IMPROVEMENTS IN MACHINERY FOR CUTTING AND FORMING THE TEETH OR COGE OF WUFFIC"
Year: 1859

page_text: LETTERS PATENT to John Lawson and Stephen Cotton,- both of Leeds, in
the County of York, Machinists, for the Invention of "IMPROVEMENTS
IN MACHINERY FOR CUTTING AND FORMING THE TEETH OR COGE OF WUFFIC"
PROVISIONAL SPECIFICATION. left by the said John Lawson and Stephen
Cotton at the Office. of the Commissioners of Patents, with their Peti:
tion, on the 30th November 1859.
4
We, JOHN LAWSON and STEPHEN COTTON, both of Leeds, in the County of
York, Machinists, do hereby declare the nature of the Invention for "IM.
PROVEMENTS IN MACHINERY FOR CUTTING AND FORMING THE TEETH OR COGS OF
WHEELS," to be as follows:-
This Invention has for its object improvements in machinery for cutting
and forming the teeth or cogs of wheels. For these purposes we employ a
machine arranged in the following manner:-It consists of a frame mounted
so as to be capable of turning on two pivots or axes, one at the upper and the
other at the lower end of such framing. The frame carries a projecting arm
or gib, on which a holder for a cutter is mounted, and this is capable of being
traversed by a screw along the arm or gib, in order to set it at any desired
distance from the axis on which the frame turns. The outer end of the pro-:
jecting arm or gib is supported by and moves on fixed bearing surfaces, and it
has a toothed arc attached to its outer end, which is actuated by a screw.
receiving motion by suitable gearing, so that the gib or projecting arm carries
the cutter in an arc of a circle. At the same time the cutter is moved up and
[Price 8d.]

page_text: down to make its cut by means of a crank shaft which receives its motion by
suitable gearing from the main shaft. The wheel in which teeth are to be
cut is fixed on an axis, and is caused to make a partial revolution while the
cut is being made, by a screw acting in a screw wheel on the axis. The axis
on which the wheel to be cut is mounted, is also provided with dividing
apparatus to turn the wheel partially round after each cut according to the
number of teeth in the wheel; this dividing apparatus moves with the axis,
when the wheel is partially rotated as above described by the screw, whilst the
cut is being made. By this arrangement the wheel and the cutter are simul-
taneously moved in two arcs, which may be said to roll the one on the other,
whilst the cutter by its additional up and down motion is making its cut.
When cutting the portion of a tooth of a wheel which is exterior of the
pitch line, which is the first operation, the tool is so set as just to cut up to
the pitch line, when it comes into the line joining the centre of the wheel
and the centre of the arc in which the tool travels, and the motion of the tool
in its circular arc is at the same speed as that of a point in the pitch line of
the wheel to be cut. In order to cut the portion of the tooth within the pitch
line, the tool is set at such a distance from its centre of motion as to cut to
the bottom of the tooth, when it comes up to the line, joining the centres as
before mentioned.
The actual distance at which the tool is set from its centre of motion will
depend on the size of the wheel with which the wheel that is being cut is
intended to work.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said John Lawson and Stephen Cotton in the Great Seal Patent
Office on the 30th May 1860.
TO ALL TO WHOM THESE PRESENTS SHALL COME, we, JOHN
LAWSON and STEPHEN COTTON, both of Leeds, in the County of York, Machi-
nists, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Thirtieth day of November, in the year of our Lord
One thousand eight hundred and fifty-nine, in the twenty-third year of Her
reign, did, for Herself, Her heirs and successors, give and grant unto us, the.
said John Lawson and Stephen Cotton, Her special licence that we, the said,
John Lawson and Stephen Cotton, our executors, administrators, and assigns,
or such others as we, the said John Lawson and Stephen Cotton, our execu-

page_text: tors, administrators, and assigns, should at any time agree with, and no
others, from time to time and at all times thereafter during the term
therein expressed, should and lawfully might make, use, exercise, and vend,
within the United Kingdom of Great Britain and Ireland, the Channel
Islands, and Isle of Man, an Invention for "IMPROVEMENTS IN MACHINERY FOR
CUTTING AND FORMING THE TEETH OR COGS OF WHEELS," upon the condition
(amongst others) that we, the said John Lawson and Stephen Cotton, our
executors or administrators, by an instrument. in writing under our or their
hands and seals, or under the hand and seal of one of us or them, should par-
ticularly describe and ascertain the nature of the said Invention, and
what manner the same was to be performed, and cause the same to be filed
in the Great Seal Patent Office within six calendar months next and imme-
diately after the date of the said Letters Patent.
NOW KNOW YE, that we, the said John Lawson and Stephen Cotton, do
hereby declare the nature of the said Invention, and in what manner the
same is to be performed, to be particularly described and ascertained in and
by the following statement thereof, that is to say:-
;
The object of these improvements is to give the geometrical form to the
teeth or cogs of wheels with an ordinary planing, slotting, or other tool, the
form of which bears no relation to the space betwixt the said teeth, and which
is not guided in the course of cutting by any gauge or pattern tooth, but
simply by an arrangement and adjustment of the machine itself, whereby
the correct form of tooth is obtained for any diameter or pitch of wheel. The
principle brought into operation in our wheel cutting machine is that of two
imaginary arcs rolling together during the process of cutting the teeth, one of
the arcs being in the pitch circle of the wheel about to be cut, and the cutting
point of the tool describing the other. The aforesaid cutting point whilst
describing its arc is also with its vertical movement cutting one side of the
tooth from the pitch circle outwards, the form thus given to the working part
of the tooth is the epicycloidal curve. When cutting from the pitch circle to
the bottom of the tooth, the cutting point of the tool. must be extended beyond
the surface of the rolling arcs the distance of said pitch circle from said bottom
of tooth. In all cases the rolling arcs must naturally have the same surface
speed, and the diameter of that formed by the cutting point of tool will vary
according to the range of wheels which the wheel about to be cut is required
to work with. In cutting spur wheels the aforesaid arcs will be in the same
plane, but for bevil wheels at an angle according to the inclination of the
shafts, which will support the, wheels when at work.
In order that our said Invention may be most fully understood and

page_text: readily carried into effect, we will proceed to describe the Drawings hereunto
annexed.
Figures 1 and 2 are elevation and plan respectively of our spur wheel
cutting machine; Figures 3, 4, 5, and 6, details of the same. A is the driving
shaft of the machine whereby motion is communicated by the two vertical
shafts B, B, and a train of spur wheels B', B', B', B', to the sliding or crank
shaft C, on the end of which is a circular head with a diagonal slot on the
outer face, in which is secured the stud or pin which gives an up-and-down
motion to the tool bar D by an ordinary connecting rod working freely on the
aforesaid stud, and another stud fastened to the said tool bar. This tool bar
slides in a framework E, which is again mounted on a swivel arm F, and
capable of being set in any required position thereon by means of an adjusting
Screw F¹.
The said swivel arm has a toothed arc or segment at each
extremity, each segment being supported from the main bed R, and worked
round the common centre G by tangential screws or worms, which are again
worked simultaneously from the shaft P. It will thus be seen that the motion
of the arm F is precisely similar to what it would be were it supported at one
end by a vertical axis springing from the point G, and this method of sup-
porting the end of the arm may be adopted; the toothed arc or segment at
the right hand end of the arm, with the worm and support, being then dis-
pensed with. The arrangement shewn in the Drawing is, however, very pre-
ferable, as it allows of a much more convenient disposition of the parts of the
machine. The tool bar D at its lower end carries the cutting tool M secured
in the usual way, and has consequently both a vertical and a radial motion,
the diameter of which latter depends upon the position of the framework E on
the swivel arm F with relation to the centre of motion G. H is a circular
table, having also on a portion of its periphery a toothed segment with a tan-
gential screw for imparting a radial motion to the same, and which is worked
simultaneously with the radial motion of the cutter from the shaft P, the
required sameness in the surface speeds being obtainable by changing the
train of wheels L, Figures 1, 2, and 4. The wheel to be cut is fastened on a
spindle or mandril N, which again passes through another spindle, to which is
attached the ordinary dividing wheel I. This second spindle passes through and
works freely in the aforesaid radiating table, on the lower side of which is a
large boss also working freely in the frame Q, which frame is moveable into
any required position on the main bed R by the screw S. To the lower end
of the boss on radiating table is attached the dividing plate J, and the other
shafts and wheels required for giving a certain number of teeth in the wheel
to be cut for a certain number of turns of the handle K.
Thus it appears

page_text: that the dividing motion will have a radial movement as well as the rotary
movement of the shafts and wheels given by turning the handle K, and these
combined movements are necessary in order to obtain a perfect division of the
wheel into a certain number of teeth whilst maintaining its radial or rolling
motion in concert with that of the cutting tool. The operation of forming the
teeth in a wheel may thus be described:-The cutting point of the tool M
being placed just so as to touch the pitch circle of the wheel to be cut (0)
when the said cutting point is in a straight line with the spindle N and the
centre of motion G, the handle on the shaft P is then turned until the cutter
just clears the periphery of the wheel; motion being now given to the shaft A,
and thereby the vertical movement to the cutter, the handle P is again gra-
dually turned until the cutting point is brought back into a straight line with
the spindle N and centre of motion G. This completes one side of the tooth
from the pitch line outwards, and the requisite turn or turns being given to the
handle K for the dividing motion, the cutter is again rolled back to the edge
of the wheel and fed forward again as before. The other sides of the working
part of the teeth are cut in the same way, except that the shaft P must be
turned in the contrary direction. In cutting from the pitch line to the bottom
of the tooth, the cutter must be set forward to the bottom of the tooth and
adjusted, so that the curve which it cuts will meet the epicycloidal curve in
the pitch circle. The shaft P is again turned to the right or the left according
to the side of the tooth which is to be cut. Figure 3 shows a section of the
swivel arm F and framework E upon an enlarged scale, and Figure 5 an end
elevation of the main bed R and frame Q. Figure 6 is a vertical section taken
through the table H and axis N. The table H and the two internal spindles
all move together when the tangential worm or screw is worked, which gives
them their back and forward rolling motion. When the dividing motion is
used the table is stationary, whilst the two internal spindles with the wheel to
be cut revolve. The wheel is not fastened to the table, but in such a way as
may be readily loosed before the dividing handle is turned; in fact, it is not
necessary that they should be fastened together further than in cutting large
wheels they might be firmer if temporarily secured together; for cutting small
The central
wheels a simple prop under the wheel would be sufficient.
spindle may be taken out and changed for one with a top of a different size
without disarranging the gearing or any of the motions.
DESCRIPTION OF BEVIL WHEEL CUTTING MACHINE.
Jaman of the

page_text: plane, and the alterations in the details of the machine consequent thereon.
The machine shewn on the Drawing Figure 7 is adapted for cutting bevil
wheel whose axes (when in position) are at right angles to each other. The
tool bar D slides in two pieces or brackets, which are capable of being turned
round a common centre on the frame E, which is again mounted on the
swivel bar or arm F, and capable of being set in any required position thereon.
This is shown on a larger scale at Figure 8. The tool bar is set at such an
angle as may be drawn from the cutting point of the tool when touching the
pitch circle of the wheel to be cut to the centre where the axis of the said
wheel and the centre of motion meet. The operation of cutting the teeth is
the same in both machines. The worm shaft S for giving the radial motion to
the table is connected by a pair of bevil wheels to a shaft running parallel with
the main bed, and which is geared up to the tangential screws for working the
swivel arm F by a train of spur wheels same as L in the spur wheel machine.
The dividing motion is on the same principle as the other machine.
In conclusion, we would remark that we make no claim to any of the
mechanical parts separately.
In witness whereof, we, the said John Lawson and Stephen Cotton,
have hereunto set our hands and seals, this Twenty-eighth day of
May, in the year of our Lord One thousand eight hundred and sixty.
STEPHEN COTTON. (L.S.)