Improvements in Screw-cutting Machines.
Year: 1889

page_text: Date of Application, 23rd Apr., 1889
Complete Specification Left, 23rd Jan., 1890-Accepted, 1st Mar., 1890
PROVISIONAL DIBITICAL
Improvements in Screw-cutting Machines.
I THOMAS BENJAMIN SMITH of 121 Saint Luke's Road Birmingham in the County
of Warwick Screw Maker do hereby declare the nature of my said invention to be
as follows:-
My invention has for its object improvements in screw-cutting machines which are
much quicker and more reliable than those at present in use while at the same time
the screw is much cleaner and sharper when finished and refers more particularly to
my former patent No. 5641 A.D. 1886, by which I am enabled by the use of separate
springs to make the resistance to each cutter independant and therefore much more
sensitive and substantial and further by the use of guides to direct the screw into
the centre and act as a fence to steady the screw and cause each cutter to do its work.
I also provide the cutters with double teeth instead of one tooth so as to form a groove
in the cutter for smoothing the edge of the thread and by which at the same time
I obtain a duplex cutter. I mount upon a suitable face or other plate three, four or
more slides radiating towards the centre of the face plate and each slide carries a
curved cutter which is provided with double teeth which operate upon the screw to be
cut the thread of the screw in passing through the groove formed by the two teeth
by which means the thread is made smoother and sharper. Each cutter slide is
provided with an expanding spiral or coiled spring having one end bearing against
the edge of the face plate and the other end bearing against the head of a bolt
projecting from the end of the cutter slide by which means each cutter is withdrawn
from the centre by a spring which forms for each cutter a separate resistance to the
operating wedge hereafter described. A guide is also attached to any convenient part
of each cutter slide having an inclined grooved point so as to direct the screw into
the centre of the cutters." The plate is carried upon a hollow shaft or spindle so that
the screw can pass inside as it is being cut. At the back of the plate and upon or
against the spindle I form jaws one from each side in which I hang levers the front
end of which lever passes through the back of the plate and enters a suitable recess in
the back of the cutter slide the other ends of the lever being provided with jointed
knuckles carrying friction wheels which may be set and adjusted by set screws and
these wheels are kept against the spindle by the afore mentioned expanding springs
on the cutter slides. Upon the back part of the spindle I place a sliding collar
which may be operated by a lever or other means and the front end is made so as
to form a circular wedge so that as it is forced forward against the said friction rollers
on the back end of the levers they are turned in the jaws upon their pivots and thereby
operate the cutter slides whether three four or more and carry the cutters against the
pin upon which the screw is to be cut and each cutter advances at the same speed
by means of the collar wedge exactly balancing each other in their action the guides
after guiding the blank into the center keeping it steadily in position. I may use my
double cutter in connection with any kind of screw cutting machines and use a con-
tracting instead of an expanding spring to the cutter slides if I so desire.
11000
GEORGE BARKER,
77, Colmore Row, Birmingham, Agent for the Applicant.

page_text: COMPLETE
SPECIFICATION.
Improvements in Screw-cutting Machines.
I, THOMAS BENJAMIN SMITH of 121 Saint Lukes Road Birmingham in the County
of Warwick Screw Maker do hereby declare the nature of my said 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 has for its object improvements in screw cutting machines which are
much quicker & more reliable than those at present in use while at the same time the
screw is much cleaner and sharper when finished and refers more particularly to my
former patent No. 5641 A.D. 1886 by which I am enabled by the use of separate
springs to make the resistance to each cutter independant and therefore much more
sensitive and substantial and further by the use of guides to direct the screw into the
centre and act as a fence to steady the screw and cause each cutter to do its work. I
also provide the cutters with double teeth instead of one tooth so as to form a groove
in the cutter for smoothing the edge of the thread and by which at the same time I
obtain a duplex cutter. I mount upon a suitable face or other plate, three, four or
more slides radiating towards the centre of the face plate and each slide carries a
curved cutter which is provided with double teeth which operate upon the screw
to be cut, the thread of the screw in passing through the groove formed by the two
teeth by which means the thread is made smoother and sharper. Each cutter slide
is provided with an expanding spiral or coiled spring having one end bearing against
the edge of the face plate and the other end bearing against the head of a bolt pro-
jecting from the end of the cutter slide by which means each cutter is withdrawn
from the centre by a spring which forms for each cutter a separate resistance
to the operating wedge hereafter described. A guide is also attached to any con-
venient part of each cutter slide having an inclined grooved point so as to direct the
screw into the centre of the cutters. The plate is carried upon a hollow shaft or
spindle so that the screw can pass inside as it is being cut. At the back of the plate and
upon or against the spindle I form jaws one from each side in which I hang levers
the front end of which lever passes through the back of the plate and enters a
suitable recess in the back of the cutter slide the other ends of the lever being
provided with jointed knuckles carrying friction wheels which may be set and adjusted
by set screws and these wheels are kept against the spindle by the afore-mentioned
expanding springs on the cutter slides. Upon the back part of the spindle I place a
sliding collar which may be operated by a lever or other means and the front end is
made so as to form a circular wedge so that as it is forced forward against the said
friction rollers on the back end of the levers they are turned in the jaws upon their
pivots and thereby operate the cutter slides whether three, four or more and carry the
cutters against the pin upon which the screw is to be cut and each cutter advances
at the same speed by means of the collar wedge exactly balancing each other in their
action the guides after guiding the blank into the centre keeping it steadily in
position.
I may use my double cutter in connection with any kind of screw cutting machines
and use a contracting instead of an expanding spring to the cutter slides if I so
desire.
In order that my invention may be clearly understood and more easily carried into
practice I have appended hereunto a sheet of drawings upon which I have fully
illustrated the nature of my improvements together with sufficient additional descrip-
tion to make their application clear.
Figure 1 is an elevation of the face plate A with the cutter holders H in position
ready for cutting the screw W.
Figure 2 is a section through the face plate A the circular wedge D being in
position before operating the cutters.
Figure 3 is an enlarged section through the cutter Q.

page_text: I mount upon the face plate A the three, four or more slides G which radiate
towards the centre of the face plate each slide carrying the curved cutter Q having
the double teeth q' and q² which operate upon the screw W to be cut the thread of
the screw passing through the groove q³ formed by the two teeth q' and q² by which
means the thread of the screw is made smoother and sharper. Each cutter is
provided with the expanding spiral or coiled spring S having the one end s¹ bearing
against the edge of the face plate A the other end bearing against the head g₁ of the
pin g² which projects from the end of the cutter slides G by which means each cutter
is withdrawn from the centre by the spring S which forms for each cutter a separate
resistance to the operating wedge D to be hereafter described. A guide K is attached
to each cutter holder H and is provided with the inclined grooved point k¹ so as to
direct the screw W into the centre of the cutters.
The plate A is carried upon and revolves with the hollow shaft or spindle M and at
the back of this plate A and upon or against the spindle M I form jaws in which I
pivot the levers F the front end F1 of which passes through slots in the back of the
plate and operates the cutter slides G the other end being provided with the jointed
knuckle F carrying the friction wheels E which are kept against the spindle M by
means of the afore-mentioned expanding springs S on the cutter slides. The sliding
collar D is provided upon the back part of the spindle and is operated by a lever or
other means the front part being made to form a wedge for forcing open the friction
rollers E which operate the levers F cutter slides G and cutters Q against the pin
upon which the screw is to be cut each cutter advancing at the same speed by means
of the collar wedge D & exactly balancing each other in their action the guides K
after guiding the screw pin into the centre continuing to keep it steadily in position.
The whole of the other details may be similar to my before mentioned patent No. 5641
A.D. 1886.
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 :-
1st. The improvements in screw cutting machines consisting of the springs S sub-
stantially as & for the purpose herein set forth & shewn upon the drawings.
2nd. In improvements in screw cutting machines the guides K substantially as &
for the purpose herein set forth and shewn upon the drawings.
3rd. In improvements in screw cutting machines the double cutters Q substantially
as & for the purpose herein set forth & shown upon the drawings.
January 1800
Dated this 22nd day of Jans
GEORGE BARKER,
77, Colmore Row, Birmingham, Agent for Applicant.