Improvements relating to Stocks for Boring-bits.
Year: 1890

page_text: Date of Application, 15th Feb., 1890
Complete Specification Left, 11th Nov., 1890-Accepted, 13th Dec., 1890
PROVISIONAL SPECIFICATION.
Improvements relating to Stocks for Boring-bits.
I, JACOB GUTMANN, of Frankfort-on-the-Main, in the Empire of Germany, do
hereby declare the nature of this invention to be as follows:-
My invention relates to stocks or holders for boring-bits.
According to my invention the boring-bit is held in the socket of the stock by
means of a number of wedges moving in radial converging guide-grooves formed in
the said socket, which wedges being subjected to an equal degree of pressure are
caused to press with equal force against the boring-bit.
The wedges are pressed along their guide-grooves by means of a nut screwed upon
the socket and formed with a face adapted to press against the lower ends of the
wedges. In the socket is a disc guided vertically by a pin and bearing against a
spring which constantly presses the wedges against the face of the nut. To fix a
boring-bit in a stock of this construction the socket from which the nut is unscrewed
is inverted when the welges and the boring-bit will rest on the disc; the nut is then
screwed on when the disc will, by means of the wedges, be pressed downwards, which
movement will be followed by the boring-bit until the wedges grip and jam.it.
To prevent the wedges leaving the groove sideways they are formed partly flat with
an enlarged portion at the back, which enters the groove.
Dated the 15th day of February 1800
G. F. REDFERN & Co.,
4, South Street, Finsbury, London, Agents for the Applicant.
COMPLETE SPECIFICATION.
Improvements relating to Stocks for Boring-bits.
I, JACOB GUTMANN, of Frankfort-on-the-Main, in the Empire of Germany, 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 :-
My invention relates to stocks or holders for boring-bits.
According to my invention the boring-bit is held in the socket of the stock by
means of a number of wedges moving in radial converging guide-grooves formed in
the said socket which wedges being subjected to an equal degree of pressure are
caused to press with equal force against the boring-bit.
In order to enable the invention to be fully understood I will describe the same by
reference to the accompanying drawing, in which,
Figure 1 is a longitudinal section of my improved stock for boring-bits.
Figure 2 is a plan showing the wedges for holding the boring-bit in the socket,
and,
Figure 3 shews a modified form of part of the holder.
The stock is constructed of a socket a the centre of which is perforated to receive
the boring bit e; radial converging guide-grooves d are formed in the socket a, and
serve to guide the wedges c between which the boring-bit e is held. The wedges are
pressed along their guide-grooves by means of a nut b screwed upon the socket a and
formed with a face adapted to press against the lower ends of the wedges c, c' which,
by reason of their centripetal movement are caused to tightly grip the boring-bit e.
In the hollow part a¹ of the socket a, is a disc g guided vertically by a pin and
bearing against a spring i which constantly presses the wedges against the face of the
nut b

page_text: To fix a boring-bit in a stock of this construction the socket a from which the nut b
is unscrewed is inverted when the wedges c, c' and the boring-bit e will rest on the
disc g; the nut b is then screwed on when the disc g will, by means of the wedges c, c¹
be pressed downwards which movement will be followed by the boring-bit until the
wedges grip and jam it.
For the purpose of screwing the parts together pins are employed which fit into
holes in the socket a and nut 6 respectively.
To prevent the wedges from leaving the grooves d sideways they are formed partly
flat with an enlarged portion c¹ at the back which enters the groove.
It will be obvious that by the use of these wedges the boring-bit can be secured in
a concentric position.
Figure 3 shews a modified form of nut for adjusting and holding the wedges in
position.
In the arrangement described with reference to Figure 1 the face b¹ which presses
against the wedges is formed integral with the nut b but I sometimes employ a loose
steel ring placed in a recess formed in the inner face of the nut b and held in
position by screws k which allow it to revolve. The surfaces of the hardened steel
ring being very smooth friction between the tightening nut b and the wedges c, c' is
reduced to a minimum.
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 :-
(1.) A stock or holder for boring-bits comprising a number of wedges moving in
radial converging guide-grooves in a socket and means for applying pressure to the
said wedges whereby they are equally pressed from all sides against the boring-bit
substantially as hereinbefore described.
(2.) A stock or holder for boring-bits of the kind referred to in claim 1 in which
the boring-bit as well as the wedges rest on a disc which by means cf a spring
constantly presses the wedges against the tightening nut on the socket substantially as
herein before described. .
(3.) A stock or holder for boring-bits of the kind referred to in claims 1 and 2 in
which the wedges holding the boring-bit bear against a moveable disc inside the
socket which disc by means of a spring constantly presses the said wedges against the
tightening nut, the frictional surface of which consists of a smooth moveable ring of
hardened steel, substantially as hereinbefore described.
(4.) The manufacture and use of the improved stocks or holders for boring-bits
hereinbefore described and illustrated in the accompanying drawings.
Dated the 11th day of November 1890.
G. F. REDFERN & Co.,
4, South Street, Finsbury, London, Agents for the Applicant.