Untitled record

No. 138,784.

W. BOURN.

Wood Screws.

Patented May 13, 1873.

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Inventor:

Witnesses.

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AM PHOTO-LITHOGRAPHIC CO Λ' Y· OSBORNES PROCESS)

United States Patent Office.

WILLIAM BOURN, OF GENEVA, NEW YORK.

IMPROVEMENT IN WOOD-SCREWS.

Specification forming part of Letters Patent No. 138,784, dated May 13,1873; application filed

August 1,1872.

To all whom it may concern:

Be it known that I, William Bourn, of Geneva, in the county of Ontario and State of New York, have invented a certain Improvement in Wood-Screw Points, of which the following is a specification:

The object of my invention is to provide a wood-screw that will cut a hole the size of the stem of the screw as it is being driven into the wood, either hard or soft, without any tendency to split the timber, as does the ordinary gimlet-pointed screw now in use; and its nature consists in making the screw with a bradawl point instead of a gimlet-point, such bradawl point having a circular cutting-edge projecting beyond the threaded portion of the screw.

Figure 1 is an elevation of an ordinary woodscrew having my improved point. Fig. 2 is a similar view of the same, but showing one side or edge of the cutting-point.

The great advantages of the gimlet-pointed over the old-fashioned screw are well-known, yet it is quite as well understood that the gimlet-point acts as a wedge in penetrating the wood, only parting the grain, there being, therefore, a strong tendency to split the timber. This tendency I wholly obviate by providing the screw with a flattened or brad-awl point, as shown at a in the drawing, which point actually bores or cuts the hole for the reception of the stem as the screw is being turned in, the thread of the screw being pressed into the wood.

In using these screws in soft wood it is only necessary to start them in with a hammer sufficiently to have one or two threads catch; but in hard wood it is necessary to bore in with a bit or brad-awl, according to the size of the screws used, far enough to take in one or two threads, as in the other case, after which the screw will cut its own hole as it is being turned in.

Of course all kinds and sizes of wood-screws may be made with this kind of point, whether they have slotted heads for a screw-driver or square heads for a wrench.

Repeated experiments with large and small screws provided with my improved points in various kinds of wood have clearly demonstrated that such screws can be used without any liability to split the timber. They can be inserted with far less labor, and, therefore, proportionally reducing the strain upon them and the liability to twist them off while they are being driven in.