Example in shading of Blake's patent direct acting steam pump 284 Example of shading an independent condenser 288

CHAPTER XV.

EXAMPLES OF ENGINE WORK.

Drawings of an automatic high speed engine; side and end views of the engine; vertical section of the cylinder through the valve face 289 Valve motion; governor 292 Pillow box, block crank-pin, wheel and main journal 294 Side and edge view of the connecting rod 295 A two hundred horse power horizontal steam boiler for a stationary engine; cross sectional view of the boiler shell 296 Side elevation, end view of the boiler, and setting 297 Working drawings of a one hundred horse power engine; plan and side view of the bed plate, with the main bearing and guide bars; cross sections of the bed plate; side elevation of the cylinder, with end view of the same 299 Steam chest side and horizontal cross section of the cylinder; steam chest and the valves; cam wrist plate and cut-off mechanism; shaft for the cam plate; cross head; side view and section through the centre of the eccentric and strap 301 Construction of the connecting rod 303 Index 305 Catalogue

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Mechanical Drawing

SELF-TAUGHT.

CHAPTER I.

THE DRAWING BOARD.

A Drawing Board should be of soft pine and free from knots, so that it will easily receive the pins or tacks used to fasten down the paper. Its surface should be flat and level, or a little rounding, so that the paper shall lie close to its surface, which is one of the first requisites requisites in making a good drawing. Its edges should be straight and at a right angle one to the other, and the ends of the battens B B in Figure 1should fall a little short of the edge A of the board, so that if the latter shrinks they will not protrude. The size of the board of course depends upon the size of the paper, hence it is best to obtain a board as small as will answer for the size of paper it is intended to use. The student will find it most convenient as well as cheapest to learn on small drawings rather than large ones, since they take less time to make, and cost less for paper; and although they require more skill to make, yet are preferable for the beginner, because he does not require to reach so far over the board, and furthermore, they teach him more quickly and effectively. He who can make a fair drawing having short lines and small curves can make a better one if it has large curves, etc., because it is easier to draw a large than a very small circle or curve. It is unnecessary to enter into a description of the various kinds of drawing boards in use, because if the student purchases one he will be duly informed of the kinds and their special features, while if he intends to make one the sketch in Figure 1 will give him all the information he requires, save that, as before noted, the wood must be soft pine, well seasoned and free from knots, while the battens B should be dovetailed in and the face of the board trued after they are glued and driven in. To true the edges square, it is best to make the two longest edges parallel and straight, and then the ends may be squared from those long edges.