An Improved Holder or Device for Grinding Twist Drills and the like.
Year: 1890

page_text: Date of Application, 11th Dec., 1890.
Complete Specification Left, 11th Sept., 1891-Accepted, 17th Oct., 1891
PROVISIONAL SPECIFICATION.
An Improved Holder or Device for Grinding Twist Drills and
the like.
I, ERNEST GUSTAV HOFFMANN Engineer, of No. 5 Clarendon Villas, Beacons-
field Road, New Southgate, in the County of Middlesex, do hereby declare the
nature of this invention to be as follows :-
My invention relates to an improved holder or device for grinding twist and like
drills the object of same being to provide a simple and effective holding device
which may be used in connection with an ordinary grindstone emery wheel or the
like in place of the more expensive means frequently employed.
The holder or device referred to consists of a metal block carrying small wheels
which wheels are adapted to bear upon the face of the grindstone and revolve
therewith or in place of said wheels the arbors hereinafter described are preferably
employed.
The block may carry in addition a roller or wheel beneath, which will bear on
the grindstone in case of need.
The block is adapted to carry or hold the drill and is placed upon the "rest" of
the grindstone in presenting the drill to the latter. It is provided with a suitable
stop device for adjusting the drill so as to regulate the amount to be ground or
taken off. This may consist of a bush which would be secured to the drill by a set
screw or the like. The drill is held on or in the block by a thumb screw which.
may press a plate or key block against same, and a further set screw is provided
for engaging with the groove of the drill so that it is accurately adjusted and also
prevented from turning when in place. When one face of the point has been
ground the drill is withdrawn turned round and again fixed in the block the set
screw last mentioned and the stop device ensuring its other face being presented to
the grindstone on the same plane as the former so that a perfect point is obtained.
In some cases in place of the wheels upon the blocks I prefer to use arbors only
which may carry bushings by which the operator is enabled to maintain the drill
upon the same portion of the face of the grindstone that is started upon and I use
in connection with the block having the arbors aforesaid a rest which is adjustable
in the grindstone frame and may carry an adjustable tool rest for ordinary purposes
if desired. This rest is adapted to receive the arbors which will bear against stops
on same when the drill is ground down to the required degree.
Dated this 11th day of December 1890
PHILIP M. JUSTICE,
55 & 56, Chancery Lane, Agent for the Applicant.
COMPLETE SPECIFICATION.
An Improved Holder or Device for Grinding Twist Drills and
the like.
I, ERNEST GUSTAV HOFFMANN Engineer, of No. 5, Clarendon Villas Beacons-
field Road, New Southgate in the County of Middlesex, 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 an improved holder or device for grinding twist and like
drills, the object of same being to provide a simple and effective holding device
which may be used in connection with an ordinary grindstone, emery wheel or the
Pl

page_text: like in place of the more expensive apparatus frequently employed. To clearly
explain the nature of my invention reference is made to the accompanying drawings
in which
Fig. 1. is plan view looking down upon the top of the grindstone.
Fig. 2. is a view looking down upon the point of the drill which is in a vertical
line below.
Fig. 3. is an end view with the drill in a vertical position.
Fig. 4. is an elevation of a part of a grindstone showing the manner of employing
the holder when grinding a drill or the like.
C
The holder consists of a metal block a through which the drill is passed its point
being allowed to project a sufficient distance through same to permit of one edge
being presented to the stone. The block carries spindles or rods b b which to
render the device or tool more portable may be screwed into same if desired.
These rods are adapted to be carried by rests attached to the grindstone frame as
hereafter described. It will be seen on reference to Fig. 2 that the centre of the
drill is not in line with the centre of the rods bb, this being necessitated by the
angle to which the drill is required to be ground to obtain the proper clearance of
the cutting edge. Upon the drill when in the block a is slid a stop device
consisting of a bushing c which is secured to the drill by a set screw d. This
bushing alone will answer the purpose but I prefer to employ for a finer adjustment
a further set screw e which works in a boss on the bushing c and bears against the
block a or preferably against a hard metal plate interposed between them. The
drill is held in the block a by a screw 9 which may be attached to a key block /
by letting its end into a recess in same and securing it by pins which embrace a
groove formed therein as shown in Fig. 1. so that the screw may revolve and thus
move the key block in or out of the groove provided for its reception in block a or
the screw may be a simple pressure screw, the key block being retracted by a
spring. This key block will bear upon and hold in the block any drill of the
diameter of the opening or of a smaller diameter:
A further set screw i is provided which passes through another boss in the
block a, the end of this, engaging with one of the grooves of the drill so that the
faces of said drill may be adjusted for grinding. The screw is provided with a set
nut as shown.
When one face of the drill has been ground as illustrated in Fig. 1. the drill is
withdrawn by loosening the key block A, turned around and again fixed in the block,
the bushing c (or the adjusting screw e) ensuring its being passed through the
block exactly the same distance as for the other face while the end of the set
screw by engaging with the groove ensures the second face being presented to the
grindstone at exactly the same plane as the first, so that two identical faces are
produced on the drill.
When using the device the rods bb are placed in the notched portion of a rest
as shown in Fig. 4 of which there is one on each side of the grindstone. The rest
may form an addition to the usual tool rest m and be adjustable by means of a slot
through which passes a screw, a nut n on which will hold the rest when in the
desired position. When the rods are on the rest the drill may be traversed to
and fro across the face of the grindstone within the limits of the rods, but in order
to finish the grinding of each face upon the same portion of the stone which is
important in view of the irregularities of a stone when at all worn I employ the
bushing (which is affixed upon one of the rods by its set screw) by causing it to
abut against one of the rests 7 after a suitable portion of the stone has been selected,
the grinding being always finished with the bushing held up to this rest.
In place of a single notch the rest may be provided with two, three, or more
arranged in step form so as to be at increasing distances from the stone. These
notches will be adapted for the different sized holders which may be made. For
instance the notch nearest the stone will be used for a holding device adapted to
take drills up to one half inch which may all be ground to the same radius. The

page_text: next notch will take a holding device adapted for drills from one half to one inch
which require to be ground to a different radius and so on, these steps obviating
the necessity for shifting the rest for each size of holder.
During grinding, the drill while being held up to the stone is worked up and
down or rocked as indicated by the dotted lines in Fig. 4.
For the purpose of enabling smaller size drills to be conveniently held I form
the opening in the block a and in the bushing c of the shape shown in Fig. 2.
To enable the person using the device to ascertain how far the drill should be
pushed through the block a when first setting same I may use a guage o indicated
by dotted lines Fig. 1 which guage is slid upon one of the rods 6 so that its end
forms a stop for the drill when it is pushed through the block. This guage is not
required after the first face has been set and may be turned around out of the way
or removed. In place of the rods 6 I may employ rollers which would travel upon
the face of the stone; or other suitable devices may be employed for maintaining
the block at a definite distance from the stone. may also employ a roller or
rollers beneath or above the block or both which would bear upon the stone in case
of need and regulate the amount of the rocking motion imparted to the drill when
grinding.
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 :-
1. For grinding twist drills and the like a holding device having means for
securing the drill in same, means for regulating the amount to be taken off each
face, an adjusting device for engaging with a groove of the drill and means for
maintaining the block at a definite distance from the stone substantially as
described.
2. For grinding twist drills and the like a holding device having an adjustable
key-block for securing the drill in same, a stop bushing applied to the drill having
means for setting same thereon and an adjusting screw, a further adjusting screw
carried by the block for engaging with a groove of the drill and rods carried by
the same for bearing on a rest, substantially as described.
3. In a device for grinding twist drills and the like, an adjusting screw or the
like for engaging with a groove of the drill substantially as and for the purpose
described.
Dated the 11th day of September 1891.
PHILIP M. JUSTICE,
55 & 56, Chancery Lane, London, Applicant's Agent.