IMPROVEMENTS IN MEANS OR APPARATUS EMPLOYED IN TURNING SPIRAL, OVAL, AND OTHER FORMS
Year: 1879

page_text: LETTERS PATENT to Andrew Charles Guy Thompson, of Cambridge Road,
Chiswick, in the County of Middlesex, for the Invention of "IMPROVEMENTS
IN MEANS OR APPARATUS EMPLOYED IN TURNING SPIRAL, OVAL, AND OTHER
FORMS."
Sealed the 12th August 1879, and dated the 22nd May 1879.
PROVISIONAL SPECIFICATION left by the said Andrew Charles Guy
Thompson at the Office of the Commissioners of Patents on the 22nd May
1879.
"
ANDREW CHARLES GUY THOMPSON, of Cambridge Road, Chiswick, in the County
of Middlesex. IMPROVEMENTS IN MEANS OR APPARATUS EMPLOYED IN TURNING
SPIRAL, OVAL, AND OTHER FORMS."
My present Invention relates to improvements on an Invention for which Letters
Patent were granted to me, dated December 20, 1876, No. 4918, by which improve-
ments I am enabled, in addition to producing circular work, to turn spirals, ovals,
eccentrics, fluted, beaded, and other forms.
For this purpose instead of employing a fixed pattern or template I employ a
revolving pattern mounted in suitable bearings capable of adjustment so as to
enable the axis of revolution of the pattern to be fixed either parallel to the axis of
the work, or at an angle thereto, as may be required.
This pattern when turning circular and certain other classes of work is driven
by suitable gearing, preferably directly from the spindle driving the article being
turned, thus ensuring continuous relative speeds.
When turning spiral work differential pullies, change wheels, or other suitable
means may be used to alter or vary the relative speed of the parts, according to the
effect required to be produced on the work, and the relative speed of rotation of
the work and of the traverse of the cutting tool may be varied as required.
I also avoid the necessity of employing separate patterns for the various sizes
that may be required, within certain limits, by connecting the pointer, guide, or
tracer, which is held against the pattern, and controls the action of the turning
tool, to one end of a lever, which is capable of having its axis of motion varied in
position, and the other end of which is connected to the slide or tool holder, by
which means the cutting or shaping tool may be given a greater or less throw than

page_text: the pattern itself contains. The axis of the aforesaid lever may be adjusted before
commencing work therewith, or it may be regulated in position as the work
proceeds.
In all cases the pointer, guide, or tracer is held against the pattern by weights,
springs, or other suitable means, and for spiral work terminates in an acute angle.
I also use the same description of cutting tool as that described in the Specification
of my aforesaid Patent, but for spiral work I prefer to set it with its lower edge on
the same horizontal plane as the centre of the work, and I give it a longer rake on
the cutting edge, whilst I also always employ such cutter as a fixed and not a
revolving cutter.
I also employ an improved form of expansive bush or support to steady the work
when the latter does not possess sufficient stability in itself.
This expansive bush or revolving support is mounted in bearings, and is pro-
vided with suitable thrust rings or collars to fit corresponding rings or collars in
the bearing. It is fitted internally with two stout washers or guides, one of which
is removeably fixed to the revolving carrier, the other being screwed therein, and
being acted upon by springs, preferably straight ones, which are kept in their
places by preference in sockets formed in both washers or guides, which sockets
receive the ends of the springs and facilitate the removal and replacing thereof, for
renewal or otherwise. A series of such holes or sockets is formed to receive the
springs to facilitate adjustment.
These washers or guides are formed with a central hole of square or other suitable
shape to support the work to be turned, and they are readily removed from their
support or holder to enable different sizes to be inserted as may be required.
By the use of the above described improved revolving bush or support the work,
notwithstanding any slight inequalities in the size thereof, will be properly sup-
ported whilst being turned, as the moveable washer or guide is acted upon by the
springs, and is turned on its axis, either by the work or by the springs, thereby
causing it to cross more or less the opening through the fixed washer or guide, and
consequently to increase or decrease the aperture for the work.
By increasing the number of headstocks and poppet heads the apparatus may be
arranged to turn more than one piece of work at the same time.
In order to avoid undue strain on the shaping tool when turning large work out
of angular stuff I mount a fixed tool just in advance of the shaping tool, and like
it, behind the support. This tool rounds the work down to the desired circum-
ference as it leaves the support, thus giving the shaping tool a uniform surface to
work on.
This tool is of similar form to the shaping tool, but has no connection
with the pattern, being fixed to the saddle and carried forward by it in a straight
line,

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Andrew Charles Guy Thompson in the Great Seal Patent Office on
the 22nd November 1879.
ANDREW CHARLES GUY THOMPSON, of Cambridge Road, Chiswick, in the County
of Middlesex. "IMPROVEMENTS IN MEANS OR APPARATUS EMPLOYED IN TURNING
SPIRAL, OVAL, AND OTHER FORMS."
My present Invention relates especially to machinery and tools employed in
turning, for which I obtained Her Majesty's Letters Patent, dated December 20th,
1876, and numbered 4918, and it has for its objects further improvements in
such apparatus, by which improvements I am enabled to turn not only articles
circular in section, but also spirals, eccentrics, and fluted, beaded, and other
forms.
In the Specification of the Letters Patent already referred to the article to be
turned is supported in a hollow bush rotating. in bearings carried by the saddle or
travelling bed of the lathe, which also carries a slide rest at right angles to the bed
of the lathe, and provided with one or more cutting or shaping tools. A template
of the pattern or design to be cut on the wood or other material is held on brackets
bolted to the side of the lathe bed, and a finger or projection from the slide rest is
held up to and caused to follow the pattern on the template by a spring or
weight.
By my present Invention instead of employing a fixed pattern or template, as
just described, for the purpose of guiding and determining the path of the cutting
tool, I employ a revolving pattern supported in suitable bearings formed upon or
attached to the lathe in such manner that the axis of revolution of the pattern may
be adjusted either parallel to that of the work which is to be turned or at an
angle with the latter. I connect the centres which carry the revolving pattern to
the spindle of the lathe which carries the work to be turned by means of suitable
toothed wheels, so that when the latter is made to revolve in the usual way by
means of a driving belt the pattern is also made to revolve continuously, their
relative speed of revolution remaining unchanged. When turning work of helical
form or design the toothed wheels may be altered in their proportion so as to alter
or vary the relative speed of the parts according to the effect which it is desired to
produce on the work, and in the same way the relative speed of rotation of the
work, and of the traversing screw by which the revolving bush which supports the
work, and the slide rest which carries the cutting tool are made to travel along
the lathe bed may be altered and varied as desired.
In order to prevent the necessity for employing a separate revolving pattern for
each of the various sizes which it may be required to produce of a particular
design, I sometimes connect the pointer, guide, or tracer, which is held against the
revolving pattern, and by its movement against the latter controls the action of the
cutting tool to a lever, one end of which turns upon an axis formed upon or
attached to the traversing saddle, and parallel to the traversing screw of the lathe,
whilst at any suitable point of its length it is connected by a jointed link to the
slide rest, which carries the cutting tool. If the said connecting link be between
the guiding point and the axis the action of the former upon the tool will be
reduced, whilst if it be on the other side of the guiding point the action of the
latter upon the cutting tool will be increased.
The relative positions of the guiding point and the connecting link with respect
to the axis of the lever may be adjusted and fixed before the turning of the work
is commenced, or it may be regulated and varied as the work proceeds by means of
a suitable cam or guide.
I arrange a sufficiently heavy weight, by which the guiding point is constantly
pressed against the revolving pattern, and I prefer to use arrangements similar to
those described and shewn in the Specification and Drawings of the Letters Patent

page_text: already herein before referred to, for the purpose of withdrawing the cutting tool
from the work when necessary, and also for disconnecting the travelling saddle
from the traversing screw when desired.
For cutting work having a helical design I make the guiding point_terminate in
an acute angle where it presses against the revolving pattern, and I use cutting
tools of a similar kind to those described and shewn in the Specification of the said
Letters Patent, but where work of a helical or spiral design is to be turned I prefer
to fix the cutting tool with its lower edge on the same horizontal plane as the
centre of the work which is being turned, and I give it a longer rake or inclination
on its cutting edge, and I make the cutting tool described always fixed, and I never
use a revolving cutter for the said purpose.
Instead of only one piece of material being turned in the manner described
several such pieces may all be turned simultaneously to the same pattern by
arranging a corresponding number of driving spindles connected together by toothed
wheels, so that they all revolve at the same speed.
In order to render the work more steady whilst it is revolving and being formed
by the cutting tool as above described, I sometimes employ an improved form of
revolving bush carried upon the traversing saddle of the lathe, and supporting the
work which passes through it, as already above described.
This revolving bush consists of a hollow cylinder, having one or more projecting
collars or rings fitting into corresponding recesses or grooves in the bearings in
which it revolves, these collars serving as thrust rings to prevent end movement of
the bush.
The hollow cylinder is fitted internally with two transverse plates, one of which
is fixed to or forms part of the cylinder, whilst the other is formed with a screw
thread at its circumference, and is screwed into a corresponding screw formed inside
the end of the cylinder.
The latter is acted on by springs, preferably straight, which are kept in their
places in sockets formed in the transverse plates, these sockets receiving the ends of
the springs, and facilitating their removal and replacing for change or adjustment,
and a series of such holes or sockets being formed in the loose plate to receive the
springs so as to facilitate adjustment.
Each of the two transverse plates described has a central hole forined through it
corresponding in shape with the transverse section of the material which is to be
turned, so that the latter is steadily supported, whilst it, together with the trans-
verse plates and hollow cylinder, can revolve freely. Revolving cylinders having
transverse guiding plates with holes of different sizes and shapes to suit different
sizes of material can be readily fitted in the bearings as may be desired. Where
work of considerable dimensions is to be turned by my improved apparatus as
described I prefer to arrange a fixed cutting tool slightly in advance of the move-
able cutting tool already described, so that it turns the material as it leaves the
revolving guiding bush down to the proper diameter for the moveable tool to act
upon it and form it to the proper design.
The accompanying Drawing is in illustration of my Invention, Figure 1 being a
front view and Figure 2 a plan of a lathe fitted with one revolving centre, and
shewn turning to a helical shape a piece of wood square in transverse section.
Figure 3 is an end view of the lathe, and Figure 4 is a transverse section;
Figure 6 is an end view, and Figure 7 a longitudinal section of the revolving bush
for supporting the material, as above described.
A is the bed of the lathe provided with headstocks and centres B and C, between
which the material D which is to be turned is supported, and made to revolve by
the driving pulley E. The pattern F is also supported between centres G and H,
and is made to revolve parallel or at any desired angle to the material D, and at
the same or any other desired speed by means of the toothed wheels I. The
saddle K carries the transverse slide rest L, and is made to travel along the bed of
the lathe by means of the traversing screw M driven by the toothed wheels I. The
guiding point N is attached to the sliding rest, L, and is pressed against the

page_text: revolving pattern F by the weight 0. The cutting tool P is also fixed to the sup-
port B upon the sliding rest L. The bearing S is fixed upon the travelling saddle
K, and contains the revolving bush, shewn on a larger scale at Figures 6 and 7.
Figure 5 is in illustration of the method of arrangement already described, in
which the relative movements of the guiding point and the cutting tool are
different, that of the former being shewn twice as great as that of the latter.
guiding point N, which is pressed against the pattern F, is attached to a lever T,
which turns upon a centre V upon the saddle K, the sliding rest L which carries
the cutting tool P being connected to the lever T by the link W. In Figure 5ª
the cutting tool P is shewn horizontal, as above described.
The
In Figures 6 and 7 a is the bearing in which the cylindrical bush b revolves,
the latter being provided with projecting rings c, c, c, which fit into corresponding
recesses in a. A transverse plate d is forined in the bush b, and a second trans-
verse plate e is screwed into the end of the bush b. The plates d and e are pro-
vided with central openings, as shewn at d, e, through which the material to be
turned passes and fits. Elastic springs are shewn at f, f', fitted into the plate d,
and passed into corresponding holes or recesses in the plate e after the latter has
been screwed up. The springs may be prevented from coming out by a washer or
cap screwed into the hollow b.
Having now described my Invention and the manner in which it is to be per-
formed, I claim, the method of turning spiral, oval, and other forms by means of a
corresponding pattern made to revolve at the same time as the material to be
turned, and regulating the position of the cutting tool against the latter, sub-
stantially in the manner described and shewn in the Drawing. Also, in such
apparatus the method of altering the relative movement of the guiding point and
the cutting tool by means of a lever turning upon a centre, substantially as
described and shewn. Also, in such apparatus the revolving bush provided with
thrust rings, and with transverse guiding plates, the relative position of which is
regulated by springs, substantially as and for the purpose described and shewn in
the Drawing.
In witness whereof, I, the said Andrew Charles Guy Thompson, have hereunto
set my hand and seal, this 21st day of November, in the year of our
Lord 1879
ANDREW CHARLES GUY THOMPSON. (L.S.)