Improvements in or relating to Screw Cutting Devices or Attachments applicable to Lathes and similar Tools.
Year: 1890

page_text: Date of Application, 20th June, 1890
Complete Specification Left, 20th Mar., 1891-Accepted, 25th Apr., 1891
PROVISIONAL SPECIFICATION.
Improvements in or relating to Screw Cutting Devices or
Attachments applicable to Lathes and similar Tools.
I, JAMES SAMUEL FOLEY, of 20, Richmond Gardens, in the County of
Middlesex, Engineer, do hereby declare the nature of this invention to be as
follows:-
be
This invention has for its object to provide an attachment for a lathe or
similar tool or machine by means of which the slide rest or tool holder may
moved along at any desired speed for forming screws of a great variety of
different pitches and which after being adjusted for cutting one thread may be
instantly re-adjusted for cutting a thread of a different pitch without having
recourse to the usually laborious necessity of re-arranging the gearing or change
wheels.
In a lathe fitted with the improved attachment a worm is provided on the
mandrel to give rotary motion to a worm wheel which may be thrown in and
out of gear with said worm and which can be secured on a short nearly-vertical
shaft to the lower end of which is secured a bevel wheel which gears with
another such wheel secured on a shaft passing longitudinally below and parallel
to the lathe mandrel. On the opposite end of this last named shaft is secured
a pinion which gears with a toothed rack either at its upper side for cutting
say right-hand screw threads or at its under side for cutting say left-hand
screw threads this rack or the sliding frame which carries it for this purpose
being reversible or adjustable.
The sliding frame is mounted in suitable guides so that it may slide in a
horizontal direction transverse to the axis of the spindle this motion being imparted
by the before-mentioned pinion and rack; instead of being arranged to move in a
horizontal direction the sliding frame may sometimes advantageously be arranged
to move in a vertical or inclined direction. To say the back end of the sliding
frame is pivoted one end of a slotted and generally straight cam bar or equivalent
the other end of which may be adjusted to any desired position on a quadrantal bar
secured to say the front end of the sliding frame the said quadrantal bar being
graduated so as to indicate the position to which the slotted cam bar is to be
moved for cutting a thread of any particular pitch, and in which position the cam-
bar may be clamped by any suitable means.
Into the slot of the cam bar projects a pin preferably carrying an anti-friction
roller so that it will move freely in said slot, this pin itself being carried on a
collar which by a pinching screw may be secured in any desired position on a
horizontal rod which is supported in suitable brackets so that it may freely move in
a longitudinal direction.
The last mentioned rod which for convenience is hereinafter termed the "slide
rest rod" may pass through and be guided in the lower part of the lathe head-
stock and at one end is screwed or otherwise detachably secured to the slide rest or
tool holder to which the necessary feed motion is to be given; at the other end this
rod may be provided with a milled head or equivalent for unscrewing the opposite
end from the slide rest when the lathe is not required for screw-cutting.
The sliding frame and the slotted cam bar carried by it receive their motion from
the before mentioned rack and pinion at a certain relative speed to that of the lathe
mandrel and the cam bar moving in one direction transmits motion in a direction
which in the illustration above given would be at right angles to its own to the slide
rest bar. The motion thus imparted to the slide rest in relation to that of the lathe
mandrel is therefore dependent upon the angle of the cam bar to the slide rest rod

page_text: and as this angle may be adjusted it follows that a thread of any desired pitch may
be cut all that is necessary to effect a change of pitch being to release the before
mentioned pinching screw and after moving the cam bar to the proper scale
marking on the quadrant to again tighten the pinching screw on to the slide
rest rod.
For making the return or idle stroke of the tool the driving strap or band of the
lathe may either be wound back by hand in the usual manner or it may be returned
by any other suitable means such for example as reversing gear.
Instead of arranging the rack so that it must be reversed for changing from a
right to a left hand thread it may be permanently fixed to the frame and the slotted
cam bar may be arranged so that it can be angled to either side of a central line
instead of to one side as before described.
It is obvious that the before described apparatus may be arranged to move the
slide rest so slowly that it may be used instead of the ordinary feed motion.
When the lathe is required for ordinary use the before mentioned worm wheel is
thrown out of gear with the worm on the lathe mandrel and the pinching screw is
released from the slide rest rod which is then detached from the slide rest and
preferably withdrawn out of reach of the slide rest.
Any suitable stop may be provided for preventing the slide rest coming into
contact with the worm and bevel gearing by which the screw-cutting attachment is
operated.
Without departing from the spirit of this invention the various parts of the
apparatus may be modified in many ways in fact it does not matter to what extent
these modifications may be carried provided the essential elements are retained; for
instance the slide rest or tool holder may be arranged as a fixture and the work and
work-holder to move to and from the tool-holder.
Dated this 20th day of June 1890.
W. P. THOMPSON & BOULT,
Agents for the Applicant.
COMPLETE SPECIFICATION.
improvements in or relating to Screw Cutting Devices or
Attachments applicable to Lathes and similar Tools.
1, JAMES SAMUEL FOLEY, of 20, Richmond Gardens, in the County of
Middlesex, 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 :-
This invention has for its object to provide an attachment for a lathe or similar
tool or machine by means of which the slide rest or tool holder may be moved along
at any desired speed for forming screws of a great variety of different pitches, and
which after being adjusted for cutting one thread may be instantly re-adjusted for
cutting a thread of a different pitch without having recourse to the usually laborious
necessity of re-arranging the gearing or change wheels.
The invention will be best understood by reference to the accompanying drawings
in which
Fig. 1 is a plan of a lathe head with the device attached,
Fig. 2 is an elevation of the same, and
Fig. 3 is an end view of the head stock of the lathe showing portions of the
driving mechanism and screw-cutting device.
Fig. 4 is a plan of a slightly modified form of the device.
Like letters represent like parts throughout the drawings.
A represents the head stock of the lathe, but it will be understood that the
application of the invention is by no means confined to lathes. B is the slide rest
and C the lathe bed. D is the spindle which supports and turns the work D' being
a worm secured upon the lathe spindle and imparting motion to the worm wheel E

page_text: secured upon the shaft E' carried in suitable bearings E upon the head stock and
having at its lower end a bevel or mitre wheel E³ which gears with another bevel or
mitre wheel upon the horizontal spindle F which passes through or beside the
head stock and carries at its end behind the head stock the pinion G. This
pinion G engages with the toothed rack H of the sliding frame 1. The rack H
may be placed either above the pinion Gas shown in Fig. 3 or it may be placed
below it; if the mechanism is so arranged that with the rack above the pinion a
right-hand screw thread is produced, by placing the rack underneath the pinion a
left-hand thread would be produced or vice versa.
The sliding frame I is adapted to be firmly carried and to slide in a suitable
bearing or bearings K upon the lathe head bed or bracket or it may be carried in
an independent support and has pivoted to it at L' an arm or cam-bar L having a
longitudinal slot L in which works the stud M which may carry an anti-friction
roller and is so.arranged that the bar L may be moved upon it as required the stud
terminating in a washer and nut M. At its lower end the stud M is pierced so as
to allow of the passage of the rod N to which the stud may be secured when
required by the set screw M which preferably has a milled or wing head. The
rod N is secured in any convenient manner but preferably by screwing to the slide
rest B, and passing through or under the head stock A the stud M and the guide
bracket or support O, may be formed at its outer end with a milled head or
equivalent device N' by which it can be turned when required and screwed into or
unscrewed from the slide rest B.
In addition to the cam bar L the sliding frame I carries the marked sector P
which may carry one or more scales 11 and upon which the cam bar L is adapted
to be moved when turned on its pivot L' and to which it may be clamped by the
screw L³ or by other equivalent means. The operation of this mechanism is as
follows:-
The tool is carried in the slide rest B in the usual manner which being well
understood it has not been considered necessary to illustrate this in the drawings;
the work is carried between the lathe centres in the usual manner and this also has
been kept out of the drawings, for the sake of clearness and to avoid complications.
When the lathe is set in motion the tool is applied to the work in the usual manner
and the worm D' through the worm wheel E bevel wheels E³ and F pinion G and
rack operates the sliding frame I say in the direction of the arrow
in
Fig. 1 for cutting the right hand thread. The effect of this is to move the cam bar L
from front to back in the drawing with the necessary result that the rod N and
consequently the slide rest to which it is attached is moved to the left hand of the
drawing as shown by the arrow, the tool being thus traversed along the work
towards the head stock and a right-hand thread being thus produced. To produce
a left-hand thread all that is necessary is to reverse the position of the rack H
placing it below the pinion I instead of above it when the direction of movement of
the sliding frame I is reversed as shown by the arrow → and the tool caused to
traverse along the work in the opposite direction. Usually when commencing a
fresh cut or thread the bar L would be moved so that the stud M was at the
appropriate end of the bar.
By moving the cam bar L along the sector Pas shown in dotted lines in Fig. 1
the angle between the cam bar and the rod N is altered and the said rod N with
the slide rest B is caused to travel at a slower or faster rate and consequently a
coarser or finer pitch is produced in the screw that is cut according to the position
of the bar L. In Fig. 1a coarser thread would be cut with the cam bar L as shown
in full lines than would be the case were the cam bar placed as in the dotted lines
because in the former case the angle is greater, and consequently the travel of N
is greater for a given distance travelled by the sliding frame I.
By this arrangement an almost infinite variety of threads may be cut and the
tool may be instantaneously adjusted for any particular number of threads by means
of the scale or scales P the bar being locked by the screw Lin the required position

page_text: when set. If desired a Vernier scale with a fine screw adjustment may be used in
connection with the bar L.
The bar L itself is shown and described above as having a longitudinal slot L
but it will be readily seen that it may take a different form if desired and the slot
be dispensed with; for example it might be square, round or triangular in shape
and pass through a corresponding opening in the stud end suitable means being
employed to prevent side play or shake in the bearing faces. The sliding frame
and its attachments are shown in the drawings arranged in a horizontal plane but it
will be understood that a vertical or any other plane may be adopted if preferred
the scales being suitably placed.
In Fig. 4 a very slight modification is shown in which the bar L instead of being
pivoted and adapted to be moved upon one side only of the sliding frame, is shown
centrally pivoted and adapted to be moved on either side of the sliding frame thus
dispensing with the need for reversing the motion of the sliding frame 1 when
changing from a right to a left hand thread or cice versa. The operations are
otherwise the same in both cases, but speaking generally the form shown in Fig. 1
is preferred as the most convenient and also because with that arrangement it can
he supported directly upon the head stock, whereas in the form shown in Fig. 4 a
long bracket Q is necessary unless an altogether independent framing be adopted.
This attachment may be applied to new lathes when they are built but it may
also be readily applied to existing lathes and may be at once detached when not
required for use and wanted out of the way by unscrewing the rod N from the slide
rest and withdrawing it altogether and if desired removing such other portions of
the attachment say the sliding frame and cam bar Las may be in the way.
this mechanism the leading screw of a lathe may be entirely dispensed with as by
placing the cam bar L at a suitable angle a cutting feed either coarse or fine may
be provided for feeding the tool for ordinary cutting purposes. This mechanism is
equally adapted for cutting inside or outside threads, right-hand or left-hand
threads and threads of any pitch to which the construction of the lathe or attach-
ment is adapted. If preferred the cam bar L can be adapted to reciprocate the
lathe spindle or a spindle or chuck carried by the lathe spindle while the tool
remains a fixture: this arrangement may be conveniently employed in some cases
where the work is chucked and not supported by the movable head stock but
generally speaking it is most convenient to cause the cam bar to move the tool or
its holder usually the slide rest of a lathe.
By
Having now particularly described and ascertained the nature of the said
invention, and in what manner the same is to be performed, I declare that what
I claim is
1. In a screw cutting device or attachment for lathes or other similar tools an
adjustable sliding cam bar such as caused to traverse in the required direction
and so connected with the slide rest as to impart to it the necessary motion and at
the necessary speed in a direction parallel with the axis of the lathe spindle substan-
tially as described and illustrated in the accompanying drawings.
2. In a screw cutting device or attachment for lathes or other similar tools an
adjustable sliding cam bar such as L driven in the required direction by or from
the lathe or driving spindle D and so connected with the slide rest as to impart to
it the necessary motion and at the necessary speed in a direction parallel with the
axis of the lathe spindle substantially as described and illustrated in the accom-
panying drawings.
3. In a screw cutting device for attachment to lathes or other similar tools the
combination with the lathe or driving spindle D of a worm D' which through the
gearing E E F and G and rack of the sliding frame I imparts the necessary
traverse to the cam bar L substantially as described and illustrated in the accom-
panying drawings.
4. In a screw cutting device for attachment to lathes or other similar tools the

page_text: combination with the head stock A of a sliding frame such as I carrying a cam bar
such as La sector P substantially as and for the purpose described and illustrated
in the accompanying drawings.
5. In a screw cutting device for attachment to lathes or other similar tools the
combination with a head-stock and slide rest of a sliding frame and cam bar such
as I, L and rod N the whole constructed and operating substantially as and for the
purpose.described and illustrated in the accompanying drawings.
6. In a screw cutting device for attachment to lathes or other similar tools the
combination with the head stock A. of a sliding frame such as I and adjustable cam
bar such as L adapted to be moved and by means of a sector such as P to be fixed
at either side of said sliding frame I substantially as described and illustrated in
Figure 4 of the accompanying drawings.
7. In a screw cutting device for attachment to lathes or other similar tools the
combination with the slide rest B and movable cam bar L of a rod such as N for
the purpose of connecting the two substantially as described and illustrated in the
accompanying drawings.
8. The combination and arrangement of parts constituting the complete screw
cutting or feeding mechanism substantially as described and illustrated in the
accompanying drawings.
Doted this 20th dow of March 1901