IMPROVEMENTS IN THE CONSTRUCTION OF MACHINERY OR APPARATUS FOR CUTTING THE TEETH OF WHEELS
Year: 1877

page_text: PROVISIONAL SPECIFICATION left by George Mason at the Office of the
Commissioners of Patents on the 28th April 1877.
GEORGE MASON, of Boltou, in the County of Lancaster.
"IMPROVEMENTS IN
THE CONSTRUCTION OF MACHINERY OR APPARATUS FOR CUTTING THE TEETH OF
WHEELS."
This Invention is applicable principally to the cutting of the teeth of bevil or
mitre wheels, the object of the Invention being to cause the cutting tool to form the
teeth to the required tapering form without the use of a model tooth as hitherto
employed in wheel-tooth cutting machines.
The Invention is applicable, with slight modifications, either for cutting wooden
patterns for casting, or wooden teeth for making what are called mortise wheels,
and also for cutting teeth directly from the metal.
Firstly. For cutting wood we arrange a cutter so that in one position its face is
radial to the centre of motion round which it revolves, and in other positions its
face is tangential to corresponding circles drawn round, and front the centre of
motion. The position of the cutter can be changed as the cutter frame traverses
across the face of the wheel to be cut. This rotation of the cutter causes it to cut
a narrower faco when tangential than when radial to its centre of motion, so that
when properly adjusted the cutter alters its position in traversing along the tooth,
and consequently cuts it the proper tapering shape.
We prefer that the end of the cutter which cuts the bottom of the tooth should
bo in the centre of the circular slot round which the cutter and block rotate, but
the cutter end may be anywhere near it, or on the pitch line, so as to be con-
venient.
To accomplish the above object the cutter is fixed to a block, which block is
fitted in a circular slot in a revolving head. The centre round which this slot is
struck should be outside the head, and we prefer that the end of the cutter should
be at this centre, but it can be varied as required. On the back edge of this block
there are teeth cut to fit in the teeth of an angular toothed rack or quick-threaded
screw, so that by drawing the rack across the edge of the block, the block is rotated,
and with it the cutter.
The head and the block with the cutter are fixed on the end of a revolving spindle
carried in a suitable bracket fitted with pulleys; at the other end of the spindle

page_text: there is another bracket fitted to the first bracket, carrying a bush, and rack, and a
toothed quadrant working in the rack.
The quadrant is firmly fixed to a shaft, to which a slotted lever; with an adjustable
stud is also firmly fixed; this rack and the angular rack in the head are connected
together with a small spindle passing through the cutter spindle. At a convenient
place a stud is firmly fixed, and a connecting rod is fitted to connect this stud and
the stud in the slotted lever above named, so that when the cutter frame is moved
across the face of the wheel the connecting rod causes the lever to rotate and so
work the racks and rotate the cutter block and cutter as required.
The cutter head can be made with two blocks, each fitted to a different radius,
so that one can take a large cog, the other a small one, and so one block balances
the other when working, and prevents vibration; the angular rack then will have
teeth on both sides to fit both blocks.
The edges of the cutter are made to the shape of the largest end of the tooth to
be cut; the face may be either flat or curved. In using the machine it is fixed on
a suitable slide and adjusted so that the side of the cutter which is to cut is in line,
which intersects the centre line of the wheel to be cut, and parallel to the slide on
which it works. The side of the tooth to be cut is adjusted to the cutter; then
while the cutter head with the cutter is quickly revolving the whole frame is slided
across the face of the wheel; and as it slides along the cutter changes its position
and so cuts the tooth to the proper shape.
For cutting metals I apply the same principle, that is, to rotate the cutter so
as to throw it to an angle with the face of the wheels as it traverses across,
but instead of a revolving or fly cutter I use it as a planing cutter. In a suitable
frame is fitted a cradle mounted in curved slots so that the cradle can rotate from a
contre which may be outside the cradle and frame. The cradle carries a cutter box
arranged to swivel on a pin, and can also be twisted sideways for clearance in the
back stroke.
The edges of the cutter are made to the shape of the large end of the tooth to
be cut; the face may be either curved or straight, and it is adjusted in the box so
that the end of the cutter is in the centre of the curved slots round which the
cradle partly rotates, or the cutter can be set differently as found desirable, and can
be outside or inside of such centre, or backward or forward of it if preferred. The
cradle has one or two toothed quadrants attached to it, and corresponding toothed
quadrants are fixed to a shaft, to which shaft a slotted lever fitted with an adjustable
stud is also fixed.
This apparatus is designed to be applied to a shaping machine as being the
most convenient, but it can be used on a planing machine; another stud is firmly
fixed in a convenient place, and a connecting rod connects the two studs, and it will
be evident that when the machine is working and the frame and cradle sliding
forward and backward, the lever will be rotated partly by the connecting rod and
studs, and with it the cradle and tool box through the toothed quadrants, and thus
will alter the angle of the cutter which alters the width of the face cut by the cutter,
and at the same time gives the requisite taper.
The cutter is fed downwards or sideways to the proper depth. When the cutter
being properly set, and the proper amount of rotation given by the position of the
stud in the slotted lever, the tooth will be cut to the proper shape.
I would remark that by slight modifications, which will be evident to any com-
petent mechanic, this apparatus may be adjusted or modified to cut the teeth of
spur, worm, ratchet, or other similar wheels.