A Screw-cutting Machine.
Year: 1889

page_text: Date of Application, 28th Nov., 1889
Complete Specification Left, 26th Mar., 1890-Accepted; 10th May, 1890
PROVISIONAL SPECIFICATION.
A Screw-cutting Machine.
I, FRANCIS HENRY RICHARDS, of 64 Farmington Avenue Hartford in the county of
Hartford, and State of Connecticut, one of the United States of America, Mechanical; '
Engineer, do hereby declare the nature of my invention to be as follows:-
This my improved screw-cutting machine cuts the threads of tapered screws, such,
as the threads of pipe-fittings and the like, by means of chasers having an advancing
motion parallel to the threaded surface.
This machine is adapted to be constructed in two forms; of which one is a simple
form adapted to be operated by hand, and the other a more fully developed: form,,
operating automatically.
In describing the invention, I will first refer to the simple form. The bed of this
machine may be of any suitable form and proportions adapted to carry the several
essential details. of. the machine. On said bed, I place a head, block, and. also a
chuck or work-holder for holding the article to be threaded. This, article may be an
ordinary cast-iron pipe coupling, but a variety of other well known articles may be
properly threaded in my machine; and for the said chuck, may use any well-known
device for like purpose. The head block may or may not be formed integral with.
the bed by which it is supported.
My improved machine has a revolving spindle, one or more chasers, having an
advancing motion at an inclination to the axis of the screw-thread to be cut,, and.
means for so advancing the chaser during the revolution of said spindle., The.
spindle consists of a stem, and a spindle-head; which head carries the chasers, and is.
fitted to revolve in a suitable bearing on the said head-block. The spindle stem
extends rearward from, and furnishes the means for revolving the spindle-head;, said
spindle being furnished with a crank, or other well-known device for such purpose.
The chaser consists of a longitudinally-sliding part provided with. thread-cutting
teeth, and having a guide-nut through which the motion is imparted thereto. For
convenience of removal of said nut and cutting teeth, which are necessarily subjected
to considerable wear, I preferably make. said chaser of a, composite construction, and
affix thereto the guide-nut, and the thread-cutting tool. This I may do where the
nut or guide-block is inserted through a. mortise in the stem.or bar, and is clamped
therein by a screw. The cutting tools constituting the." chaser” proper, are (or may
be) similarly held in place, or they may have the clamp screws differently-arranged;
but in a well known manner.
For preventing rotation of said chaser-bars in said. head,, (when said bars. are
cylindrical,) may employ ordinary keys, fixed longitudinally in the: bars,, and
sliding in corresponding key-ways formed in said head. But said bars may be of
other, than cylindrical form, and be fitted to slide in correspondingly shaped holes in
the chaser head.
For actuating the chasers, to have the proper advancing movement, corresponding
to the pitch of the thread-cutting tools, I provide a. pattern, or guide-screw, which I
ordinarily arrange rearward of the head, and concentric, to the axis thereof.. This.
pattern is conveniently made hollow, and placed over the stem; being held: in place.
by clamping it in a rear bearing on the head block. When thus placed, its threaded
guide-surface is preferably formed conical, of a taper corresponding to the inclination
of the chaser movement, so that the blocks may properly mesh with, the, said; pattern
thread at all times during the movement, of said. chasers..
This construction and, arrangement while constituting one, part of my present:
invention, is not indispensable to a proper operation of the, chasers, since these may
be connected indirectly with the actuating pattern-thread or cam.

page_text: For retaining the spindle in proper longitudinal position, nuts may be used; also
a holder or flange may be formed on one or both ends of the head. The pattern
serves as a stop in a direction opposing the nuts and flange.
and
The chaser-carrying head and the work-holding chuck have one of them a revolving
motion, relative to the other, at fixed positions longitudinally of a common axis;
during such revolution, the chasers have a movement longitudinally of and at an
inclination to such common axis.
By reason of this peculiar mode of operation, the teeth of the cutting-tool or chaser
follow parallel to the threaded surface after the same manner in which the teeth of the
ordinary plug top follow the threaded surface of a cylindrical bore. And by reason,
also, of this peculiar feature, tapered (or conical) holes are threaded by my improved
machine, with the same ease and economy of power, as straight (or cylindrical) holes
have heretofore been threaded.
It should be clearly understood that the common axis referred to, extends through
the head, and the work to be threaded, and that the line of movement is inclined to
said axis. The cutting teeth of the tool stand adjacent to the work to be
threaded.
On revolving the head the chaser is advanced along the inclined line of movement,
and the teeth along a line parallel thereto, and the thread is chased out in accordance
with the pattern, and of a taper according to the said line of movement. The thread
being finished, the movement of the machine is reversed, and the chasers retracted to
their former position:
Taper threads formed by this method have the same true and smooth surface of
straight threads made by well constructed taps; and are free from the sharp edges or
"nicks" left by the ordinary taper tap when this is reversed to be retracted. In
using the latter kind of tool, all the teeth within the hole are cutting teeth, so that
on reversing the motion a great number of "chips or cuts are suddenly stopped
and broken off, leaving the projecting edges referred to, of a height equal
to the thickness of the chip or cut that was being made by the several teeth
respectively.
"
In pipe-fittings for high-pressures, this irregularity is inimical, and especially
prejudicial to fittings to be used for air and gases under pressure. It is not
necessary to my invention, that the chaser shall be carried by a revolving
spindle; the article to be threaded may be revolved, and the chasers have only an
inclined motion.
THE AUTOMATIC MACHINE.
This form of the screw-cutting machine cuts threads of tapered screws, such as the
threads of pipe-fittings and the like, by means of chasers having an advancing motion
parallel to the threaded surface, and which are automatically reversed and withdrawn
when the thread is completed; it is in the nature of an improvement on the simple
form thereof herein before described.
The framework of this machine may also be of any form and construction suitable
carry the several details. On said frame I place a main bearing and a rear bearing,
and also. a. chuck or work-holder for holding the article to be threaded. The said
bearings may or may not be formed integral with the framework by which they are
supported. Said framework comprises a top-plate carrying the said bearings and
work-holder, a base frame, and uprights. On these several portions are formed or
affixed the bearings for the several shafts and levers as herereinafter set forth.
My improved machine has a revolving spindle, one or more chasers having an
advancing motion at an inclination to the axis of the screw-thread being cut, and
means for so advancing the chasers. The spindle consists (or may consist) of a stem,
and a spindle-head rigidly affixed thereto by usual means. This spindle-head carries
the chaser-actuating stems, and is fitted to revolve in the main bearing, on the frame.
The stem extends rearward from, and furnishes the means for sliding the spindle-head
in its bearing; it being provided with a device for such purpose.

page_text: The spindle is revolved by means of a gear formed thereon, which meshes with the
driving pinion that is fixed on the driving shaft of the machine: which shaft is carried in
suitable bearings, and is provided with a fast pulley, and two reversely-revolving loose
pulleys fitted thereon in a well known manner. Two belts, one of them a crossed-belt,
are employed to drive said pulleys in a well-known way. For properly "shipping"
these belts, a rock-shaft carried in suitable bearings, and provided with two shipper.
levers, said levers being each furnished with the usual belt-guide, is provided.
The said shaft is operated by means of an arm and a connecting rod, said rod being
attached to a crank-pin fixed in the disc of the reversing shaft; which shaft is
journalled in suitable bearings on the framework of the machine, and is furnished
with a hand-lever for operating the same by hand. When the said lever is thrown fully:
over to the left hand, the driving shaft is revolved forwardly: when said lever is
thrown fully over to the right hand the said shaft is reversely revolved; and when
it is in an intermediate position the said driving shaft is at rest.
The screw-cutting tap used in this machine consists or may consist of a central
core or arbor, having a series of grooves adapted to receive the sliding chasers for
cutting the thread. Said arbor is usually fitted to the spindle with a taper, after the i
well known manner of fitting the stems or shanks of "lathe centers" and drill chucks
into their spindles. An ordinary key is usually employed to prevent rotation of
the arbor, in the head, said key being located midway between two adjacent
grooves.
The said grooves are formed longitudinally of the said stems, and the latter are each.
furnished with a driver rigidly clamped or fixed thereto, and firmly engaging with
the chaser. This engagement is usually effected by forming the inner end of the
driver to mesh with the teeth of the chaser. Between the core and the chaser-driving
stems, slots are formed, into which the driver may enter as the stems are drawn back.
Said stems are each fitted with a key, which fits in the said slot, to prevent them
from revolving the stems in practice being made cylindrical to facilitate
construction.
:
For operating the stems in the spindle head; I provide them with collars, between
which I fit the flange of a sleeve, the intermediate part of the stem fitting in a slot
formed in the said flange or disc. The said sleeve slides on the stem of the spindle,
and carries at its outer end a guide-screw, which fits in a guide-nut that is fixed to
the rear bearing by screws or otherwise. The said guide-screw is held in place on
the said sleeve, by a collar fixed to said sleeve in any well-known manner.
pitch of the guide-screw should exactly correspond with the pitch of the chasers
being used in the machine; and when the one is replaced by parts of a different
pitch, the other must be similarly changed.
The
1
:
For sliding the spindle, a sleeve (fitting freely on the afore mentioned sleeve,) is :
rigidly connected by a screw or stud to the stem of said spindle, through a slot formed."
in the last mentioned sleeve. The former of these two sleeves has thereon a collar,
(held in place by check-nuts,) which is carried by and between the two arms of the
rock-shaft: which arms have pivots, entering sockets in said collar. The said shaft
is carried in suitable bearings, and has fixed thereon an arm, connected to the herein--
before mentioned connecting rod, that is operated by the pin in the hereinbefore]
mentioned disc; which pin works in a slot formed in the said rod.
When the said disc is thrown into a position with the pin therein standing in à
line between the reversing shaft, and the pivot which connects the said connecting.
rod to the arm of the rock-shaft, the spindle is held (as by a toggle-joint,) in its
forward position, with the gear that is on the spindle, against the main bearing. On
now turning the said disc to the right, the pin of said disc moves in the slot formed
in the said connecting rod, and does not retract the said rod nor the spindle...
The object of this arrangement is to permit the spindle and chasers, after the latter
has been driven fully forward, to be withdrawn together; so that the chaser points
shall always be supported by the core, and not left projecting beyond the same, as
would obviously be the case if the core were to be retracted by the said movement of
the disc.

page_text: The apparatus for automatically operating the belt-shipping devices, I construct as
follows: On the driving shaft there is formed a traverse-screw or thread, and on this
a clutch-pinion is fitted as a nut. This pinion meshes with a segment which is pivoted
to a bracket depending from the bed plate of the framework. The segment has an
arm whose point (which is preferably a conical roller,) engages between and with the
leaves or wings of the reversing cam that is carried on the cam shaft; said shaft is
journalled in bearings formed on the above mentioned bracket.
The said shaft has an arm fixed thereto, which is attached to a connecting rod, that
is attached at its opposite end to the disc. If, now, the pinion be turned, the segment
arm strikes the cam, turns the cam shaft, and through the connections turns the disc;
and this disc through its other connections described, operates the belts either to
reverse or to stop the machine, as the case may be.
The pinion is revolved at the proper time by clutch-collars, adjustably fixed on the
threaded projecting part of the main shaft. To prevent the pinion sticking against
the said collars, (owing to the firmness of the said thread,) I form thereon oppositely-
disposed clutch-faces, and corresponding faces on the collars. By means of this
construction, a little space may be left between the said parts, so that all tendency of
said parts to adhere, or stick together, is avoided.
The driving shaft being revolved in one direction, the pinion, (this being loosely
fitted thereon,) is carried end wise until it engages with one of the said collars, and
through this collar is turned with the shaft, to actuate the several connections
described and reverse the machine.
The segment arm works between the two wings of the cam, as aforesaid, but it
should be understood that the said wings are not parallel throughout their length.
The exact form of construction, and the mode of operation of the said cam, will be
more particularly described in the complete specification in connection with suitable
drawings to be filed therewith.
The chasers, in practice, are made of considerable length, and are driven by the
engagement of the driver with the chaser-teeth near the point of the chaser. By this
means, the chaser may be moved out as the point wears away, and thus nearly the
whole length of the chaser ultimately utilized.
Dated at Hartford, State of Connecticut, U.S.A., this 31st day of October
COMPLETE SPECIFICATION.
A Screw-cutting Machine.
I, FRANCIS HENRY RICHARDS, of 64 Farmington Avenue, Hartford, in the County
of Hartford, and State of Connecticut, one of the United States of America,
Mechanical Engineer, do hereby declare the nature of this invention and in what
manner the same is to be performed, to be particularly described and ascertained in
and by the following statement :-
This my improved screw-cutting machine cuts the threads of tapered screws, such
as the threads of pipe-fittings and the like, by means of chasers having an advancing
motion parallel to the threaded surface.
This machine is adapted to be constructed in two forms, of which one is a simple
form adapted to be operated by hand, and the other a more fully developed form,
operating automatically.
In the drawings accompanying and forming a part of this Specification,
Fig. 1 is a plan view, partially in section, of a screw-cutting machine of the simple
form.
Fig. 2 is a front elevation of the machine.
Fig. 3 is an elevation of the front end of the spindle and head-block.
Figs. 4 and 5 are views illustrating the method of cutting the screw-thread.
Fig. 6 is a plan view, with some details broken away, of a screw-cutting machine
constructed to operate automatically.

page_text: Fig. 7 is an elevation of the left hand end of the same.
Fig. 8 is an elevation of the right. hand end of the machine.
Fig. 9 is a vertical transverse section forward of the rear spindle-bearing.
Fig. 10 is a front elevation, partially in section, shewing the parts in position ready
for operation.
Fig. 11 is a similar view shewing the spindle thrown forward and the machine
started operating.
--
Fig. 12 is another similar view shewing the parts after the completion of the thread,
and after the movement of the chasers has been automatically reversed.
Fig. 13 shows, in four enlarged detail views drawn in projection, the reversing-
cam.
Fig. 14 is a view of the reversing-pinion and adjustable stop-collars on the threaded.
shaft.
Fig. 15 is a side view, partially in section, of one of said collars.
Fig. 16 is a longitudinal sectional view of the spindle-head and threading-tool, and
shows these parts in the position shown in Fig. 10.
Fig. 17 is a similar view in which the positions of the several details correspond to
those in Fig. 11.
Fig. 18 is a similar view in which the said positions correspond to those in Fig. 12.
Fig. 19 is a front view of the parts in Fig. 16 and drawn in projection thereto.
Fig. 20 is a section in line c c, Fig. 17.
Fig. 21 is a section in line 6 b, Fig. 18.
. Similar characters designate like parts in all the figures.
In describing the invention, I will first refer to the simple form. The bed of this.
machine, which is designated by A, may be of any suitable form and proportions.
adopted to carry the several essential details of the machine. On said bed, I place
the head block B, and also the chuck or work-holder C for holding the article D.to be
threaded. This article, as shown in the drawings, is an ordinary cast-iron pipe:
coupling; but a variety of other well known articles may be properly threaded in my
machine, and for the said chuck C, I may use any well-known device for like, purpose.
The bead block may or may not be formed integral with the bed by which it is
supported.
My improved machine has a revolving spindle, one or more chasers having an
advancing motion at an inclination to the axis of the screw-thread to be cut, and
means for so advancing the chaser during the revolution of said spindle. The spindle
consists (or may consist) of the stem T and the spindle-head H. This head carries
the chasers R, and is fitted to revolve in a suitable bearing N on the said head-block B.
The spindle stem T extends rearward from, and furnishes the means for revolving the
spindle-head H, said stem being furnished with a crank K or other well-known device:
for such purpose. The chaser consists of a longitudinally-sliding part provided with
thread-cutting teeth, and having a guide-nut through which the motion is imparted.
thereto. For convenience of removal of said nut, and cutting teeth, which are
necessarily subjected to considerable wear, I preferably make said chaser of a com-
posite construction, and affix the guide-nut 3 and the thread-cutting tool 4 to the
chaser stem or bar 5. This I may do where the nut or guide-block 3 is inserted
through a mortise in the stem or bar 5, and is clamped therein by the screw 6. The
cutting tools 4, constituting the "chaser" proper, are (or may be) similarly held in
place; but in the drawings these parts have the clamp screws differently arranged,
but in a well-known manner.
For preventing rotation of said chaser-bars 5 in said head H, (when said bars are
cylindrical,) I may employ ordinary keys 7, fixed longitudinally in the bars, and
sliding in the corresponding key-ways 8, formed in said head; but said bars 5 may
be of other, than cylindrical form, and be fitted to slide in correspondingly shaped
holes in the chaser head.
For actuating the chasers, to have the proper advancing movement, corresponding.
to the pitch of the thread-cutting tools 4, I provide a pattern, or guide-screw, which
I ordinarily arrange rearward of the head H and concentric to the axis thereof. This.

page_text: pattern P is conveniently made hollow, and placed over the stem T, being held in place
by clamping it in the bearing M on the head block B, or otherwise as may be
preferred. When thus placed, its threaded guide-surface 10 is preferably formed
conical, of a taper corresponding to the inclination of the chaser movement, so that
the guide blocks 3 may properly mesh with the said pattern thread 10 at all times
during the movement of said chasers.
This construction and arrangement, while constituting one part of my present
invention, is not indispensable to a proper operation of the chasers, since these may
be connected indirectly with the actuating pattern-thread or cam 10.
"
For retaining the spindle in proper longitudinal position, nuts 12 may be used;
also, the holder or flange 13 may be formed on one or both ends of the head H. As
shown the pattern P serves as a stop in a direction opposing the nuts and flange.
The chaser-carrying head H and the work-holding chuck (have one of them a
revolving motion, relative to the other, at fixed positions longitudinally of a common
axis; and during such revolution, the chasers have a movement longitudinally of
and at an inclination to such common axis.
By reason of this peculiar mode of operation, the teeth of the cutting-tool or chaser
follow parallel to the threaded surface after the same manner in which the teeth of
the ordinary plug tap follow the threaded surface of a cylindrical bore. And by
reason, also, of this peculiar feature, tapered (or conical) holes are threaded by my
improved machine, with the same ease and economy of power, as straight (or
cylindrical) holes have heretofore been threaded.
This will be clearly understood from Figs. 4 and 5 in which the dotted line 15
represents the common axis referred to, extending through the head H and the
article D to be threaded, and that the line of movement is inclined to said axis.
The cutting teeth of the tool stand adjacent to the work to be threaded. The dotted
line 16 is the line of movement inclined to the said axis of the chaser. In Fig. 4
the cutting-teeth 20 of the tool 4 stand adjacent to the coupling D to be threaded.
On revolving the head H the chaser is advanced along the inclined line 16 and the
teeth 20 along the parallel line 18, and the thread 22 is chased out in accordance
with the pattern P and of a taper corresponding to the inclination of line 16 to the
axis 15. The thread 22 being finished, the movement of the machine is reversed,
and the chasers retracted to their former position.
THE AUTOMATIC MACHINE.
This form of the screw-cutting machine cuts threads of tapered screws, such as
the threads of pipe-fittings and the like, by means of chasers having an advancing
motion parallel to the threaded surface, and which are automatically reversed and
withdrawn when the thread is completed; it is in the nature of an improvement
on the simple form thereof herein before described.
The framework of this machine which is designated in a general way by A, may
also be of any form and construction suitable to carry the several details. On said
frame I place the main bearing B the rear bearing B', and also the chuck or work-
holder C, for holding the article D to be threaded. The said bearings may or may
not be formed integral with the framework by which they are supported. As shown,
this framework comprises the top-plate 100, carrying the bearings B and B and
work-holder C, the base frame 102, and the uprights 103 105 106 108. On these
several portions are formed or affixed the bearings for the several shafts and levers as
hereinafter set forth.
My improved machine has a revolving spindle, one or more chasers having an
advancing motion at an inclination to the axis of the screw-thread being cut, and
means for so advancing the chasers. The spindle consists (or may consist) of the
stem T and the spindle-head H, rigidly affixed thereto by usual means, (not shown)
which means may consist in a driving fit of the stem in said head, supplemented by
a key, or by a pin cross-wise through the head and stem. This spindle-head carries
the chaser-actuating stem R, and is fitted to revolve in the main bearing B on the

page_text: frame A. The stem T extends rearward from; and furnishes the means for sliding
the spindle-head H in its bearing, it being provided with a device for such
purpose.
The spindle is revolved by means of the gear G formed thereon, which meshes
with the driving pinion 30, that is fixed on the driving shaft 32, of the machine:
which shaft is carried in suitable bearings as shown, and is provided with the fast
pulley 36, and the reversely-revolving loose pulleys 35 and 37, fitted thereon in a
well known manner. Two belts, 33 and 34, one of them a crossed-belt, are employed
to drive said pulleys in a well-known way. For properly "shipping" these belts, a
rock-shaft 8 is carried in suitable bearings 39 and 40 on posts 106 108, and is
provided with two shipper levers 41 42, one for each belt 33 and 34, respectively,
said levers being each furnished with the usual belt-guide 43.
The said shaft 38 is operated by means of the arın 44 and the connecting rod 46,
said rod being attached to said arm at 45, and at 47 to a crank-pin fixed in the
disc 48 of the reversing shaft 50, which shaft is journalled in suitable bearings 51 53.
on the posts 103 and 105 respectively of the machine. This shaft is furnished with
a hand-lever 54, for operating the same by hand. The three positions of said hand-
lever are shown in Figs. 10, 11, and 12. In Fig. 11 the lever 54 is thrown fully
over to the left hand, and the shaft 32 is revolving forward by belt 33 on pulley 36,
the belt 34 being on pulley 37. In Fig. 12 the lever 54 is thrown fully over to the
right hand and the shaft 32 is reversely revolved by belt 34 on pulley 36, the belt 33
being now on pulley 37. In the intermediate position in Fig. 10 the belts are both.
ou loose pulleys, and the shaft 32 is at rest.
The screw-cutting tap used in this machine consists or may consist of a central
core or arbor 2, having a series of grooves 4, adapted to receive the sliding chasers 3
for cutting the thread. Said arbor is usually fitted to the spindle with a taper, after
the well known manner of fitting the stems or shanks of "lathe centers" and drill
chucks into their spindles. An ordinary key not shown is usually employed to
prevent rotation of the arbor 2 in the head H, said key being located midway between
two adjacent grooves 4.
The said grooves 4 are formed longitudinally of the said stems R, and the latter
are each furnished with a driver 5 rigidly clamped or fixed thereto, and firmly
engaging with the chaser. This engagement is usually effected by forming the inner
end of the driver to mesh with the teeth of the chaser. This feature is well shown
in Fig. 16. Between the core 2 and the chaser-driving stems R, slots 6 are formed,
into which the driver may enter as the stems are drawn back. Said stems are each
fitted with a key 7, which fits in the said slot 6, to prevent them from revolving: the
stems in practice being made cylindrical to facilitate construction.
For operating the stems R in the spindle head H, I provide them with collars 8
and 9 between which I fit the flange 10 of a sleeve S, the intermediate part 11 of
the stem fitting in a slot 12 formed in the said flange or disc. The said sleeve S
slides on the stem T of the spindle, and carries at its outer end the guide-screw 15,
which fits in the guide-nut 16, that is fixed to the rear bearing B₁ by screws 13.
or otherwise. The said guide-screw 15 is held in place on the said sleeve S by a
collar 17, fixed to said sleeve in any well-known manner. The pitch of the guide-
screw 15 should exactly correspond with the pitch of the chasers being used in
the machine; and when the one is replaced by parts of a different pitch, the other
must be similarly changed.
For sliding the spindle, a sleeve 20, (fitting freely on the aforementioned sleeve S,)
is rigidly connected by a screw or stud 21 to the stem T of said spindle, through a
slot 19, formed in the last mentioned sleeve S. The sleeve 20 has thereon a
collar 22, (held in place by check-nuts 23,) which is carried by and between the two
arms 24 of the rock-shaft 25, which arms have pivots 26 entering sockets in said
collar 22. The said shaft 25 is carried in suitable bearing 27 28, and bas fixed
thereon an arm 29, connected at 60 to the hereinbefore mentioned connecting rod. 61,
that is operated by the pin 61 in the hereinbefore mentioned disc 48, which pin works
in the slot 62 formed in the said rod,

page_text: When the said disc 48 is thrown into the position in Fig. 11, the pin 61 therein
standing in a line between the reversing shaft 50 and the pivot 60, which connects
the said connecting rod to the arm of the rock-shaft, the spindle is. held (as by a
toggle-joint,) in its forward position, with the gear G that is on the spindle, against
the main bearing B. On now turning the said disc to the right, as in Fig. 12 the
pin 61. of said disc moves in the slot 62 formed in the said connecting rod, and does
not retract the said rod 64 nor the spindle.
The object of this arrangement is to permit the spindle and chasers, after the latter
has been driven fully forward, as in Fig. 12, to be withdrawn together; so that
the chaser points shall always be supported by the core 2, and not left projecting
beyond the same, as would obviously be the case if the core were to be retracted by
the said movement of the disc 48.
The apparatus for automatically operating the belt shipping devices, I construct as
follows: On the driving shaft 32 there is formed a traverse-screw or thread 70, and
on this the clutch-pinion 72 is fitted as a nut. This pinion meshes with the segment 74
which is pivoted at 71 to a bracket 73, depending from the bed plate 100 of the
framework. The segment has an arm 75, whose point 76 (which is preferably a
conical roller,) engages between and with the leaves or wings 77 78 of the
reversing cam M that is carried on the cam shaft 80; said shaft is journalled in
bearings 79.81 formed on the above mentioned bracket 73.
The said shaft 80 has an arm 84 fixed thereto, which is attached at 83 to a connecting
rod 85, that is attached at its opposite end at 86 to the disc 48. If, now, the
pinion 72 be turned, the arm 76 strikes the cam M, turns the cam shaft 80, and
through the connections turns the disc 48, and this disc through its other connections
described, operates the belts either to reverse or to stop the machine, as the case
may be.
The pinion 72 is revolved at the proper time by clutch-collar 88 90, adjustably
fixed on the threaded projecting part 70 of the main shaft 32. To prevent the
pinion sticking against the said collar, (owing to the firmness of the said thread 70),
I form thereon oppositely-disposed clutch-faces 92 94 and corresponding faces 93 95
on the collars 88 90 respectively, (see Fig. 14). By means of this construction, a
little space may be left between the said parts at 96, so that all tendency of said
parts to adhere, or stick together, is avoided.
The driving shaft 32 being revolved in one direction, the pinion, (this being loosely
fitted thereon,) is carried endwise until it engages with one of the said collars 88 or 90
and through this collar is turned with the shaft, to actuate the several connections
described and reverse or stop the machine.
The arm 75 works between the two cam-wings 77 and 78, as aforesaid, but it will
be understood from Fig. 13, that the said wings are not parallel throughout their
length. When the machine is running forward, the arm 75 stands (at 75* in Fig. 13)
against the wing 78, as in Fig. 11, and thus continues until the pinion 72 engages
collar 88 and throws the arm 75 to its position in Fig. 12, corresponding to 75 in
Fig. 13, and the machine is reversed. The arm 75 stands as last stated until the
said pinion engages collar 90, when said arm is thrown over to its position in Fig. 10,
corresponding to 75° in Fig. 13, and the machine is stopped. On starting
the machine again, the cam M being operated by hand, the arm 75 passes directly
from. position 75° to position 75, after which the said series of movements are
repeated. The extent of the movement of the machine before the same is reversed
or stopped is governed of course by the distance apart at which the collars 88 and 90
are set on the inain shaft, and this distance in practice is adjusted experimentally to
correspond with the length of thread to be cut.
The chasers 3 in practice, are made of considerable length, as shown, and are
driven by the engagement of the driver 5 with the chaser-teeth near the point of the
chaser. By this means, the chaser may be moved out as the point wears away, and
thus nearly the whole length of the chaser being ultimately utilized.
machine, the chasers being retracted, as in Fig. 10 and 16, the. operator clamps in
In using the

page_text: position the piece D to be threaded, and then throws the handle 51 from its position
in Fig. 10 to that in Fig. 11. This drives forward the spindle H and projects the point
of the core 2 into said piece D, as in Fig. 17, at the same time shifting the belts, as
aforesaid, to start the machine. Next the chasers as they are revolved are fed
forward by the guide or lead screw and chase out the thread in said piece D. This
operation continues until the work is finished, as in Fig. 18, when the collar 88 engages.
the pinion 72 and causes the machine to be reversed, as set forth. The spindle, the
sleeve S, the driver R, and the chasers then move back together to their original
position, when the machine is stopped, as aforesaid, by the belt-shipping devices and
stands ready for another operation.
Taper threads formed by this method have the same true and smooth surface of
straight threads made by well constructed taps, and are free from the sharp edges or
"nicks" left by the ordinary taper tap when this is reversed to be retracted. In.
using the latter kind of tool, all the teeth within the hole are cutting teeth, so that
or cuts are suddenly stopped
on reversing the motion a great number of "chips
and broken off, leaving the projecting edges referred to, of a height equal
to the thickness of the chip or cut that was being made by the several teeth.
respectively
"
In pipe-fittings for high-pressures, this irregularity is inimical, and especially
under
gases
prejudicial to fittings to be used for air and
pressure.
Having now particularly described and ascertained the nature of my said inven-
tion, and in what manner the same is to be performed, I declare that what.I.
claim is:
1. In a machine for forming tapering internal screw-threads, the use of a disc
or head, carrying chasing bars, made to revolve and advance, in manner substantially
as herein shewn and described.
2. In a machine for forming tapered internal screw-threads, the use of a disc or
head, carrying chasing bars, made to revolve and advance, in combination with a
stationary chuck or work holder, in manner substantially as herein shewn and
described.
3. In a machine for forming tapered internal screw threads, the use of an advancing
disc or head, carrying chasing bars, in combination with a revolving chuck or work
holder; all as shewn and described.
4. The combination, in a screw-cutting machine, of a work-holding chuck, a
revolving chaser-carrying head, sliding chasers carried by said head and constructed
and arranged to have a movement at an inclination to the axis of revolution of said
head, and a pattern connected to slide said chaser correspondingly to the pitch of the
thread cutting tool constituting a part of the chaser, all substantially as described.
5. The combination, in a screw-cutting machine, of the revolving head, sliding
chasers carried by, and at an inclination to the axis of said head, said chasers being
furnished with thread-cutting tools, and a pattern-screw operatively connected with
said chasers by guide-nuts, substantially as described.
6. The combination, in a screw-cutting machine, of the revolving non-sliding
head H, the chaser bars carrying thread cutting tools, the pattern thread P, and guide
nuts removably fixed in said bars, and meshing with said pattern thread, substantially
as described.
Dated this Sixteenth day of December A.D. 1990
TASKER & CROSSLEY,
Huddersfield & Halifax, Agents.