Untitled record

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, 5 have invented a new and useful Lag-Screw, of which the following is a specification.

The object of this invention is to construct a lag-screw having a peculiarly-constructed threaded portion above the point and a head io shaped angular to form a wrench-seat, as below set forth and claimed.

In the drawings forming a part of this specification, Figure 1 is a side elevation looking from a point at the right of Fig. 2, and 15 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 c and a long plain body portion below 20 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 e of the lag-screw is in 2 5 the main circular in cross-section, but has flattened sides. The spiral threads a are thus on two opposite* sides only, the other two opposite sides being flat, as in Figs. 1 and 2. The surfaces between the separated threads 30 of the portion e for the most part at least are vertically straight. However, said screwthreaded body e may be greater in diameter at the upper end S, and from thence gradually taper for a short distance, as in Fig. 1, to 35 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 40 with two diagonally-opposite 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 45 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 a out of the 50 wood broomed by them when driving the lagscrew, and forces them into the solid wood, which was at the flat sides before the lagscrew was turned. By the expression “broomed” I mean the condition of the wood 55 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 60 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. 65