US240780A - smith - Google Patents

Description

(No Model.)

J. D. SMITH.

Screw.

E.: A WINE.

INVENTORI MM ATTORNEYS.

UNITED STATES PATENT OFFICE.

JOHN D. SMITH, OF FAYETTEVILLE, NORTH CAROLINA.

SCREW.

SPECIFICATION forming' part of Letters Patent No. 240,780, dated April 26, 1881.l

Application filed October 18, 1880.

'new and Improved Screw"""""'and l do hereby declare that the following is a full, clear, and

exact description of thesame.

My invention relates more particularly to screws heretofore made entirely ot' wood and used to operate the vise-jaws of carpenters benches, but which by myimprovcd construction may be used for many purposes, such as for cider-presses, cotton-gine, and whenever a stron g cheap screw is employed.

The object ot'Y my invention is t0 make the thread ot' the screw in an extremely cheap and simple manner and ot' sufficient strength to resist all strains that may come upon' it, and that will be luorc durable, more et'ticient, and more easily operated than woodscrews ofthe usualconstruction.

To these ends my invention consists in form` ing a screw by winding a metal rod spirally around a cylindrical wooden body, and securing thetwo together by embedding the rodwhich constitutes the thread ofthe screw-in the wood, as hereinafter described.

In the accompanying drawings, Figure l is aside elevation of a section of screw made according to my invention; Fig. 2, a central longitudinal section thereof, and Fig.3 an elevay tion of the metal screw-thread detached.

The stock A is made ot' hard wood, and is of any required shape at its end to suit the purpose for which it is to be used. but in most cases has an enlarged head, A', through which a handle may be passed to operate it, and has a cylindrical portion, A2, around which the metal thread B is secured. This ma e done in various ways-as, for instance, cylindrical portion A2 of the stock may be" cut with a spiral depression, a, of a pitch to correspond with that of the thread, into which depression the metal thread B may be screwed on from (No model.)

the end ot" the stock, or into which it may be placed by wrapping it around the stock as the coil is made by suitable bending machinery. The thread B is preferably made ot" iron or steel, and may be shaped in cross-section to the established form for screw-threads, or it may be simply made of a rectangular bar. The ends b` b' ot' the bar or thread-coil are turned or bent in radially to enter holes a in `the bottom ot' the depression a, by which means, together with the spiral depression, the thread is securely held in place upon the stock.

Another mode of securing the thread to the stock in a simpler manner, and, by means of ordinary shop appliances, without the employment ot' a screw-cutting lathe to form. the depression a, is by first coiling the rod to the re quired shape and then reheatiug` it to a very highheat to expand it sufficiently to allowit to pass snugly over the cylindrical portion" A2 ofthe stock. The coil is then allowed to cool, and will burn the wood and shrink until it has embedded itself into the stock a sufficient distance to be firmly held upon the stock.

The nut into which the screw ts Ymay be made to conform to the thread ot' the screw in the, usual manner, and will work more freely upon it than it' the thread were made of wood, as it is well known that the friction between wood and iron is less than thefriction between wood and wood.

Other modes of securing the thread to the stock may be employed without departing from the spirit of my invention.

A screw for a carpeuters bench-vise which consists of a cylindrical wooden body and a metal rod coiled spirally around it and partly embedded in its surface, as specitied.

JOHN DAWSON SMITH.

Witnesses:

W. L. HAWLEY, CEAS. GLOVER.

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