Читать книгу The Handyman's Book of Tools, Materials, and Processes Employed in Woodworking - Paul N. Hasluck - Страница 179

Screws, which, like nails, consist of two parts—head and shank—are made in almost endless variety, but the three following examples are sufficient for the present purpose. Fig. 472 is the most common, being made from iron, steel, or brass, according to the purpose for which it is to be used. Fig. 473 shows a round-headed screw. These are usually japanned, being used principally in fixing bolts, locks, etc. Fig. 474 is a variety known as a cup screw, because it has a cup into which the head of the screw fits; this cup is let into the work flush with the surface, the screw being turned down through it. It will be noticed that the thread extends for only about two-thirds the length of the screw, this being all that is really requisite. Further threading would only weaken the lateral strength of the screw. The sizes in which wood screws are made are almost endless, but usually they range from 1/4 in. to 6 in.

Fig. 475.—Wood Bored ready for Screw.