and engineering college students. It is a revised, enlarged and newly illustrated edition. Price, $1.25. A catalog, listing and describing over 300 books on the Manual Arts, sent on request. Published by the Manual Arts Press - - Peoria, 111. UNIVERSITY OF CALIFORNIA LIBRARY Los Angeles This book is DUE on the last date stamped below. BIl NO PHONE 00 fl**, F c B ] D 198? FEB221987 RENEWALS II Illl Illl II im ii" '" " "illl M*-itf\ 1158 01167 4370 y