AN IMPROVED MODE OF AND APPARATUS FOR CUTTING THE TEETH OF MITRE AND BEVIL WHEELS, AND ALSO FOR GIVING AN IMPROVED FORM TO THE TEETH OF OTHER WHEELS."
Year: 1878

page_text: LETTERS PATENT to Willian Tighe Hamilton, M.A., of Rathmines, Dublin,
Ireland, for the Invention of "AN IMPROVED MODE OF AND APPARATUS FOR
CUTTING THE TEETH OF MITRE AND BEVIL WHEELS, AND ALSO FOR GIVING AN
IMPROVED FORM TO THE TEETH OF OTHER WHEELS."
PROVISIONAL SPECIFICATION left by the said William Tighe Hamilton at
the Office of the Commissioners of Patents on the 16th February 1878.
WILLIAM TIGHE HAMILTON, M.A., of Rathmines, Dublin, Ireland. " AN IMPROVED
MODE OF AND APPARATUS FOR CUTTING THE TEETH OF MITRE AND BEVIL WHEELS,
AND ALSO FOR GIVING AN IMPROVED FORM TO THE TEETH OF OTHER WHEELS."
The novelty of this Invention lies in giving to an ordinary circular cutter such
extent and kind of alternate motion that in its passage across the face of a wheel
the intervals cut between the teeth may be of any desired width, and either parallel
or tapered.
This object is attained by imparting to the spindle which carries the cutter a
reciprocating motion, whilst it rotates in the manner specified in my Patent bearing
date the 6th day of December 1872, No. 3704.
A sheave or grooved pulley is mounted upon the spindle, to which it can be
inclined at any desired angle by set screws, whilst a ring is introduced into the
hollow of this sheave within which the sheave can revolve when the ring is pre-
vented from turning.
A circular pin is fixed into this ring in a line through the centre of the sheave
and the axis of the spindle; these two parts are analogous to the strap and rod of
an excentric.
The outer portion of this pin passes through a vertical stud which is free to turn
as a hinge upon concs or journals, its axis of motion being at right angles to the
above line of the pin. Thus the pin is free to have a twisting as well as an endway
Dine S31

page_text: motion; then, when the spindle rotates, the pin acts as a lever with the stud as
its fulcrum, and therefore compels the spindle to reciprocate with a throw propor-
tioned to the inclination of the sheave, and the distance of the stud from the axis
of the spindle.
Then again this stud is so shaped that the centres on which it turns can pass
above and below the spindle, and then when these centres are in a vertical line
through the axis of the spindle all reciprocation will cease.
The special application of this principle in the present case will be more clear
from a general description of the machine in which it is applied.
The cutter spindle is placed in the bearings of an ordinary headstock capable of
moving forward or backward by screw action upon a slide bed.
A bracket of the ordinary sort provided with a quadrant and division plate is
so fixed upon the bed that the cutter can traverse the face of any wheel when
mounted upon it at such angle or in such position that the bottom of the cut
shall be parallel to the slide bed.
Then when the head moves forward, and the stud is fixed to travel with it so
that its centres may remain over the axis of the spindle, there will be no recipro-
cation, and the cut will be of the width of the cutter; whilst if the stud centres
are similarly fixed, but at some distance from the spindle, there will be a propor-
tionate degree of reciprocation, and therefore width of cut. In these two cases the
sides of the cut will be parallel as in spur wheels.
On the other hand, if the stud is fixed whilst the head only moves forward, the
interval will be divergent or tapered in proportion to the throw of the spindle, as
in mitre or bevil wheels.
By altering the extent of throw the teeth and teeth intervals can be made of such
a size as may be required for any particular pitch.
The same principle as that requisite for mitre wheels may also be applied to
giving a new form for the teeth of spur wheels; they also can receive a convergent
or tapered form, so that the teeth of any pair can indent into each other, and then
any convenient method of endway adjustment will take up all lache in a way
analogous to the angular contact of frictional gearing.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said William Tighe Hamilton in the Great Seal Patent Office on the
16th August 1878.
WILLIAM TIGHE HAMILTON, M.A., of Rathmines, Dublin, Ireland. "AN IMPROVED
MODE OF AND APPARATUS FOR CUTTING THE TEETH OF MITRE AND BEVIL WHEELS,
AND ALSO FOR GIVING AN IMPROVED FORM TO THE TEETH OF OTHER WHEELS."
The novelty of this Invention lies in imparting to a circular cutter of the ordinary
or other suitable form such extent and kind of alternate motion that in its passage
across the face of a blank when prepared for a mitre, bevil, spur, or other wheel or
rack in metal or other material, the intervals cut between the teeth may be tapered,
and of any desired width.
This can be effected at either one or several passages of the cutter, according as
may be most convenient; and the apparatus can be used either for cutting the
teeth intervals in solid blanks, or for trimming them when partially formed in the
castings.
This Invention is a particular application of the mode of motion of which the
fundamental principle is that specified in my Patent bearing date the Sixth day of
December One thousand eight hundred and seventy-two, No. 3704, but with certain
modifications requisite for its present purpose.
The annexed Drawings do not purport to show all the parts of a complete
machine, but only to indicate the proper lines of its construction, and the proper
functions and relations of the essential parts which constitute the present
Invention.
With respect to these a grooved sheave A, Fig. 1, is so mounted upon the spindle B
that it can be inclined to it at any desired angle by the set screws C, C¹, whilst
a ring D is introduced into this groove by the removal and replacement of a side
plate.
The boss of this sheave, that is to say, the bottom of the groove revolves within
the ring, when this is prevented from turning by the round radial pin E, which is
fixed into it in a line through its centre, and through the axis of the spindle.
These three parts are analogous to the body strap and rod of a steam engine
excentric; but here the sheave must be concentric with the shaft, and not at right
angles to it, and therefore the derivative motion is of a different nature and in a
different direction.
The outer portion of this pin passes through a round hole F in the boss G
of a vertical stud H, which is free to swing or rock as a hinge upon pivots or
trunnions I, I, see Fig. 4. Its vertical axis of motion is through the trunnions,
and at right angles to the line of the pin.
The pin E is thus free to have a twisting as well as an endway motion, and
then when the spindle and sheave rotate this pin acts as a lever with the boss of
the stud H as a fulcrum, and compels the spindle to reciprocate as it rotates with
a throw in proportion to the inclination of the sheave and the distance of its
centre from the vertical line which passes through the trunnions or pivots of the
stud.
This combination of parts constitutes what is termed a reciprocater from the
effects it produces.
The trunnions of this stud H are free to turn in suitable holes K, K¹, in the
frame L, L'. This frame is fixed, and the stud is so shaped that its trunnions cau
stand over and under the reciprocater when this is brought into that relative
position.
Then when the vertical line through the trunnions also passes through the axis of
the spindle there will be no reciprocation. The reciprocater will then be at its
dead point; but when the axis of the spindle is moved to a position, either before

page_text: or behind this vertical line, there will be a degree of reciprocation increasing in
proportion to the distance moved, and to the inclination of the sheave.
The dotted lines in Fig. 2 shew the extreme positions of the reciprocater caused
by the throw of the spindle when moved forward to a position in advance of the
vertical line of the trunnions.
In order to put these various parts into operation a spindle without shoulders is
mounted in the usual bearings of an ordinary headstock M. This spindle carries
the cutter N at its extremity, and the reciprocater at its middle portion.
This headstock is moveable backwards and forwards upon a slide block O, O',
fixed upon the bottom of the frame which carries the stud by such means as may
be deemed most convenient.
The blank to be cut is mounted upon such convenient form of apparatus as may
afford suitable means for setting it at any angle, or for any depth of cut, and for
turning it round upon its axis for any pitch distances; but as this apparatus forms
no part of the present Invention only so much of it as holds the blank is shewn in
the Drawings.
As an example this blank is shewn set at an angle of forty-five degrees, and
mechanics are already familiar with the many and various forms which may be
used in order to obtain this or any other desired angle.
With respect to the results of this arrangement, when the headstock is moved
forward, and the sheave is not inclined, the cut will be the exact width of the cutter
with parallel sides, as in the usual form of spur wheels. But when the headstock
is moved forward, and the sheave is inclined, the sides of the cut will be divergent,
as in mitre wheels.
The degree of this divergence will depend upon the degree of inclination given
to the reciprocater, and can thus be adapted to any size of cut or pitch of
wheel
The action of a cutter upon the face of a blank is shewn at Figures 1, 2,
and 3, where the dotted lines in Fig. 3 indicate the extreme positions of the cutter
when it has passed out of the cut.
The degree of curvature along the side of the tooth will depend upon the form of
the cutter. When for a single passage it may be of the form usually adopted to
effect sufficient rolling contact, but if a different degree of curvature is desired, it only
involves the passage of a second differently curved cutter at a lesser depth along the
pitch line. Again, the second or third tooth of the cutter following that which first
enters the blank may be shorter and more curved than the first, and thus produce
every desirable form of tooth in the wheel. In either case the teeth will require
no filing or other finish.
The width of the teeth intervals will depend upon the distance from the dead
point at which the cutter enters the blank.
The motions of the headstock may be effected by either hand or self-action.
The rotation of the spindle may be effected by any convenient form of.driving
gear, but its rotation should be suspended on the return, so as not to injure the
cutter or the sides of the cut in its backward application or contact.
The same principle of divergent teeth intervals and tapered teeth is also applicable
to spur wheels, as well as to racks and pinions..
The teeth of these can be cut of that form, and then when indented into cách
other any convenient method of endway adjustment for one of them will take up
all lache between both in a manner analogous to that used for the contact of fric-
tional gearing. It thus combines the advantages of end way adjustment with the
side or overlapping action of helical teeth, but with improved effect.
I do not limit myself to the exact details of the constructions as above
described.
The several parts may, of course, be varied in form, so long as their use is the
same, and their combination produces the same results. For instance, the con-
struction of the reciprocater may be varied by fixing the pin into an outer ring,

page_text: which swivels upon the inner one. The twisting motion of the pin is thus trans-
ferred to the gimbals on which the outer ring swivels, and this ring will then
always swing in vertical planes.
It may be of any convenient form, whether rectilinear or curvilinear; its upper
and lower edges can slide in hollow guides which carry the trunnions, and these
again can work in the fixed frame, as before described, with like results. But the
simplest construction is that shewn in the Drawing, where the stud is single and
of a forked form, with its back boss perforated for the pin to traverse, and so to
act as the necessary fulcrum.
Having now described the essential features of this Invention, and explained the
manner of carrying the same into effect, what I claim is,―
First. Imparting a gradually increasing throw or spreading action to a cutter
whilst it passes through a cut so as to cut or trim the teeth of wheels of a tapered
form either in whole or partly formed blanks of metal or other material.
Secondly. The use for this purpose of the particular mode of motion derivable
from a sheave, ring, and pin, either in the manner first above described or in.
the modified manner produced by the general combination of parts next above
described, and shewn in the accompanying Drawings.
Thirdly. The use for the purpose of this Invention of cutters either of the ordinary
form or with teeth of different lengths and degrees of side curvature when applied
in the manner above set forth.
Fourthly. The mode herein set forth of constructing the teeth of spur wheels and
pinions with a view to take up lache by means of endway adjustment.
In witness whereof, I, the said William Tighe Hamilton, have hereunto set
my hand and seal, the Fifteenth day of August, in the year of our Lord
One thousand eight hundred and seventy-eight.
W*. TIGHE HAMILTON. (LS.)