A New or Improved Collapsible Tap.
Year: 1889

page_text: Date of Application, 30th Mar., 1889
Complete Specification Left, 30th May, 1889-Accepted, 3rd Aug., 1889
A New or Improved Collapsible Tap.
I, JOHN WOTHERSPOON, of Clyde Tube Works, Coatbridge in the county of Lanark,
North Britain, Tube Manufacturer, do hereby declare the nature of this invention to
be as follows:-
This invention relates to a new or improved Collapsible tap preferably used for
tapping or screwing the inside of pipes, couplings, and the like but may be used for
analogous purposes.
In accordance with my invention 1 form the tap of four or any other number of
steel bits having the necessary cutting threads cut upon them the said bits being of an
Lshape in section and tapered lengthwise capable of movement longitudinally in
suitable grooves cut out in cylindrical plug which is formed on the end of the spindle
for fitting into the head or stock, so that on the said bits being drawn towards the one
end of the plug the tap opens out to its full diameter and again on the said bits being
pushed or driven to the other end of the plug, the tap collapses and thus allows of it
being withdrawn from the inside of the pipes after the screw has been formed.
To enable me to obtain the necessary longitudinal movement of the bits, I form
them at the one end with a small flange or projection the said projections fitting into
a suitably grooved nut formed with preferably a left hand screw for working upon a
small screwed collar or tube, the said collar or tube being also capable of screwing on
preferably a right handed screw formed on the plug spindle, and having an end formed
into the necessary means of screwing it either by being formed with holes into which
a pointed pin is put in and turned, or formed as an ordinary nut and worked with a
common screw key.
The action thus caused is that upon the said collar or tube being turned to the right
it moves down the spindle towards the plug, at the same time causing the grooved nut
to move up or away from the plug by means of the left handed thread forined on it
and thus bringing the bits up or extending them to the required diameter or vice-versa
which causes the bits to collapse.
For larger taps 1 may as a modification instead of the grooved nuts for moving the
bits form the nut with recesses, for the ends of the bits to lie in, the said bits having
an oblong hole formed in them for allowing a square pin to pass through, the said pin
also passing through two lugs or the sides of the recess before-mentioned, thus
allowing of the necessary movement to the bits.
COMPLETE SPECIFICATION.
A New or Improved Collapsible Tap.
I, JOHN WOTHERSPOON of the Clyde Tube Works, Coatbridge, in the County of
Lanark, North Britain, Tube 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 which relates to a new or improved collapsible tap is preferably used
for tapping or screwing the inside of pipes, couplings and the like but it may also be
used for analogous purposes.
In order that my said Invention may be easily understood and readily carried into
effect I will now proceed to describe the same, reference being made to the
accompanying sheet of drawings.

page_text: In carrying out my Invention I form the tap of four or any other number of steel
bits A, Figures 1, 1₁ having the necessary cutting edges or threads thereon, the.said
bits being preferably of an L shape (as shewn in Figure 1) in section, and tapered
lengthwise, and being capable of movement longitudinally in suitable or corresponding
grooves, cut out in a cylindrical plug B, which is formed in one piece with the
spindle C, for fitting into the head or stock, so that on the said bits A, being drawn
towards the one end of the plug the tap opens out, and on the bits being pushed to the
other end of the plug, the tap collapses.
To obtain the necessary longitudinal movement of the bits, I form them at the one
end with a flange or projection a, the said projections fitting into a suitably grooved
nut or ring D, which I screw on the end of a nut or gland E, the said gland being
preferably formed with an internal left handed screw e, into which works a collar or
tube F, being screwed left handed on its outside to fit the said gland. The said collar
or tube is formed with a right handed internal screw, on its inside f, for working upon
a corresponding screw formed on the plug spindle C. The said collar or tube F, having
the necessary means provided at its one end for allowing of its being screwed or
turned round, either by having a number of holes f', formed in it for the introduction
of a pin, or it may be formed as an ordinary nut and worked with a common spanner
or screw-key.
As a modification (preferably for larger taps) in lieu of the flanges or projections a,
on the end of the bits, and of the grooved nut or ring D, screwed on the end of the
gland E, I may form the end of the gland E, with a number of recesses G,
Figures 2, 2, for the ends of the bits A, to lie in, the said bits having no projections
formed on them, but having an oblong hole g, formed in them for allowing a square
pin g', to pass through, the said pin also passing through the two sides or lugs g² of
the recesses, thus allowing the bits to take up their proper positions.
The arrangement thus described being such, that on the collar F, being turned to
the left it moves up the spindle C, away from the plug B, at the same time causing the
gland or nut (with grooved nut or ring D) to move up or away from the plug by
means of the left handed screw formed on said collar and gland, thus bringing the
bits A, up the tapered grooves in the plug and extending them to the required
diameter, or vice-versa, which causes the bits or tap to collapse, and thus allowing the
tap to be very easily withdrawn after the required screw has been formed.
As a guide for properly adjusting the said bits, I may use any suitable index, such
as that shown at H, in Figures 1 and 2, having a finger J, for indicating on said
index.
As another modification, I may use in lieu of the double screw arrangement a single
screw arrangement as shewn in Figure 3. In this case the gland E, with recesses G,
is made shorter and has an external screw K, formed thereon and having an internal
screwed collar or tube L, abutting against its end, the said collar or tube having a
flange l, formed thereon for the purpose of being held close against the end of the
gland E, by means of a nut M, screwed on the outside of gland E. This nut has a
projecting ledge m, for holding against the flange 1, and which also allows of the
collar or tube revolving, by means of the screw L', without turning the gland and bits,
the said revolving of the collar or tube being effected by mounting a washer N, at the
end of the collar or tube L, and the said washer having openings therein for allowing
a turning pin to be put into it, or its outside may be formed as an ordinary square
(the said washer being held on the end of the collar or tube by any suitable means,
preferably by screw pins O) or a hexagon nut, and turned by an ordinary spanner..
Having now particularly described and ascertained the nature of my said Invention,
and in what manner the same is to be performed, I declare that what I claim is-
First. The general arrangement and combination of parts constituting the new or
improved collapsible tap, all substantially as and operating in the manner set forth
with reference to the annexed drawings.
Second. In collapsible taps the employment of any number of steel bits A, the
cylindrical plug B, on the end of the spindle C, with grooved nut or ring D, screwed

page_text: gland or nut E, and the screwed collar or tube F, all substantially as and for the
purposes herein before described and shewn in Figures 1, 1ª, 1° of the accompanying
drawings.
Third. In collapsible taps the employment of any number of steel bits A, having
oblong holes g, lying in recesses G, formed in end of screwed nut or gland E, and
pins g', as also screwed collar or tube F, all substantially as and for the purposes
hereinbefore described and shewn in Figures 2, 2, 2b of the accompanying drawings.
Fourth. In collapsible taps the employment of a gland E, having an external
screw K thereon, also the screwed collar or tube L, nut M, washer N, and pins O,
constituting my single screw arrangement, substantially as hereinbefore described and
set forth, with reference to Figure 3, of the accompanying drawings.
Dated this 29th day of May 1889
JOHNSONS,
115, St. Vincent Street, Glasgow, Applicant's Agents.