IMPROVEMENTS IN GEAR-CUTTING MACHINERY
Year: 1882

page_text: LETTERS PATENT to Herbert John Haddan, of Kensington, Middlesex, for an
invention of "IMPROVEMENTS IN GEAR-CUTTING MACHINERY."-A commu-
nication from abroad by Amos Hale Brainard, of Massachusetts, United
States of America.
PROVISIONAL SPECIFICATION left by the said Herbert John Haddan at the
Office of the Commissioners of Patents on the 28th April 1882.
HERBERT JOHN HADDAN of Kensington, Middlesex,
GEAR-CUTTING MACHINERY," a communication from abroad by Amos Hale
Brainard, of Massachusetts, United States of America.
"
IMPROVEMENTS IN
This invention relates to that class of gear cutters in which the necessary
divisions are made by means of a worm and worm-wheel as distinguished from
those in which the dividing mechanism is either a dial drilled with the necessary
number of holes; or a spur and ratchet wheels:
-
The invention consists in the combination of a worm-wheel with a vertically
adjustable worm-carrying bracket, adapted to be adjusted on the standard of the
machine by means of set screws, and having fastening screws passing through slots
for fixing the bracket after it has been placed in the required position. Also in
the combination of a worm with a worm-wheel and an annular rim screwed to the
worm-wheel and gearing into the worm. Also in the combination of a dividing
shaft with a toothed wheel mounted on the shaft, a recessed plate, crank lever,
pawl, hinged crank, latch, and button, all for setting the wheel into the position
required to cut the sides of bevelled teeth. Also in the combination of the cutter
arbor and cutter with an extensible collar and fastening nut for the purpose of
setting the cutter into the position required for cutting bevelled teeth. Also in a
centering device for centering the cutter with the arbor, consisting of a rod, set
screw, adjustable pointed strip, collar, and shank, adapted to be inserted in a hole
or slot in the bearing for the cutter arbor. Also in the combination of the crank
shaft and intermediate mechanism for raising or lowering the carriage with a
stationary and graduated dial and adjustable index or pointer for obtaining the
required depth of cut. Also in a vertically and laterally adjustable rim-rest
adapted to be secured to the front of the standard of the machine, and having its
set screw arranged to support the rim of the wheel that is to be cut.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent file
by the said Herbert John Haddan in the Great Seal Patent Office on th
27th October 1882.
k
HERBERT JOHN HADDAN, of Kensington, Middlesex. IMPROVEMENTS 11
GEAR CUTTING MACHINERY," A communication from abroad by Amos Hal
Brainard of Massachusetts, United States of America.
On the drawings, Figure 1 represents a perspective view of the improved gea
cutting machine. Figure 2 represents a detail rear view of the worm wheel, it
worm shaft, and adjustable bracket. Figure 3 represents a detail side view of the
dividing mechanism for turning the worin wheel and the gear to be cut. Figure 4
represents a side elevation of the adjustable table for the cutter shaft. Figure 5
represents a partial front elevation of the machine. Figure 6 represents a detail
view of the centreing device for arranging the cutter centrally with the axis of the
wheel to be cut. Figure 7 represents a cross section of the worm and worm wheel
on the line X Y, shown in Figure 2. Figure 8 represents an enlarged central
longitudinal section of the cutter arbor and cutter; and Figure 9 represents an
enlarged cross section on the line U V, shown in Figure 5, showing the
indicator for setting the cutter to the exact depth of the desired teeth to be cut on
the wheel.
Similar letters refer to similar parts wherever they occur on the different parts
of the drawings.
This machine is of that class of gear cutters in which the necessary divisions are
made by means of a worm and worm wheel, as distinguished from those in which
the dividing mechanism is either a dial drilled with the necessary number of holes
or a spur and ratchet wheels.
In this machine are several special devices to attain and maintain unusual
accuracy, as will herein be more fully described.
a is the standard or frame of the machine, having in its upper end a bearing b,
for the shaft c, to the rear end of which is secured the worm wheel e, and to the
forward end of which is secured the wheel & that is to be cut.
fis the worm, and f' is the worm wheel shaft by means of which the worm
wheel e is operated. The shaft f¹ is located in bearings f"f" on the vertically
adjustable bracket F, the latter being adjustable up and down on the rear of the
standard a by means of the set screw a passing through the screw threaded ear or
lug a, cast on the standard a, and by these means the worm ƒ can be adjusted in
its relation to the worm wheel e to the utmost nicety, and after being so
adjusted the bracket F is firmly secured to the standard a by means of the set
screws g g passing through slot holes g' g' in the bracket F and screwed into the
standard a.
The purpose or object to be attained by the above named combination of worm
wheel e, worm carrying bracket F, set screw a¹, and fastening screws gg is accuracy
and an entire absence of backlash. The combination used secures this by affording
a means of adjusting the worm to such a depth in the worn wheel that the
slightest notion of the worin shall also move the worm wheel, and this not only
when the parts are new, but furnishes a ready and exact compensation for wear.
This is a matter of much importance, not only in the attainment of accuracy in
dividing, but in rigidly holding the worm wheel without allowing it to move in
the slightest degree, and thereby insuring a smoother cut for the teeth of gear
wheel on the other end of the arbor than is possible in ordinary gear cutting
machines.
The bracket F is also provided with bearings f" fill for the dividing shaft f¹v.
hhh are the change gears connecting the shafts f¹ and fIV to convey motion
from the latter to the former.
The worm wheel e is made in two parts-namely, the main body e and the

page_text: annular rim e', the latter being made half as wide as the whole worm wheel e, and
fitted into an annular recess on the side of the worm wheel e, and secured thereto
by means of set screws ell ell, as shown in Figures 2 and 7.
The thread in the worm wheel for the worm f is made one half in the body of
the wheel and one half in the annular rim e¹, and in this manner I obtain a divided
worm wheel in more easy, simple, and durable manner as compared with the usual
way of making worm wheels of two equally large disks or plates, which is
objectionable in wheels of large size on account of the difficulty of getting a
perfect bearing all over such large surfaces, and it would require very thick and
heavy disks or plates to finish well. The same result is obtained in a more simple
way in the arrangement and construction as above described.
I do not claim as this invention a worm wheel made in two parts, as such have
heretofore been made; but they have in fact been two wheels divided through
their whole diameter. By making the worm wheel as hereinabove described in
accordance, with this invention—that is, with a main body and a separate rim―
the labour of making is very much simplified, and the strength and stability of the
wheel increased without increasing its weight, a very important consideration in
making wheels of large diameters.
When cutting bevel gears with a rotary cutter it is usually necessary to
make three cuts, the first directly to the centre in a straight line, then one on
each side of the centre line to get the necessary difference in width of cut on the
outer and inner ends of the teeth. In common practice this is altogether a matter
of experiment with each bevel gear, depending entirely on the eye and experience
of the workman, and no certain way has heretofore been devised for cutting two
bevel gears exactly alike by a system of actual measurement in the gear cutting
machine itself. In this machine, after one gear has been cut correctly, or even one
side of a tooth has been cut, a record can be made of the necessary amount of
"set over," and ever after that particular size gear can be cut exactly without
further experiments. For this purpose I arrange upon the end of the shaft ƒ a
toothed wheel, i, fitting loosely on said shaft, which can be held firmly in position
by means of the latch lever and locking button i¹. (Shown in full lines in
Figure 3.).
On the end of the shaft fIV is firmly secured the crank lever %, to the lower end
of which is hinged the crank . The upper end of the crank is hinged to the
rod m, projecting through a sleeve, k¹, on the lever, as shown in Figure 2. The
rod m terminates as a pointer or pawl, m', which is adapted to rest in a notched
plate, m, secured to the outer face of the toothed wheel i, the pointer or pawl m¹.
being actuated toward the wheel i by means of the coiled spring within the
sleeve k¹, as shown.
When cutting spur gears wheel i is not used at all, and the lug m¹¹ might be
secured directly to the bracket F, dispensing with wheel i altogether; but when
cutting bevel gears it is necessary to use a cutter thin enough to pass through the
narrowest part of the space between the teeth, and this would of course leave the
outer and wider end of tooth in a wrong shape. Some means must therefore be
used to set over the gear in such position that the cutter may form one side of the
tooth, and then to set it in position to form the other. To accomplish this I
release wheel i, and leaving the pointer or pawl m³ in its seat m¹¹, I rotate the
notched wheel i, which then moves the worm f and worm wheel e a sufficient
distance to bring the tooth of bevel gear on the arbor c of the machine in proper
position for the cutter to form one side of the tooth. The wheel is then locked,
and the proper division for toothing the gear proceeds by raising the pawl m' out
of its seat and rotating the crank the requisite number of times, the wheel i
remaining stationary until one side of all the teeth in the bevel gear has
been cut.
The process of unlocking wheel is now repeated, when it is rotated in the
contrary direction the proper distance, relocked, and the gear-cutting proceeds as
before. Thus when it becomes necessary to set over a bevel-wheel to make the

page_text: side cut the button is turned to the position shown in dotted lines in Figure 3,
and the latch ' is raised out of contact with the toothed wheel i, and leaving the
pawl m' in its notch m" the wheel i is turned by the crank the requisite distance
to one side. The teeth of the wheel i being numbered from each side of the upper
tooth when in its normal position, it is evident that when the proper position of
one side of the tooth of gear to be cut is ascertained the wheel i has only to be
rotated the same distance from zero in the opposite direction to bring the other
side of the tooth in its proper position, and a record can be made, saving any
further trials with a gear of the same description; but while the above arrangement
brings the gear tooth in proper position, a change of position of the cutting tool n¹
is also necessary upon the cutter arbor n. To effect this an extensible collar made
in two parts, n¹¹ and n¹¹, is used, as shown in Figures 1, 5 and 8. The two parts
of said extensible collar are composed of an outer shell, n", having a male screw
thread fitting within a corresponding female screw thread in the part n, which
latter is made stationary on the arbor n by means of a key or other equivalent
On the periphery
device, and made to rest against the collar n on the shaft n.
of the stationary part n is made a zero-mark, and on the periphery of the
adjustable part n₁ is a uniform series of numbered lines lengthwise upon its
surface.
The end of the cutter arbor n is screw threaded, as shown in Figure 8, and
there provided with a nut n¹V, and sleeve nv, located between said nut and the
cutting tool n. The requisite distance necessary to move the cutter having been
determined, the nut n. is loosened, and the parts n¹¹ n111 expanded or contracted
to the necessary point, after which the nut nIV is again tightened and the machine
is ready for work. Like the device for moving the gear wheel, so this device for
changing the position of the cutter can be made. a matter of record,. so that it can
ever afterward be adjusted with certainty upon the same description of bevel
gears. Furthermore, it is essential that the rotary cutter n¹ should be in a plane
passing through the centre of the arbor c of the machine which carries the gear d
to be cut. The method of effecting this in common use is to turn the centre arbor
to a point at its outer end and running the parts carrying the cutter up to this
point to adjust the cutter by it. This, especially in a machine worked with
screws, involves much time and labour, and to obviate this I use a device as shown
in Figure 6. This consists of a rod of metal, o, tapped at its outer end for a set
screw, o¹, to secure an adjustable sharp-pointed strip of metal, o, as shown.
The other end of the rod o has a shoulder, o, at a proper distance from
the end of the shank oIV. The device, after being properly fitted to the
machine and adjusted by actual experiment, is used by inserting the shank O.
up to its shoulder o in a socket bored out in the bearing N¹ of the cutter-arbor,
as shown by dotted lines in Figure 5, and the cutter set so that the centre of its
cutting-edge coincides with the sharp edge of the metal strip or gage ol. A
slot o, is made in the strip o¹¹ to allow of its adjustment for different diameters of
the cutters. Another careful adjustment needs to be made namely, the depth of
cut for the teeth for gear wheels; and in practice this is so difficult that only by
the aid of special gages made by experts can the average workman set a gear
cutter to the proper depth; but by the mechanism described below this machine
can be set with mathematical exactness by any mechanic capable of running the
machine. This mechanism consists of a dial, p, secured to the bearing, p¹, and
usually made in one piece with it. A finger or pointer, pl, loosely embraces the
crank shaft p, one end of the pointer p¹ being split or sawed through, and
provided with a clamping-screw 2TV, so that it can be clamped to turn with the
shaft p or loosened to turn on it. The dial p is marked with zero at its central
top edge, and has a series of lines upon its face to correspond with thousandths of
an inch of elevation of the cutter-arbor and its attachments. In practice the
gearing is commonly so arranged in relation to the elevating screw q that a
complete revolution of the crank shaft 21 actuating it raises or depresses the
cutter and its appendages one eighth of an inch. The dial then having one

page_text: hundred and twenty-five divisions, each division will correspond with one
thousandth of an inch elevation. The setting for depth of tooth then proceeds as
follows: The cutter and gear to be cut being in place, the cutter is raised under
the gear till its outer edge or circumference is touched. The pointer p₁, loosened
upon the crank-shaft p, is brought to zero-point and clamped there to the shaft.
As the depth of cut for teeth of any given pitch is well known, the cutter needs
only to be raised the requisite number of thousandths of an inch to be in position
to make the proper depth of cut.
When cutting gear of considerable diameter the strain upon the arbor carrying
it is very great, and the gear itself is liable to spring, causing the cutter to chatter,
with danger of breakage, and making rough work. To prevent such chattering or
yielding of the gear that is being cut I use the rim-rest shown in Figure 4. It
consists of a stud, r, secured to the standard a of the machine, and provided with
an adjustable set screw, r¹, and check-nut 11 as shown. The stud r, may either
be arranged to be vertically adjustable in a slot 1 in the front of the machine,
as shown in Figure 1, or may be bolted to it with adjustment for different
diameters of gears. The set screw r1 being set out till it touches the gear-rim d,
supports the rim and prevents its vibration, by which smoother work is produced
than could possibly be done without it.
S is the vertically adjustable table or carriage, actuated up and down by means
of bevel-gear p on crank-shaft pl. and bevel gear q', on the vertical screw-shaft q,
which works in the stationary nut q" as usual. N is the laterally adjustable
cutter shaft carriage, with its bearings N¹, N" as usual.
Having thus fully described the nature, construction, and operation of the
present invention I wish it to be understood that I claim :-
1st. In a gear cutting machine, the worm-wheel e in combination with the
vertically adjustable worm carrying bracket F, adapted to be adjusted on the
standard a. by means of set screw a¹, and having fastening screws g g. as and for
the purpose set forth.
2nd In a gear cutting machine the combination of the worm f with the worm
wheel e. and its annular rim e¹. and fastening screws e¹¹, el, as and for the purpose
set forth.
3rd In a gear-cutting machine, the dividing shaft f its toothed wheel i,
recessed plate m", crank lever k, k', pawl m, m³, hinged crank 1, latch ¹, and
button all combined and arranged to operate as and for the purpose described.
4th In a gear cutting machine the cutter arbor n and cutter n¹ in combination
with the extensible collar n", n. and fastening nut n. as and for the purpose
set forth.
5th. The herein described centreing device for centreing the cutter n¹. with the
arbor c, consisting of the rod o, set screw o¹, adjustable pointed strip o", collar o
and shank o. adapted to be inserted in a hole or slot in the bearing N¹. for the
cutter arbor as set forth.
6th In a gear-cutting machine the combination with the crank shaft p¹¹¹ and
intermediate mechanism for raising or lowering the carriage S, the stationary and
graduated dial p and adjustable index or pointer p". as and for the purpose
set forth.
7th In a gear cutting machine the vertically and laterally adjustable rim rest r,
, adapted to be secured to the front of the standard a, and having its set
screw r¹ arranged to support the rim of the wheel & that is to be cut, as set forth.
In Witness whereof I the said Herbert John Haddan have hereunto set my
band and seal this twentieth day of October A.D. 1882.