AN IMPROVED WOOD-SCREW
Year: 1883

page_text: "
LETTERS PATENT to Henry Harris Lake of the firm of Haseltine, Lake and Co,
Patent Agents, Southampton Buildings London for an Invention of AN
IMPROVED WOOD-SCREW A communication to him from abroad by The
Harvey Screw Company (Incorporated) of the City and State of New York,
United States of America
COMPLETE SPECIFICATION filed by the said Henry Harris Lake at the
-Office of the Commissioners of Patents on the 19th January 1883.
"
HENRY HARRIS LAKE, of the firm of Haseltine, Lake, and Co, Patent Agents,
Southampton Buildings, London, "AN IMPROVED WOOD-SCREW communicated
to me from abroad by The Harvey Screw Company (Incorporated) of the City and
State of New York, United States of America
•
This invention relates to an improvement in that class of wood-screws which are
made with a point, and on to which point the thread from the body is continued,
to form what is commonly called a Gimlet-point," (because of its resemblance to
boring instruments which are provided with a screw point, and by which point the
instrument is drawn into the wood) such point on the screw enabling it to bé
turned into the wood without first boring a hole for its introduction.
In the usual mode of constructing these screws, a spiral groove has been cut in
the body of the blank to produce a thread, this groove being continued on to the
point. Cutting the groove into the blank removes a large portion of the metal,
and the groove extending on to the point, makes it not only difficult to form a
perfect thread on the said pointed portion, but very difficult to make the point.
concentric, or in perfect axial alignment with the body of the screw
The object of the said invention is to overcome these defects, and produce a
gimlet-pointed screw not only having the thread more perfect throughout, and the
point in perfect axial alignment, but to make the screw much stronger than the
usual cut scrows of this class.

page_text: According to the said invention the spiral rib which forms the thread of the
screw is raised from the body of the blank by the process of rolling, in contra-
distinction to cutting a spiral groove in the said blank, the said raised spiral rib
extending around the pointed part of the blank.
In the accompanying drawing
Figure 1 is an elevation of a headed blank as prepared for the rolling and
pointing operation.
Figure 2 is an elevation of a finished screw.
In manufacturing this new gimlet-pointed screw, the wire is first cut into blanks
of suitable length; the said blanks are then headed, and prepared for threading sub-
stantially in tho usual manner; a prepared blank is shown in Figure 1.
To form the spiral rib or thread the blanks are rolled between dies, which have
in their adjacent surfaces diagonal ribs. As the said blank is rolled between such
ribbed surfaces, the ribs thereof impress the blank, and raise or force up the metal
into the spaces between them. The metal so raised or forced up forms a spiral rib
on the body corresponding to the spaces between the ribs on the dies.
This method of rolling spiral ribs on scrow-blauks to form the thread, broadly
considered, is not new, but prior to this invention such rolled screws have been.
cylindrical throughout the threaded portion, that is, of equal diameter, and con-
sequently, what are, commonly called “ Blunt-pointed" screws. In this new and
improved screw, the end is drawn or wrought into a conical or pointed shape, and
the spiral rib on the body is continued down on to the point by the same rolling
operation; the pointed screw thus produced is shown in Figure 2.
One of the great advantages of this gimlet-pointed screw over the cut screw, is,
that the process of rolling which draws down the point, and raises the spiral ribs
thereon as a continuation of the raised spiral rib on the body, not only brings the
point concentric, that is into axial alignment with the body of the screw, but
prevents the breaking up of the fibre of the metal, unavoidable in a cut thread
point, thereby rendering the point of this new screw harder and stronger than the
cut point.
On account of the concentric or axial alignment of the point of this new screw,
it more readily enters wood, and requires less power to drive it than the usual cut
thread point. Another and important advantage is, that the said point may be
made sharper than that of a cut screw; this sharper point also facilitates the
driving or turning of the screw into the wood.
3
A gimlet-pointed screw of a given size can thus be made from wire of smaller
diameter than a cut threaded screw of the same size, for the reason that the rib
which is raised from the body of the screw-blank enlarges the diameter of the
threaded portion (as shewn in Figure 2). It will be seen that the threaded portion
of this improved screw is not of the same diameter as the neck, which is the case 4
with cut screws, while the diameter of the body of the threaded portion at the
bottom or root of the thread is the same as in the cut screw, the metal not being
removed to form the thread as in the cut screw.
The strength of the screw is dependent upon, and limited by, the body at the
bottom of the thread, and not by the diameter of the neck, henco by raising the 4
spiral rib by the rolling process in contradistinction to cutting the spiral groove,
and continuing the said spiral rib down on to the pointed portion of the blank,
substantially the same size screw is produced by so much less cost of material, as
the diameter of the blank is less than must be used to produce the usual cut thread
gimlet pointed screw.
Having thus fully described the said invention as communicated to me by my
foreign Correspondents, and the manner of performing the same, I wish it understood
that I Claim.
A pointed screw having the spiral rib which forms the thread raised from the
6

page_text: body of the blank, in contradistinction to being formed by cutting a spiral groove in
the blank, the said raised spiral rib being continued around the pointed part of the
body and forming a gimlet-point, substantially as described.
In Witness whereof I the said Henry Harris Lake, have hereunto set my
hand and seal this Nineteenth day of January in the year of our Lord
One thousand eight hundred and eighty three.