IMPROVEMENTS IN SCREW CUTTING LATHES
Year: 1884

page_text: PROVISIONAL SPECIFICATION.
I, WILLIAM PHILLIPS THOMPSON, Fel. Inst. P.A. of the Agency for Foreign
Patent Solicitors, 6 Lord Street, Liverpool, in the County of Lancaster, and
323 High Holborn, in the County of Middlesex Civil Engineer do hereby declare
the nature of the said invention for "IMPROVEMENTS IN SCREW CUTTING LATHES,"
(a communication from abroad by Nathan Blum of Paris in the Republic of France
Mechanician) to be as follows:-
The principal improvement which forms the object of the present application for
Letters Patent, consists in communicating motion to the movable slide rest by the
interposition of a lever capable of being adjusted to various lengths, instead of
actuating the slide rest directly by the parallel screw as in lathes of the usual con-
struction. This enables the workman to increase or diminish at will the travel of
the tool, whilst the speed of the parallel screw and of the work remains unaltered,
by simply adjusting the lever accordingly.
By this arrangement the tool may be set to cut threads of any size which the
speed of the parallel screw and of the object itself will produce.
The principle of this improvement is shewn by the diagram forming Fig. 1 of
the annexed drawings.
.
Let the lever be propelled by the screw B at the point C, if the slide rest be
secured by screw D at the point E, the distance travelled may be represented as a b:
if however the screw D is fixed to the point F the distance is as a' b¹ and by
shifting the screw D to any given point intermediate between E and F, any
intermediate distance between a b and a b¹ is obtainable.
The regularity of the progression of the tool is assured by the parallelism of the
actuating screw and of the lathe bed.
In order to illustrate the practical carrying out of the invention it will be
described with reference to the annexed drawings

page_text: ine lathe 18 of ordinary construction, excepting that the lever which forms thO
principal object of this application for Letters Patent replaces the train of gearing
employed in ordinary lathes for the same purpose.
Fig. 1 is a diagram of the invention already explained.
T'
The lathe 18 of ordinary construction, excepting that the lever which forms the
principal object of this application for Letters Patent replaces the train of gearing
employed in ordinary lathes for the same purpose.
Fig. 1 is a diagram of the invention already explained.
elevation of the lathe.
Fig. 3 is a partial front elevation.
Fi &io a mortial plan
The lathe 18 of ordinary construction, excepting that the lever which forms the
principal object of this application for Letters Patent replaces the train of gearing
employed in ordinary lathes for the same purpose.
Fig. 1 is a diagram of the invention already explained.
Fig. 9 is a side elevation of the lathe.
Fig. 3 is a partial front elevation.
Fig 4 is a partial plan.
In these 3 last drawings the same figures indicate the same parts.
1. Object to be turned and threaded.
2. Tool.
3. Piece for setting the tool.
4. Screw for holding the tool.
5. Slide rest.
6. Lathe bed.
7. Parallel screw.
8. Lever.
9. Axis of lever.
10. Piece for altering the rate of progression.
11. Screw for fixing.
12. Stud travelling in the groove of the elide rest 5.
13. Graduated scale.
14. Articulated threaded piece upon the screw 7 for propelling lever 8.
The precise form given to these pieces is only for the purpose of illustrating the
invention, and may be varied according to the description of lathe of which they
form part, the invention lies in the combination of parts and in the principle of the
application of the lever 8. The lathe is worked as follows:-The object to be
turned and threaded having been secured in position, the screw 7 is put out of gear
and the object is turned as usual. To cut the thread, the parallel screw is geared
to a speed proportioned to the speed of the piece to be screwed, and to the length
of the lever. It is then only requisite to place the piece 10 at the point corre-
sponding to the progression desired, and to secure it by means of the screw 11 and
the apparatus is ready for work. The lever may carry a scale with metric or
arbitrary divisions. The cutting movement may be reversed by suitable intermediate
gearing.
Boted thi. 104
1004
13. Graduated scale.
14. Articulated threaded piece upon the screw 7 for propelling lever 8.
The precise form given to these pieces is only for the purpose of illustrating the
invention, and may be varied according to the description of lathe of which they
form part, the invention lies in the combination of parts and in the principle of the
application of the lever 8. The lathe is worked as follows:-The object to be
turned and threaded having been secured in position, the screw 7 is put out of gear
and the object is turned as usual. To cut the thread, the parallel screw is geared
to a speed proportioned to the speed of the piece to be screwed, and to the length
of the lever. It is then only requisite to place the piece 10 at the point corre-
sponding to the progression desired, and to secure it by means of the screw 11 and
the apparatus is ready for work. The lever may carry a scale with metric or
arbitrary divisions. The cutting movement may be reversed by suitable intermediate
gearing.

page_text: COMPLETE SPECIFICATION,
I, WILLIAM PHILLIPS THOMPSON, Fel. Inst. P.A, of the Agency for Foreign
Patent Solicitors, 6 Lord Street, Liverpool, in the County of Lancaster, and
323 High Holborn in the County of Middlesex, Civil Engineer do hereby declare
the nature of the said invention for "IMPROVEMENTS IN SCREW CUTTING LATHES,"
(a communication from abroad by Nathan Blum, Paris) and in what manner the
same is to be performed, to be particularly described and ascertained in and by the
following statement :-
The new or improved lathe which is the subject of the present application for
Letters Patent differs from lathes hitherto in use in the arrangement for regulating
the movement of the slide rest and tool bearer, which instead of being actuated
directly by the parallel screw shaft, is regulated by a lever capable of being set to
different lengths in such a manner that the movement of the tool, and consequently
the path traversed by it may be increased or diminished at will, by simply moving
the lever without altering the speed of the screw shaft, or of the work on the
centres.
In order to show the method of carrying this idea out in practice, I will describe
in detail a lathe constructed according to this system.
•
It comprises, like other dathes, a frame, a chuck head, and two centres, the
arrangement of these parts varies of course according to the size of the lathe, and
the dimensions of the work to be threaded.
It is obvious that the pitch of the thread cut, depends upon the proportion
between the speed at which the slide-rest advances, and that of the speed of
rotation of the article to be threaded.
This proportion, in ordinary lathes, is regulated usually by means of a train of
wheel-work, which complicated device is replaced in the lathe of this invention by
a simple lever, the arrangement and the mode of application of which constitute my
invention.
Referring to the drawings annexed,
Figure 1 is an elevation of an entire lathe.
Figure 2 is a transverse section.
Figure 3 is a longitudinal section of the lever.
Figure 4 shews a graduated scale, the object of which will be explained further
on. In all the drawings, like numbers serve to indicate like parts.
The lever 1 is articulated upon the female screw nut 2 which travels upon the
screw shaft 5 and serves to convert the rotary movement of the shaft 5 into
a rectilinear backwards and forwards movement of the slide rest. The end of the
lever 1 is furnished with a fork or slide 3 which admits of the effective length of
the lever being altered, and of its revolving upon the pin 4 in consequence of the
displacement of the screw nut along the shaft 5.
The inside face of the lever (that which faces the slide rest) is provided with
a rib 6 opposite which is placed the graduated scale 7 (Figure 4) aliding in
a projection attached to the slide rest, and indicating by its gradation the pitch of
the screw which is to be cut.

page_text: Upon the scale 7 is fixed a pin 8 the end of which is provided with a stud 10
engaging in the rib 6 of the lever on the position of this pin, determined by that
of the graduated scale 7 on which it is fixed, depends the effective length of the
arm of the lever 1 and consequently the speed communicated to the slide rest, and
the pitch of the thread. In order to fix and secure the scale 7 in the desired
position which determines the pitch of the thread, use is made of the nut with
rays 9 which is fixed upon the pin 8 the special form of the rayed nut facilitating
the movement of the scale.
The above explanation serves to shew that this system of lathe construction
admits of the workman regulating at will, the size and speed of the cut by varying
the effective length of the lever 1, comprised in the distance between the fixed
pin 4 and the variable point of articulation of the lever 1 with the slide rest.
It is therefore obvious that the smaller the pitch of the thread to be cut, the
nearer the pin 8 fixed upon the scale must be brought to the axis 4. The form of
the other portions of the lathe is only shewn in the drawings for the purpose of
shewing clearly the working of the apparatus, they can obviously be varied as
desired according to the requirement of the case. This invention consists of the
special arrangement of the lathe and application of the lever as set forth.
The mode of working an apparatus such as that set forth in Figures 1, 2, 3, and 4
is as follows.
The article to be turned and threaded is mounted upon the centres. To centre.
it, the shaft 5 is isolated and it is turned by hand in small lathes, as in ordinary
turning in large lathes, this is effected in the well known way.
For the screw threading, the screw shaft is driven by a train of wheel work
combined with the speed of the piece to be threaded and the length of the lever; it
is therefore only necessary to place the scale 7 in a position corresponding to the
pitch desired, indicated by the graduations, to fix it firmly by means of the rayed
nut 9 and to set the lathe in motion.
The scale may have a greater or less number of divisions arbitrary or metrical.
for standard or for foreign pitches.
The thread may be cut right hand or left hand by means of an intermediate
wheel work shown in the annexed drawing.
Having now particularly described and ascertained the nature of the said
invention, and in what manner the same is to be performed, as communicated to
me by my foreign correspondent, I declare that what I claim is
In a system of screw cutting lathes in which the slide rest is controlled by a lever
of variable length for the purpose of changing the pitch of the thread cut corre-
spondingly, the mechanism for controlling the slide rest consisting essentially of
the lever 1 having screw nut 2 upon the screw shaft, said nut being adjustable in
a slot of this lever, which ends in a fork 3 traversed by the articulating pin 4 and
having a slide or rib 6 in combination with a graduated scale 7 carrying the rayed
screw nut 8 ending in a stud which travels and fastens in the slide 6 of the lever,
transmitting the motion of the screw shaft to the slide-rest, substantially as
described and shewn in the annexed drawings.