Читать книгу The Handyman's Book of Tools, Materials, and Processes Employed in Woodworking - Paul N. Hasluck - Страница 178

The screw nail used for uniting woodwork is known as the “wood screw”. This combines several of the most important principles of science and mechanics. As a mechanical power its basis is the inclined plane. Previous to the opening of the nineteenth century, iron, brass, and steel screws were but rarely used. During 1813, Penniman, in America, perfected machinery for drawing wire suitable for screws of all kinds. During 1817, Dow and Treadwell, of Boston, made other improvements; their machine drew the wire from the reel, cut it to the length required for each screw, headed the screw, cut the thread, and polished the screw. Meanwhile English manufacturers were also making improvements in the quality and finish of screws for woodwork, until these screws obtained, on both sides of the Atlantic, the commercial name of “wood screws,” to distinguish them from those used to put together and operate machinery. But the wood screw had one obvious defect. The worker was compelled to use a bradawl, gimlet, brace and bits, or some similar implement to make a fairly large hole to give the screw an entrance, and this operation occupied so much time that many workmen chose well-finished nails in preference to screws. During 1841, however. Thomas J. Sloan invented the now familiar “gimlet point” wood screw, which, under the pressure of a good screwdriver in a workman’s hand, entered any kind of wood as readily and with no more danger of splitting the wood than the entrance of a carefully handled bit or gimlet. From that time screws replaced wrought and annealed nails in all fixing where the hammer could not conveniently be used, or where jarring was to be avoided. It was soon demonstrated that the wood screw possessed ten times the compression and attractive strength of ordinary nails, especially in all pine and other soft and open grain woods. The screw was found to be convenient for use in putting work together which was soon to be taken down, because its removal did not injure anything.

Fig. 471.—Secret Nailing.

Fig. 472.—Flat-head Wood Screw.

Fig. 473.—Round-head Wood Screw.

Fig. 474.—Cup Wood Screw.