AN IMPROVED MACHINE FOR MAKING SCREW TAPS
Year: 1872

page_text: LETTERS PATENT to George Haseltine, of the "International Patent
Office," Southampton Buildings, London, Doctor of Laws, for the
Invention of "AN IMPROVED MACHINE FOR MAKING SCREW TAPS."-A
communication from abroad by Alfred Goddard and Alfred Edward
Goddard, both of Essex, Connecticut, United States of America.
Sealed the 10th October 1872, and dated the 26th August 1872.
COMPLETE SPECIFICATION filed by the said George Haseltine at the
Office of the Commissioners of Patents, with his Petition and
Declaration, on the 26th August 1872, pursuant to the 9th Section
of the Patent Law Amendment Act, 1852.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, GEORGE
HASELTINE, of the "International Patent Office," Southampton Build-
ings, London, Doctor of Laws, send greeting.
WHEREAS I am in possession of an Invention for "AN IMPROVED
MACHINE FOR MAKING SCREW TAPS," and have petitioned Her Majesty to
grant unto me, my executors, administrators, and assigns, Her Royal

page_text: Letters Patent for the same, and have made solemn Declaration that
it has been communicated to me from abroad by Alfred Goddard and
Alfred Edward Goddard, both of Essex, Connecticut, United States of
America.
NOW KNOW YE, that I, the said George Haseltine, do hereby
declare that the following Complete Specification, under my hand and
seal, fully describes and ascertains the nature of the said Invention, and
in what manner the same is to be performed, in and by the following
statement, reference being had to the accompanying Drawing forming
a part of this Specification.
This Invention has for its object the formation of the threads on tools
known as screw taps in combination with the requisite degree of "relief”
necessary in such tools, and this object is accomplished by cutting the
threads automatically by a scries of cutters successively presented to the
blank, as will be herein-after described.
]
Figure 3 is a sectional view of the same through the plane x, x.
"
Figure 4 is a diagram illustrating the "relief" on a tap.
The frame A of the machine is similar in appearance and construction
to an engine lathe, and is mounted on any suitable supports or feet, as
shewn. There are also mounted upon said frame, and in a similar
manner to a lathe, a head stock B and tail stock C, provided with 2
centres for supporting the blank D from which the tap is to be formed.
In tho head stock B a driving mandrel carrying pulleys E is mounted
to receive the driving power, and from which motion is given by suitable
gearing to all the other parts of the machine.
At F, upon suitable guides on the upper surface of the frame, is 3
mounted the tool rest for supporting the cutter head G. This tool rest
receives motion along its guides from the screw H, extending through a
nut h upon a bracket underneath, and projecting down from the under
side of the rest, as shown at K, Figure 3, and similar to the tool rest of
an engine lathe.
3

page_text: The screw H also receives motion by intermediate gearing from the
driving mandrel, similar to an engine lathe, and for the same purpose,
viz., to permit it to be adapted to the various pitches of the thread to
be formed upon the tap. But instead of reversing the driving mandrel
as in such lathes by shifting the belts, a reversing clutch L is provided
on one of the intermediate shafts between two bevel wheels M and N,
loose on the shaft shown in Figure 1, and which engage with a
horizontal bevel wheel connecting them in such a manner that the
motion is changed by shifting the clutch from one to the other, as
from M to N, or both are stopped when the clutch is out of contact
with both wheels.
The bevel wheel M is attached to the intermediate wheel O, which is
also loose on the same shaft, consequently the action of the screw H is
determined by the position of the clutch. This clutch is shifted by a
forked lever P pivoted at p and connected with the shipping bar R,
upon which are adjustable stops S and T; the latter are arranged to
come in contact with springs upon the rod R, and, when sufficiently
compressed by the movement of the tool rest by the fixed stops S' and T
upon the rear of the rest, change the shipping bar from left to right,
and vice versa; by this combination the tool rest is caused to move to
and fro along its guides automatically, while the driving mandrel con-
tinues revolving in the same direction.
At r, r¹, upon the tool rest F are arranged studs to give positive
motion to the shipping bar when not acted upon by the springs, so that
the clutch may be shifted to the proper position to engage with the
wheels M and N.
The tool rest is properly composed of a series of sliding blocks F, F¹, F³,
and F³, fitted one upon the other and held in position thereon by dove-
tail guides, the ends of which are plainly shewn in Figure 1. Upon the
upper one of these blocks suitable bearings are provided for holding the
axis of the cutter head G and the said block as the block F is moved
longitudinally by the set screw u.
To the front end of the block Fa bracket is attached that carries
a guide roller V which presses against an adjustable bar W; the latter
has one end pivoted to the frame at to, and its other end is adjusted by
a set screw at w³ to a position parallel with the taper of the blank D,
as shown in Figure 2. This is one method of making the cutters

page_text: -
conform to the. taper of the blank, but the same result may be accom-
plished by shifting the tail stock relatively to the guides upon which
the tool travels, as is commonly done in turning taper work in lathes.
'
The cutters, X, X, X, are mounted in the cutter head G (which is a
disc or circular plate similar to a face plate in a lathe) in such a manner
as to stand radially upon its outer face, and as many cutters are used
as the times required to run over the blank to complete the thread.
For example, if ten cuts will be required to finish the thread ten
cutters may be used, so that each successive cut is made with a special
tool, and the tools are set to the proper distances from the cutter head
to give to each its required depth of cut, though it is obvious that
the cutter head may be set forward as each cutter comes into working
position.
These cutters are partially inserted in recesses in the face of thic
head G, and held therein by clamping screw bolts passing through the
disc of the cutter head, and they are set and held out radially by the set
screws through a flange near the centre of the disc or head, as shewn
at y, y, Figure 1. The cutting point of each cutter or tool is made
to correspond with the spaces between the threads to be formed as
V shaped for a V thread, or square for a square thread, or otherwise,
according to the form required.
On the opposite end of the cutter bead axis at Z is a ratchet wheel
provided with teeth or 'notches corresponding to the number of the
cutters, that is to say, the same number or multiples thereof, so that as
the pawl Z acts upon the ratchet wheel it will bring each successive
tool into its proper place for work upon the blank D. This pawl Z is
pivoted to a bracket-projecting from the upper end-of-a-vertical-stud-Z₁
which projects down through a tubular support attached to the basc
of the tool rest F, as shown in Figure 1, and the lower end of the stud
is rounded slightly to permit it to rise easily upon its lifting levers 1
and 2 The said levers 1 and 2 are pivoted to adjustable supports
which are fastened in a slotted projection from the side of the frame,
and are so made adjustable to correspond with the various lengths of
the taps.
•
The short arms of the said levers are bent upward at right angles
to their lifting arms to bring them in contact with their actuating
brackets 3 and 4, which are attached to one corner of the tool rest-E;

page_text: consequently as the tool rest moves to and fro along its guides on
the frame the levers 1 and 2 will be tilted to raise the stud which
carries the pawl, and will thereby rotate the cutter head G. Regu.
lating screws 5 and 6 are arranged under the levers 1 and 2 to
determine the distance to which the pawl may drop in its action upon
the ratchet Z.
When the cutter head G is brought to the proper working position
it is held firmly therein by a spring bolt 7, Figure 2, which is mounted
upon the top of the tool rest F³; one end of the said bolt enters a hole
in the back of the cutter head, the said holes corresponding to the
tools X, X, X, shown at 8, Figure 3.
The said spring bolt 7 is forced back from contact with the cutter
head by a lever 9, at one end of which is a cam; this cam presses against
a pin through the bolt, the middle of the lever being attached to the
tool rest at F, and the free arm reaching down to and in contact with
a bell-crank lever 10, the latter is attached to the lower portion of the
tool rest near F, and is operated by contact with a bracket or stop at 11
on the frame, in such a manner that as the tool ceases its work upon
the blank the spring bolt is forced back out of the hole 8 in the back
of the cutter head G; the cutter head is then left free to be revolved
by the pawl at Z', a partial movement of which is produced by the
forward movement of the tool rest that brings the lever 10 in contact
with the stop 11.
By the combination of these several elements the operation of auto-
matically forming the thread upon the tap is accomplished by a
succession or series of cutters, but to produce the desired "relief"
or clearance necessary in a perfect tap a secondary movement must
be given to the cutters whereby the thread is cut deeper at the points
to be relieved, as shown at 12 in the section of the tap, Figure 4.
This part of the operation is effected by a cam shown at 13, which
operates a lever 14 connected with one of the sliding blocks in the tool
rest, and which gives the cutter head and its tools a motion to and from
the blank D, and causes it to be cut deeper at the points required for
the "relief."
The relieving cam at 13 is mounted on a shaft 15, which receives
motion from the gearing in the head B, and it extends through supports
and guides on the rear of the tool rest F; at 16 these guides embrace

page_text: the cam between them and it is forced to and fro along the shaft as the
tool rest moves.
•
The said cam is provided with a spline which works in a groove in
the shaft to connect it with the said shaft, and the said cam is provided
with as many lifting points on its perimeter as there are grooves
required in the tap provided the shaft 15 has precisely as many
revolutions as the tap. For example, four projections will be required
on the cam if four grooves for "relief" are to be produced on the tap
as shown in the Drawing. But it is obvious that the same result
would be produced with only one projection on the cam if the shaft. 15ª
had four revolutions to one of the tap or blank. It will be found
however easier in practice to give the shaft 15 the same speed as the
blank D, and to change the cam to correspond to whatever grooves are
desired for the "relief." A friction roller is introduced between the
cam and the lever 14 to prevent wear and loss of power.
The lever 14 is. pivoted to a bracket on one of the blocks of the tool.
rest, and is bent at a right angle to the free end, and then attached to
the block to be moved backward and forward; the free end of the lever.
may be weighted to retain. the block in the position whence the cam
has moved, or a second bell-crank lever may be introduced. underneath!
the tool rest, as shown at 17, in Figure 3, to one end of which a;
weight 18 is attached to produce the same effect and which will be
found in practice to be preferable, as the cam will have less to do, and.
the weight will be completely out of the way of the operator.
The blank D is introduced between the centres, and connected with
the rotating mandrel by a dog 19, or the end may be squared and enter
a socket, or it may be connected in any convenient manner to receive
motion. Therefore the cutter head is revolved to the proper point to
bring the first tool in working position, and the various-stops-arc..
properly adjusted-to-perform their various operations, and it is evident å
that the entire operation of cutting the thread and giving the requisite
relief will be effected automatically by the successive series of cutters
until the work is completed.
Having thus fully described the said Invention as communicated to
me by my foreign correspondents, and the manner in which the same is į
to be performed, I claim;-
First. The combination of the cutter head and the series of chasing
tools arranged thereon, the mechanism to intermittingly rotate the

page_text: said cutter head, the slide or tool rest, and the cam 13 to reciprocate
the said slide, so as to produce the desired "relief," as herein described.
Second. The combination of the ratchet wheel and pawl, the stud 7,
hinged levers 1 and 2, brackets 3 and 4, and the tool rest, substantially
as described.
Third. The combination of the spring locking bolt, cam-headed lever 9,
the lever 10, the springs and the stop 11, substantially as described.
Fourth. The combination of the clutch and its lever, the shipping bar,
the adjustable and fixed stops and springs thereon, and the studs r, r³,
substantially as described.
In witness whereof, I, the said George Haseltine, have hereunto
set my hand and seal, this Twenty-sixth day of August, in
the year of our Lord One thousand eight hundred and seventy-
two.
Witness,
CHAS. J. GoOCH.
GEORGE HASELTINE. (L.s.)