A New or Improved Tool for Screwing or Chasing Stud Bolts.
Year: 1895

page_text: Date of Application, 11th June, 1895
Complete Specification Left, 26th Oct., 1895-Accepted, 30th Nov., 1895
PROVISIONAL SPECIFICATION.
A New or Improved Tool for Screwing or Chasing Stud Bolts.
I JOHN DONALD of 78 Hyde Road Woodley in the County of Chester do
hereby declare the nature of this invention to be as follows:-
The object of this invention is to enable the screw threads of stud bolts to be
re-cut without the necessity of removing the studs from the casting or forging in
which they are fixed.
Now according to this invention I provide a hollow mandrel of somewhat larger
internal diameter than the external diameter of the stud to be chased. The top
of the mandrel is made square or hexagonal to receive a rachet brace or spanner.
The body of the mandrel has a screw thread on the outside thereof on which rotates
a collar the lower portion of which is conical inside and engages with dies passing
through slots in the mandrel so that when the collar is screwed downwards the 'dies
are forced inwards. The collar is preferably hexagonal externally for a portion of
its length to receive, a spanner. When the collar is screwed upwards the dies are
forced outwards by means of a spring or springs. Any suitable number of dies
may be used. To renovate a worn stud the dies are expanded until they will-pass
over the end of the stud the collar is then screwed downwards until the dies
engage with the threads on the stud and the tool is then rotated (in whichever
direction is most suitable) by means of a ratchet brace or spanner until the threads
are re-cut the collar is then screwed upwards and the tool removed.
Dated this 11th day of June 1895.
.
T. E. HALFORD,
11 Furnival Street, London, E.C., Agent for Applicant.
A New Or improved 1001 for porewing or using, Dvul
JOHN DONALD of 78.Hyde Road Woodley in the County of Chester Mill-
wright etc. 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:-
The object of this invention is to enable the screw threads of stud bolts to be
recut without the necessity of removing the studs. from the casting or forging in
which they are fixed.
Now according to this invention I provide a hollow mandrel of somewhat larger.
internal diameter than the external diameter of the stud to be chased. Thettop
of the mandrel is made square or hexagonal to receive a ratchet brace or spanner.
The body of the mandrel has a screw thread on the outside thereof on which
rotates a collar the lower portion of which is conical inside and engages with dies
passing through slots in the mandrel so that.when the collar is screwed downwards
the dies are forced inwards. The collar is preferably hexagonal externally for a
portion of its length to receive a spanner.
When the collar is screwed upwards
the dies are forced outwards by means of a spring or springs. Any suitable
number of dies may be used. To renovate a worn stud the dies are expanded
[Pin 77

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prace of spauner
until the threads are re-cut.
The collar is then screwed upward and the tool removed.
And in order that my said invention may be fully understood I will explain the
same with reference to the accompanying sheets of drawings in which:
Fig. 1 represents section of a tool for screwing or chasing stud bolts constructed
according to this invention.
•
I
Fig. 2 is elevation of same.
Fig. 3 is plan of same.
Fig. 4 shews elevation of mandrel partly in section.
Fig. 5 shews elevation of collar partly in section.
Fig. 6 is side view of die.
Fig. 7 is plan of same.
Fig. 8 is view of underside of tool.
The same letters denote the same parts in all the figs.
a is a hollow mandrel of slightly larger internal diameter than the stud 6 the
top of the mandrel is made square or hexagonal as shewn at c to receive a ratchet
brace or spanner by means of which it may be rotated. The body of the mandrel a
has a screw thread on the outside thereof as shewn at Figs. 1. 2. and 4 on which
screw rotates a collar d.
The collar d has a female screw in the upper portion thereof to receive the
mandrel a while the lower portion is conical inside with the larger diameter at the
hottom as shewn at Figs. 1 and 5. The upper portion of the collar e is square or
hexagonal outside to receive a spanner or wrench by means of which it may be
rotated on the mandrel a. Slots are formed in the mandrel a in which slots are
dies or chasers g having screw threads on their inner faces. The outer faces of
the dies g are tapered. as shewn in Figs. 1 and 6 to bear against the conical portion
of the collar d.
The dies or chasers 9 are normally forced outwards by means of a spring / which
passes through holes or slots in the said dies or chasers. When the collar dis
screwed downwards the dies are forced inwards and are forced outwards by the
spring when the collar is rotated in the reverse direction. When it is desired to
use the tool to renovate a worn or burred stud the collar d is rotated until the dies
will pass easily over the top of the stud b the mandrel is then held fast while the
collar dis turned until the dies or chasers g engage with the threads on the stud.
The mandrel a is then rotated by means of a ratchet brace or spanner preferably
running the dies down the bolt and back again to the top until the threads are
recut or chased.
The tool after the threads are renovated may be removed from the stud by
opening the dies or by rotating the mandrel.
Having now particularly described and ascertained the nature of my said
invention I declare that what I claim is :-
1. In a tool for screwing or chasing stud belts the combination of a hollow
mandrel having slots near one end thereof to receive dies or chasers with a means
for causing the said dies or chasers to approach towards or recede from the centre
of the said mandrel for the purpose stated.
2. In a tool for screwing or chasing stud bolts the combination. of a hollow
maudrel a having slots near one end thereof to receive dies or chasers g normally
pressed outwards by a spring h with a collar d having the lower portion thereof
conical to bear on the outer faces of the said dies or chasers and a means whereby
the said collar may be forced over the said dies substantially as hereinbefore
specified.
3. In a tool for screwing or chasing stud bolts the combination of a hollow
mandrel a having a screw thread on the outside thereof and a square or hexagonal

page_text: portion at one end thereof and slots at the other end to receive dies or chasers g
normally forced outwards by a spring with a collar d conical internally for a
portion of its length and provided with an internal screw thread for the remainder
of its length and having a square or hexagonal portion e whereby the said collar
may be rotated on the said mandrel substantially as hereinbefore specified and for
the purpose stated.
4. The construction of a tool for screwing or chasing stud bolts substantially as
hereinbefore specified and shewn by the accompanying drawings.
Dated this 26th day of October 1895.
T. E. HALFORD,
11 Furnival Street, London, E.C., Agent for Applicant.