BUTTON DEPARTMENT OF VOCATIONAL EDUCATION GENERAL EDITOR FRED D. CRAWSHAW, M.E. PROFESSOR OF MANUAL ARTS THE UNIVERSITY OF WISCONSIN MECHANICAL DRAWING FOR INDUSTRIAL AND CONTINUATION SCHOOLS BY PHILIP W. HUTTON TEACHER OF DRAWING AND WOOD-WORKING, CHICAGO PUBLIC SCHOOLS SCOTT, FORESMAN AND COMPANY CHICAGO NEW YORK COPYRIGHT 1915 BY SCOTT, FORESMAN AND COMPANY EDITOR'S NOTE In commercial shop and construction work a mechanically drawn plan invariably accompanies the work of construction. Such a plan is the chief means of giving information to mechanics concerning work to be done. Upon their ability to read and properly interpret these drawings will depend the accuracy of construction and the proper assembling of parts. In learning a trade under ordinary commercial conditions only incidental practice is afforded in reading drawings. Experience has shown, however, that when such practice is an integral part of trade instruction, proficiency in tool operations comes more quickly and surely. One of the most satisfactory methods of learning to read draw- ings is to make them. Hence it is desirable in the preparation for industrial pursuits that students be given a simple and practical course in mechanical drawing The Author has, as a result of his experience in trade work and industrial teaching, prepared a text which is peculiarly suitable for use in continuation, all-day industrial, and evening classes. It is well arranged to enable those interested in a particular trade to become familiar with essential drawings, and to learn how to make them quickly and accurately. These characteristics should recommend the book to those in charge of industrial work in schools, including high schools. F. D. CRAWSHAW. 2065916 PREFACE The arrangement of the following course is the outgrowth of several years of experience in teaching the subjects of Mechanical Drawing and Industrial Arts to boys of the intermediate grades. Since the organization of Industrial Departments in the schools of Chicago, the author has taught an average of one hundred boys per day and has given his whole time and attention to Mechanical Drawing. Having had years of experience as a practical wood-worker and mechanical draftsman, he has applied this practical experience to the school room. He has endeavored to make drafting interesting by making it practical. Exercises and fundamental and essential conventions have been com- bined in practical problems suitable for those engaged in various lines of industrial work. These follow an elementary course on principles wliicli should be mastered by all beginners. The special industrial courses following the elementary course may be taken with profit by all. However, beginning with SHEET METAL WORK, each course is prepared with reference to peculiar industrial interests. Up to this point the work, as outlined, should be regarded as a unit. The purpose of the author has been : (1) To arrange a course especially adapted to, and within the limit of, a boy's ability. (2) To give the boy an intelligent idea of what a mechanical drawing is for, how to make it, and how to read and work from one made by others. (3) To awaken an interest in the common industries of life, and to create a desire for as complete an education along industrial lines as possible. If the boy is to enter industrial life at an early age, the course in drafting herein outlined will give him a foundation for his life duties far beyond that of the average mechanic. The course is both logical and practical. PHILIP W. HUTTON. [4] CONTENTS PAGE Editor's Note 3 Preface 4 Introduction 7 Equipment 9 Description, Care, and Use of Tools 10 Lines to Use 22 Lettering 24 Drill in Use of Instruments 27 Exercise I Lay Out of Sheet 28 Exercise II Basket Weave 32 Exercise III Application of Basket Weave 34 Exercise IV Circular Weave 36 Exercise V Straight Lines Tangent to Arcs of Circles 38 Exercise VI Arc Tangents 40 Projection Drawing 43 Projection I Cube 44 Projection II Wedge 48 Projection III Hexagonal Prism 49 Approximate and True Ovals 53 Projection IV Cast Iron Ring 54 Section Lines 56 Projection V Pipe Cut at an Angle 58 Projection VI Cone Cut Parallel to Its Axis 62 Wood- Working Drawings 65 Drawing Board 66 Pin Tray 68 Clothes Line Reel 70 Clothes Lifter 72 Foot Rest 74 Shelf, Sleeve Ironing Board, Mail Box, Book and Magazine Rack 77 Pedestal . 86 PAGE Inking and Tracing 93 Sheet Metal Drawing 9.~> Bread Pan 96 Dust Pan 100 Lawn Sprinkler 102 Water Pail 104 Sugar Scoop 106 Float Ball 110 Sink Strainer 112 Machine Drawing 115 Screw Threads 116 Hand Wheel 120 Plain Bearing 122 Wrench 122 Monkey Wrench and Wood Workers' Vise 124 Architectural Drawing 129 Electrical Conventions 145 Problems in Electric Wiring 151 Bell Wiring 152 Gasoline Engine Wiring 154 House Wiring 154 Gas Plumbing Conventions 156 Problems in Pipe Fittings 159 Problems in Plumbing 165 Hot Water Connections 166 Lavatory Connections 168 Problems in Brick Work 171 [6] INTRODUCTION. A mechanical drawing is an assembly of views of an object which show the length, width, thickness, and form of each and every part of it. l>y means of dimensions and notes, the size of each part and the material of which it is to be made are given. In fact, a mechanical drawing gives all the details about an object which a workman or series of workmen may need in its construction. Mechanical Drawing may be classed as a universal language by which the designer of an object can, through a drawing of it. transmit Ids ideas clearly to the man or men who are to make it. In the construction of a building, or a bridge, the foundation is first laid. So it is in the study of Mechanical Drawing. The use and care of all drawing tools must first be thoroughly understood. After this, some general principles must be mastered. These principles will not be given all at once, but will be introduced from time to time as a need for them arises in the different problems to be worked out. After the foundation is laid, certain fundamentals must be given consideration, such as the work an object has to perform, the use to which an article is to be put, etc. These fundamentals are effected by: (1) The most suitable materials for strength, wearing ability, etc., to perform the desired work. (2) The construction to be used. (3) The design or shape, so as to make the object pleasing to the eye and still to allow it to perform its work. [7] EQUIPMENT The necessary equipment consists of the following: 1 Drawing Board 1 T-Square 1 30-degree 60-degree Triangle, 8" 1 45-degree 6" 1 12" Rule graduated to sixteenths. 1 Irregular or French Curve 1 Protractor 1 Soft red rubber Eraser 1 Ink Eraser 1 Cleaning Eraser 1/2 dozen Thumb Tacks 1 3H Pencil 1 4H Pencil 1 12" Triangular Scale Rule 1 Penholder 1/2 dozen fine pointed Pens. (Gillotts No. 303) 1 Bottle Drawing Ink 1 Drawing Set consisting of the following: 1 Compass with Lengthening Bar, Pencil, and Pen Points 1 Divider 1 Bow Divider 1 Bow Pencil 1 Bow Pen [9] DESCRIPTION, CARE, AND USE OF TOOLS The selection and care of drawing tools and instruments must be given careful thought and consideration. DRAWING PENCILS By referring to the equipment list it will be seen that two pencils of different degrees of hardness are required. The degree of hardness is designated by the number of II 's stamped on the pencil. Experience has taught that the HHH and the HHIIH, in other words the three II and four II pencils, are best fitted for use in beginners' hands. The more II's the pencil has the harder the lead is; the four II pencil is, therefore, harder than the three H. The three II pencil sharpened to a long round point (Fig. I) is used for all freehand work, such as the making of arrow points, figures, etc. The four II pencil sharpened to a long wedge-shaped point (Fig. I) is used for all line work such as light construction lines, dimension lines, object lines, and dotted lines. Care must be taken not to apply so much pressure on the pencil that it will cut the paper. Figure I, which shows the proper and improper sharpening of the pencil, should be given careful examination. A pencil cannot be prop- erly sharpened with a dull knife, and the knife, however sharp, should never be employed for anything except the whittling away of the wood. Allow about 14" of the lead to project from the wood after whittling, and by the aid of fine sand paper, or a fine file, shape the lead prop- erly, as shown in the illustration. ERASERS Very little needs to be said on the use of Erasers. Each student should be provided with one soft red rubber eraser for the removal of pencil lines, one eraser containing a gritty substance for removing ink, and one cleaning eraser such as art gum for removing dirt, finger marks, etc., from the paper. THUMB TACKS Thumb Tacks are used to hold or fasten the paper in its proper position on the Drawing Board. A tack with a round tapering pin and 5/16'" round oval head is best. With careful use half a [10] nc.i n EDGE 4 H PENCIL. PROPERLY WRONG Srt*f?f a E/VE& roJ* LINE: WO&K <5 H F^NC/L WlTM FfOUND fO//VT FOR LETTER/NO, HUT TO* n] dozen tacks should be sufficient. The tacks should never be driven in with the T-Square or any other instrument, but should be pressed in with the ball of the thumb. As the Drawing Board is constructed of soft pine, this operation is not at all difficult. Care should be exercised in the extraction of thumb taeks. If they are pried out by placing an instrument under the edge, the stem is very apt to bend, and after a few such operations it will break off. The simplest way to extract a thumb tack is to grasp the edge of the head with the nails of the thumb and middle finger, at the same time twisting the tack to the right and left. It will be found that this loosens it so that it can easily be pulled straight out, since the action applies no leverage or side motion. This method greatly increases the life of the tack. INK It is advisable not to purchase the drawing ink until the time ar- rives for ink work to be taken up, for ink, unless it is in a perfectly air- tight bottle., evaporates quickly. A black water-proof drawing ink of any standard make will answer. PENS A fine-pointed steel pen such as the Gillott No. 303 or its equivalent must be used for arrow points, figures, etc. The pen must be wiped thoroughly after using and before the ink dries, or its life will be of short duration. THE PROTRACTOR The Protractor is an instrument used for measuring and laying off angles (Fig. II, p. 13). It is semicircular in shape and is usually grad- uated in degrees and half degrees. In laying off or locating an angle, the point on the Protractor representing the horizontal center (A) is to be placed on the vertex point of the angle, or the place where the vertex of the angle is to appear. The horizontal line (B) on the Protractor should coincide with the base line of the angle (C) as shown in the illus- tration. The number of degrees to be found or located can then be read off on the semicircular or graduated edge (D) of the Protractor. [12] 20' ric. n PROTRACTOR [13] THE IRREGULAR CURVE The Irregular or French Curve (A, Fig. Ill) is an instrument used for the construction of lines which are not straight but which cannot be drawn with a compass. In the construction of such lines, points should be located in the direct path of the line 1, 2, 3, 4, etc. (Fig. III). After these points have been located the curved line must be drawn, a little at a time. In this process the edge of the Ir- regular Curve (A) is used as a guide. To insure perfect results the edge of the Irregular Curve must pass through at least three points at each setting and as many more points as possible. If the curve to be constructed is of considerable length, adjust the Irregular Curve so that the edge of it will pass gracefully through three or four points, and draw this section ; then, using the last two points in the section just drawn as a guide, readjust the Irregular Curve so that it will pass through these last two points and as many new points as possible. Continue this process until the required curve is completed. Both the Protractor and the Irregular Curve should be made of a transparent material such as is used for the Triangles. THE RULER The Ruler best adapted to Mechanical Drawing work is the beveled edge type, 12" in length and graduated to sixteenths (B, Fig. IV). The Ruler is used only to determine distances. It is not intended to be used as a guide for drawing lines. The T-Square and the Triangles are for this purpose, as will be explained later. [14] r/c. m HUTTON [15] THE SCALE RULE (A, FIG. IV ) The principle involved in the Scale Rule is very puzzling to the beginner, but he will see clearly its use and advantage by giving strict attention to the following explanation. Let us suppose that we are to make the drawing of a certain object, the length of which we will say is nearly twice that of the paper on which it is to be drawn. How can we accomplish this? It should occur to us at once that the object must be drawn half its actual size. Let us analyze what this means. We have practically, as far as this indi- vidual drawing is concerned, reduced the size of our rule just one- half. In other words a 6" measurement on our half-size drawing equals a 1' measurement on the object being drawn. Our drawing, then, if made to a scale of 6" equals 12", or I' (commonly called scale 6" - 12"), will be one-half size. Suppose that we are required to make a drawing of a building 100 feet in length, and that we have a piece of paper just 30 inches long on which to represent or draw this building. If we were to draw it full size it would require a paper 100 feet in length. If we were to draw it half size it would require a paper 50 feet in length. So, knowing that the size of our drawing must be within the limit of 30 inches, we must look for a scale on our Scale Rule that will meet the requirements. Let us say we will make our drawing to a scale of "y" equals 1'." It can be readily seen that, drawn according to this scale, our building will be just 25" long on paper. On your triangular Scale Rule you will find spaces as follows: 3 inches long representing 1 foot. I/ /4 3/16 1 / 78 3/32 " You will find, also, a regular 12" Rule divided in inches, halves, quarters, eighths, and sixteenths. [16] XVA 0) * -3 * v *? (A 5 * [17] Now notice the 3" scale (C, Fig. IV) and you will sec that it is divided into twelve equal parts; therefore at a scale of 3" to the foot, each one of these divisions equals 1". The 1" space is divided in the center by a long line ; this makes two shorter spaces eacli repre- senting the half of V, or */>". The 1/2" space is divided by a line not so long, which makes two still shorter spaces each representing the half of !/", or 14". This 14" space is divided by a line shorter than the rest and represents a distance of %". It will be seen, therefore, that the 3" Space (C, Fig. IV) thus divided is nothing but a miniature 12" rule in exact proportion in .every way. So it is with every scale shown on the Scale Rule. They are all miniature 12" rules, but they are not all divided to %", for if they were the divisions would be so small they could not be read. Look at the %" scale and see how small the divisions are. Each small division on this scale represents 1 inch. Now let us turn our rule so that we again have the 3" scale before us. From the 3" scale, reading to the left, you will find in the groove the figures, in their order 0, 1, 2, etc. which mean that the distance from the to the figure 2 represents 2' on the scale of "3" equals 1'." Suppose we wish to step off a distance of 2' and 6" on this scale. From the to the right in their order and in the groove you will see the figures 0, 3, 6, 9. So the distance from the figure 2 at the left of the in the groove to the figure 6 at the right of the in the groove will be an exact measurement representing 2', 6" at a scale of "3" equals IV By dividing 12" by 3" we find that in drawing the object to a scale "of 3" equals 1','' we will have the drawing when finished, exactly ^ size. Drawing an object 14 size without the use of a Scale Rule would require considerable time in figuring for each dimension. Moreover, the possibility of making a mistake would always be on . the draftsman 's mind, which would take his attention from his work. Later, as a matter of practice, so that you will become familiar with the Scale Rule in all its details, you will be required to draw a series of lines all of different lengths and to different scales. When you arrive at the part of the work which requires this, review very carefully all that has been said about the Scale Rule. In this re- view keep the Rule itself constantly before you for reference. [18] DRAWING BOARD The first tool with which we come in contact is a Drawing Board. The kind and size of board to purchase depend largely upon the future use to which you intend to put it. If you contemplate High School or University, a board of considerable size would be advisable. If a board is not furnished by the school, ask the advice of your teacher as regards the size. Any board chosen should be constructed of select dry white pine properly reinforced to prevent warping. DRAWING SETS A Drawing Set containing the variety of tools specified in the equip- ment list can be purchased at various prices according to the quality and amount of material and workmanship expended on them. A medium priced set will, with proper care, last for a number of years; A set constructed with all center points removable is, when con- sidered from a standpoint of accuracy and durability, advisable. Any set purchased must be kept bright and clean. Ink must never be al- lowed to dry in the pens as this corrodes the metal and causes a rough- ness which naturally interferes with the proper flow of the ink. When the pens are not in use be sure that the adjusting screw is set so that the pen points are open. If the pens are laid away with adjusting screw run up tight so as to place considerable tension on the pen blades it will be found in time that the natural spring of the blades will be lost and that the pen will be rendered useless. The individual use of the drawing instruments will be taken up as the use for them arises in the different exercises, problems, etc. [19] T-SQUARE The T-Square consists of head and blade (see Fig. V, p. 21). The inside edge of the head and both edges of the blade must be perfectly straight and free from nicks, and the head and blade must be set perma- nently at an angle of 90 degrees to each other. The blade of the T-Square should not be shorter than the length of the Drawing Board. TRIANGLES The Triangles (see Fig. V) are two in number, one of which is com- monly called a 45-degree and the other a 30-degree Triangle. These tools are, as the word triangle implies, three-cornered. The 30-degree Triangle has one corner which measures 30 degrees, or the twelfth part of a circle, one 60 degrees, or the sixth part of a circle, and one 90 degrees, or the fourth part of a circle. The 45-degree Triangle has two corners, each of which measures 45 degrees or the eighth part of a circle, and one which measures 90 degrees. Both Triangles should be made of a transparent material such as celluloid. They are to be used in connection with the T-Square. HORIZONTAL AND VERTICAL LINES All horizontal lines (see Fig. V) are drawn by using the upper edge of the T-Square blade as a guide for the pencil. All perpendicular or vertical lines are drawn by using an edge of one of the Triangles as a guide for the pencil. In order to get proper results and to have all horizontal lines parallel, the head of the T-Square must be used in direct contact with the left end of the Drawing Board. Much care must be exercised in this, for if the full length of the inside edge of the T-Square head is not firmly pressed against the left end of the board, corresponding lines on the drawing will not be parallel. The top edge of the T-Square blade is used also as a base for the Triangles. The edge of the Triangle perpendicular to the T-Square blade is used as a guide for the pencil in drawing vertical lines. Therefore, it should be readily seen that the foundation guide for vertical lines as well as hori- zontal lines is the T-Square head in contact with the end of the Draw- ing Board (see Fig. V). This is a fundamental principle which must be mastered. It can be done quickly if the directions given are carefully followed. [20] [21] LINES TO USE Examine carefully the several different kinds of lines used (Fig. VI). When inked in, the construction, the dimension, center, and dotted lines should be much lighter than the object line, yet heavy enough to be distinct. The dimension line consists of two long dashes with space between them for the dimension, or distance between arrow points, as shown. All arrow points must be small, narrow, and solid black. The wide, uneven arrow point is to be avoided. Points of the arrows must touch the lines, the distance between which is represented by the figure. To extend the arrow points through these lines or to place them away from the inside of these lines is absolutely incorrect. The center line is constructed the same as the dimension line with the exception that two short dashes are placed in each space between the long dashes. Center lines are used, as the name implies, to represent centers of objects or parts of objects. At times the crossing of two center lines represents the location of centers of circles or parts of circles. The dotted or hidden line as shown is used for representing that part of an object which lies behind the surface. When inked the object line must correspond in thickness with the object line shown in Figure VI. [22] nc.m CoNSTFlUC TION L INS CENTE, '/? L FNE5 DOTTED Of? HWDCN LINES DIMENSION LIMES OBJECT LINES LINES [23] LETTERING After the proper drill on the obstruction of different kinds of lines has been had, it will be found easy to construct guide lines for letters as shown in the examples of alphabets and illustrated as con- struction lines in Figure VII, p. 25. If the illustrations are studied attentively little need be said on the subject. Notice carefully the differ- ent steps taken in constructing the letters that make up the word Chicago (Fig. VII). Draw horizontal construction lines representing top, cen- ter, and bottom of letters. Space off all letters to be drawn (A, Fig. VII) with the Bow Dividers. Draw your slant lines mechanically, as illustrated in Figure I, page 26, and mark each space with the letter it is to develop into, as show T n at B (Fig. VII). Brighten all horizontal lines for letters (C). Brighten all vertical lines for letters (D). Draw in and brighten all other lines as the bar of the G, the side of the A, etc. (E). Erase all construction lines so that the word will be neat and clear as at F. Some letters, on account of their peculiar shape, require a little diversion from the ordinary rule, as A, B, K, M, V, W, etc., shown in Plate, page 26. Note their peculiarities and construct them accord- ingly. All mechanical lettering is to be done as just described. In the small letters, which are made freehand, draw first the guide lines, top and bottom. The distances between the guide lines should corre- spond with those shown on Plate, page 26. Considerable practice is required before one can letter properly, either mechanically or freehand. The letters must all be the same in height and in case of slant letter the slant should be uniform. As an aid in making all freehand letters the same slant, place your arm so that its slant relation with the guide lines is the same as the desired slant of the letter. Make sure that all letters touch both top and bottom guide lines and construct them so that they will be a little wider than they are high. Always keep an even space between letters and double this space between words. All lettering given is of a simple type. Good results will be easily obtained through practice if directions are followed. As good lettering is essential to the neat appearance of a drawing there should be practice in lettering whenever an opportunity presents itself. It may be well, un- der the guidance of the instructor, to prepare a formal sheet of letters. NOTE. If it is so desired, a special angle for lettering only can be constructed as shown in Figure II, Plate, page 26. [24] no. JZE / // /// // // // / / // /// // // // 7" c "ill f ji 'ii'n I II 777/7 C , , A , . C,. O i II ! II! It 11 I II in I I I! In II if it c // "/// c l il t I nil! II I CH/C/7CO [25] g ? 8 DRILL IN USE OF INSTRUMENTS Before attempting any of the exercises a short drill on the proper method of fastening a sheet of drawing paper to the drawing board by means of thumb tacks will be necessary. After the pencils have passed the inspection of your teacher proceed to fasten a piece of paper, size 9" X 12" on your Drawing Board by the aid of thumb tacks. Observe strictly the following method, as it is practical, simple, easy, and correct. Place the paper, a good quality for drawing, in the center of the Drawing Board and with the ball of the thumb press into place one thumb tack in the upper right hand corner of the paper. As there is but one thumb tack in place the paper can be easily moved up and down with that corner of the paper the thumb tack has pierced acting as a pivot. Now place the T-Square in position as in Figure V, page 21, with the head of the T-Square to the left, and the inside of the head held directly and firmly against the end of the Drawing Board. Keeping the head in this position move the T-Square up with the left hand until it is in line with the corner of the drawing paper through which the thumb tack has been passed. With that corner of the paper acting as a pivot, as previously explained, move the paper up or down, as the case may be, until the top edge of the drawing paper is in perfect line with the top edge of the T-Square. Hold the paper in this position with the hand and press into place one more tack in the upper left hand corner. In pressing the tack into place, care must be taken that it travels perpendicularly to the surface of the Drawing Board, and that the under part of the tack head comes, in direct contact with the paper at all points. The contact of the under surface of the tack head with the paper, when the tack is pressed firmly against the board, gives far more holding power than the pin of the tack passing through the paper. If desired, additional tacks may be placed in both lower corners, but for a paper of this size it is not necessary. If tacks are placed in the lower corners of the paper it will cause some inconvenience when drawing in that immediate section, as a rocking motion of the blade is unavoidable when the T-Square is in position and directly over the tacks. Then, too, the T-Square blade is apt to become nicked or marred if it comes constantly in contact with the edge of the tack. [27] EXERCISES. In selecting the exercises much care has been taken to have a series that not only embraces the proper use of all drawing tools but at the same time presents a pleasing appearance and an interesting set of problems. It will be found that these exercises bring together and develop the best facul- ties of the brain, the hand, and the eye, and promote neatness and accuracy. They impress on the mind of the student the absolute necessity of light construction lines. Without the proper and accurate use of the Ruler, T-Square, Triangles, etc., and with- out pencils sharpened in the proper manner, they cannot be executed. Each exercise should be worked through as described below. EXERCISE I LAY OUT OF SHEET Study Figure V, page 21, carefully. When the paper has been prop- erly fastened to the Drawing Board proceed to construct the border lines. These consist of a horizontal line at the top and bottom and a vertical line on each side (Ex. I, page 29). Each of these lines should be ^2" from the edge of the paper. In drawing each horizontal line, measure the }" distance in from the edge of the paper in one place only. After you are sure that the T-Square is held in the proper position, draw the line through this point, with the blade of the T-Square as a guide. The vertical lines also are to be drawn with but one measurement for each. Use one 90-degree edge of the Triangle as a guide for the line; let the other rest on the T-Square. Make sure, as before, that the T-Square is held in the proper position. (Examine carefully Fig. V, page 21.) These lines must be very faint construction lines, as it is required that they be gone over or brightened in the spaces between the inter- section or crossing of horizontal and vertical lines. The short construc- tion lines which remain at each corner (Ex. I, A) outside of these inter- secting points, will later be erased so as to leave a perfect rectangle. If it is found that the paper is not exactly square at the corners, the sur- plus can be trimmed off when the plate is finished. [28] EDGE: or 3 ^ X, ^ CD 3 h 4 * \) | i t o 1 1 S x^ EXERCl ConsTFfucrtc ^ *K t ' Do X ' . In this operation use the other end of the line or point 6 as a center. Draw a line as shown connecting the points of intersection of the arcs. This line will be found to pass through the exact center of the line to be bisected. Bisect in this manner the base line of the front view of the Wedge thus locating the center of the base. Draw 7 a vertical line through this center and extend it far enough to locate the vertex of the Wedge, C, and also the line, D D 1 , representing the edge of the Wedge as seen in the top view 7 . The geometrical solution at the top can be omitted in the finished drawing if desired. It is assumed that by this time the student under- stands what lettering each individual drawing requires, and also which lines are to be brightened and which are not. With this drawing that part of the explanation will be discontinued. PROJECTION III HEXAGONAL PRISM Projection III is the representation of a Hexagonal Prism 2" in height, with a hole 1/2" in diameter passing through it lengthwise. In discussing Projection II it was said to be advisable, whenever pos- sible, to draw the front view first, but in the construction of such draw- ings as the Hexagonal Prism, the top view should be drawn first, to locate at once the long and short diameters or to determine the exact width of [491 PROJECTION H [50] the front and side views. The drawing of the top view applies the geometrical principle of inscribing a regular hexagon in a given circle, (Fig. 1). The diameter of the given circle equals the long diameter of the hexagon, which in this case is two inches. In Figure 1 in the upper right hand corner of the plate are shown two methods of procedure, lu both methods it is necessary first to construct the circle of a given diameter. A, and through the exact center of this circle to erect ;i vertical center line, B. By the dimensions shown in Figure 1 it will be seen that the radius of the circle and the length of one side of the hexagon are equal. As the sides of a hexagon are all of an equal length it is plain that by the aid of the Compass or Divider, set to an exact distance of one inch, or the radius of the circle, the six equal sides can be easily located by spacing them off on the circumference of the circle, A. The starting point in this case should be at point C or the point where the vertical center line B intersects circle A. The other commonly used method of constructing a perfect hexagon is by the use of the T-Square and the 30-degree Tri- angle as shown in Figure I. This method should be understood without further explanation, as it involves only the proper use of the T-Square and Triangle. The drawing shows, as has been previously stated, that a hole Vi/' in diameter is to extend through this prism lengthwise. The top view shows clearly the location of the half-inch hole. In the side and front views the hole would of course be shown by hidden lines; these lines would be i//' apart, each 1 / 4" from the center line of the view. If this hole were to extend only part way through the prism this information would be transmitted without verbal explanation by extend- ing the vertical dotted lines to the required depth only, and by giving a dimension for this depth. The bottom of the hole would be shown by a dotted line drawn from the bottom of one vertical line to the bottom of the other or from one vertical dotted line to the other at the proper depth, thus showing the termination or the bottom of the y*" hole. It will be noticed that in representing the front view of the hexagon placed in this position three vertical object lines are necessary, while in representing the side view four are required. The reason for this should be thoroughly understood by the student. It will also be noticed that in order to locate the center line in the side view the geometrical principle of bisecting a straight line is again used. [51] If the problem in Projection III involved the making of a polygon with more than six sides, a different method of construction would neces- sarily be used. In Figure IV, p. 53, a convenient and easy method of dividing a circle into any number of equal parts is given. After drawing a circle of the proper diameter, draw through its center a horizontal and a vertical center line as shown at A B and C D. Then divide the horizontal center line A B into as many equal parts as it is required to divide the circle in this case seven. Divide the upper half of the vertical center line into four equal spaces as 1, 2, 3, and 4, and extend it upwards to point E beyond the circle, a distance equal to the length of three of these parts. Through point E and the second division point from the left of the center on the horizontal line A B, draw a line intersecting the circle at point G. It will be found then, if the work has been accurately done, that the distance represented by the heavy line A G is the required length of each of the seven sides. Set the Dividers to this distance and step around the circle. If the top view in Projection III were to assume the shape of an ellipse, an approximately correct ellipse (Fig. II) or a true ellipse (Fig. Ill) could be constructed as described below. To construct an approximately correct ellipse draw first the hori- zontal center line A B (Fig. II) then the vertical center line, C D. On each of these center lines, from their intersecting point E measure off one-half of the corresponding long and short diameters of the ellipse. On the long diameter, from A, measure off a length equal to the short diameter, thus locating point F. Divide the remaining portion of the horizontal line into three equal parts as 1, 2, 3. With E as a center and the Compass set to a distance equal to the length of two of these parts, as 1 and 2, draw arcs cutting horizontal center line A B at points Y and Z. Set the Compass to the distance Y Z, and with Y as the center draw arcs P and Q ; with the same radius, and with Z as a center draw arcs M and N. With the intersecting points of arcs M and P and N and Q and the points Y and Z as centers draw the ellipse as shown by the radial dimension lines. In constructing a true ellipse it will be necessary to draw from the same center two circles, one with a diameter equal to the short and one with a diameter equal to the long diameter of the desired ellipse. Divide the larger circle into an equal number of parts (24 will be suffi- cient) by the aid of the 45-degree and 30-degree Triangles, used singly [52] and in combination. Connect these division points with the center of the circles as shown. From the division points of the large circle project vertical lines A, B, C, D, E, etc., and from the division points on tli<- small circle, formed by the radii of the large circle, project horizontal lines 1, 2, 3, 4, etc. Through the intersection points of these correspond- ing vertical and horizontal lines, as 0, O 1 O 2 , etc., carefully draw by the aid of the Irregular Curve, the desired ellipse. PROJECTION IV CAST IRON RING Projection IV is that of a cast iron cylindrical ring. Two methods of representation are shown, both of which are correct. If in drawing the front and side views of the ring, no principles other than those that have been previously given were to be used, the front view (Fig. I) and the side view (Fig. II) would be sufficient. But in the represen- tation of objects it is often necessary to make what is termed a section drawing, a drawing of a section or cut through the object, (Fig. III). In drawing the section of an object a true representation must be shown of what the object would look like at the particular place where the object is cut in imagination. Imagine a cut made through an object, as with a saw, and then show an exact representation of that part of the object the saw passed through as looked at squarely toward the cut surface. This method of representing an object, or some particular part of an object, is used principally to show more completely the shape, location, or construction of some part or parts not clearly shown in the ordinary way. Advantage is generally taken of a sectional drawing to make it show from what material the object is to be made, by crossing the sec- tion diagonally with a series of lines and combinations of lines, each combination representing a certain material. (See page 56.) In Projection IV, Figure III, is shown a sectional drawing of the cylindrical ring, the line of intersection being A A (Fig. I). By com- paring the section lines shown in Figure III with the small squares on page 56, properly sectioned as previously mentioned, it will be seen that cast iron is the material from which the ring is to be made. In the execution of this problem the usefulness of an occasional sectional drawing is by no means fully covered. The problem is given only to acquaint the student with the principle involved. [54] HZ nc.m FIG. I r 55 SECTION LINES C/JST IRON 3 r CEIL WPOUGHT!RON BRASS B/JBBJTT WOOD [561 PROJECTION V PIPE CUT AT AN ANGLE The projection drawing of a piece of pipe to show all required dimensions would necessitate but two views, the front view to show the length, and the top view to show the inside and outside diameters. If, for any purpose, this pipe were to be cut at an angle, the angle also could be shown in the front view, but if for any reason it were required that the exact shape of the end cut at an angle be shown, this exact shape would have to be developed or drawn in a view parallel to the cut. The drawing of a piece of pipe cut off at one end at an angle of 45 degrees is shown in Projection V. Four views are given so that all principles involved can be easily understood. In reproducing this drawing the inside diameter should be I 1 /-/', the outside diameter 2", and the extreme length 3". Draw the top and front views according to the above measurements, and show the top end of the pipe cut at an angle of 45 degrees. Divide the upper half of the circle representing the outside diameter into any number of equal parts (12 will be sufficient, as 1, 2, 3, 4, 5, 6, etc.). Draw the series of lines, R, connecting these points with the center of the circle 0; then with the series of lines X project points 1, 2, 3, 4, etc., until they intersect or cross line B B, which represents the edge of the top of the pipe. It has been previously stated that if an exact representation of the end of the pipe cut at an angle be desired, the view of the end would have to be made with its center line parallel to the cut B B. Draw center line CC exactly parallel to BB as shown, and with the 45-degree Triangle and the T-Square draw projecting lines Z from the intersecting points of lines X and line B B through center line C C. This will locate on center line C C the true length of the slanting end of the pipe. By referring to the perspective drawing of this pipe it will be seen that the end of a pipe cut at this or any other angle gives the appear- ance of an ellipse. The line representing an ellipse comes under the head of a line otherwise than straight, but which cannot be drawn with a compass. It must therefore be drawn by the aid of an Irregular Curve. [58] [59] By referring to the description and use of the Irregular Curve (page 14) we see that a series of points directly in the path of the curve to be drawn must be located. Before proceeding with the location of these points the student's attention is called to the fact that the space between the view of the outside and the inside " lonjr. At a glance it can be seen that the block thus described is to have the top edges chamfered to a required dimension. This is shown plainly in any one of the three views. The fact that a dimension for this chamfer is given at only one point on the drawing indicates that the size of the chamfer continues to be the same at all points on the ed.se of the tray. The outline of the groove as shown in the top view with its given dimen- sion denotes its width and shows that it is semicircular in shape at botli ends. With the radius of the circles omitted and the distance between centers given, as in this case, it is understood that the diameters of tin- circles to be drawn equal the distance separating the lines they are to connect, or l 1 /^". As the radius of a circle always equals the half of its diameter, the full length of the groove is plainly but indirectly shown. The groove is shown in the side or front view to extend the same depth for a distance of 2%", or the distance between the centers of the end circles. If it were not to extend the same depth, a dimension for its depth at various points between these centers would be given. The end view shows by dotted lines the end shape of the bottom of the groove, which is also circular. The proper placing of this dotted line appears at first an easy matter, but it will require considerable thought on the part of the student. Considering that in the top view there is no dimen- sion given for the exact location of the groove, it will be understood that it is to appear in the exact horizontal and vertical center of the tray. The ends of the dotted lines representing the bottom of the groove in the end view must show the width of the groove at the top or widest point, and must appear at the exact required distance each side of the vertical center of this view. As the bottom of the groove is circular in shape, as previously explained, a point must be located from which the circle can be drawn to allow it to pass through a point on the end view center line representing the exact depth of the groove. There are. there- fore, three given points through which this circle must pass : A and B rep- resenting the top edges, and C the bottom center of the groove. In the upper right hand corner of the plate is given the geometrical principle involved in locating a point, from which, when used as a center, a circle can be passed through any three points not in a straight line. Let 1, 2, 3 be the points through which the required circle is to pass. Bisect the distance betw r een the points 1 and 2, allowing the bisecting line to extend upward. Bisect the distance between the points 2 and 3 [68] ro OoiG, [69] and extend the bisecting line upward until it crosses the bisecting line of points 1 and 2. The intersecting point of these bisecting lines will be found to be the desired point from which a circle may be drawn that will pass through the given points 1, 2, 3. Apply the same principle in passing a circle through the given points A, B, and C in the end view and study until thoroughly under- stood. Dimension the drawing as shown. Erase all construction lines and the plate entitled "Pin Tray" is completed. CLOTHES LINE REEL Before attempting to draw the Clothes Line Reel, review thoroughly the description and use of the Scale Rule as given on page 16, and at the same time space off on a series of lines a distance representing : 2' 0" at the scale of 3" equals 1 foot. 1' 6" ' 3" i i t t 8'0" " " t I t I Q// I i t i it 141/," " " " 3" " ' ; 2' 6" '' " I 1 //' " . . tt 1' 9" " " 1U," " it t t 2' 4" . . - . 1 " i i t i t . -I / o// it tt . . . . 1 // 4 t < < . . 3' 9-" " " tt tt 3 ^,, tt i i i i 2' 7i/ " ' ' ' ' t t t t 3 / // . . t t t l K> C"~ "' 1 1 1 1 i/ '/ t i t) O 7'2 2' 3" " " tt tt 1Xi/ , < ( t ( 12' 6" " " ( I it q / // . . 78 t < < t Af Q// " ^ %" " tt tt 20' 0" " " " l/^" it tt 18' 6" " " " 14" " 1 1 1 1 32' 6" " " < < < < 3 // < < it 1 1 11' 6" " " 11 " A" " 1 1 ll 20' 6" " " " l/ 8 - " 1 1 1 1 15' 9" " " t < 4 < 1 / // . . 78 1 1 t t 40' 0" " " t l 1 1 3 f/ tl 1 1 t t 37' 6" " " t t it 3 // < < it it By measuring accurately from center lines in both horizontal and vertical directions, and by working carefully, the student should be able to draw straight and curved lines in combination and produce this plate properly without further explanation. [70] T OBlN -22- /-y">> -3S- ] Ts .3i Tr"vK ^ -3S- -6*- -j n r i PI ' CO (r 2 [71] CLOTHES LIFTER The Clothes Lifter shown is constructed of three pieces, namely: bar, handle, and spreader. It will therefore be necessary to make, aside from the assembly, a detailed drawing showing eacli piece in as many views as is necessary to locate all dimensions. The sectional square drawn in the center of the assembly shows the size and shape of the bar between rivets. In the detail of the bar both ends are shown to be tapered on two sides from the rivets out. In the front view of the handle are shown dimensions for making the saw cuts, while in the end view the handle is shown to be round. In the front view of the spreader the shape is shown to be that of a wedge, with sides concave to the extent of y". The end view of the spreader shows both width and thickness. Where objects are constructed of several parts, as is the case in the Clothes Lifter, a material list must be compiled. In compiling a material list allowance must always be made for material to be wasted in the process of finishing or bringing the piece to its actual shape and size. The detail of the bar shows it to be, when finished, 1%" X I 1 /*" X 3' 1". In order to make proper allowances, the material list for the bar must read: 1 piece, \y>" X I 1 /-" X 3" 2", etc. In the following problems the student, after the assembly and details have been drawn, should be able to furnish accurate material lists without further help or explanation. In compiling any material list composed of numerous parts and materials, the most concise method is to make a tabulation as shown below. MATERIAL LIST LIBRARY TABLE No. PIECES REQD. NAME SIZE MATERIAL 1 4 Top Posts %" X 30" X 46" 3" X 3" X 29" Oak Oak Etc. [72] T _/ 1 CD \ > P D [73] FOOT REST The drawing of the Foot Rest presents a principle which can very often be applied, especially when it is desired to draw to as large a scale as possible within a limited space. It will be noticed in the front view that the length of the top is to be 16". This, drawn to a scale of 6" to the foot, or half size, would be 8", while the length of the drawing is considerably less. Since there is not room 011 the paper for a full half-size view, and since the size and shape of all parts of the stool between the legs are the same, it is customary and proper to show this view with a piece broken out ; thus the legs and ends are brought closer together than the scale demands. The over-all dimensions, however, must be fully indicated, and the legs and ends of the sides and top must be drawn true to scale. In the top view it is not necessary to show the entire top as the corners are all constructed alike. In certain cases it is customary and proper, in order to show clearly some particular part or construc- tion of an article, apparently to break out a section of the surface, thus allowing the construction to be shown clearly and with a full line. To a person accustomed to working from a drawing this practice is not at all confusing, while its saving in time and space in drawing is yery apparent. [74] [75] s I -*- Q in tt X S 1*1 Q: M kJ Q ^ ly h [76] SHELF, SLEEVE IRONING BOARD, MAIL BOX, BOOK AND MAGAZINE RACK The drawings of the objects mentioned above will require two sepa- rate sheets for each, one for the assembly and one for the details. It is not essential that they be drawn to one scale. Any convenient scale or scales can be used, according to the size of the part and its position on the drawing paper. It is desirable, however, to make all drawings on the same sheet to one scale whenever possible. By observing carefully each detailed part and locating it in the assembly, a complete knowledge of the working principles of each com- plete object can be obtained. [77] -J tn C78J u. b H n. IS io 1 ^ ^ "Q [79] 8 S U .J en I [80] b 5 a LJ Uj I .0 1 L I I L-L Q Uj $ o- -- 0) t . Q Q: Q: vj ^. k 1 1 . , *)IOO o r. [83] tfSSEMBL Y DF^/JWINC LJ. h -22 COMBINED BOOK tt LL R/JCK HUTTOH [84] DETAIL. DF CE]MB I NED BEHHK AND MAGAZINE Borrow J SZ" [85] Hurra* PEDESTAL Since the Pedestal is of considerable size, and since it is square, it will be necessary to draw only the front view, aside from the section, to show clearly the shape of the base. The base could of course be shown in a top view, but in that case it would be necessary to represent a portion of its outline by dotted or hidden lines, as in this view it would be in direct line with the top. Representing the base in the manner shown not only gives a clear outline of the base but shows also the box construction of the post as well as a full top view of the brackets. As previously explained on page 54, an imaginary cut must be made in the pedestal at points A, A, enabling a correct top view of the lower remaining section to be drawn. [86J // ASSEMBLY or [87] a h P i Uj Lj * cm. -if- W *0 .-Q oy Q: cu Q <0 o 10 k <0 ->-* .Q .Q i [88] STUDENTS' FOLDING DRAWING TABLE In the top view of the Drawing Table it will be noted that the under side is shown in full lines, which is exactly contrary to all prin- ciples heretofore given regarding hidden lines. This is permissible, however, when such a view does not conflict with the clear representation of some other part of the object. It will also be noticed that the top view is drawn parallel with the top of the table which is on a slant. This is done to show the under section of the top in its true dimensions. If the top were shown directly above the front, a foreshortening of the top in the top view would be the result. The greater the slant given to the table top, the greater would be the fore- shortening. [90] r I r 1 1 ^^ m 1 ; r> 1 i 1 OBls t ? M r-J i K. : fc X' 1 ( 1 \) <. < ~JL O/ND ^ i REWIND T/IBLE: CALE /'=/" .-Xs\ " UDEN ^i 1 T *?/\, // y L J 1 - [91] to u s -J U k a Q: " Q tn u. Q .,*? 8 k t i [92] INKING AND TRACING INKING If an entire volume were to be written on the use of drawing ink and inking tools, a certain amount of careful inking practice would still be necessary before proper results could be obtained. Consider- ing this fact, and believing that many who use this text will do only a moderate amount of ink work, it has been deemed advisable to give merely a few instructions and precautions which will enable the student to obtain neat and accurate results. A quill will be found connected with the stopper of each bottle of drawing ink. This is to be used in tilling the drawing pens. Never dip the pen directly into the ink. Hold the pen in the left hand in a per- pendicular position, with the handle at the top ; then by placing the quill filled with ink, and held in the right hand, between the points of the pen blades the ink will flow from the quill to its proper position between the blades at the point. Put no more than three-sixteenths of an inch of ink in the pen. Make sure that not one particle of ink rests on the outside of the pen blades. If ink is left on the outside of the pen it will come in contact with the T-Square blade or the edge of the Triangle. A flow of ink will thus be started from the inside of the pen to the paper or even under the T-Square or Triangle, and an ugly blot will be the result. It is best to have near at hand a good pen-wiper 1 so that all superfluous ink on the outside of the pen can be removed before the pen is brought in contact with the paper. After the pen has been properly filled, place the T-Square or Triangle parallel to but not quite in contact with the line to be traced. Keep the pen in a position perpendicular to the drawing paper and place the point on the line so that the back of the pen will touch the edge of the T-Square or Triangle that is to act as a guide. Never let the point of the pen touch the edge of the T-Square or Triangle, as this will immediately start the ink flowing under it. In inking over a line keep the handle of the pen in a plane perpen- dicular to the paper but allow it to slant a little in the direction that the line is to be drawn. 1 The pen-wiper should be a piece of material free from lint, such as the back of an old kid glove or a piece of chamois skin. [93] Never lay away a pen even for a few minutes without first removing all ink from between the points, as the ink dries very quickly. If it is allowed to dry it must be scraped out, and this is injurious to the pen. By a turn of the set screw on the front side of the pen the thickness of the line can be regulated. After obtaining the right thickness by experimenting on a piece of scrap paper, commence at the top of the drawing, working downward, drawing all horizontal object lines first. Nothing must touch these lines until they are perfectly dry. Then com- mence at the left side to draw the vertical object lines. In doing this, work away from the wet lines. Draw all lines that are to be of the same thickness before resetting or readjusting the pen. (Be sure that the pen is always clean and free from any foreign substance.) After all lines of one thickness are drawn, readjust the pen and proceed in the same manner to draw lines of another thickness. In inking drawings composed of straight and curved lines it is always advisable to draw the circles or parts of circles first, as it is easier per- fectly to adjust straight lines to circles than it is to adjust circles to straight lines. TRACING When an inked drawing is desired for exhibition purposes a good hard surfaced paper should be used ; otherwise an ordinary paper can be used for pencil work, which may be traced in ink on a good quality of tracing paper or tracing cloth, from which any number of blue prints can be made. Before any inking is done on the tracing cloth, scrape from a stick of chalk a small quantity of powder and with a dry cloth rub this powder over the surface of the tracing cloth. This will remove any moisture or grease and will allow the ink to flow freely and evenly. [94] SHEET METAL DRAWING In a complete execution of a drawing of any article constructed of one or more pieces of sheet metal there must be, in addition to the regular two or three view projection drawing, a drawing showing the article completely unfolded. Sheet metal constructions, as far as pos- sible, are made from one piece of material. The laying out of one or more unfolded surfaces is commonly called a Development. The dimensions of parts when finished and the kind of joints to be used, whether soldered, lapped, etc., are to be shown in the two or three view mechanical projections. It is from the information given in these projections that the development is drawn. NOTE. Students should construct the following sheet metal prob- lems from heavy paper or card board, no matter whether they intend making them from metal or not. This will ensure an absolute under- standing of the principles involved as illustrated in the drawing. The educational value in all pattern drawing lies more in being able properly to develop the projects as drawn than in the ability to make them from patterns developed by others. All drawings should be made by each student in the order shown. [95] BREAD PAN The first problem in sheet metal drawing is a common Bread Pan with which all are familiar. It is constructed of tin with lapped corner joints. A wire is to encircle the top completely and is to be covered by a projecting portion of the sides of the pan. Allowance for this must be made in the development. The drawing shows the pan to have a bottom S 1 /^" wide and 1" long. The pan is to be 2 1 /2 // in height. The sides have a flare or slant of y" all around. The lap at the corners will be 1^", and when folded or finished the top edge of this lap is to be securely held in place by the stiffening wire which is covered with the projecting portion of the sides. In laying out the development it is well for the beginner to dis- tinguish clearly between the cutting, bending, and construction lines in order that he may not become confused. In the case of the Bread Pan development shown, the full heavy line represents where the metal is to be cut, while the dotted line repre- sents the place for bending. Light full lines represent, as usual, the construction. To draw the development lay out first to the dimensions shown in the mechanical drawing a rectangle representing the bottom of the pan. Set the Dividers to a distance equal to the slant height of the [96] P/7/V hi -35 ~T SfOE BOTTOM MEN T [97] sides and step off this distance in a horizontal direction from the ends of the rectangle just drawn. Also step off the same distance outward in a vertical direction from the sides of the rectangle. Care should be taken not to confuse the slant height with the vertical height of the pan. The height given as 2 1//' is the vertical height. The slant height is taken from the bottom to the extreme top in the direction of the flaring sides of the pan in the mechanical drawing. After these points representing the slant height of the pan are located from both sides and both ends of the rectangle in the development, draw lines through them with T-Square and Triangle parallel to the sides and ends of the rectangle. These lines, if continued outward or upward, will cross or intersect and thus form a second rectangle which will represent the exact location of the finished top edge in the developed pattern. Extend the lines of the first rectangle until they cross or intersect the lines of the second or larger rectangle, and from these intersections, as at A, step off a distance equal to the slant or flare of the pan, which, as previously explained, is Vii"- From the points just located pass lines B through the corners D. When the work thus far described is accurately accomplished, the attention must be directed to the proper construction of the lap. This is done by extending the sides and cutting them to an angle yet to be determined, so that the upper edge of the lap \vhen the pan is completed will lie exactly parallel to the top edge of the end of the pan. To construct this angle a point on the top edge of the end of the pan must be located that will represent the exact position to be taken by the point of the lap when the pan is completed. The end of the pan shows the lap to extend along the top edge for a distance of I 1 /-/' from each side. Measure off this distance on the end development as shown at C and pass a line from point C through corner D. As this shows the exact position that must be taken by the lap when the pan is completed, triangle D E C on the end cannot be other than the exact shape of the lap to be located at the ends of both of the sides. 98 ] It is evident that the shape of this lap is triangular. It is also evident that the length of lines B on the sides and ends of the pan is the same. This being true, it is plain that the length of one side of the triangle is equivalent to the slant height of the pan or line B whieli has pre- viously been located. To transfer the remaining sides of the triangle located on the ends of the pan to their true position at the ends of the sides, set the Compass to the distance C E, or 1V/'. With the point of the Compass placed at point E on the end of the sides draw the arc of a circle F. Set the Compass to the distance D C, and with the point of the Com- pass on D draw arc G. From the intersecting point of arcs F and G draw lines H and I through E and D. The triangle representing the position to be taken by the lap on the end of the pan when finished is thus transferred to its correct position at the end of the sides and becomes a true outline of the lap. As the pan is of an equal height and flare on all sides the four corners will necessarily be constructed alike and can be drawn as a whole instead of singly. This simplifies the work and also makes it more nearly possible to obtain an accurate result. The allowance necessary as shown at J for bending the metal over the reinforcing wire depends on the size of wire used. Special attention should be given to the transferring of an angle from one position to another by means of the Compass, as this principle is extensively used in some of the problems to follow. [99] DUST PAN The principles involved in the development of the Dust Pan shown are practically the same as those involved in the development of the Bread Pan previously given. The exceptions are that a double angle has to be contended with, and that the back of the Dust Pan, corre- sponding in shape to the side of the Bread Pan, is extended to form the hood. By means of a carefully executed two-view mechanical drawing the true view length of every necessary line can be located. In constructing the development draw first the bottom of the pan, making it, as shown, 11" wide in front, 9" wide at the back, and 8" deep. The vertical height of the pan is shown to be 2", with a flare of 1/2" & t the top. It is necessary, then, in order to have the finished pan 2" high, to deal only with the slant heights in the development. Therefore lay off the widths of the side and the back in the develop- ment equal to the slant height of the pan. The length of the back at its narrowest point must remain the same as the width of the bottom at the back, or 9". As the sides and back have a flare of Vi/'j the extreme length of the back will be 9" plus 1 X>" at each end, or 10". As the back is a continuation of, and directly connected with the bottom, so the hood is a continuation of, and directly connected with the back. It will be noticed in the development that the length of the hood varies at different points. Being directly connected with the back, the length of one side of the hood remains the same as the length of the side of the back with which it is directly connected. The true length and width of the hood can be seen plainly in the top view of the mechanical drawing, the extreme length being A B, and the width 2". In order to complete the development of the sides draw a line, C D, at an angle of 90 degrees, or perfectly square with the bottom of the side, and pass this line through the point F representing the exact corner of the pan. Were the sides of the finished pan straight this line would represent the cutting line, but as they are to have a flare of !/" it will be necessary to lay off this flare on the top edge of the pan from line C D, as shown at G. Measure off on the line representing the top edge of the side a distance equal to the width of the hood, [100] DUST P/7/V Sorrow c [101] or 2" from G to H, as this is the position to be taken by the ends of the hood in the finished pan. Lay off the lap in exactly the same manner as described for the Bread Pan and make proper allowance at the ends of the hood for soldering surface as shown. For strengtli and to stiffen the upper edges of the sides, a wire reinforcement should be run along the slant edges of the sides continuing in one piece along the edge of the hood. The handle being V square, the lines A, B, C, D, and E in the handle development, will be 1" apart and parallel to each other. The lengths of these lines, as shown in the side view, are to be : A, 4%" ; B, 4"; C, 4"; D, 43/ 8 "; and E, 43/ 8 " long. Lines B and C must be extended about 1/2" or %", and lines D and E also so as to form laps F and G. These laps, when soldered to the pan as shown in the mechanical and perspective views, support the handle. The lines B and C must also be extended at the end opposite lap F, a distance of 1", to form the closed end of the handle, H. Around this closed end and also on line A a small allowance must be made for solder contact. LAWN SPRINKLER The Lawn Sprinkler shown is constructed entirely along straight lines. The perspective drawing shows it to have the appearance of being constructed from square tubing, but this is not the case. If properly used, a piece of metal 8^/2" wide and 1414" long will be suffi- cient to construct the top, the bottom, and all inside and outside edges. The general dimensions show the sprinkler to be 6" square and V deep, and the opening in the center to be S 1 /^" square. The section marked A is the top; B is the bottom; C, C, C, C are the four out- side edges which are to be bent upward; D, D are the two inside edges which are also to be bent up. E, E when bent up, and the bottom, B, bent over in place, form the remaining inside edges. All joints are supposed to be soldered, and a small allowance is made on one section of each joint for a lap, F, to aid in giving more contact surface for the solder. All laps are to be on the inside and a hose coupling is to be soldered on the side as shown. The perforations in the top, marked G, must be punched carefully and not be over -fa" in diameter. L 102 J r~ i . 4 ] i -h S/^1 h I V ^ \i m f /^ ^ 1 1 / " F ^ ' --r OS- AJ >J _,"_ ^ =^*^ DEL/ELEIF'MENT Dr LSIWN SPRINKLER J r ::.j ^r t - - C 1. V3 \ y /TOS" CONNECT/ON g ^ (a Q 8 Cj c . /' CD i 4 " +-* '-- & ^ tn Li --H I I [103] WATER PAIL The Water Pail shown is 12" in diameter at the top, 8" in diameter at the bottom, and 8" high. It is necessary, to get the development of this pail, to draw an exact view (A, B, C, D) witli a vertical line E passing through its exact center. Extend the lines A C and B D, representing the sides of the pail, downward until they cross each other on center line E at point F; set the Compass at point F and draw an arc of a circle through points A and B. From the same center draw the arc of a circle through points C and D. Compute the circumference of the pail at the top and locate this distance on the first arc drawn so that the half of this distance will lie on each side of the center line E, as at G and H. NOTE. A very convenient plan for locating the proper circular length (or circumference of the pail at the top) on the development of the side of the pail, is to draw a circle of proper diameter on a piece of card board and to cut it out with a pair of scissors. The required dis- tance can then be easily measured along the edge of the card board with a tape-line and transferred to its proper position on the drawing, with a pair of dividers. Draw a line through center F and point H, also one through center F and point G. This will determine the angle of the cuts to be made. The circumference of the bottom of the pail will not have to be com- puted, as the proper points on the second arc, representing the bottom of the pail, have been automatically located by the intersection of this arc with the lines passing through F II and F G. The pail will, of course, have a wire reinforcement around the top, and the proper allow- ance for tin must be made according to the size of the wire used. A little study must also be given the method of inserting the bottom and of joining the sides to it so that the completed pail will not vary from the original dimensions. In the drawing showing the enlarged section of the lap joint it will be seen that a double allowance must be made on one end of the pattern for the side of the pail, while on the other end but a single allowance will be necessary. These lines representing the allowances must be drawn parallel with lines H F and G F, and will not, therefore, pass through center point F. The development of the bottom will be 8" in diameter, as given, with the necessary allowance for the bend, as shown in the enlarged drawing of the bottom. [104] [105] SUGAR SCOOP For the development of the Sugar Scoop it will be necessary to have an end and side view drawn. The curve shown in the side view repre- sents the shape of the finished scoop from a side view. It may be drawn to accord with the individual taste of the designer. As the cud and back views are represented by circles of the same diameter it does not make any material difference which is named the end or which is named the back. The only real value of a back view is to have a space that does not conflict with the rest of the drawing on which to show the proper location of the handle. This view gives the true widths of the handle at its extreme ends. Divide the circles representing the back and end views, shown directly over the side and top views, into an even number of equal parts. (In this case twelve will be sufficient.) Project these division points down- ward and through the side and top views as shown. Through the inter- secting points of these projected lines and the curve of the side view draw horizontal lines A, B, C, D, E, F, and G. Through the intersecting points 1, 2, 3, 4, etc., of lines A, B, C, etc., and the lines projected from the division points on the circle representing the end view, pass a curved line representing the opening in the front of the scoop shown in the top view. This should be done with the Irregular Curve as described on page 14. To draw the development of the scoop (Fig. I) extend line H repre- senting the edge of the back in the side view across the paper. On this line locate a distance equal to the circumference of the scoop, in this case 7.06", or about 7 T V'. (Calculate this circumference.) Divide this distance into as many equal parts as are in one of the circles repre- senting the end view. Through each of these division points erect perpendiculars to A, B, C, D, E, F, G, and H; at points o, o, o, etc., as shown in Figure I, and through intersecting points o, o, o, etc., pass the required curve. In the scoop, as in the pail previously drawn, the lap joint is used. The allowance for this joint must be twice as much at one end as at the other. [106] [107] In Figure II is shown an easy method of dividing a given distance into any number of equal parts. Let A B represent the given line or distance to be divided. From one end draw a line, A (.', at any convenient angle. With the Dividers set at any convenient distance, step off on this line as many spaces, or points 1, 2, 3, etc. as it is desired that the given line AB be divided into. Set the 45-degree Triangle so that its edge covers point B on the given line, and point 9 on the line A C. With the 45-degree Triangle held in this position place the 30-degree Triangle so that its edge will come in direct contact with the edge of the 45-degree Triangle as shown. With the 30-degree Triangle held firmly in this position slide the 45-degree Triangle up- wards, keeping it constantly in contact with the 30-degree Triangle, until the edge of the 45-degree Triangle covers point 8. Mark the point on given line A B that is crossed at this time by the edge of the 45- degree Triangle, and again slide it upward until point 7 is covered. Continue this process until all points on diagonal line A C have been covered, and it will be found that the given line A B has been equally divided into the required number of spaces. NOTE. The geometrical principle involved in dividing a given line into any number of equal spaces should be dwelt upon until thoroughly understood. It is simple and accurate. Figure III shows the side view of the handle of the scoop and gives the method of its development. This side view can be drawn from the dimensions of the handle given in the side view of the scoop. With the Dividers step off a series of spaces on the side view as shown in Figure III; then, by stepping off in a straight line the same number of spaces, an approximate length of the handle will be located. With the width of the handle given at each end as shown in the back view of the scoop and the length located, develop the handle as shown in Figure III. Figure IV represents a section of the handle showing the edges turned over. Determine the amount to be turned over and add this to each side of the development as shown in Figure III. To allow for the construction as shown in Figure V makes it necessary that allowance be made on the back (Fig. VI) for the metal to turn over and form a rim around the edge of the scoop. [108] FLOAT BALL In the development of the Float Ball illustrated, the patterns for the several sections are drawn in exactly the same manner as was the pattern for the side of the pail, (page 105). It will be seen that the complete ball is composed of 6 sections, A, B, C, two of each of which are required. Draw, first, a circle of the proper diameter, 3", and erect the vertical center line D. Divide the circle just drawn into twelve equal parts, 1, 2, 3, 4, 5, etc., commencing at the intersection of the circle with center line D as at point 1. Connect by horizontal lines, E, F, G, II, and I representing the edges of the sections, points 12 and 2, 11 and 3, 10 and 4, 9 and 5, and 8 and 6. Also connect points 1 and 2, 2 and 3, and 3 and 4, etc., as shown, with lines J, K, L, M, N, 0, etc. Continue lines K and L upward, as shown, until they intersect center line D at points 13 and 14, thus locating the proper radii to be used in the laying out of the different patterns, as Figures II, III, and IV. From lines E, F, G, H, and I, which are the diameters of the sections, the circumference of the ball at various levels can be computed. The outside circular length of each pattern equals the circumference of the sections just found. The slant cuts of the ends of the patterns are located by passing a line from the radial center of each pattern through the points marking its circular length, as shown in Figures II, III, and IV. The circular length can easily be measured on each pattern by the method described in the development of the pail. [110] [111] SINK STRAINER The problem of developing the Sink Strainer is one that will require the close attention of the student. Constructed as it is, it is im- possible to give the true length of all lines in two or three views, and as a development is composed entirely of true lengths it is necessary that a method for determining the true length of a foreshortened line be given and mastered. In the side view line A, and in the top view lines B, C, D, E, F, G, H, and I are shown in their true lengths. Lines J and K of the top view represent the front corners of the strainer as shown at J and K in the perspective, but do not represent their true length ; neither do lines L, M, and N in the side view. As the true lengths of all fore- shortened lines can be determined in the same manner, the attention of the student is called to the method used in determining the true length of lines J and K in the top view. At a perfect right angle with line J draw the two parallel lines from each end of this line J, as lines 1 and 2. Parallel with line J, and in any convenient location, draw line 3. From the intersection of lines 3 and 1 measure off on line 1 a dis- tance equal to the vertical height of lines J and K as shown in the side view to be 4". Draw line J 1 K 1 connecting the intersecting point of lines 2 and 3 with the vertical height, as measured off on line 1. The true length of lines J and K will be the length of diagonal line J 1 K 1 . After locating in the same manner the true lengths of all foreshort- ened lines proceed to draw the development as follows: By examining and studying carefully the side view and the per- spective it will be seen that the altitude or the true height of the tri- angular shaped front is equal to the length of line J in the side view. So measure this height off on a vertical center line and draw line C, making half of its length lie on each side of the center line in a horizontal direction. Draw lines J 1 and K 1 (which are the true lengths of lines J and K) as shown, terminating at point S. Construct the rectangular shaped front as shown by setting the Compass to a distance equal to the length of line B, and from point R draw an arc of a circle. [112] [113] Set the Compass to a distance equal to the length of line G, and from point S also draw an arc of a circle. In order to locate points U and P on the arcs just drawn it will be necessary to have the true diagonal length of the rectangular front which will be found to be O 1 . With the Compass set to a distance equal to the length of O 1 draw an arc of a circle from point S, cutting the first arc drawn at point U. With the Compass set at a distance equal to the length of line X 1 , which is the true length of line N, draw an arc from point U, crossing the second arc at point P. Draw all bending lines as shown. To draw the triangular shaped sides set the Compass at a distance equal to line L 1 , and from point U draw an arc of a circle. With Compass set to a length equal to line M 1 , which is the true length of line M, draw an arc of a circle from point P intersecting the arc drawn from point U at point T. The back and bottom are drawn in exactly the same manner. Make the proper allowance on line M 1 of the back, and also on lines F and G of the triangular bottom, for soldering surface as shown. The series of small circles shown on the bottom and back represent drain holes. The 1" straight perpendicular top edge of triangular front C and rectangular fronts B and D are to be drawn with the edges A at a perfect right angle with lines B, C, and D. It can be seen in the mechanical drawing, the perspective drawing, and the development that the perpendicular top edges of the triangular shaped sides are one inch high in front, tapering to nothing in the back ; therefore, from point U, with the Compass set at a distance equal to the length of line A, or 1", draw the arc of a circle, and with the Compass set at a distance equal to the length of line I, and using point T as a center, draw an arc intersecting the arc drawn from point U. From this point of intersection construct the tapering perpendicular top of the triangular side as shown. Make an allowance around the extreme top for a reinforcing wire. This wire, while being inserted, can be made to form a loop at the extreme back top corner to be hooked over a small nail or hook placed in the corner of the sink frame, thus forming a support for the strainer. [1141 [115] SCREW THREADS A curved line formed by a point moving around the surface of a cylinder, and at the same time advancing at a uniform speed along its length, is called a Helix. The distance this point advances lengthwise on the surface of the cylinder during each revolution is called the Pitch of the helix. By the careful examination of a bolt and its thread it will be seen that the bolt is cylindrical in form and that the thread in passing around the bolt advances a certain distance in every revolution, thus forming a helix. The distance along the bolt that this thread travels in one revolution of the bolt is called the pitch of the thread. The method of drawing a helix is shown in Figure I, Machine Details. The four-inch circle represents the diameter of the cylinder on which the helix is to be formed. The lines A and G projecting upwards from the horizontal diameter of the four inch circle represent a portion of the side of the cylinder. On line A lay off the distance the helix is to travel lengthwise in one revolution, or the pitch. Divide the circle into an even number of equal parts (twelve will be sufficient) and project these division points upward as shown by lines B, C, D, E, and F. Divide the pitch that has been previously laid off on line A into the same number of equal parts (twelve), using the same method as shown in Figure II of the drawing entitled Sugar Scoop. Project these divisions horizontally from line A to line G, passing them through lines B, C, D, E, and F. By the use of the Irregular Curve, draw the required helix as shown, passing it through the intersecting points of the horizontal lines projected from the divisions on the pitch and lines B, C, D, E, and F. In Figure II is shown a drawing of a square thread; 4" outside diameter, 3" inside diameter, with 1" pitch. To show square threads in this manner requires considerable time and careful work. While it is advisable that the student understand this method it is advisable also in the problems to follow that he use the more conventional method shown in Figure III, or even Figure IV. In Figure IV the thread is shown in a manner that necessitates the use of straight lines only. It is not theoretically correct, but for all [116] riG.nz DETAILS ric.rz: [117J practical purposes it answers every requirement, as the diameter at the top and the diameter at the bottom of the thread, as well as the si/e and pitch of the thread, can all be accurately given. At A, in Figure V, is shown a single square thread, the outside diameter of which is 3", the inside diameter 2^,4", and the depth of the thread %" with %" face arid a I 1 /*/' pitch. This necessarily has the advantage over the thread shown in Figures II, III, and IV of being able to travel exactly twice the distance of the ordinary thread (Fig. IV) in proportion to its size. It has the disadvantage of being only one-half as strong. To overcome this lack of strength another thread of the same size and pitch is placed between the single threads forming a double thread, as shown at B in Figure V. A bar with a double thread then has the same strength as a bar with a single thread, and has the advantage in speed, as it travels, in one revolution, exactly twice the distance, as previously explained, of a similar single thread screw. Owing, however, to the double work accomplished it requiries a double amount of power to do this work. In representing a common thread, such as is used on bolts, machine screws, etc., the conventional method shown in Figure VIII is generally used. The pitch of the thread shown in Figures VI and VII can be determined only by the required number of threads per inch ; the more threads per inch the less will be the pitch. When the threads are standard the number of threads per inch can be determined from a table. The number is fixed for any one diameter of bolt or rod. In the case of Figures VI, VII, and VIII the bolt or rod is V in diameter and has 8 threads per inch. Figure IX is an illustration of a tapering pipe thread. The object of making a pipe thread tapering is to insure a perfectly air, gas, or water tight joint. As the size of a pipe is always determined by the inside instead of the outside diameter, and as it is necessary to construct a thread on a pipe so that its depth will not materially weaken the pipe, it is necessary that a standard for the number of threads per inch on a pipe differ materially from the standard for the number of threads per inch on a solid bolt or rod of the same size. This will be seen by comparing the number of threads per inch on the 1" pipe (Fig. IX) with the number of threads per inch on a V rod as in Figure VI. From the dimensions and dimension arcs given, the Hexagonal and Square Head Bolts and Nuts can be drawn without further explana- tion. [118] I | ^ j-t t/a 2 $ <* n * CB Ck j 1 Oi HI 5 s a a ^ 5 n X \ 0) 1 r= o N en [119] HAND WHEEL The Hand Wheel shown is such as would be used on a book-press or steam valve. The section lines show that it is to be made of cast iron. The small oval section shown in the spoke or arm at A represents the sectional shape of the arm. The shape and size of the rim B, the thickness of the arm at rim C, the thickness of the arm at hub D, and the diameter and length of hub at each side of center E, are all plainly shown by a drawing of a sectional side view. [120] MACHINE. DE T/1IL S s * to 1 1 | [121] PLAIN BEARING It is intended that the student will make drawing's of tlie Plain Bearing in four distinct sizes. The dimensions for each bearing must all be in proportion to the diameter of the shaft for which it is to be used. It will be noticed that the diameters of the shafts for the four bearings are 1", l 1 ^", 2", and 2^", respectively. The general dimensions such as the length of the bearing (A), the width of the bearing (B), the diameter of the outside of the bearing (E), and the height of the center of the bore from the base (C) must be calculated by the student. Use the formulae given, which will deter- mine all dimensions of a bearing appropriate for the diameter of the selected shaft or bore. The dimensions D, F, G, K, M, N, and P can be found at once by referring to the figures in line with the different shaft diameters and under the letter in question. WRENCH The Wrench is designed by the author so that from the given formulae all dimensions can be calculated for the drawings of a series of wrenches, or for the drawing of a wrench to fit any desired hex- agonal nut. It will be seen that the foundation of all dimensions is the distance A, which can be determined by taking the measurements of the short diameter of the nut. Procure four or five hexagonal nuts and from the short diameters (A) of each make a drawing of a wrench for each, showing all dimensions in their proper location. [122] 7/6 //<> "2 28 = *.* */ PL/7/N 73 - v / f X / 5 C - => X X .5- c = /I X .9 D = * X .55 c: - * .6 F - f\ x .3 *- yrt V .4 H " /J x % HUTTCH [123] MONKEY WRENCH AND WOOD WORKERS' VISE A Monkey Wrench and Wood Workers' Vise are tools -with which all are more or less acquainted. The assembly drawing of each is given in section and without dimen- sions. The detail drawings of these tools show each and every part dimensioned, in two or three views, as the case may be. The object of showing the assembly drawings in section is to enable the student to see the exact location of each part, as w T ell as to judge of the work each part has to perform. By referring alternately to the detail and the assembly the student can readily determine the exaot shape, size, and location of each part. After the drawings have been given proper attention and study, the student will be expected to draw the sectional assembly with little or no trouble, locating the position of each part from the dimensions of the different parts given in the detail sheet. While the same principles are involved in drawing either of these tools, the friction surface of the moving parts of the wrench need not be given the attention that the friction surfaces of the vise require, owing to the different quality of work it has to perform, and to the different class of tools to which it belongs. It will be noticed in the details of the vise that the friction surfaces, such as the beam and the surfaces of the slot in the base of the rear jaw in which the beam travels, are marked "f." This designates that these surfaces are to be finished to exact size, thus insuring a perfect surface so that the beam may be guided accurately in the direction it is to travel. [124] ro ^J n n 0] ci [125] T 0/0 w -3 <7> !' \ > \i 4- l^- CO/V/C/tt. JYOr I -f?EOL>'lD IO 31- 5 Off 'A 'W/v Q y SCHOOL HurroN [126] B en Efl n [n n R [127] [128] ARCHITECTURAL DRAWING [129] ARCHITECTURAL DRAWING The particular Architectural Problem herein given has been selected because in it we are to cover the points in frame construction that are apt to be met with in the designing and drawing of almost any ordinary modern frame dwelling house. In designing a dwelling house, the first and second floor plans must be drawn, practically speaking, as one unit; the inside walls for different stories in a house should, for strength, be placed, as nearly as possible, one above the other in planning the rooms on each floor. The location of chimneys must be determined so that they will not conflict with the walls, windows, etc., of the floor above or below, as the case may be. The position of the stair landings should be definitely determined as early as may be, and other inside details arranged accordingly. The placing of the bath room and its plumbing should be, as nearly as possible, in line with the plumbing of the kitchen and laundry, so that all drainage pipes will lead directly to one point. Ample closet accommodation should be made in all upstairs rooms, and whenever possible in the upstairs hallway. The placing of all ordinary household furniture, such as a kitchen cabinet, kitchen table, dining room table, dining room chairs, buffet, piano, couch, beds, and dressers, should be considered as the house design proceeds, so that these articles may not interfere with windows, doors, etc. The arrangement of rooms should be made so as not -to have any waste space, that is, any space that can not be conveniently utilized. The windows and doors should be placed so as to give the best light and ventilation possible. By referring to the first floor plan it will be seen that the design of the house calls for a front reception hall 9' X 10', with an open stair- way leading from it ; a living room 13' X 13'6", with an open fireplace ; an open space, or colonnade, between the living room and the recep- tion hall ; a dining room 12' X 13', with sliding doors connecting it with the living room. In the dining room there will be a bay window, built-in china closets and buffet, over which are small triple windows. The kitchen, 9' X 10', has swinging doors connecting it with the dining .room. The kitchen contains a sink and drain board, a chimney in the wall for the accommodation of a kitchen stove or range, and a small win- [130] HVTTON [131] dow over the sink. A pantry 3'6" X 3'6" adjoins the kitchen. In the hall is an inside cellar-way. On this floor there is also a back porch 4' X 6'. In the second floor plan the design calls for a front bedroom, 10'X14', with mantel, and a closet 3'6' / X4 / 6"; an alcove 8' X 10', from which opens a stairway leading to the attic ; two back bedrooms, one 8' X 8', the other 10' X 12'6", in each of which is a closet 1'G" deep X 4' wide; and a bathroom 4'6" X 8', to be provided with a small window on the outside wall. Just outside of the bathroom partition is the kitchen chimney projecting slightly into the 8' X 8' back bed room. From the upstairs center hall, which is 3'G" wide, direct access is made with all upstairs rooms, and also to a hall closet 3'6" X 5'. The building, with the exception of the front porch and bay win- dow, is seen on the first floor plan to cover a space of ground 23'6" X 28'. The front porch extends across the entire front of the house and is 9' deep. The floor of the porch is to be made of concrete. In the foundation plan, the concrete foundation walls for the porch and basement partitions are to be 8" thick, while the thickness of the main foundation wall is to be 10", with but a 5" wall for the outside cellar-way. The ceiling height of the basement, when finished, is to be 7" ; that is, there must be 1' in the clear from the concrete floor of the basement to the top of the foundation wall. A room is to be pro- vided and equipped in the basement for a laundry, as shown, and an ample and convenient space is left for the storage of coal. In drawing the foundation plan, the number of basement windows, and the spacing of the same, must receive considerable attention. If the porch floor is to be built solid from the ground up the front basement window will, of necessity, be omitted. The point at which a house is sectioned in order to show a proper floor plan is just a few inches above the windowsill. All doors, win- dows, and openings must be shown in the plans at their exact location, so that in drawing the front, side, and back elevations these locations can be readily transferred to their proper position in the elevation. It will be noticed that the front elevation is drawn to a scale of 14" to the foot, thus permitting the showing of considerable detail. [132] /3ec/Aocfrj /?/c 1 HUTTOH [133] This is the usual scale used for such work, but owing to the limited space, the side and back elevations are drawn to a scale of %" to the foot. By referring to the plates showing construction, the name of the timbers used, as well as the position taken by each, can be easily learned. The height of the ceilings in the first and second floors must be determined by the length of the 2" X 4" studding used. If the usual eighteen foot studding is used it will allow for about a 9'6" ceiling on the first floor with the second floor ceiling somewhat lower, or about 8'3". If higher ceilings are desired longer studding will be required. With a complete study of the plates, the student should be familiar with the timbers used, their size and location, and be able not only to draw this house, but also to draw a frame house of his own design and from it to figure a fairly accurate material list. 1134] I D 0) i^-=ir / I I IE-^T 0) I t ^' ! I j I s? [135] mi [136] BC/7t- g '- [137] [138] [139] 4 5 [140] [141] [142] CO [144] ELECTRICAL CONVENTIONS The twenty-six electrical conventions given are the standard conven- tions used by the United States Patent Office. They are not drawn to any particular scale, for this is not necessary. The drawing of these conventions not only affords the student exceptional practice in drawing, but also acquaints him with the common standard method of expressing easily, clearly, and quickly his ideas along electrical lines. [145] EL EC TRICrfL C ONI/EN T/E/N5 *- /%>/< G>S* c/ /7/fem a /c G o stretchers tn /he -same i r i I I I_L ' r [174] DRD/N/JRY BOND \ c 1 I . I II'' r I I I ill i i i i i i J L J_ L I . . I . . I . . I J LJ 1 1 I L_L I_L \ \ 73/0 s? &/* /?