Improvements in metallic Wood-Screws
Year: 1887

page_text: I, CHARLES D. ROGERS of the City and County of Providence State of Rhode
Island U.S.A. Mechanic, do hereby declare the nature of this invention and in what
manner the same is to be performed, to be particularly described and ascertained
in and by the following statement:―
My invention relates to Improvements in metallic Wood-Screws, so-called, the said
improvements consist, essentially, in the novel construction of the screw-shank, or
stem, contiguous to the head.
The class to which the said improved wood-screws belong, being that in which the
screw-thread is made comparatively coarse, thereby more particularly adapting it to
be used as a wood-screw.
The object of my invention
to produce a better and stronger screw. To attain
this result the diameter of the core, or bottom of the screw, at the commencement of
the screw-thread nearest the head, is made to gradually increase up to its intersection
with the head, thereby forming a conical (or substantially so) shank, or unthreaded
portion intermediate of and uniting the screw-threaded portion and the head of the
screw, all as will be more specifically hereinafter set forth and claimed.
Usually, so far as I am imformed, such plain portion of a wood-screw is made
cylindrical or uniform in its diameter throughout.
In my improved screw the outer diameter of the thread is practically the same (or
nearly the same) diameter as that of the shank at its junction with the head; the
shank from this point being gradually reduced in diameter, as before stated, toward
the point, until it merges into the core or root of the screw-thread.
In order to more clearly exhibit my invention, I have prepared the accompanying
sheet of drawings, in which—
Figure 1 represents (enlarged) a perspective view of a wood-screw provided with
the improvement; the screw terminating in a screw-threaded or gimlet" point.
Figures 2 and 3 represent similar views of the plain or unthreaded portion of the
shank of the screw. The outline of said plain portions having a slightly different
form from that shown in the preceding Figure.

page_text: The following is a detailed description of the improved wood-screw
A, referring to the drawings, indicates the screw as a whole, the convolutions of the
screw-thread t, the core or root c, and the screw-threaded point p, being substantially
as usually constructed, or rather the screw-thread t, is preferably produced upon the
wire by what is known as the "rolling process," wherein the screw blank is passed
between the grooved faces of two suitably mounted and operated dies, thereby forcing
a spiral groove into the blank which becomes gradually deepened corresponding to
the outward lateral flow of the metal, and finally produces à screw-thread which is
somewhat larger in diameter than that of the normal size of the wire or stock forming
the blank. A further description of the means for forming the screw-thread is not
deemed essential to this specification.
The novel feature of the wood-screw illustrated herewith, consists in the peculiar
form of the plain or unthreaded portion s, of the shank, the same commencing at the
root of the screw-thread t, and extends rearwardly from the point c¹, in an increasing
diameter up to and intersecting the head h, at a point c². The latter being practically
the same diameter as the outer diameter of the screw-thread. See dotted lines.
By means of this construction it is obvious that the strength of the screw A. is
greatly increased, more especially immediately adjacent to the head h.
The plain
portion, as s, having a conical form.
In Fig. 2 the sides of the cone are represented as being slightly concave in the
direction of its length, as at s¹. Its diameter, however, at the junction with the head
being enlarged and corresponding substantially with the outer diameter of the screw-
thread t, as previously described with reference to Fig. 1. In Fig. 3 the sides of the
conical portions, are made slightly convex, as at s².
The head h, of the screw may be of any desired form as usual, the same being
provided with a nick n, or its equivalent, by means of which the screw is adapted to
be axially turned.
I would state here that the tapering or conical portion s, of the shank, as well as
the head itself, may be produced by previously upsetting the wire or stock while it is
retained in a die having a correspondingly shaped cavity.
Having now particularly described and ascertained the nature of my said invention,
and in what manner the same is to be performed, I declare that what I claim is ;—
First. The wood-screw herein before described, having the unthreaded shank
portion thereof, which connects the head and the screw-threaded portion, extending
rearwardly from the core of the screw in a divergent direction, substantially as shown
and set forth.
Second. The improved wood-screw herein before described, the same consisting of a
screw-threaded portion terminating in a sharpened point, a head adapted to receive a
screw-driver, and a tapering or cone-shaped shank connecting said head and screw-
threaded portion, substantially as shown and set forth.
Third. The improved wood-screw, having the diameter of the shank at the inter-
section with the head, substantially the same as the outer diameter of the screw-thread,
and tapering therefrom in a decreasing ratio to the root or core of the thread, for the
purpose hereinbefore set forth.
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