US408751A - Lag-screw - Google Patents

Description

1 (No Model) I G. P. RO$E.

LAG SCREW. No. 408,751. Patented Aug. 13, 1889.

UNITED STATES PATENT OFFICE.

GEORGE PAYNE ROSE, OF FENTQN, MICHIGAN.

LAG-SCREW.'

SPECIFICATION forming part of Letters Patent No. 408,751, dated August 13, 1889.

Application filed November 21, 1888. Serial No. 291,434. (No model.)

To all whom it may concern.-

Be it known that I, GEORGE PAYNE RosE, a citizen of the United States, residing at Fenton, county of Genesee, State of Michigan, have invented a new and useful Lag-Screw, of which the following is a specification.

The object of this invention is to constructa lag-screw having a peculially-constructed threaded portion above the point and a head shaped angular to form a wrench-seat, as be low set forth and claimed.

In the drawings forming a part of this specification, Figure 1 is aside elevation looking from a point at the right of Fig. 2, and Fig. 2 is an elevation looking from a point at .the left of Fig. 1.

Referring to the letters marked on the drawings, B is the lag-screw, having an angular head 0 and a long plain body portion below said head, forming a bearing in the wood when the screw is turned, and a screw-threaded portion flattened on two opposite sides below the plain body portion.

The threaded part c of the lag-screw is in the main circular in cross-section, but has flat tened sides. The spiral threads at are thus on two opposite sides only, the other two opposite sides being fiat, as in Figs. 1 and 2. The surfaces between the separated threads of the portion e forthe most part at least are vertically straight. However, said screwthreaded body 6 may be greater in diameter at the upper end S, and from thence gradually taper for a short distance, as in Fig. 1, to give greater strength at this point; but this is a matter of choice. The upper faces of the threads are at right angles to the body e and beveled on the under side.

The point of the lag-screw is wedge-shaped with two diagonallyopposite edges chamfered off at r 'r to facilitate turning after the lag-screw is driven. The lower end may be conical-pointed, instead of wedge-shaped,if preferred.

In the use of the lag-screw it is driven like a nail with a hammer, the long way of the wedge end being crosswise of the grain of the Wood into which it is driven. The lag-screw is then given a quarter-turn with a wrench, which action takes the threads 0. out of the wood broomed by them when driving the lagscrcw, and forces them into the solid wood, which was at the fiat sides before the lagscrew was turned. By the expression broomed. I mean the condition of the Wood on the threaded sides of the lag-screw, which is broken and left splintered or ragged by the threads being forced through the wood when the screw is driven with a hammer. This action is not here shown, but will be readily understood.

It will be observed that in Fig. 1 the grooving of the threads extends onto the beveled part of the wedge-point. This facilitates turning the lag-screw after it is driven.

Having thus described my invention, what I claim as new, and desire to secure by Letters Patent, is-

A lag-screw having a square head for the attachment of a wrench thereto, said screw being flattened and having threads on two opposite sides, the upper sides of said threads being at right angles to the screw-body and having vertically-straight intermediate sur- GEORGE PAYNE ROSE.

Witnesses:

ARTHUR M. RAIsoM, J. L. HAWES.

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