Improved Apparatus for Tapping or Cutting Internal Screw Threads.
Year: 1895

page_text: Date of Application, 24th Aug., 1895
Complete Specification Left, 23rd May, 1896-Accepted, 27th June, 1896
PROVISIONAL SPECIFICATION.
Improved Apparatus for Tapping or Cutting Internal Screw
Threads.
1, JAMES YATE JOHNSON, of 47 Lincoln's Inn Fields, in the County of
London, Gentleman, do hereby declare the nature of this invention (as com-
municated to be from abroad by La Société A. Janet & Co., 58bs Chaussée
d'Antin, Paris, in the Republic of France) to be as follows:-
The object of this invention is to provide an improved apparatus constituting a
tool holder enabling holes to be tapped or cut whether extending partly or right
through the material by the employment of any suitable motive power flexible or
otherwise, the said apparatus being held in the hand while in operation, no matter
what the position or direction may be in which the work to be performed requires
it to be placed.
The main advantages of the improved tool holder are as follows:-
(1.) It is only .necessary to press upon the tool holder in order to force or drive
the tool into the material to be tapped, and to draw back the said holder, towards
the operator after it has cut the desired thread for removing it from the hole.
(2.) The progress of the tool or tap through the material will be checked of its
own accord as soon as the aperture has been threaded down to a predetermined
depth; and
(3.) Either of the results.above stated are obtained by the arrangement. of 'the
tool holder itself without any stoppage or reversion of motion of the motor
employed.
One form of arrangement according to this invention involves the employment of
bevel gearing, or conical friction wheels, while the other necessitates the use of
worm wheels and tangential screws.
and
The tapping tool proper is secured to a rod adapted to slide longitudinally,
freely to revolve, between two sleeves, which sleeves are firmly connected, or
integral, with two gear wheels arranged to revolve in opposite directions.
Each sleeve is provided with a coupling or friction clutch.
I will suppose, in the first instance, that this clutch is in the case of each 'sleeve
located on the side opposite to that on which the other sleeve is situated. The
tool holding rod is provided with two pieces similar in shape, and forming
counterparts of the clutches on the sleeves, but situated farther apart from one
another than the said clutches so that a certain amount of longitudinal play is
allowed owing to which the rod may be caused to gear either with one or the
other of the sleeves at will, or, if neither engagement should be required, remain
altogether independent of both sleeves.
Where the parts of the sleeves forming friction clutches are arranged so as to
face each other instead of being situated on opposite sides, it is only necessary to
mount upon the rod one piece suitably cut on the opposite faces; the length of
which piece should be less than the space remaining free between the friction
clutches so that, in this case also, there may be a certain amount of longitudinal
play producing the same effect as that obtained with the arrangement already
described.
The complete arrangement or combination comprising the rod, sleeves, and gear
wheels is supported by a piece, or by a series of pieces of any convenient shape
constituting a supporting frame and provided with handles enabling the whole
device to be held in the hand when in use.

page_text: In most cases it will be found preferable to form one of the handles as a guard
on the driving spindle (no matter whether such spindle be flexible, or whether it be
a rigid shaft operated by any suitable transmission gearing), but this arrangement
is not absolutely necessary.
Such being the construction of the apparatus let it be supposed that the operator
who holds the frame by the handles turns bis tapping tool towards an aperture to
be tapped. As soon as he exerts a certain amount of pressure upon the apparatus
the frame and sleeves slide on the tool holding rod until the clutch on one of the
sleeves engages with the counter part on the tool holding rod which will then
participate in the rotary motion of the corresponding wheel which should be
arranged to correspond with the direction in which the tap cuts the material.
When the aperture or hole has been tap to a sufficient depth and it is desired
to check its further progress (no matter at what moment of its operation) it is only
necessary to pull the tool holder backwards. As the rod is retained in its position
by the threads engaging with the tap, the sleeves slide ou the said rod the
clutch becomes first disengaged, and then, when the frame reaches the end of its
back stroke the clutch on the other sleeve engages or becomes coupled with its
counterpart on the rod when it will turn in a direction opposite to that in which it
had previously turned.
The tap will thus become unscrewed from the thread it has cut, and leave the
aperture without the need of changing or reversing the direction of rotation of
the driving spindle.
Notwithstanding that this arresting and reversing operation is practically
instantaneous, it may happen in the case of apertures which do not extend through
the whole thickness of the material that the operator inadvertently allows the
tapping tool to advance further than is required, and in that case, the tool meeting
with the bottom of the aperture or recess, would cause so abrupt an interruption of
the operation that the mechanism would be liable to be damaged by the sudden
strain. To prevent this a stop may be provided; which may be formed by rods or
by a length of tube, the length of which should be so regulated that by pressing it
against the frame and placing the advancing clutch in engagement with its counter-
part the tap should extend beyond the said stop, for a distance equal to the extent
to which the hole or recess should be tapped.
By this arrangement, when once the tap is in gear, it will first commence its
operation in the manner described but as soon as the stop comes into contact with
the piece to be provided with the tapped hole, such stop will prevent the frame
from participating in the movement. The tap will still have to travel a distance
equal to the extent to which the coupling clutches engage, the consequence being
that, whilst the tap is completing its work, the rod firmly connected therewith will
slide within the sleeves and the mechanism will be released. The tap will therefore
be arrested exactly at the predetermined point, without any necessity to stop the
motor or driving medium.
The reversing the direction of motion of the wheels mounted upon the sleeves,
may be performed in various ways. Where the strain is but slight friction cones
may be employed, for strains of medium power bevel wheels operated by one pinion
common to both are preferably used, and in the case of more powerful strains, worm
wheels, operated by tangential screws which in their turn are operated by toothed
wheels in gear with each other, are preferable.
The speed or motion of the two sleeves may readily be varied, so that their
power should go ou increasing whilst the tap is being driven into the material, and
that their velocity may be accelerated when the tap is to be withdrawn from the
tapped hole.
Dated this 24th day of August 1895.
JOHNSONS & WILLCOX,
47 Lincoln's Inn Fields, London, W.C., Agents.

page_text: Improved Apparatus for Tapping or Cutting Internal Screw
Threads.
I, JAMES YATE JOHNSON, of 47 Lincoln's Inn Fields, in the County of
London, Gentleman, do hereby declare the nature of this invention (which has
been communicated to me from abroad by La Société A. Janet & Cie. of
58bis Chaussée d'Antin, Paris, in the Republic of France) and in what manner
the same is to be performed, to be particularly described and ascertained in and
by the following statement :-
The object of this invention is to provide improved apparatus constituting a tool
holder enabling holes to be tapped or cut whether extending partly or right
through the material by the employment of any suitable motive power flexible or
otherwise, the said apparatus being held in the hand while in operation no matter
what the position or direction may be in which the work to be performed requires
it to be placed.
The main advantages of the improved tool-holder are as follows:-
(1.) It is only necessary to press upon the tool holder in order to force or drive
the tool into the material to be tapped, and to draw back the said holder towards
the operator after it has cut the desired thread for removing it from the hole.
(2.) The progress of the tool or tap through the material will be checked of its
own accord as soon as the aperture has been threaded down to a predetermined
depth; and
(3.) Either of the results above stated are obtained by the arrangement of the tool
holder itself without any stoppage or reversion of motion of the motor employed.
In the accompanying drawings Figures 1 and 2 respectively represent by way
of example, two modifications of the improved apparatus constructed according to
this invention.
One form of arrangement, as shewn in Figure 1, involves the employment of
bevel gearing, or conical friction wheels, while the other as shown in Figure 2
necessitates the use of worm wheels and tangential screws.
Referring to Figure 1, the tapping tool proper T, is secured to a rod t adapted
to slide longitudinally, and to revolve freely between two sleeves E E', which are
firmly connected, or integral, with two gear wheels D D arranged to revolve in
opposite directions by the pinion A' mounted on the driving shaft A.
Each such sleeve is provided with a coupling or clutch as shewn in the
drawings.
I will suppose, in the first instance, that this clutch is in the case of each sleeve
located on the side opposite to that on which the other sleeve is situated, and this
arrangement is accordingly assumed to have been adopted in the drawings. The tool-
holding rod is provided with two pieces F F similar in shape and forming
counterparts of the aforesaid clutches on the sleeves E E¹ but situated further
apart from one another than the said clutches so that a certain amount of
longitudinal play is allowed owing to which the rod t may be caused to gear either
with one or the other of the sleeves E E' at will, or, if neither engagement should
be required, remain altogether independent of both sleeves.
Where the parts of the sleeves forming the clutches are arranged so as to face
each other instead of being situated on opposite sides, it is only necessary to mount
upon the rod one piece suitably cut on its opposite faces, the length of this piece
should be less than the space remaining free between the friction clutches so that,
in this case also, there may be a certain amount of longitudinal play producing the
same effect as that obtained with the arrangement already described.
The complete arrangement or combination comprising the rod t clutch

page_text: sleeves EE¹ and gear wheels D and D₁ is supported by a piece C or by a
series of pieces of any convenient shape constituting a supporting frame and
provided with handles B B enabling the whole device to be held in the hand when
in use.
In most cases, it will be found preferable to form one of the handles as a guard
on the driving spindle A as shewn in the drawing (no matter whether such spindle
be flexible, or whether it be a rigid shaft operated by any suitable transmission
gearing) but this arrangement is not absolutely necessary.
Such being the construction of the apparatus, let it be supposed that the
operator who holds the frame C by the handles B, B', turns his tapping tool T
towards an aperture to be tapped. As soon as he exerts a certain amount of
pressure upon the apparatus the frame C and sleeves E E' slide on the tool holding
rod t until the clutch E on one of the sleeves engages with the counterpart Fon
the tool holding rod t which will then participate in the rotary motion of the
corresponding wheel D which should be arranged to correspond with the direction
in which the tap T cuts the material.
When the aperture or hole has been tapped to a sufficient depth, and it is desired
to check its further progress (no matter at what moment of its operation) it is
only necessary to pull the tool holder backwards. As the rod t is retained in its
forward position by the threads engaging with the tap, the sleeves E E' slide on
the said rod t, the clutch E F becomes first disengaged, and then, when the frame C
reaches the end of its back stroke the clutch on the other sleeve El engages or
becomes coupled with its counterpart F on the rod when it will turn in a
direction opposite to that in which it had previously turned.
The tap will thus become unscrewed from the thread it has cut, and leave the
aperture without the need of changing or reversing the direction of rotation of
the driving spindle.
Notwithstanding that this arresting and reversing operation is practically
instantaneous it may happen in the case of apertures which do not extend through
the whole thickness of the material that the operator inadvertently allows the
tapping tool to advance further than is required and in that case the tool meeting
with the bottom of the aperture or recess, would cause so abrupt an interruption
of the operation that the mechanism would be liable to be damaged by the sudden
strain. To prevent this a stop G indicated by dotted lines in the drawing may be
provided, the stop may be formed by rods or by a length of tube, the length of
which should be so regulated that by pressing it against the frame and placing
the advancing clutch in engagement with its counterpart the tap should extend
beyond the said stop, for a distance equal to the extent to which the hole or recess
should be tapped.
By this arrangement, when once the tap is in gear, it will first commence its
operation in the manner described but as soon as the stop comes into contact with
the piece to be provided with the tapped hole, such stop will prevent the frame
from participating in the movement. The tap will still have to travel a distance
equal to the extent to which the coupling clutches engage, the consequence being
that, whilst the tap is completing its work, the rod firinly connected therewith will
slide in the sleeves, and the mechanism will be released. The tap will therefore
be arrested exactly at the predetermined point, without any necessity to stop the
motor or driving medium.
The reversing the direction of motion of the wheels mounted upon the sleeves,
may be performed in various ways. Where the strain is but slight friction cones
may be employed; for strains of medium power bevel wheels operated by one
pinion common to both are preferably used, and in the case of more powerful
strains, worm wheels D D', such as are shown in Figure 2, operated by tangential
screws, which in their turn are operated by toothed wheels A' A² in gear with
each other, are preferable.
The speed or motion of the two sleeves may readily be varied, so that their
power should go on increasing whilst the tap being driven into the material,

page_text: and that their velocity may be accelerated when the tap is to be withdrawn from
the tapped hole.
Having now particularly described and ascertained the nature of this inven-
tion, and in what manner the same is to be performed, I declare that what I
claim is :-
Apparatus for tapping or cutting internal screw threads adapted to be operated
substantially as described and illustrated by way of example in the accompanying
drawings.
Dated this 02nd 1 f ... 1000
JOHNSONS & WILLCOX,
47 Lincoln's Inn Fields, London, W.C., Agents.