Improvements in or relating to Screwing Devices.
Year: 1895

page_text: Date of Application, 18th Sept., 1895
Complete Specification Left, 18th June, 1896-Accepted. 25th July. 1896
PROVISIONAL SPECIFICATION.
Improvements in or relating to Screwing Devices.
I, CHARLES JAMES DALE, of New St. Pancras Station, Euston Road, County
of Middlesex, Stoneware Manufacturer, do hereby declare the nature of this
invention to be as follows:-
This invention relates to screwing devices applicable to various materials, but as
it is more particularly designed for use with plastic materials I will describe it in
its application to such materials, and particularly for tapping porcelain and similar
insulators for electrical purposes. The invention may be applied in two ways; in
one the insulator itself is rotated during the screwing process and the tap is not
rotated, and in the other the tap is rotated and the insulator held stationary. I
will describe the latter arrangement first:
I prefer to make the apparatus in such a form that it can be applied to an
ordinary potter's or other lathe, although if desired the whole device may be made
self-contained and capable of being attached to standards, a bench or other support.
When attached to the lathe I employ a carriage adapted to run upon the bed or.
gantry of the lathe and preferably operate it by means of a lever pivotted to the
bed or bench and capable of imparting to the carriage the necessary amount of
travel in either direction. The carriage is part of or carries a head stock in which
is a screw something like the movable poppet of an ordinary lathe, but the screw
is preferably made of the same pitch as the thread to be screwed so that as the tap.
carried by the poppet head is moved forward the speed and rotation correspond
with the pitch of its own thread. The poppet may be provided with an ordinary.
hand wheel or other handle for turning it, and has preferably a spring detent or
equivalent for holding the tap. Suitable stops may be provided both for the
poppet head and for the screw conveniently one in the bed of the lathe and the
other at the end of the nut in the head, or in place of a stop in the poppet head
the length of travel may be regulated by the length of the screw and nut.
using this apparatus the insulator is chucked and rotated in the ordinary manner
and a drill inserted in the poppet head and used for boring the hole after which
it is withdrawn, the drill removed from the spindle of the poppet and the tap
substituted and the tap then after being moved forward by the lever is turned by
the handle of the poppet into the insulator which for this part of the process is
kept stationary. When the thread is completed the handle is reversed, the tap
withdrawn, and the poppet head drawn back by the lever when the same process
can be repeated with another insulator.
In
In another arrangement with the insulator fixed, a travelling carriage is provided
with a spindle and tap similar to those previously described, but without the screw
and hand wheel a bevel or equivalent wheel being placed upon the back end of the
spindle; this gears with a horizontal bevel, crown or equivalent wheel carried upon
a vertical spindle at the lower end of which is a spur pinion engaging with a fixed
rack upon the lathe bed. A lever similar to that previously described may be
employed for traversing the carriage and head. In operation the spindle is first
provided with the drill and moved forward, the spur pinion engaging with the rack
is thus turned rotating its spindle and the bevel gearing, and thus rotating the
drill. An increased speed for drilling may be obtained by rotating the chuck in
the ordinary manner by the spindle in the fixed head-stock. When the hole is
bored the carriage is drawn back by the lever the drill removed and the tap

page_text: inserted and the screwing effected by moving the lever again, driving the carriage
forward and rotating the tap in the same way as the drill was previously rotated,
the rack, pinion, and bevel-wheels rotating the tap at the speed appropriate to the
pitch of the thread on the tap and the rate at which the carriage travels. Should
the gearing as above described not impart, sufficient speed of rotation to the tap
this speed may be obtained by introducing multiple gearing or the toothed rack
instead of being a fixture may be arranged to slide and the lever may be s0
connected with it as to cause the rack to travel in the opposite direction to that of
the carriage, thus increasing the speed of rotation of the spur pinion and other
gearing.
Where the rotation for screwing takes place in the insulator and not in the tap
the following apparatus may be employed. The carriage carries a holder for the
tap and is reciprocated upon the lathe bed by the lever as before but during the
screwing operation the tap is not permitted to rotate.
A fixed detent may be
secured to the lathe bed or other support and the head is provided with a spring-
controlled arm or equivalent which carries a half nut so arranged that while the
end of the arm is underneath the fixed detent the nut is in gear with the ordinary
leading screw of the lathe, but when it passes the detent the spring draws the arm
back and releases the nut from the leading screw and so stops the forward travel
of the carriage. At the same time the arm releases another spring-controlled
detent which while in engagement with the tap holder prevents the tap from
turning, but when released allows the tap to rotate so that the instant the screwing
operation is completed the head ceases to advance by reason of the nut being
released from the leading screw and the tap is allowed to rotate by reason of its
detent being withdrawn. The lever as before may be employed for the adjustment
of the carriage and head. Instead of having an independent spring-controlled
detent for preventing the rotation of the tap this may be effected by operating the
tap detent by the same arm or device which operates the half nut of the leading
screw.
In all these arrangements means other than the lever may be employed for the
quick adjustment-gearing for example.
The details may be varied without departing from the spirit of the invention.
Dated thie 18th dow of Sentember 1895
BOULT & WADE,
Agents for the Applicant.
Improvements in or relating to Screwing Devices.
I, CHARLES JAMES DALE of New St. Pancras Station, Euston Road, County
of Middlesex, Stoneware Manufacturer, 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 invention relates to screwing devices applicable to various materials, but as
it is more particularly designed for use with plastic materials I will describe it in
its application to such materials, and particularly for tapping porcelain and similar
insulators for electrical purposes. The invention may be applied in two ways; in
one the insulator itself is rotated during the screwing process and tap is not rotated,
and in the other the tap is rotated and the insulator held stationary.
The invention will be best understood by reference to the accompanying drawings
in which
Fig. 1 is an elevation of one form of the improved tapping or screwing machine,
the screw forming device in this arrangement being adapted to rotate while the
work is stationary.

page_text: g
PIRD showu party in norizontal Section
represented in Fig. 1.
portion OF
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Fig. 3 is a vertical section of the upper part of the poppet head shown in Fig. 1
drawn to a larger scale than Figs. 1 and 2.
Figs. 4 and 5 are respectively an elevation and a plan of an alternative arrange-
ment of the tapping or screw-cutting mechanism shown in Figs. 1 and 3.
Fig. 6 is a view partly in vertical section on the line 6-6 of Fig. 4 and partly
in elevation.
Fig. 7 is a view partly in elevation and partly in vertical section of another form
of the improved tapping, or screwing machine, the screw forming device in this
arrangement being held stationary while the work is rotated.
Fig. 8 is a plan of Fig. 7 and
Fig. 9 is a vertical section on the line 9-9 of Fig. 7 and
Fig. 10 is a view partly in vertical section and partly in elevation.
Fig. 11 is a plan and Fig. 12 an end elevation partly in section of a modification
hereinafter fully described.
Like letters indicate like parts throughout the drawings.
In carrying my invention into practice 1 prefer to make the apparatus in such a
form that it can be applied to an ordinary potter's or other lathe such as shown in
Figs. 1 and 2, although, if desired, the whole device may be made self-contained
and capable of being attached to standards, a bench or other support. When
attached to a lathe A as in Figs. 1 and 2 I employ a carriage B adapted to move
on the bed or gantry A 1 of the lathe, and preferably operate it in either direction
by a lever C pivotted to the lathe bed A 1 conveniently by means of an adjustable
pivot or fulcrum C1 the lever C being connected with the carriage by a link C 2.
The carriage B is formed in part with or carries a head-stock or poppet-head B 1
in which is a screw D something like the movable poppet of an ordinary lathe, but
the screw D is preferably made of the same pitch as the thread to be formed so
that as the tap E, Figs. 1 and 3, carried by the poppet bead, is rotated, it will at
the same time be moved forward at a speed corresponding to the pitch of its thread.
The screw, or as it is hereinafter termed, the poppet D, may have secured to its
back or outer end a hand-wheel or equivalent D 1 for turning it and at its inner
end it is formed with a conveniently tapered socket D 2 for receiving the stem El
of the tap E, this socket if desired being provided with a spring detent or equivalent
(not shown in the drawings) for retaining the tap therein until positively disengaged
therefrom. In Figs. 1 and 3 I have represented the tap E as provided with a pin
or projection E 2 adapted to engage with a notch or recess D 3 in the end of the
poppet D and, as a ready means of forcing the tap E out of the socket should it
become jammed or otherwise fixed therein, I provide a screwed rod F passing
axially through the poppet D and provided with a knob or handle F1 by means
of which latter the rod may be rotated independently of the poppet D and thereby
caused to press against the end of the tap stem E 1.
Suitable stops may be provided both for the carriage B or poppet head B1 and
for the poppet D; the stops for the carriage may conveniently be in the form
of a plate G bolted or otherwise adjustably secured to the lathe bed A 1,
and the end B 2 of the poppet-head-nut B 3 may constitute the stop for the
poppet D.
Instead of the stops B 2 and G last described any other suited to the requirements,
may be employed; for example a collar adjustable on the outer or back end of the
poppet D may be provided for the purpose. To prevent dirt or the like having
access to the thread of the poppet DI prefer to use a bush B 5 adapted to prevent
any of this thread being exposed when the poppet is wound back, this bush being
secured in the poppet-head B1 conveniently by set screws B6 similar to those
used for securing the nut in position.
In drilling say an insulator X it is secured in a suitable chuck H and the lathe
is started. The lever C is then operated so as to feed the drill into the insulator
this operation continuing until the poppet-bead B1 is prevented from moving

page_text: .
further by the carriage B thereof abutting against the stop G, the drill then having
penetrated the insulator to the required depth, viz. :-as far as the line X1 Fig. 1
or this limit of penetration of the drill may be determined by a collar or equivalent
on the drill coming into contact with the end of the insulator. The poppet-head B 1
is then moved away from the insulator by the lever C, after which the lathe may
be stopped. The drill is then removed from the socket D2 and the hand wheel D 1
rotated in the direction necessary to move the poppet D farther away from the
insulator this motion being terminated as soon as there is sufficient room to insert
the tap E.
The tap E is then inserted in the socket D 2, and the poppet-head B 1, by means of
the lever C is moved towards the insulator until stopped by the stop G. The lathe
is then positively prevented from rotating in any convenient manner, as for example,
by the operator placing his foot on the treadle if the lathe be a treadle-operated
one. The hand-wheel D1 is then rotated so as simultaneously to rotate the tap E
and move it into the then-stationary insulator the recess x 2 of which is thereby
screw-threaded this operation being terminated when the end of the tap E reaches
the recess end a 1, by means of a collar or equivalent on the tap abutting against
the end of the insulator.
After this the hand wheel D 1 is rotated in the reverse direction and the tap
thereby unscrewed and withdrawn from the screwed insulator; this insulator may
then be removed from the chuck and a fresh one substituted for it and the same
process immediately thereafter repeated.
The collars or stops on the drill and tap may be adjustable so as to provide for
the drilling and tapping of holes of varying depths.
In the arrangement shown in Figs. 4, 5 and 6 in which similarly to that previously
described, the insulator or work is stationary while the screw-thread is being
formed, the poppet head B1 is provided with a socketted shaft or poppet D
somewhat similar to the previously described poppet D but without the screw-
thread. This poppet or shaft D is free to rotate but not move longitudinally in
the poppet head B1 and on its back end is secured a bevel or equivalent wheel D4
which gears with a horizontal bevel crown or equivalent wheel J secured upon a
vertical spindle J 1 on whose lower end is fixed a spur wheel J 2 engaging with a
rack J 3 fixed to the lathe bed A 1. A lever C similar to that shown in Figs. 1 and 2
is connected by a link C 2 to the poppet head B 1 so that the latter may be moved
backwards and forwards along the lathe bed A 1.
In the operation of the last described apparatus a drill is first fitted in the
spindle D and afterwards moved up to its work by means of the lever C during
which motion the pinion J 2 by being in engagement with the rack J 3, causes the
spindle J 1 to be rotated and consequently, through the wheels J D4 and spindle D
causes the drill also to rotate. If desired the work may be secured against rotation
during this drilling operation or to increase the speed for drilling it may be rotated
in the ordinary way by the lathe mandrel, the work and the drill then being
simultaneously rotated in opposite directions.
After the hole is bored, the poppet head B1 is drawn back by means of the
lever C, the drill removed from the spindle D and the tap inserted therein, the
screwing afterwards being effected by moving the tap up to the work (which is
then prevented from rotating) by means of the lever C. During this latter
operation the tap is rotated in the same way as the drill was previously rotated at
the speed appropriate to the pitch of the tap-thread and the rate at which the
poppet head B 1 travels, the gearing D 4 J J 2 J 3 being so proportioned or arranged
as to properly secure this result. Should the gearing arranged as last described
not rotate the tap quickly enough the necessary increase may be provided by
introducing multiplying gearing or, the toothed rack J 3 instead of being a fixture
may be arranged to slide and the lever C may be so connected to it as to cause the
rack to travel in the opposite direction to that of the carriage, thus increasing the
speed of rotation of the gearing J 2 J 1 D 4. Inversely the speed of rotation of
the tap E may be decreased in relation to its longitudinal travel of the poppet

page_text: head, by introducing decreasing gear or by causing the toothed rack to travel in
the same direction as, but at a different speed to, that of the poppet head.
When the rotation for screwing takes place in the insulator and not as in the
previous examples in the tap, the apparatus shown in Figs. 7 8 and 9 may be
employed. In this apparatus the carriage B carries a tap-holder D which, when
released as hereinafter described is capable of rotating independently of the carriage,
but at no time is it free to move in a longitudinal direction independently of the
carriage. The carriage B is reciprocated on the lathe-bed A 1 by a lever C as-
in the preceding examples and during the screwing operation the insulator is:
rotated by the lathe mandrel, and the tap and tap-holder are prevented from
rotating by a spring controlled detent K Fig. 9. A fixed detent L may be secured
either as shown in the drawings to the lathe-bed A 1, or to any other convenient
support, and to the carriage B is pivotted an arm or equivalent M which, by one.
or more links M 1, is connected to a half-nut N adapted to engage with the ordinary
leading screw NI of the lathe. A spring M 2 connected at one end to the arm M
and at the end to the carriage B or poppet head B 1 constantly tends to disengage
the half-nut N from the leading screw N 1. The free end of the arm M is adapted
to engage with the fixed detent L in the manner shown in Figs. 8 and 9 and when
it is thus engaged the half-nut is retained in engagement with the leading screw N 1;.
as soon however as the arm M leaves the detent L the spring M 2 draws it upwards
and thereby releases the half-nut N from the leading screw NI, the forward
movement of the carriage consequently ceasing at the same instant. At this.
moment also, the spring-controlled detent K is released by the outward movement
of an arm M 3, formed conveniently in part with the arm M; the two arms M M 3
constitute what is hereinafter referred to as a bell-crank lever. As soon as the
bell-crank lever M M 3 is released and the half-nut N thereby disengaged from the
leading screw as before described, the tap holder D is also released by the outward
movement of the detent K under the influence of its spring K 1 whereby the tap E.
is free to rotate along with the work or insulator so that the instant the screwing
operation is completed the carriage B ceases to advance by reason of the half nut N
being released from the leading screw N and the tap E is allowed to rotate by
reason of the detent K being disengaged from the tap-holder D. The adjustment
of the carriage B may be effected by a lever C and link C2 as in the before.
described examples.
In the apparatus represented in Figs. 10, 11 and 12 I mount the carriage B so
as to be adjustable along the lathe bed Al as in the previously-described examples
and the upper part or poppet head B 1 so as to be adjustable on the carriage in a
direction transverse to that of the carriage itself. The poppet D in this example
is mounted in the head B 1 and its exterior is screw-threaded and engages with the
nut B 1 in substantially the same manner as that represented in Fig. 3. Within
this poppet Dhowever I form a key-way D5 with which engages a key or feather O
secured in a shaft 01 on whose outer end is fixed a spur pinion 02 engaging with
an internally-toothed wheel P. The shaft O1 is prevented from moving end wise
by a fixed yoke Q which fits between a shoulder O 3 on the shaft, and the inner side
of the spur pinion O2 as shown in Fig. 10. The yoke Q may also serve to limit
the outward movement of poppet D for which purpose the outer end of the latter
would be caused to abut against the yoke when the limit of its outward motion is
reached. The internally toothed wheel P is pivotted on a stud PI secured to the
poppet head B1 and it is also provided with a handle P 2 by means of which it may
e readily rotated.
The inner end of the poppet D is provided with a tap-holder or socket D2 as in
he previous examples, and at a suitable distance at the back of this socket the
oppet head B1 is provided with a socket B4 Figs. 11 and 12 for supporting the
rill. The transverse movement allowed to the poppet head is just sufficient to
nable either of the sockets D2 or B 4 to be brought directly into line with the
athe mandrel, suitable stops R being provided for preventing the poppet head
rom being moved beyond these two limits. To lock the poppet head in either of

page_text: its two positions of adjustment I form two holes or recesses S S 1 in the upper face
of the carriage B, and in the poppet head I mount a spring controlled bolt T
which by means of a spring T1 is forced into engagement with the holes, S SI
when the latter are beneath the bolt. To release the bolt T from the holes, S S 1
I provide a frame or lever T2 pivotted at T 3 to the poppet head and the forked or
slotted arm T 5 of which engages with the head T 6 at the upper end of the bolt T.
At its front part the lever T2 is provided with a handle T 7 which serves for
raising the bolt T out of engagement with the holes S S 1 and as a ready means
for moving the poppet head on the carriage B after the bolt has in this manner
been released.
The carriage B may be operated by means of a hand lever C and link C 2 in the
same manner as before described in connection with the other machines. When
the drilling is to be effected the drill socket B4 is brought into line with the
then-rotating lathe mandrel and the drill is advanced and withdrawn by means of
the hand lever C as in the previously described drilling operations. The handle T 7
is then depressed so as to release the bolt T from the holes S1 and, by means of
this same handle, the poppet head B1 is then pushed backwards so as to bring the
tap (fixed in the socket D 2) directly into line with the lathe mandrel which, for
the subsequent tapping operation is not allowed to rotate. The bolt T then
automatically engages with the hole S after which the wheel I' is rotated and
consequently the tap is simultaneously rotated and advanced into the insulator or
work. At the completion of this tapping operation the wheel P is rotated in the
reverse manner and the tap thereby rotated in and withdrawn from the insulator.
The before described apparatus may be modified without departing from the
spirit of the invention for example instead of having in the arrangement shown in
Figs. 7, 8 and 9 an independent spring-controlled detent K for preventing the
rotation of the tap, this function may be fulfilled by a detent operated by the
arm M, and instead of in all the foregoing arrangements, employing a lever C for
adjusting or moving the carriage B any other quick-operating means such for
instance as gearing may be employed for the purpose.
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. Tapping plastic material by a mechanically rotated tap.
2. The employment for tapping plastic material of a tap combined with mechanism
for simultaneously rotating and propelling it.
3. The employment, for tapping plastic material, of a tap and a revolvable
poppet or shaft adapted to carry the tap and having a screw thread of the saine
pitch as that of the tap thread.
4. In a machine for drilling and tapping plastic material the combination with a
tap and a revolvable poppet or shaft adapted to carry the drill or tap of means
such as a lever C and link C 2 for quickly advancing and withdrawing the poppet
towards or from its work substantially as described and illustrated in the
accompanying drawings.
5. In a machine such as described the combination with a screw-threaded tap- or
drill-carrying poppet or shaft -such as D of a screw-threaded rod such as F
substantially as and for the purpose described and illustrated in Figures 1 and 3
of the accompanying drawings.
6. In a machine for forming a screw-thread in plastic material the combination
with the carriage movable along the machine-bed and a shaft revolvable therein
and carrying the screw-forming tool of gear wheel such as D4 J J 2 and a stationary
or movable rack such as J 3 for simultaneously rotating and propelling the tool
substantially as described and illustrated in Figures 4, 5 and 6 of the accompanying
drawings.
7. In a machine for forming a screw-thread in plastic material the combination
with the tool-carrying head or carriage and a leading screw for moving the

page_text: carriage of a device for simultaneously releasing the carriage from the leading
screw and the tool from the carriage.
8. In a machine for forming a screw-thread in plastic material the combination
with the tool-carrying head or carriage of a device for, at a pre-determined moment,
releasing the tool and allowing it to rotate with the work.
9. In a machine for forming a screw-thread in plastic material the combination
with the tool-carrying head or carriage and a leading screw for moving the
carriage of a fixed detent spring-controlled arm and half-nut and respectively
such as L. M and N substantially as and for the purpose described and illustrated
in the accompanying drawings.
10. In a machine for forming a screw-thread in plastic material the combination
with the tool-carrying head or carriage and a leading screw for moving the
carriage of a spring-controlled lever such as M M 3 fixed and spring controlled
detents respectively such as L K and a half nut such as N, all operating
substantially as and for the purpose described and illustrated in Figures 7, 8 and 9
of the accompanying drawings.
11. The combination and arrangement of parts constituting the complete machine
for forming screw-threads in plastic material substantially as described and
illustrated in the Figures, 1, 2 and 3 Figures 45 and 6 Figures 7 8 and 9 or
Figures 10, 11 and 12 of the accompanying drawings.
Dated this 16th of June 1896.