IMPROVEMENTS IN WOOD SCREWS, AND IN MACHINERY FOR MAKING THE SAME, AND IN MEANS, METHODS, AND PROCESSES CONNECTED THEREWITH
Year: 1876

page_text: LETTERS PATENT to Thaddeus Hyatt, of No. 60, Gloucester Gardens, Hyde
Park, in the County of Middlesex, London, Manufacturer of Patent Lights,
and Thomas Rickett, of No. 3, Devonshire Place, Pershore Road, near Bir-
mingham, Engineer, for the Invention of "IMPROVEMENTS IN WOOD SCREWS,
AND IN MACHINERY FOR MAKING THE SAME, AND IN MEANS, METHODS, AND
PROCESSES CONNECTED THEREWITH.”
Sealed the 14th November 1876, and dated the 15th September 1876.
PROVISIONAL SPECIFICATION left by the said Thaddeus Hyatt and Thomas
Rickett at the Office of the Commissioners of Patents on the 15th September
1876.
THADDEUS HYATT, of No. 66, Gloucester Gardens, Hyde Park, in the County of
Middlesex, London, Manufacturer of Patent Lights, and THOMAS RICKETT, of No. 3,
Devonshire Place, Pershore Road, near Birmingham, Engineer. "IMPROVEMENTS IN
WOOD SCREWS, AND IN MACHINERY FOR MAKING THE SAME, AND IN MEANS, METHODS,
AND PROCESSES CONNECTED THEREWITH.'
"
The object of our Invention is to make a screw the threads of which and the
shape and construction of which resemble ordinary wood screws so nearly that they
may be used in place of them, being as readily withdrawn from the wood by means
of a screw driver as ordinary wood screws, and yet capable of being driven like an
ordinary nail, the shape and arrangement of the threads being such in connexion
with the form of the point of the screw as to not injure the grain of the wood for
holding purposes when thus driven, a part of the Invention consisting in so shaping
the screw as to render the driving of it easy. The common wood screw cannot be
advantageously used as a nail that is driven instead of being screwed because when
thus used the threads destroy the holding power of the fibres of the wood by
tearing them; this arises from the character of the threads, which are thin and
high, and made with nearly parallel sides, and are set wide apart, and also, from the
form of the screw point.

page_text: According to one part of the Invention our improvements consist,-
First. In making wood screws with a chisel or cutting instead of a screw or
gimlet point to cut a passage for the easy entrance of the body of the screw.
Second. Our improvement consists in forming the threads of our improved screw
with such an obliquity or angle as is most consistent with its greatest holding
power in the wood and least destructive effect upon the fibres thereof, that is to
say, the sides of the threads are less perpendicular than those of the ordinary wood
screws, being more inclined, like metal screws, the troughs however between the
threads, when seen in profile, being preferably formed of curved lines.
3d. Our improvement consists in a taper form of screw, by which means it may
be driven not only more easily into wood but more easily withdrawn from it; the
taper form also adds to the holding power of the screw.
And, 4thly. Our improvement consists in strengthening the head of the improved
screw on its under side where it joins the blank by increasing the metal at that
point, in order to enable it to resist the impact of blows from a hammer in its
employment as a nail.
According to another part of our Invention our improvement consists in making
the ordinary wood screws with a chisel point. In preparing material of which to
make the new screw our improvement consists according to one part of our
Invention in forming the taper blanks by means of rolls upon the general principle
already in use for making gun barrels, the rods or wire being fed to the rolls which
impress the taper form upon it in pairs or otherwise; this wire is afterwards cut
into the lengths required and headed in the usual way. The threads may then be
cut upon the blanks by machinery similar to that ordinarily used, modified however
to suit the taper form of screw.
According to another part of the Invention our improvement consists in putting
the threads of wood screws on to the blanks by a rolling process; that is to say,
by means of rollers which have threads upon their peripheries in counterpart to
those to be formed upon the blanks, a part of the Invention consisting in making
the rolls of taper form and with their axes inclined.
According to one part of the Invention our improvement consists in the use and
application of one large central roll and a series of two or more smaller ones located
at convenient points at the circumference of the same. These rolls are all connected
together by gearing, so that they move at the same circumferential velocity;
according to the number of pairs of small rolls surrounding the large one will be
the number of blanks operated upon, the movement of the large roll being eccentric
and operating successively upon each of the blanks; or by another arrangement the
central roll is made concentric, and the several pairs of rolls are made to approach
and recede from the central roll by suitable mechanism. In place of having one
central and a series of surrounding rolls we prefer in some cases to have only one
set of two, three, or more rolls, either eccentric or concentric, as may be required.
The blanks are to be fed to the machine by suitable well-known automatic means.
SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Thaddeus Hyatt and Thomas Rickett in the Great Seal Patent Office
on the 14th March 1877.
THADDEUS HYATT, of 66, Gloucester Gardens, Hyde Park, in the County of
Middlesex, London, Manufacturer of Patent Lights, and THOMAS RICKETT, of 3,
Devonshire Place, Pershore Road, near Birmingham, Engineer. "IMPROVEMENTS IN
WOOD SCREWS, AND IN MACHINERY FOR MAKING THE SAME, AND IN MEANS, METHODS,
AND PROCESSES CONNECTED THEREWITH."
Our Invention relates to improvements in wood screws having for their object

page_text: the production of a screw which in its threads and in its shape and construction
generally shall so closely resemble the wood screw in common use that it may be
employed in the same manner, with the same effect, and for the same purposes,
being as readily entered and withdrawn, by means of a screw driver, as the ordinary
screw, and yet shall be capable when driven with a hammer of entering the wood
after the manner of a nail without turning on its axis, whilst at the same time
holding with the power of a screw. The principles upon which ordinary nails and
wood screws operate may be briefly enunciated as follows:-The driving principles
of a nail is progression without rotation, friction, or side pressure being its holding
power or principle. The driving power of a screw is progression by means of
rotation, its holding power or principle being the interlock of a male and female
thread; now according to our Invention we construct a screw combining the
facility for insertion presented by ordinary nails with the holding power peculiar to
screws.
Our Invention is based upon the model of the wood screw in common use, which
may be regarded as the standard for holding power, convenience, and cheapness.
This screw has but one thread, which coils around the core or solid centre in tho
form of a helix or spiral inclined plane, the power of the screw being produced by
the gradual or slight incline of the planes in convolution.
It has been previously proposed to construct what has been designated a screw
nail, videlicit a multiple-threaded screw, to bo inserted by being driven with a
hammer, but this hammer-driving screw could only enter the wood by rotating
upon its axis.
In the Specification to Letters Patent granted to the said Thaddeus Hyatt (one
of the parties hereto) and Thaddeus Pomeroy Hyatt, dated the 21st day of October,
1875, No. 3650, there is described a wood screw capable of entering without
rotation when driven with a hammer, but this screw is subject to the defect of a
want of holding power in its two unthreaded sides which it is one object of our
Invention to remedy.
The various contrivances proposed from time to time previously to the date last
mentioned with the view of avoiding the use of the gimlet, bradawl, or other
instrument for fixing the screw preliminarily to the use of the screw driver had no
bearing on the general character of the screw, and though never adopted they
seem to have led to the pointed form now in common use, and which may be
regarded as the perfected result of them all. The slight taper of its core and
pointed end enables it to be driven by the hammer to any required distance
necessary to fix it for the screw driver, though to the extent driven it injures the
wood, the shape and form of the threads being such as to break the fibres of the
wood crosswise when forced into it in this manner. This shape and form of the
screw which causes it thus to injure the wood when driven into it after the manner
of a nail has been adopted by screw makers after years of experience as the best to
impart to it the utmost efficiency as a screw, the theory of its use being that for
the metal screw to be capable of properly exerting its holding power it is indis-
pensable there should be another screw in the wood, so that the threads may
interlock one with the other, and as the screw itself has to serve as a screw tap to
cut the threads in the wood its construction has reference to this duplicate function.
It is obviously necessary that the threads formed by the screw in the wood should
be stouter than the threads with which the screw itself is provided in order to
obtain equal strength, for which reason the threads of a "wood screw
" are get
wider apart than those of "metal screw," or screws to be used in metal. The exact
character of the wood screw in common use is due then to the fact that it is
contrived and constructed to do the work of a screw tap and to be inserted in the
wood by being rotated upon its axis, and to the theory and assumption that it is
indispensable there should be a proper screw thread in the wood in the nature of a
counterpart to the screw, in order to enable the latter to exercise the proper
prehensile effect. Upon this theory and assumption the screw is about as perfect,

page_text: as can well be, and its existence in this shape is a proof that it is totally unfitted to
be driven into wood by the hammer, as much so as though the design had been to
prevent its ever being employed in such a manner.
It is also evident that in order to obtain the desideratum of a screw capable of
being driven like a nail, and yet retain its holding power as a screw, the retaining
power of the wood must be made available by means other than that of a counter-
part screw. According to our Invention the screw is required to cut its thread
within the fibres of the wood only as a means of leaving and not as a means of
entering, as in the case with the ordinary wood screw.
Our Invention is based upon a holding principle or power in wood which we
have discovered to be sufficient for giving effect to the threads of a wood screw
when the latter are suitably modified for the purpose, which holding principle or
power we designate the "arrow head or barb holding principle," this designation
expressing most nearly, although not fully, the power of the force employed.
And in order that our said Invention may be fully understood we shall now
proceed more particularly to describe the same, and for that purpose shall refer
to the several Figures on the annexed Sheet of Drawings, the same letters of
reference indicating corresponding parts in all the Figures.
The principle upon which our Invention is based will be understood by a
reference to Figure 1, which represents a thin or "French nail," formed at the end
with an arrow head or barb a of a conical shape, and inserted in the wood A, A.
In driving the nail into the wood the cut or separated fibres b, b, are necessarily
bent down in the direction in which the nail is driven, but after the arrow head
has passed them, they spring back and close in behind it around the shank c of the
nail, so that it cannot be withdrawn.
Figure 2 represents the nail with a number of arrow heads a, a, formed upon it
to give it increased holding power. These two Figures illustrate in nail form the
principle which we term the "arrow head or barb principle," the bent elastic fibres
of the wood taking into the indentations of the nail in a somewhat similar
manner to a pawl engaging with the teeth of a ratchet wheel.
Figure 3 represents the arrow heads or barbs a, a, joined together and forming a
It
continuous thread in spiral form, so that what was a nail has now become a screw.
is represented as having been driven into the wood A, A, precisely as the nail.
Figures 1 and 2 have been driven, and holds in the wood in a similar manner by
virtue of the bent or pawl like fibres b, b, of the wood, which resist the direct
withdrawal of it, but the barbs being in the form of a spiral thread, the screw has
been turned by means of a screwdriver, and thus partially withdrawn, as shewn.
Figures 4 and 5 represent a stouter screw than that shewn in Figure 3, videlicet,
one constructed in about the proportions of the ordinary screw. The point d of
this screw is in the form of a cutting wedge, Figure 4 being a side view, and
Figure 5 a face view of the same. When the screw has considerable thickness this
form of point is essential in order to cut and separate the fibres, and thus give easy
entrance to the threads which join it, and which die out or merge in the sides of
the wedge. We also prefer to make the screw of a taper shape, not only in the
shank and core or solid portion c which, as shewn in Figures 4 and 5, is of a taper
form from the head e to the point d, but also in the threaded portion a, which
tapers in conformity to the core around which it coils. This screw when driven in all
the way by a hammer possesses a holding power equal to or greater than that of an
ordinary wood screw inserted all the way by a screwdriver, and possesses a still
greater holding power having been driven in to within a single turn, only that
turn is made by a screwdriver.
Figure 6 represents a modified form of the barbs a, the profile shewing curved or
waved lines. The holding power of this screw when driven all the way into the
wood by a hammer is nearly or quite equal to that of the ordinary screw when
inserted all the way by means of a screwdriver, but greater than that of the
ordinary screw when at the last one single turn is imparted to such improved screw

page_text: by means of a screwdriver. The depth of the thread may be uniform upon the
tapering core, as shewn, or the thread may be made of greater or less depth at
particular parts of its length for special purposes.
We have described our Invention as an improvement upon the ordinary wood
screw made with a single thread, but it may be applied to a two-threaded screw, as
shewn in Figure 7, the scope of our Invention embracing generally any wood screw
which could fairly be regarded as an equivalent to the ordinary one for being
entered by the power of a screwdriver. As our screw is designed to be driven by a
hammer we also find it desirable to strengthen the head by additional metal, and
by modifying the form of the nick.
Figure 8 represents our method of strengthening the head of the screw, both by
the form of the nick, which is made half round at the bottom, as shewn at f, and
by more metal being left at the junction of the head e with the shank c, as shewn at g.
It should be understood that the forms herein-before described and illustrated by
our Drawings are those we have found to be the best for being manufactured with
economy and employed to advantage, but that the screws may be otherwise
modified in various ways without departing from the principle of our Invention.
For example they may be constructed of an oval in lieu of a circular section, the
outline and depth of the threads may also be varied, and the sides of the screw inay
be made parallel in lieu of tapering, or they may be tapered in the reverse direction if
found desirable. The screws are made from taper blanks produced by turning in a
lathe or by rolling in any usual or suitable manner, and the threads may either bo
cut upon such blanks by the ordinary travelling tool in a screw-cutting lathe or be
formed thereon by a rolling process, the wedge formed point being subsequently
shaped by a file or otherwise. When the screw threads are formed by rolling, the
threads are put on to the blanks in lieu of being cut therein, the effect being to
produce a screw, the threaded portion of which is of larger diameter than the shank
or core, that is to say, the threads of which project beyond the shank or core, which
constitutes the body of the screw, as shewn in the Drawings.
When the thread is formed by screw-cutting machinery, the shank or core is also
made of less diameter than the threaded portion, the diameter of the shank or core
being reduced after the operation of screw cutting or otherwise, as desired.
Having now described and particularly ascertained the nature of our said Inven-
tion, and the manner in which the same is or may be used or carried into effect,
we would observe in conclusion that what we consider to be novel and original,
and therefore claim as the Invention secured to us by the herein-before in part
recited Letters Patent, is,-
First. Shaping and forming the body of the screw and its threads, in combination
with its point or entering end, in such a manner as to impart to it the hammer
driving character of a nail to enter the wood without cutting a screw thread or
materially injuring the fibres, whilst possessing the necessary screw tap power for a
back-cutting action, in order to leave the wood by cutting a screw thread therein,
as the means of its exit therefrom, substantially as and for the purposes herein-before
described and illustrated by the accompanying Drawings.
Secondly. Making a wood screw with a tapering shank and core in combination
with a tapering thread of larger diameter than the shauk, substantially as and
for the purposes herein-before described and illustrated by the accompanying
Drawings.
Thirdly. The combination in a wood screw of threads formed with sloping sides
or tapering edges, and of a piercing or cutting end formed with inclines leading
from the point or cutting edge upwards to the threads, so as to open the cut or
pierced wood sufficiently to admit of the entrance of the threaded portion of the
Screw without material injury to the wood fibres, substantially as and for the
purposes hercin-before described and illustrated by the Drawings.
Fourthly. Making a wood screw with a cutting wedge shaped end or point
immediately at the end of the thread, and without prolongation of the solid portion

page_text: or core of the screw, the threads terminating or merging in the wedge, so that the
wedge forms the commencement of the threads, as the point of the ordinary screw
commences its threads, substantially as and for the purposes herein-before described
and illustrated by Figures 4 and 5 of the Drawings.
In witness whereof, I, the said Thaddeus Hyatt, on behalf of myself and
the said Thomas Rickett, have to this our Specification set my hand and
seal, the Fourteenth day of March, One thousand eight hundred and
seventy-seven.
THADDEUS HYATT. (L.S.)