IMPROVEMENTS IN THE MANUFACTURE OF SCREWS
Year: 1881

page_text: LETTERS PATENT to William Robert Lake, of the Firm of Haseltine, Lake
& Co., Patent Agents, Southampton Buildings, London, for an Invention of
"IMPROVEMENTS IN THE MANUFACTURE OF SCREWS." A communication from
abroad by the American Screw Company (Incorporated), of Providence,
Rhode Island, United States of America.
COMPLETE SPECIFICATION filed by the said William Robert Lake at the
Office of the Commissioners of Patents on the 1st December 1881.
WILLIAM ROBERT LAKE, of the Firm of Haseltine, Lake, & Co., Patent Agents,
Southampton Buildings, London. "IMPROVEMENTS IN THE MANUFACTURE OF
SCREWS." A communication from abroad by the American Screw Company
(Incorporated), of Providence, Rhode Island, United States of America.
This Invention relates to the heads of screws, and consists partly in forming the
heads with a continuous rim, countersinking a portion of the head, and providing
such portion with a projecting bar or bars, with which the screw-driver can engage
when the screw is being driven or removed. It also consists in locating the faces
of the bars in a plane below the face of the head, whereby the amount of shaving
necessary to finish the head of the screw is materially diminished.
As usually constructed the head of a screw is provided with a diametrical slot
or "nick," which is produced by the process of milling. Attempts have been
made however to produce the nick by indenting the head with a punch. It is
impracticable however to produce screws of this character in any considerable
numbers on account of the delicacy of the punch used to indent the head.
The object of the said improvements is to produce a screw without the aid of
the usual nicking machinery, the head of which will possess greater strength and
lurability than is found in the ordinary screw, which will present a desirable
appearance, and which can be economically produced in large quantities.
In the accompanying Drawing,—
Figures 1, 4, and 7 represent in perspective portions of screws embodying my
improvements.
Figures 2 and 3 represent sections of Figure 1 on the lines x, x, and y, Y.
Figure 5 represents a section of Figure 4 on the line <, >, and
Figure 6 represents in section a modified form of cavity in the screw-head

page_text: A is the body or shank of the screw, and B is the head. As shown in each of
the Figures, the head is surrounded by a continuous rim b, and is countersunk, as
at C. I prefer to make the counter sunk portion concavo, as particularly shown in
Figures 2, 3, and 5, but the form shown in Figure 6 is equally serviceablo. As
shown in Figure 1, the countersunk portion of the head is crossed by a projecting
bar D, which strengthens the head and affords an engagement for a specially
shaped driver having a slot of the requisito width and depth across its face.
As shown in Figure 4, the countersunk portion of the head is crossed by
bars D, D, preferably at right angles to each other, theroby giving still greater
strength to the head.
As shown in Figure 7, the bars D, D, do not extend across the countersunk
portion C, but project radially from the rim b. This form of screw-head is adapted
to be engaged not only by a driver of special shape, but also by a driver of the
common variety.
As particularly shown in the sectional views, the faces of the bars D are below
the face of the rim b. This feature of construction is preferable in that only the
rim 6 of the head need be shaved to produce a finished head; less time therefore is
required to shave the head, and the shaving machines can be run at a much higher
speed.
The countersunk portion and bars of the scrow-head are preferably formed when
the head is upset in the usual process of manufacture. The tools or punches for
forming such portions may be made very durable, so that large quantities of screw-
blanks can be made without renewing such tools.
The advantages of my improved screw-head are great strength and durability, a
desirable and finished appearance, and economy in manufacture. The form of the
head also allows the driver to be made much stronger than those of ordinary
construction.
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,
First. A screw having a countersunk head with a continuous rim surrounding
its countersunk portion, and a bar or bars crossing the said portion and joining the
riin, substantially as above set forth.
Second. A screw having a countersunk head with a continuous rim surrounding
its countersunk portion, and a bar or bars projecting from the central countersunk
surface, substantially as and for the purpose specified.
Third. A screw having a countersunk head with a continuous rim surrounding
its countersunk portion and radial bars projecting therefrom, substantially as above
set forth.
Fourth. A screw having a countersunk head with a continuous rim surrounding
its countersunk portion, and a bar or bars superimposed theroon below the said ring,
substantially as above set forth.
In witness whereof, I, the said William Robert Lake, have hereunto set my
hand and seal, this First day of December, in the year of our Lord One
thousand eight hundred and eighty one..