It is a part of the work of the designer of any mechanical structure or machine to determine not only the material of which each piece of the structure is to be made, but the general method of making it, which necessarily includes a designation of the shops in which the work is to be done.

If an article is to be shaped in cast iron, cast steel, or other cast metal, a pattern, usually of wood, must first be made in the pattern shop. This is made according to dimensions and other information given on the drawing. This pattern is used in the foundry as a model for a mould, which, when prepared, is poured with molten metal. The piece thus cast more or less roughly, is cleaned and used sometimes without further work upon it, but if accurate fitting and exact dimensions are necessary for the casting, it goes to the machine shop to be machined, and possibly ground if very accurate fitting is needed.

If the article is to be made as a forging, a bloom, billet, or smaller piece from the rolling-mill stock kept on hand is forged to the required shape either by hand or by steam hammer in the blacksmith shop, and the forging may, in some cases, be used just as it comes from the anvil, or, if it must be finished to particular shape and dimensions, it goes to the machine shop.

Many articles may be made in the machine shop directly from rods, bars, plates and shapes from the rolling mill, without having been given preliminary form in the foundry or the blacksmith shop.

Fig. 93. - Orthographic Projections.

Fig. 94. - Isometric Projection.

The boiler shop works into shape plates, sheets, tubes, etc., direct from the rolling mill, and fittings produced in other shops.

The copper and sheet-metal shop draws its sheet material direct from the rolling mill. Much copper and brass tubing, obtained from the tube mills, is used in the copper shop.

The plate and angle shop uses plates and structural shapes supplied direct from the rolling mills.

All shops of building and repairing plants find more or less use for bolts, rivets, screws, and various other products of the re-manufacturing industries in connection with their own shop products.