Year: 1887

page_text: I, ALEXANDER GRAY of 25 Greenhill Road, Hampstead London, N.W., Gentleman
do hereby declare the nature of this invention to be as follows:-
The invention consists of a machine by means of which cutting tools can be
ground with precision and facility to any angle or combination of angles.
By this invention a receptaclo in which the tools are fixed and held is furnished
with two circular motions at right angles to each other, and the apparatus thus
constructed is mounted upon a vertical spindle on which it may revolve and it has a
provision for vertical adjustment.
The tool when fixed in the receptacle and adjusted by means of the two circular
motions can thus be swung to and fro in a horizontal plane and be brought in contact
with a grinding surface." In this way the tool can be ground with precision &
facility to any angle that may be desired.
It is preferable that the spindle should be vertical, and that the grinding surface
should be horizontal. But all that is indispensable is, that the spindle should be at
right angles to the plane of the grinding surface, or to a plane tangent to the grinding
surface if such grinding surface be curved.
The grinding surface may be in motion or not.

page_text: I ALEXANDER GRAY of 25 Greenhill Road Hampstead in the county of Middlesex
Gentleman 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 invention consists of a machine by means of which cutting tools can be ground
with precision and facility to any angle or combination of angles.
The arrangement of the machine shown in Figures 1 & II of the drawing hereto
annexed is that for grinding chisels, plane-irons and the ordinary tools used in turning
planing & shaping machines.
The apparatus consists of an emery ring A revolving in a horizontal plane, an arm F
which revolves on the base H and is fixed by the nut G, and which carries in its
tubulated part L the pillar D which can be slid up or down and be fixed by the set
screw O. By the movement of the arm F on the base EI, the distance of the pillar D
from the ring A can be rapidly adjusted. On the pillar D is mounted the piece M
fitted so as revolve upon it, and at the top of M is a cap E with a screw inside bearing
on the top of the pillar D. The height of M can be adjusted roughly by sliding the
pillar up or down and can be adjusted more accurately by the screw inside the cap E.
Standing out from M is the arm with its axis at right angles to the pillar D and
provided with a graduated base I, which revolves on M; the face of M on which I
revolves is parallel with the axis of the pillar D, so that the axis of Cis always at right
angles with the axis of D). At the other end of C is mounted a "Willis" or other
tool holder B with a graduated base K which revolves on Cat right angles to the
graduated base 1.
To use the apparatus, the tool is first fixed in the tool holder B and is set to the 2
required angle of relief by the graduated circle I, & is then set for the side angle by
the graduated circle K.
The rough adjustment for height is obtained by sliding the pillar D up or down.
The tool is swung over the ring A and brought down to contact with it by turning the
cap E. The emery ring being made to rotate rapidly, the tool is swung backwards a
& forwards over it, being fed down as required by turning the cap E.
One facet being ground, the graduated base K is released and fixed at any desired
angle with its previous position; on bringing the tool down as before and swinging
it to and fro over the ring A, another facet is ground at the desired angle.
Both facets will have the same angle of relief.
2

page_text: The apparatus shown in Figures 11I & IV is arranged for grinding twist, straight-
fluted, and other drills. The arm C & tool holder B shown in Figs. I & II, are
removed and the arm N put in their place. This arm N also has a graduated base I
5 which revolves on M at right angles to the pillar D. At its other end it has a
V groove at right angles to the axis on which it revolves and the angle of the V is
intersected by that axis.
MODE OF USE.
The drill is placed in the V groove and fixed by the clamp R. The graduated
0 base I is turned round to the angle of 34° with the perpendicular to the grinding
surface, or to whatever other angle may be desired, and the drill is then turned in the
groove to obtain the desired angle of relief. (For twist drills, the drill must be
turned so that the cutting edges are at an angle of 65° with the axis of N, the drill
being ground at an angle of 34° with the perpendicular.)
The drill is then brought down into contact with the emery ring, and one side of
the drill is ground, the drill being fed down as required by turning the cap E.
The position of the graduated cap E is noted. The arm N is then released and the
V groove with the drill turned over to the other side the same degree as before; the
drill is raised, if need be, by the screw-cap E and is ground till the graduation on the
cap E reads the same as when noted after grinding the other side of the drill. Both
sides of the drill will now be found alike.
In the case of twist- & straight-fluted drills, the part of the drill behind the cutting
edge will require grinding away so as to give the requisite clearance.
This is best done by hand.
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
A pillar perpendicular to the grinding surface combined with a tool holder which
swings on the pillar in a plane parallel with the grinding surface, if such surface bo
flat, or parallel with a tangent to that surface if it be curved, and provided with
adjustment in the direction of the axis of the pillar.
131
. 1.... 1960