Improvements in Lathes for Turning Irregular Forms.
Year: 1894

page_text: Date of Application (in United Kingdom), 15th Oct., 1894
Complete Specification Left, 10th June, 1895-Accepted, 13th July. 1895
Improvements in Lathes for Turning Irregular Forms.
I, WILLIAM ANDERSON ROBERTSON of 4th Avenue, Cedar Rapids, County of
Linn, State of Iowa, U.S.A., Mechanic, do hereby declare the nature of this
invention to be as follows:-
This invention relates to a lathe mechanism which is more especially designed
for relieving screw taps. Upon the face plate of the same is fixed a cam corre-
sponding to the form to which it is desired to turn the object carried between the
lathe centres. The cam operates so as to reciprocate an arm fixed on a rod located
between the head and tail stocks of the lathe. There is also carried upon said arm
a sliding crank in connection transversely to the lathe bed with the slide rest and
having normally a tendency to be drawn inwards by the force of one or more
springs fixed at one end to or in connection with the lathe bed or base. Thus when
the face plate is set in rotation the cam will through the arm and crank and a
connecting rod communicate to the slide rest a reciprocating motion corresponding
to the desired form of the object, for instance, a fluted screw tap.
ה.
hd of October 1894
THOMAS R. SHILLITO,
89 Chancery Lane, London, W.C., Agent for the Applicant.
Improvements in Lathes for Turning Irregular Forms.
I, WILLIAM ANDERSON ROBERTSON of 4th Avenue, Cedar Rapids, County of
Lion, State of Iowa, U.S.A., Mechanic, 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 relates to a lathe mechanism which is more especially designed
for relieving screw taps although it may be employed for turning many varieties of
irregular forms.
In the drawing
Fig. 1 is a plan view of the device of this invention as applied to an ordinary
lathe.
Fig. 2 is an end view as seen from the tail stock end of the lathe, the lathe bed
being in section.
Fig. 3 is a view, from the opposite end, of the lathe, of the operative parts there
shewn.

page_text: Fig. 4 a view of a face plate with a heart shaped cam attached thereto.
Fig. 5 a similar view with a circular cam part.
Fig. 6 a transverse section of one of the bearings for the square har carrying the
levers hereinafter referred to.
A is the head and C the tail stock. B the bed. D the slide rest or tool carriage.
E the face plate.
In
To the ways of the lathe are connected bearing blocks G by clamping bars G1
and bolts g. In the upwardly extending portions of the blocks G at the back of
the lathe are mounted rotary sleeves apertured to receive a square bar H.
the case of lathes in ordinary use, this construction is suitable and necessary, but
where the device is applied to new lathes, these may be provided at the head and
tail stock with a projecting lug C¹ which is similarly provided with a sleeve to
receive the bar. In this case the bearing blocks may be dispensed with altogether
or one or more of them may be used intermediate of the head and tail stock and
thus serve as a steady rest for the bar.
The invention is more especially applicable to lathes provided with a compound
tool slide D, as this admits of one part of the slide being used with its regular screw
feed whilst in the other part the screw feed may be disconnected as by the use of
the common split nut. The back end of the disconnected part of the slide should
be provided with lugs D¹ between which is fitted a bar L extending backwards and
connecting with a short crank arm K mounted to slide freely on the bar H. Near
the face plate is fixed to the bar a longer upwardly extending crank arm I provided
with a flange traveller J the position of which may be changed in holes i and the
movement of the tool carriage varied accordingly. On the same bar H between
the face plate and the head block is mounted another crank arm or lever M provided
with a spring N connecting it with a transverse bar O, this latter being clamped to
the lathe bed plate by a clamping bar O¹, the lower end of the spring engaging with
an eye n. Underneath lever M is fixed an adjustable stop rod P. The action
of the spring tends to throw the crank I inwardly whilst the stop rod serves to
limit such inward movement of the arm thus preventing the traveller J from moving
so far inwardly towards the centre of the face plate as to catch on the cams.
device is shewn in use in connection with a tap mounted between the centres of the
lathe. The tap has four flutes and corresponding thereto the face plate is provided
with four cams F. It is to be understood, however that any number of cams may
be used to correspond with any desired number of flutes or the corresponding parts
of any other piece of work. For this purpose it is but necessary to provide a
suitable number of holes e in the face plate and make the cams of suitable length.
It will be seen in Fig. 1 that the cams are separated a little distance from the
face plate by washers thus leaving a space between the cams and the face plate
for the inner flange of the traveller J. The slots f" and tightening screws fl allow
of adjusting the cams at one end, the other end being pivoted to the face plate by
screws f.
The
As the face plate revolves the arm I is carried a limited distance backwards and
forwards by the cams F or more strictly speaking, outwardly by the cams and
inwardly by spring N, a reciprocating motion being thereby given to the tool
slide D. As the cams coincide with the threaded portion of the tap, it will be seen
that the thread tool is drawn inwardly as the tap revolves thus relieving the tap on
all its four sides. It is to be understood that this is done after the tap is cut and
fluted consequently the tap being adjusted with proper relation to the cams the
relieving is done with perfect accuracy. As the tool carriage moves, following the
screw thread of the tap the crank arm K slides along the bar. In cases where there
is considerable side pressure against the tool the bar L may be steadied by suitable
guides l.
The cams in Figs. 4 and 5 are merely shewn by way of example. It is of course
impossible to exactly reproduce in the work the same form as that attached to the
face plate. In practice I mount on a mandrel a form of the exact shape desired in
the work, cause it to travel in connection with the traveller J and by means of a

page_text: suitable style or other marker, trace on the face plate the form of the desired cam
to be attached thereto.
In Fig. 6 the particular construction of the sleeve his shewn. This is provided
at one end with a flange and at the other end with a ring h. By means of the
device taps may be completely finished without any hand labour. The tap is turned
in a lathe in the ordinary way, then passed to the milling machine and fluted, then
brought back to the lathe and relieved, when it is ready to be tempered.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed, I declare that what I
claim is :-
1. The combination with a lathe of cams mounted on its face plate and separated
a short distance therefrom by intermediate washers, a flange traveller mounted on
an upwardly extending arm connected with a rectangular rocking shaft, suitable
bearings for said rocking shaft, a crank arm mounted to slide freely on said rocking
shaft and a bar connecting said crank with the tool slide and means for holding said
traveller in contact with the cams, for the purpose specified substantially as
described and shewn.
2. In a lathe, the combination with its face plate, of adjustable cams correspond-
ing in number to the sides of the work designed to be turned, a crank arm provided
with a suitable traveller adapted to ride on the outer faces of said cams, means for
retaining the same in contact with said cam surfaces, a rocking shaft on which said
arm is mounted, a crank thereon and a connection of said crank with the tool slide,
for the purpose specified substantially as described and shewn.
3. The combination with a lathe for one or more cams mounted on the face plate,
a rocking shaft and bearing blocks for the same, a crank arm or lever with a traveller
in connection therewith adapted to ride on said cams, a crank connection of said
rocking shaft with the tool slide, a spring connected with an arm extending from
said rocking shaft to draw the traveller into contact with the cams, and a stop to
limit the inward throw of said traveller, for the purpose specified, substantially as
described and shewn.
4. In a lathe, the combination of a face plate provided with one or more cams,.
the rocking shaft H angular in cross section, the arm I suitably fixed thereto and
provided with a traveller moving on the surface of said cams, the crank K adapted
to slide on said rocking shaft, connecting rod or bar L, bearings and the bearing.
blocks G, for the purpose specified, substantially as described and shewn.
5. In a lathe, the combination with a face plate provided with one or more cams
of the rocking shaft H, the traveller J and its arm I connected with said rocking
shaft, crank K adapted to slide on said rocking shaft, connecting bar L, lever M,.
spring N and adjustable stop rod P, for the purpose specified, substantially as
described and shewn.
Dated this 10th day of June 1805
THOMAS R. SHILLITO,
89 Chancery Lane, London, W.C., Agent for the Applicant.