Improvements in Wood Screws.
Year: 1891

page_text: Date of Application, 7th Apr., 1891-Accepted, 9th May, 1891
COMPLETE SPECIFICATION.
Improvements in Wood Screws.
I, CHARLES DAKE ROGERS of 21 Stevens Street Providence in the State of
Rhode Island, United States of America, Works Superintendent, 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 wood screws, but more particularly to the screw-threads
formed on the point portions of such screws.
Heretofore, in the manufacture of wood-screws, whether produced by cutting away
the stock to form the threads or made by the "rolling" process, so-called, the height
of the threads formed on the point portions of such screws gradually diminished
from the base of the point where the full height or depth is attained to the end of
Sometimes the thread
the screw, as in the well-known gimlet-pointed screws.
vanishes or terminates in the beveled side of the point portion before the actual end
is reached, thereby producing an unthreaded end or tip which serves to center the
screw upon entering the wood, followed by a screw-thread having a gradually
increasing height which extends rearwardly toward the head until it reaches the
base of the point portion, where it (the thread) then unites with and forms a part
of the thread formed on the cylindrical or body portion of the screw; an example
of this latter screw is shown and described in the Specification to British Letters
Patent No. 17,067 of 29 Oct. 1889.
Gimlet-pointed screws as generally made are objectionable in that they will not
readily enter the wood unless a hole be first made therein for their reception, and
even when screwed home the threads formed on the point portions of such screws
possess little if any holding power owing to their inclination; moreover, such
inclination or bevel forms a comparatively blunt point which acts to prevent the
screw from readily entering the wood; even when driving the screw in the usual
manner the threaded blunt point continually ruptures the fibres of the wood as it
advances, thereby reducing the holding power of the entire screw, which is
equivalent to a corresponding reduction in the strength of the screw.
referred to some of the disadvantages inherent in gimlet-pointed wood screws are
overcome.
In the Patent
The object I seek to attain in my present invention is to fully overcome the dis-
advantages before set forth, and in order to effect such improvement my invention
consists in providing the point portion of the screw with an unthreaded sharpened
entering end or spur (either conical or pyramidal in form), and having the other
part of the point portion provided with one or more screw-threads integral with the
threads formed on the body of the screw, the diameter of the screw on both the
said screw-threaded portions being substantially alike. By means of this improve-
ment the screw is rendered stronger by reason of the increased holding power; it
enters the wood readily; it is self-centering, and the operation of driving it into the
wood ruptures the fibres of the wood to a less extent than heretofore.
In the accompanying drawings,
Figure 1 is a side elevation of a single-thread wood screw embodying my
improvement;
Figure 2 is a similar view, in partial section, showing my improved screw provided
"double thread";
with a
Figure 3 is a longitudinal sectional view, taken through the center of the lower
portion of the screw shown by Figure 1;
Figure 4 is an inverted end view of the screw enlarged;
Figure 5 is a central longitudinal sectional view of the lower portion of a wood

page_text: screw as heretofore made, the same having an unthreaded spur or end communicating
with the other part of the point portion, which is provided with a screw-thread
gradually increasing in height until it unites with the thread formed on the body of
the screw, and
.
Figure 6 is a similar sectional view of the ordinary gimlet-pointed wood screw.
My improved wood screw is indicated by a; d being the plain or unthreaded
shank portion of the screw, the same having at its upper end a head pro-
vided with a nick n to receive the blade of a screw-driver; or the screw may
be provided with any well-known form of head. The unthreaded shank portion
may be cylindrical, although I prefer to make it tapering, substantially as drawn,
the diameter at its intersection with the head being practically the same as the
diameter of the screw, taken across the threads. The body of the screw is
provided with threads projecting from the cores c. The threads may be
produced by cutting away the metal, as commonly practiced in the manufacture
of cut screws," or they may be produced by suitably operated swaging-dies
by what is known as the "rolling process." I would state that I consider the
last named method of manufacture the most practical as well as being the most
economical.
*
The inclined sides of the core of the point-portion p of the screw I make
somewhat longer than usual, the same terminating in an unthreaded, sharpened
spur-like ends, having a conical or pyramidal form, as desired. The screw-
threads formed on the body of the screw extend past the base of the point-
portion p and terminate abruptly at or near the base of the said spur-portions,
as indicated, see see also Figure 4. The threads formed on the point-portion
have substantially the same diameter as those of the cylindrical or body portion
of the screw, as clearly represented; such construction being in marked contrast
with the construction and arrangement of the point-threads formed on the well-
known gimlet-pointed wood screws, see Fig. 6, or even the threads formed on the
point of the screw patented to me as hereinbefore referred to, and as sectionally
represented herewith by Fig. 5. In both these last named cases the threads
gradually increase in height and diameter toward the body portion of the screw, as
indicated by the inclined dotted lines o, Figs. 5 and 6, whereas in my present
improved screw the thread t has the greatest height at or near its commencement
on the point portion and gradually decreases therefrom to the base a of the point p
where it then forms a part of the main thread'; its diameter, however, is substantially
uniform throughout, see dotted lines m. m.
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 :
A pointed screw having the thread or threads upon the cylindrical body extended
with the same diameter over a part of the surface forming the point.
Dated this 14th day of March 1891.
CHARLES DAKE ROGERS,
Inventor.