Improvements in or relating to Tool-holders for Capstan or Turret- lathe Tools and the like.
Year: 1898

page_text: Date of Application, 10th Feb., 1898
Complete Specification Left, 5th Nov., 1898-Accepted, 10th Feb., 1899
PROVISIONAL SPECIFICATION.
Improvements in or relating to Tool-holders for Capstan or Turret-
lathe Tools and the like.
We, ALFRED HERBERT, of "Brantwood," Spencer Road, Coventry, in the County
of Warwick, Engineer, and OSCAR HARMER, of Hopedale, Spencer Park, Coventry,
in the County of Warwick, Engineer, do hereby declare the nature of this invention
to be as follows:-
The invention relates to tool holders for capstan or turret lathe tools and the
like, its principal objects being the construction of a type of tool which is readily
adjustable even whilst actually effecting the cut and which is provided with a type
of controlling device comprising an adjustable stop not only enabling the tool to
be readily withdrawn from cut but to be put back again into cut with an extreme
precision which is unimpaired by yielding or inaccuracy of fit of the parts.
This adjustability permits the same tool and cutter to be used for work of any
size within the range for which the tool is designed, and to he readily changed
from one side to another-whereas in other capstan tools it is usually necessary to
have one tool for each different size, or if adjustments are provided they are
usually of such a nature as to be not readily operated.
It is very desirable after the tool has taken a cut along a piece of work to be
able to readily withdraw it so as to avoid marking the work whilst the cutter is
being returned to the starting point for a fresh cut.
Further objects of this invention are the construction of the improved tool in
a manner which will permit of the actual cut being effected by an ordinary turn-
ing tool made from plain bar steel: also its construction in a manner which will
enable work of any reasonable length to be turned.
The cut may also be taken in either direction along the work, that is to sav
so that a cut putting the work in tension can be employed as well as one which
puts it into compression.
According to this invention the cutting tool proper is held in a
cross slide
by set screws and may be provided with wedges for regulating its height. This
slide travels in an undercut groove or on a dovetailed projection on the body of
the device and has on its back a rack engaging with a pinion on a shaft working
in the body or main casting. On the other end of this shaft is a pinion into which
gears a circular rack, that is to sav a rack in which the teeth each extend all
round the shaft like rings on a thrust-shaft. This circular toothed rack is movable
endwise, the means for producing such endwise movement, and for determining
with precision its extent when the tool is being moved into cut, being as follows:-
On the spindle carrving the circular toothed rack a screw thread is formed to
turn in a tanned portion of a stationary bracket attached to or integral with the
hody of main casting of the tool. By screwing the screwed portion of the rack
spindle into or out of the bracket the circular toothed rack is caused to move
endwise and through the gearing described operates the slide.

page_text: The combined screw-and-rack shaft is bored and has a fine-threaded screw
extending through it so as to project beyond its end and abut against a fixed stud.
By adjusting this central fine screw by means of a milled head the endwise
movement of the screw-and-rack shaft occurring in putting the tool into cut
can be stopped with great precision at any point desired.
Owing to the fact that the stop screw is co-axial with the combined screw and
rack shaft it is exactly in line with the pressure exerted by the hand in returning the
tool to place and any variation in the amount of such pressure does not to any
material extent disturb the definite action of the stop, whereas if the stop and
rack shaft were not co-axial certain cross-winding strains would be set up causing
the slide to spring and thus effect the final position of the tool according to the
amount of pressure exerted in returning it to position.
"
In order to sunmort the work being turned from springing away from the tool
steadies" (generally V shaped) are provided. These steadies are fitted within
a recess in a projection on the main casting or body of the tool and are provided
with a convenient adjustment for work of different sizes and also with a clamp-
ing arrangement by which they may be held firmly in position when set.
The steadies and their guides are so arranged upon the face of the device as
to offer no obstruction to a cut in either direction along the bed of the machine
and there is a hole in the centre of the tool so that the work may extend through
it and so enable any reasonable length to be turned.
.
1011 1
ד.
1000
BOULT & WADE,
Agents for the Applicants.
Improvements in or relating to Tool-holders for Capstan or Turret-
lathe Tools and the like.
We, ALFRED HERBERT, of "Brantwood," Spencer Road, Coventry, in the County
of Warwick, Engineer, and OSCAR HARMER, of Hopedale, Spencer Park, Coventry,
in the County of Warwick, Engineer, 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 tool holders for capstan or turret lathe tools and the
like, its principal objects being the construction of a type of tool-holder which is
readily adjustable, even whilst the tool is actually effecting the cut, and which
is provided with a controlling device comprising an adjustable stop, which not
only enables the tool to be readily withdrawn from cut, but to be put back again
into cut with an extreme precision, which is unimpaired by yielding or inaccuracy
in the fit of the parts.
This adjustability permits the same tool to be used for work of any size within
the range for which the holder is designed, and be readily changed from one size
to another, whereas in other capstan tools it is usually necessary to have one tool
for each different size, or if adjustments are provided they are usually of such a
nature as to be not readily operated.
It is very desirable after the tool has taken a cut along a piece of work, to be
able to readily withdraw it, so as to avoid marking the work whilst the cutter is
being returned to the starting point for a fresh cut.
Further objects of this invention are the construction of the improved tool-
holder in a manner which will permit of the actual cut being effected by an
ordinary turning tool, made from plain bar steel; also its construction in a manner
which will enable work of any reasonable length to be turned. The construction

page_text: of this tool-holder is such that the stress produced by the operation of the tool
merely tends to bring parts already in contact closer together, whereas in tool-
holders as at present constructed those parts tend to separate and thus any play
which may exist produces inaccuracy in the work.
The cut may also be taken in either direction along the work, that is to say,
so that a cut putting the work in tension can be employed, as well as one which
puts it into compression.
In the accompanying drawings
Figure 1 is a plan of one construction of tool-holder according to this invention;
Figure 2 is a front elevation of the same, parts being in section;
Figure 3 is an end elevation of the same partly in section on the line 3-3
of Figure 2;
Figure 4 is an elevation of part of the tool-holder looking in the direction
indicated by the arrow in Figure 2;
Figures 5 and 6 show in further detail two parts which have been removed from
the tool-holder;
Figure 7 is a perspective view showing by way of example one form of too!
suitable for use in the improved tool-holder.
Like letters indicate like parts throughout the drawings.
A is the base of the tool-holder, it is provided with four holes A¹ through which
bolts may be passed to attach it to the face of the turret of a lathe or other suitable
portion of a machine-tool. A boss A upon the back of the base A fits into a corre-
sponding hole in the face of the turret and is bored as at A³ so that the work may
pass through it and thus enable any reasonable length to be turned.
B is a cross-slide (or sliding tool-holder) having upon one surface an under-
cut groove B which engages with a dovetailed projection A upon the base A,
any play in the joint thus formed being taken up in the usual manner by the
loose piece B2 and set screws B³.
Upon the back of the cross-slide B is a rack B the teeth of which engage with
a pinion C¹ formed on the end of a shaft C which works in a bearing A5 in the
base A, and is kept from longitudinal movement by means of a screwed pin D
which engages with a groove C2 formed in the shaft C. Another pinion C3 is
carried upon the other end of the shaft C and gears with a circular rack E¹ carried
by a screwed shaft E; the teeth on the circular rack E extend all round the
shaft like rings on a thrust shaft. This screwed shaft E works in the tapped
portion of a bracket A6 on the base A and it is moved by means of a milled
handle E.
The screwed shaft E is hollow and internally threaded as at E³. A fine threaded
screw F works inside the shaft E and the end of it abuts against a stop G which
is fastened to the base A by means of bolts G¹. The serew F is operated by means
of a milled head F' and may be locked relatively to the screwed shaft E by means
of a lock nut F³.
The cutting tool H is carried in a slot B5 in the cross-slide B; its height may
be adjusted by means of wedges J and it is secured in position by set screws K.
It will be seen that any ordinary turning tool may be used in this improved tool-
holder, the form illustrated in Figure 7 being shown merely by way of example.
In order that the work may not spring when the tool is in operation," steadies" L
are provided. They are fitted in a recess A8 in a projection A7 which forms part
of the base A, and their adjacent faces are bevelled at one end as at L¹ so that
when in operation they form a V where they bear against the work. The
steadies L are adjusted and held in place by means of the bolts M and a plate M¹.
Thumb screws M² are provided for the bolts M in order that they and the screws M³
may hold the steadies L firmly and accurately in position when set.
It will be seen that the steadies L offer no obstruction to a cut in either direc-
tion along the bed of the machine and afford support for the work just where
it is needed viz. at a point opposite to the cutting tool.
By screwing the screwed shaft E into or out of the bracket A6, the circular

page_text: rack E¹ is caused to move longitudinally and thus, through the pinion C³, shaft C,
and pinion C to operate the cross-slide B carrying the tool H.
The amount of the longitudinal motion of the screwed shaft E depends upon
the distance between the end of the screw F and the stop G, and as the screw F
has a very fine thread this distance, and consequently the motion of the tool H,
is capable of very accurate adjustment.
Owing to the fact that the screw F is co-axial with the screwed shaft E, it is
exactly in line with the pressure, exerted by the hand in returning the tool to
place, and any variation in the amount of such pressure does not, to any material
extent, disturb the definite action of the F and stop G, whereas if the screw F
and screwed shaft E were not co-axial certain cross-winding strains would probably
be set up, causing slide B to spring, and thus affect the final position of the tool
according to the amount of pressure exercised in returning it to position.
The firmness and rigidity of the tool holder is greatly increased by so con-
structing the dove-tailed sliding joint between the cross-slide B and the base A,
that the stress produced by the operation of the tool tends to press the contiguous
faces of the cross slide B and base A closer together.
Thus, in the tool-holder illustrated, the stress produced by the cut will be
in the direction of the arrow in Figure 3, and will tend, through the wedge-like
ection of the upper part of the dove-tailed projection A4 to press the cross slide B
and base A into more intimate contact whereas, if, as in some tool holders (as at
present constructed) the dove-tailed projection was upon the slide, and the groove
in the base, the stress would tend to separate the contiguous faces and produce
springing of the parts and inaccuracy in the work.
Having now particularly described and ascertained the nature of our said inven-
tion and in what manner the same is to be performed, we declare that what we
claim is:-
1. A tool-holder for a turret-lathe by which the tool can be adjusted whilst the
cut is being effected.
2. A tool-holder for a turret-lathe having a cross-slide in which the tool is
carried, and means for regulating its movement substantially as described.
3. In a tool-holder a circular rack such as E for regulating the movement of
the cross-slide substantially as described.
4. In a tool-holder the combination with an internally threaded shaft which
controls the motion of the tool of a screw co-axial with the shaft and co-operating
with a stop substantially as described.
. In a tool-holder the combination with a shaft such as E E¹ of a screw F and
stop G arranged and operating substantially as described.
6. In a tool-holder of the kind described mounting the cross slide upon the
base so that the stress produced by the eut tends to press the contiguous faces of
the cross-slide and the base closer together.
7. The combination and arrangement of parts constituting the complete tool-
holder substantially as described or illustrated in the accompanying drawings.
Dated this 3rd day of November 1898.
ALFRED HERBERT.
Boult & Wade,
Agent for the Applicants.