Untitled record

E. S. WILLS.

Improvement in Wood-Screws.

No. 126,366.

Patented April 30, 1872.

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136,366

United States Patent Office.

EDWIN S. WILLS, OF PHILADELPHIA, PENNSYLVANIA.

IMPROVEMENT IN WOOD-SCREWS.

Specification forming part of Letters Patent No. 126,366, dated April 30,1S72.

Specification describing certain Improve* ments in Wood-Screws, invented by Edwin S. Wills, of the city of Philadelphia, and State of Pennsylvania. «

The first part of my invention relates to a spoon-shaped point to the screw for forming a boring and tapping device, so as to dispense with the necessity of boring the wood previous to the insertion of the screw. The second part of the invention relates to a central bore of the screw from the concavity of the point throughout its whole length for the passage of the borings.

Figure 1 is an end view of a· large wood-screw on the improved plan having a flat head. Fig. 2 is a side view of the same. Fig. 3 is a longitudinal section at the line a δ of Fig. 2. Fig. 4 is a side view of a screw of smaller dimensions, having a conical head, A', the bore E being omitted.

Like letters in al! the figures indicate the same parts.

A, Figs. 1, 2, and 3, represents the head of the screw; B, the smooth part of the shaft; (J, the thread portion, and D, the spoon point, the concavity a of which extends into one or more of the threads. Throughout the whole length of the screw, and meeting the concavity a, is a central bore, E, for the passage of the borings. On the smooth part B of the shaft, at the ends of the threads, there is a series of hacks or barbs, δ, which enlarge the hole as the screw advances into the wood to prevent the splitting of the latter. On the lower side of the head A there is also a series of hacks or barbs, c, which form a countersink for the reception of the head.

In Fig. 4 a screw is represented like that shown in Fig. 3, with the exception of the central bore E being omitted and the head A' being conical. For machine screw-bolts, I make the heads square.