An Improved Tool for Cutting Recesses on the Inside of Fire-plug Casings.
Year: 1894

page_text: COMPLETE SPECIFICATION.
An Improved Tool for Cutting Recesses on the Inside of
Fire-plug Casings.
I, HUGH THOMSON, of "Thornton " Studley Park Road, Kew, near Melbourne,
in the Colony of Victoria, Tanner, 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 improved tool has been devised for the purpose of enabling recesses to be
quickly and easily cut on the inside of fire-plug casings, principally for the purpose
of providing a support for the valve.
It is specially useful in cases where (as described in the Specification accom-
panying my application No. 4015 of even date herewith) notches or recesses are
required in the lower part of the inside of such casing to form a support for a cage
in which the valve works.
It consists essentially of one or more rotating cutters mounted upon the lower
end of a support and adapted to be driven through the medium of suitable gearing
by means of a handle at the upper end of the tool. These cutters are preferably
four in number and means are provided for adjusting them vertically so that they
can be fed downwards to the required depth.
The accompanying drawing is a vertical central section of my improved tool
for cutting recesses on the inside of fire-plug casings to enable valves to be
fitted therein.
A-A represent the rotating cutters which are mounted on the lower end of a
sleeve or support B. Rotary motion is imparted to these cutters by bevel
gearing C-C from a spindle D passing down through the centre of the sleeve B
which latter is capable of being moved up and down within an outer fixed sleeve E
by means of a screw-threaded nut F working upon a correspondingly threaded
part of said sleeve and having a handle f¹ whereby it may be rotated.
is prevented from moving vertically by pins f³, passing through a groove therein
and extending into the outer sleeve E whilst the movement of the sleeve B
is stopped at a certain point by a stude working within a slot e¹ in the outer
sleeve E.
This nut
The upper end of the spindle D is fitted with a handle d whereby it can be
conveniently rotated and the outer fixed sleeve or support E is provided with
projecting arms b at its lower end through which pass holding down bolts b' whose
lower ends can be passed through and then turned into engagement with the usual
lugs on the fire-plug casing G.
In order to use my improved tool for cutting. recesses on the inside of fire-plug
casings, as for instance, to enable valves to be fitted therein, it is merely necessary
to remove the cover of such casing and to secure the tool centrally upon said casing
by means of the holding down bolts 6' as just described. The spindle D is then
rotated by means of the handle d so as to cause the cutters A to revolve and the
sleeve B is fed downwards by means of the nut F so as to keep the rotating
cutters A against their work.
When the stud or stop pine is at the bottom of the slot e¹ the recesses H on the
inside of the fire-plug casing G will have been cut to the required depth, the pin e
and its slot e acting as a gauge and being arranged to suit the depth of recesses
required.
It will be readily understood that with a tool such as I have described, recesses
or notches can be cut on the inside of the casings of fire-plugs at a trifling expense,
and without having to remove each one.

page_text: 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 :-
First. The herein described tool for cutting recesses on the inside of fire-plug
casings, consisting of the various parts constructed arranged and operating
substantially as and for the purposes specified and as illustrated in the accompanying
drawings.
Second. In tools for cutting recesses on the inside of fire-plug casings, a rotating
cutter or set of cutters (such as A) driven by gearing from a central spindle
substantially as and for the purposes specified.
Dated this Twenty-second day of January One thousand eight hundred
and ninety-tour.
and ninety-four.
HUGH THOMSON.
G. F. Redfern & Co.,
4, South Street, Finsbury, London, Agents for the Applicant.