Earnest T. Child.

The student who is ambitious to become a draftsman must, like any other artisan, become perfectly familiar with his tools before he may attempt to perform his work. Of course, experience will in time teach one the proper use and care of his instruments, but the man who is forewarned is forearmed, and "a stitch in time may save nine," as the old proverb goes. It has been thought wise, therefore, to preface our talks on mechanical drawing by a few words on the use and care of drafting instruments, together with a brief description of those necessary and others which, while not absolutely indispensable, may aid in the production of more uniform and perfect work.

Mechanical Drawing I Instruments Their Use And Car 15Mechanical Drawing I Instruments Their Use And Car 16Mechanical Drawing I Instruments Their Use And Car 17Mechanical Drawing I Instruments Their Use And Car 18

Set of Instruments.

The first requisite of any draftsman is a set of drawing instruments. This may be secured at a price varying from four or five up to twenty-five dollars for a set. One which will fill every requirement, and will last a long while with proper care, maybe obtained for aboutten dollars. It is foolish for a beginner to pay more, and on the other hand a cheaper set will not be apt to retain its .accuracy, so this may be set down as a fair average figure. The instruments which should be found in such a set comprise the following:

One pair 6" dividers with fixed needle-point, pen, pencil, and lengthening bar; one pair 5" plain dividers with hairspring adjustment; one pair spring-bow spacers, one spring-bow pencil, one spring-bow pen, one 5" pen and one 41/2" pen.

To work readily, none of the above instruments may be dispensed with, though it would be possible to get along with a single pair of dividers with pen and pencil point. The advantage of the spring-bow instruments lies in their small size, and the fact that they will stay where adjusted and enable one to duplicate circles in any part of a drawing.

The hairspring adjustment on the plain dividers is very handy and saves much time and patience. This attachment is also applied to the larger divider, but it is not popular among professional draftsmen, although it has been found very useful by the writer. In selecting a set of instruments, the most important point is that the pens are of the best quality. The other instruments may be of a second grade, but the pens must be strictly first class. Those manufactured by Theo. Altene-der are considered the best, and they are certainly worth the difference in cost. The necessity of having first-class pens must appeal to all, as a large part of the finishing work has to be done with them.

Great care must be taken when using instruments to keep them in good condition. The box should be closed at night after work is over, the instruments having been previously wiped with a small piece of chamois skin kept for the purpose, and no dampness should be allowed near them. Pay particular attention to the care of the pens. Almost all drawing inks will corrode them more or less, and they should be carefully wiped, not only at the end of the day's work, but also at intervals during the work. The best penwiper is made of an old piece of sheet or shirt that is past other usefulness.

Drawing Board.

Drawing boards are of many kinds and sorts, varying in size from one large enough for a sheet of letter-paper to the long table used in railroad offices for profiles and other very long or large plans. The most convenient size is 23" x 31", built of 1" pine, with cleats at the ends to prevent warping, and may be made at home, or may be purchased for about one dollar. The edges of the board should be straight, and it must be square, so that any side may be worked from. The best boards are made by gluing together narrow strips of pine and then planing the whole smooth. Pine is the most satisfactory wood, as it takes the thumb-tacks most readily.

The Square and Triangles.

The tee square consists of a long, thin strip of wood with its edges straight and with a cross-piece attached to one end at right angles. This cross-piece slides along the edge of the drawing board, and permits of drawing parallel lines. Triangles are used for drawing vertical lines from those drawn to the edge of the tee square. These are made in two forms; first 45 degrees having one right angle and two angles of 45 deg.; second, 30 x 60 deg. having one right angle, one 30 deg. angle and one 60 deg. angle. The 45 deg. triangle is used for cross hatching, and the 8" size is the most convenient. It is necessary to have but one 30 x 60 triangle of about 6" size, but it is very convenient to have another about 10", making three triangles in all. The cost of a plain pearwood tee square and three rubber triangles will be about two dollars. The rubber triangles however have been almost entirely superseded by transparent "amber" triangles, and the plan tee squares have been given place to others fitted with air edge of transparent substance; and while the expense is slightly greater, they are worth the larger outlay. One irregular curve will be found very useful on special work, especially in connection with machine drawing. Thumb-tacks are used for securing the paper to the drawing board. These are short tacks with a large metal head, which makes them readily removed from the board. The most convenient size is about 3/8" diameter, with short points. First-class pencils must be used. There are several makes; but those manufactured by A. W. Faber are very reliable for grade and quality. For paper drawing H H is the proper grade, though some prefer harder; while for marking on tracing cloth a softer pencil, H grade, must be used. Nearly all pencil drawing is done on paper, and then traced in ink on the tracing cloth. Almost any rubber may be used, but for general work Tower's Multiplex is best, and Faber's circular is most convenient for fine work when there are many lines, only one of which is to be erased. Sand rubbers are made for erasing ink, and these should be always used in place of a knife, as the latter spoils the surface of the paper or tracing cloth, and makes it difficult to make a clear ink line after erasing. India ink in stick form was for a long time considered superior to all other inks. It had to be ground in a saucer, and it was necessary to grind it fresh nearly every day. While this is still used in some drawing-rooms, in a majority of instances it has been superseded by liquid ink of some make or other. The best liquid ink is manufactured by Higgins, and is almost universally used. In school work it is customary to have the pupil work on Whatman's drawing paper. This is the best paper made, and is comparatively expensive, listing 90 cents per quire for 15" x 20" size. A manilla detail paper may be obtained, which will answer every purpose, and not cost nearly so much. This is the paper most commonly used in drawing-rooms for laying out details of machines, etc. No draftsman's outfit is complete without a scale. The most convenient style of scale consists of a triangular piece of boxwood about 121/2" long. Being triangular it presents six straight edges, which are subdivided for scale drawing so that one inch may equal four, eight, or any number of feet. The common scales are 1/8" to 1', 1/4" to 1', 3/8" to 1, 1/2" to 1', 3/4" to 1', 1" to 1', 11/2" to 1', 3" to V and one side is divided into inches and sixteenths of an inch.

The Square and Triangles 20The Square and Triangles 21

The above-described outfit will be quite sufficient for any draftsman's needs, but there are other instruments which will often be found helpful. The first of these is the beam compass, which must be used where large radius circles are to be drawn. Proportional dividers are very useful in transferring a drawing from one scale to another, and a pentagraph may be used for the same purpose.

In laying off angles other than a right angle, a protractor must be used. This is a semicircle, subdivided into degrees. There are several devices in use for drawing section lines, but space does not permit of a full description of them. (To be continued.)