AN INTRODUCTION
TO
MACHINE DRAWING AND DESIGN.
I. INTRODUCTION.
Drawing Instruments.—For working the exercises in this book the student should be provided with the following:—A well-seasoned yellow pine drawing-board, 24 inches long, 17 inches wide, and 3⁄8 inch or 1⁄2 inch thick, provided with cross-bars on the back to give it strength and to prevent warping. A T square, with a blade 24 inches long attached permanently to the stock, but not sunk into it. One 45° and one 60° set square. The short edges of the former may be about 6 inches and the short edge of the latter about 5 inches long. A pair of compasses with pen and pencil attachments, and having legs from 5 inches to 6 inches long. A pair of dividers, with screw adjustment if possible. A pair of small steel spring pencil bows for drawing small circles, and a pair of small steel spring pen bows for inking in the same. A drawing pen for inking in straight lines. All compasses should have round points, and if possible needle points. A piece of india-rubber will also be required, besides two pencils, one marked H or HH and one marked HB or F; the latter to be used for lining in a drawing which is not to be inked in, or for freehand work.
Pencils for mechanical drawing should be sharpened with a chisel point, and those for freehand work with a round point. Do not wet the pencil, as the lines afterwards made with it are very difficult to rub out.
Drawing-paper for working drawings may be secured to the board by drawing-pins, but the paper for finished drawings or drawings upon which there is to be a large amount of colouring should be stretched upon the board.
The student should get the best instruments he can afford to buy, and he should rather have a few good instruments than a large box of inferior ones.