Year: 1886

page_text: Date of Application, 24th Apr., 1886.
Complete Left, 24th Jan., 1887.
Complete Accepted, 22nd Apr., 1887.
I, THOMAS BENJAMIN SMITH of 104, Sandwell Road West Bromwich in the
County of Staffordshire, Screw Maker, do hereby declare the nature of my said
invention to be as follows:—
This invention has for its object improvements in screw cutting machines which are
much quicker in their action than those now in use and the screw is cleaner when
made.
I mount upon a suitable face or other plate three four or more slides radiating
towards the centre of the face plate and cach slide carries a curved cutter which
operates upon the screw to bo cut. The plate is carried upon a hollow shaft or
spindle from the back thereof 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 for
each slide in which I hang levers the front end of each lever piercing the
back of the plate and entering a suitable recess in the back of its slide and
the other ends are provided with jointed knucles carrying friction wheels
which may be set and adjusted by set screws to a great nicety and these wheels are
kept against the spindle by a circular or other spring. Upon the back part of tho
spindle I place a sliding collar which may be operated by a lever or other means and
the front end is made-conical or other shape so as to be one circular wedge so that
as it is forced forward against the said friction wheels on the back end of the levers
they are turned in the jaws upon their pivots and so the slides whether three four or
more are operated thereby which carries 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
circular collar wedge and they exactly balance each other in their action thus
preventing friction or even turning it into account in assisting to form the thread.
GEORGE BARKER,
77, Colmore Row, Birmingham,
Agent for the Applicant.

page_text: •
I THOMAS BENJAMIN SMITH of 104 Sandwell Road West Bromwich in the County
of Stafford 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:
This invention has for its object improvements, in screw cutting machines which are
much quicker in their action than those now in use and the screw is cleaner when
made. 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
operates upon the screw to be cut. The plate is carried up a hollow shaft or spindle
from the back thereof 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 for each slide-in
which I hang levers the front end of each lever piercing the back of the plate &
entering a suitable recess in the back of its slide and the other ends are provided with
jointed knuckles carrying friction wheels which may be set and adjusted by set screws
to a great nicety and these wheels are kept against the spindle by a circular or other
spring. 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 conical or other shape
so as to be one circular wedge so that as it is forced forward against the said friction
wheels on the back end of the levers they are turned in the jaw upon their pivots and
so the slides whether three, four or more are operated thereby which carries the
cutters against the pin upon which the screw. is to be cut and cach cutter advances at
the same speed by means of the circular collar wedge and they exactly balance each
other in their action thus preventing friction or even turning it into account in
assisting to form the thread.
In order that my invention may be clearly understood and casily carried into
practice I have appended hereunto two sheets of drawings upon which is illustrated
not only the parts thereof which form the subject of my invention but also a sufficient
number of other parts to enables me to more fully explain the action of my invention.
when applied to screw machinery generally.
Figure 1 is a front elevation of a screw machine. with my improvements applied
thereto. A being the face plate and B the stop to prevent the shaft P going forward
while the screw is being gripped. O¹is the rod for operating the pointer.
Figure 2 is a section through the face plate A the circular wedge D is in position
for being forced forward against the friction wheels E which by means of the levers F
operate the cutter slides G and cutter holders H upon the screw W. The pointer Cis
shewn in retreat after having pointed the screw.
Figure 3 is an elevation of the face plate A with the cutter slides G and cutter
holders H removed and shewn the method of tightening up the slides by the loose
pieces J and screws J¹.
Figure 4 is an elevation of the front or face plate with the cutter holders H in
position ready for cutting screw.
Figure 5 is a section through the cutter holders H and cutters K.
Figure 6 is a plan of the pointer C.
Figure 7 is a longitudinal section of the pointer C shewing the tool L fixed in the
pointer by the screws L¹.
Figure 7 is a cross section of same.

page_text: Figure 8 is a sectional elevation through a face plate shewing an alternate mode of
operating the cutter holders by means of a cup or equivalent arms M having an
inclined or other recess or opening acting upon the friction wheels for operating the
cutter.
The action is as follows -The screw blank W upon which the screw is to bo cut is
delivered into the jaws N, Figure 1 which are made to grip it by the action of the
loose collar O which is brought forward upon the shaft by any suitable cam motion
and as the shaft P moves longitudinally it is held back during the operation of
gripping the screw by means of the projection on the slide B passing in front of the
collar P which is fixed to the shaft P and which would at the same time be behind it
at P when the screw blank is fixed in this position a pointer C is brought forward by
any suitable cam movement acting upon the pointer rod C until it comes in contact
with the screw blank W which at the same time is revolving and is pointed by the
edge of the tool L Figure 7 after which the pointer retreats. Two motions then
simultaneously occur:-
Firstly. The shaft P is moved longitudinally forward by means of the regulator R
having threaded jaws R¹ which by means of the weight 2 grip the thread p³ formed
upon the shaft P which continuing to revolve is thereby moved in the direction of
the arrow.
Secondly. The circular wedge D is brought forward by any suitable cam movement
and wedges-open the friction wheels E by means of the levers F which are pivoted
at and are connected by the ball bearing F¹ to the cutter slides G and thereby
operate the cutters Q, QQ and Q³ upon the screw blank W which at the same time
is being brought forward by the shaft P as before described. The circular wedge
then retreats, and the cutters open again by means of the circular spring or other
device S pressing the other ends of the levers F together and at the same time the
weight 2 is raised by means of a cam movement and the regulator R and jaws ¹ open
and release the shaft which is then brought back to its original position at the same
time as the screw is released by the collar O. The one pulley X and bevel wheel Z
are provided with a fixed key which slides in a grove formed on shaft P. The depth
of the screw thread is adjusted by means of the set pins V.
It will be understood that the jaws N shaft P and indeed the whole of the back
working parts and gear together with any mode of feeding which may be used do not
form a part of my invention which is entirely confined to the mode of cutting the
thread shown at the left hand part of drawing I and in greater detail on drawing 2
that is to say to the arrangement of three or more moving cutters upon a face plate A
and operated simultaneously by an internal wedge piece D or external wedge piece M
or their equivalents so as to render practical and active support to each other whilst
the thread is being cut upon the screw i.e. in such a manner that each cutter is a
support to an opposite or almost opposite one and at the same time is also a cutter
itself.
Having therefore now particularly described and ascertained the nature of my
said invention and in what manner the same is to be performed what I claim is:-
The improvement in screw cutting machines of three four or more moving cutters
brought to bear simultaneously upon the material as and for the purpose substantially
as herein set forth.
GEORGE BARKER,
77, Colmore Row, Birmingham,
Agent for the Applicant.