An Improved Cutter for Boring Holes of Variable Diameter within a Given Range of Expansion.
Year: 1890

page_text: Date of Application, 30th Oct., 1890
Complete Specification Left, 14th July, 1891-Accepted, 26th Sept., 1891
PROVISIONAL SPECIFICATION.
An Improved Cutter for Boring Holes of Variable Diameter within
a Given Range of Expansion.
.
GEORGE WILLIAM DAVIS 54 New Spring Street Hockley Birmingham in the
County of Warwick Engineer and Machinist do hereby declare the nature of this
invention to be as follows:-
The principle upon which my improvement is based, is that of a solid cutter,
(as in the case of rose-bits, boring, and reamering cutters) capable of expansion,
or contraction, within a given range, by means of the direct action of a conical
headed pin, passing as a core through the centre of the said cutter, and which pin
acts at its conical extremity. This conical headed pin is secured in position, by
means of lock-nuts or other suitable means.
The expansion, or contraction, of the cutter is caused as follows:-
A hole is bored through the entire length of the cutter, its mouth being coned
to suit the conical headed pin, which passes through it, and is pulled up to its
adjustment by means of lock nuts or other suitable means.
Or the hole may be bored through a given distance up the length of the cutter,
which distance is to be regulated by the requirements of the cutter, its central core
being secured in position by means of a cotter, or other suitable means.
This conical headed pin being pulled through a certain distance, (which amount
is regulated by a vernier arrangement) by means of its nuts, or other means, causes
the cutter to expand (at its wearing point, to its original dimensions) by slitting
the cutter a certain distance up its length, which length is regulated according
to the several requirements of the cutter.
29th October 1890.
GEORGE WILLIAM DAVIS.
COMPLETE SPECIFICATION.
An Improved Cutter for Boring Holes of Variable Diameter within
a Given Range of Expansion.
GEORGE WILLIAM DAVIS 7 Thynne Street West Bromwich, late 54 New
Spring Street Birmingham Foreman Tool Maker & Machinist 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 basis upon which my cutter is founded, is that of employing a central core
to either penetrate its entire length, or partially so, according to the requirements
of the said cutter. This is done in the following manner :-
A hole is bored in the cutter longitudinally and axially, and a pin B as shown
in Figures 2-4-9 & 10 is inserted in this hole having a coned extremity
(B Fig. 2). The other end of pin B is screwed to fit a nut C as shown in
Figures 2 & 9 which also acts as a vernier having divisions on its periphery.
The pin B is also slotted as shown at S Fig. 2 to receive a pin D to prevent the
pin B turning with nut C while adjusting.
The pin B can also be pulled up to its adjustment by means of a cotter E shown
in Figures 4 & 5.
In cutters that will not admit of either of these means, the pin B can take the
form of a countersunk headed screw as shown in Figures 6 & 7, the head of which
is graduated to dispense with nut C.

page_text: To allow expansion, three or more slits are made as shown at a, a, a
2-4-7-8-9 & 10.
A lock nut may be used to preventinut: C. slacking back after adjustment, as
shown in Fig. 10 at G..
It will also here be seen that if the pin B has a known taper & also a standard 5
pitch of thread, & nut C has a certain number of divisions to suit these, then each
division can easily amount to as small a degree of expansion as he of 1" or
more.
The chief advantage of this cutter over any ordinary solid one is, that when the
old one is worn below the standard dimensions, it is a very expensive method to
renew the size, which can only be done by heating & compressing the end until
the dimensions are again obtained, & then must be recut.
All this takes place by the aid of nut C, which pulls through A the pin B, &
thereby expands cutter A at its extremity.
In cutters of large dimensions, that shown in Fig. 10 may be used, where the
central pin B is formed to fit collet, or run between centres of lathe, & cutter A is
forced over pin B by means of the adjusting nut C.
This arrangement is similarly applied to plug-guages as shown at Figures 8 & 9,
so as to enable a hole to be bored say within ths of its finished dimensions, the
same guage registering the size of the bore.
Having now described & ascertained the nature of my said invention, and in
what manner the same is to be performed, I declare that what I claim is :-
1st. Any solid cutter or guage that has a hole bored axially through, to receive
a conical headed 'pin to be pulled through by means of a nut or cotter as shown in
my drawings.
2nd. The vernier construction upon the adjusting nut C, to self register th
amount of expansion.
3rd. Any conical headed screw whose conical end shall act at wearing extremit
of cutter or guage.
T1, 1891
GEORGE
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