Year: 1886

page_text: Date of Application, 20th Mar., 1886.
Complete Left, 20th Dec., 1886.
Complete Accepted, 21st Jan., 1887
I, EDWARD DUNNING BARKER, of 115 Cannon Street, in the City of London,
Engineer, do hereby declare the nature of this invention to be as follows:-
This invention relates more especially to twist-drill grinding apparatus for which
I applied for a patent on the 9th day of March A.D. 1885, No. 3,076, and consists of
certain improvements and modifications of the means for obtaining the necessary
motions for effecting the grinding.
I have found that in some cases it is desirable to impart to the cutting edges of
twist drills a lesser amout of clearance than can be conveniently obtained by the
devices described and shewn in the specification of my aforesaid application for a
Patent, and the object of the present invention is to enable such lesser amount of
clearance to be obtained.
In order to effect this object, the bar which carries the V grooved piece for holding
and steadying the drill whilst being ground, oscillates on a fulcrum pin carried by
the arm or plate fixed to the frame or headstock as before, but the said fulcrum pin
and bar carrying the V grooved piece are so arranged that the said bar is free to
move, to a limited extent, towards and away from the edge of the grinding wheel,
simultaneously with its movement round the said fulcrum pin, such compound
movement being controlled by means of a crank, arm, slot, cam, or other suitable
mechanical devices.
.
E. D. BARKER.
Per W. H. Beck,
115, Cannon Street, London,
Agent.

page_text: Improvements in Apparatus for Grinding Twist Drills.
I, EDWARD DUNNING BARKER, of 115 Cannon Street, in the City of London,
Engineer, do hereby declare the nature of the said invention and in what manner
the same is to be performed, to be particularly described and ascertained in and by
the following statement, reference being had to the accompanying two sheets of
Drawings and to the letters and Figures marked thereon, that is to say :-
This invention relates more especially to twist drill grinding apparatus for which
Letters Patent were granted to me dated the 9th day of March A.D. 1885 No. 3076,
and consists of certain improvements and modifications of the means for obtaining the
necessary motions for effecting the grinding.
I have found that, in some cases, it is desirable to impart to the cutting edges of
twist drills, a lesser amount of clearance to the cutting edge of the drill remote from
the chisel-point, than can be conveniently obtained by the devices described in the
specification, and illustrated in the Drawings annexed thereto, of my aforesaid Patent,
without grinding away the point so as to spoil its chisel-like edge, and the object of
my present invention is to enable such lesser amount of clearance to be obtained,
whilst still preserving the chisel-like edge of the point of the drill. In order to effect
this object, I employ improved arrangements of the mechanism whereby I am enabled
to obtain a much greater backward and forward movement of the central portion of
the drill (which has to be ground to a knife edge) at right angles to the grinding
surface of the grinding wheel, while a much smaller radial movement of the drill,
during its rotation, is employed to give the required clearance to the cutting edge of
the drill remote from the chisel point.
For this purpose, I employ the devices illustrated in the two sheets of Drawings
hereto annexed, in which Figure 1 is a plan of so much of a twist drill grinding
apparatus of the kind described in the Specification of my aforesaid Patent No. 3076,
as is necessary for the illustration of my present improvements as applied thereto;
Figure 2 is an elevation of the same; Figure 3 a plan with the V grooved piece C
and the drill removed; and Figure 4 is a section on line Z Z of Figures 1 and 3.
Letters of reference, in the Figures of the Drawings hereto annexed, which are
similar to those in the Drawings annexed to the Specification of my aforesaid Patent
No. 3076, relate to parts which are similar to those described in the said Specification.
The bar B, which carries the V grooved piece C for holding and steadying the
drill D whilst being ground, oscillates on a fulcrum pin B¹ carried by the arm or
plate A fixed to the frame or head-stock A¹ as before, but the said fulcrum pin B¹ and
bar B carrying the V grooved piece C are so arranged that the said bar B is free to
move, to a limited extent, towards, and away from, the grinding surface of the
wheel A² simultaneously with its movement round the said fulcrum pin B¹. This
compound movement is controlled by means of the fulcrum pin B₁ and a crank
arm B2 which lies in a recess A* in the plate A forming an extension of the arm A,
and turns on a pin B3 which takes into a hole in the plate A. A pin B is rivetted
into, or otherwise secured in, a hole in a part of the bar B, and after passing through

page_text: a hole in the crank arm B³, it passes through a curved slot B' in the bottom of the
recess A* of the plate A, and receives at its end a nut B which is screwed on to it
so as to keep that part of the bar B in close contact with the plate A but with
sufficient play to allow that part of the bar B to oscillate steadily on the plate A
round the fulcrum pin B¹. This fulcrum pin B' is cylindrical at its lower end and
free to turn in a hole in the plate A, but is square, or oblong, at its upper end, and
takes into a slot B' in the bar B. The shape, or curvature, of the slot B', is dependent
upon the throw of the pin B, and the amount of travel to and from the grinding
wheel A2, that it is desired to impart to the bar B, and to the drill D carried by it, is
governed by the distance existing between the centre of the said pin B' and that of
the fulcrum pin B³.
It will now be understood that when the bar B is caused to oscillate on the fulcrum
pin B', the crank arm B³, being of shorter radius from the centre of its axis B³ to the
centre of the pin B than the radius from the centre of the fulcrum pin B' to the
centre of pin B, gives a supplementary motion to the bar B, and consequently to the
drill D, which brings the point of the latter first forwards towards, and then backwards
away from, the grinding wheel, by traversing it through an arc, or curve, having a
greater versed sine than that through which it is traversed by the arrangement
described and illustrated in the Specification of my aforesaid Patent No. 3076, and
therefore the point of the drill is moved away from the grinding wheel quickly, and
before its chisel edge can be spoilt. The extra movement given by the crank arm B³
is permitted by the slot B' sliding on the fulcrum pin B¹.
By these means, the chisel-edged point of the drill is preserved, at the same time
that the clearance of the cutting edge of the drill, remote from the chisel point, is
made less than by the arrangements described and illustrated in the Specification of
my aforesaid Patent No. 3076.
Instead of the crank arm B2, a fixed pin in the arm B taking into a curved slot in
the plate A, or a fixed pin in the plate A taking into a curved slot in the arm B, or
a cam, or other suitable mechanical device, may be employed to produce a similar
effect.
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 In combination with the bar B, carrying the twist drill to be ground, which
bar oscillates, and slides, on a fulcrum pin in, or on, a part of the arm or plate A ;
the crank arm B² arranged and operating to impart an increased forward and
backward motion to the drill, as hereinbefore described, and illustrated in the
Drawings hereto annexed, and for the purposes specified.
Second In combination with the bar B, carrying the twist drill to be ground,
which bar oscillates, and slides, on a fulcrum in, or on, a part of the arm or plate A,
a pin fixed in the bar B, or in the arm or plate A, and taking into a curved slot in
the arm or plate A, or in the bar B, or a cam, or other equivalent devices for
imparting an increased forward and backward motion to the drill, as hereinbefore
described, and for the purposes specified.
EDWARD D. BARKER,
115, Cannon Street, London,
Applicant.