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Патент USA US2136616

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Nov. 15, 1938.
Filed Oct. 26, 1936
Patented Nov. 15, 1938'
Martin Hokanson, Duluth, Minn., assignor tov
Eidco, Inc., Duluth, Minn., a corporation of
Application October 26, 1936, Serial No. 107,564
3 Claims.
(Cl. 51--239)
This invention relates to work tables or sup
beyond the hole obviously being for the pur
ports applicable to a common bench grinder, and pose of selectively clamping the work table in
relates particularly to improvements in a sup
any desired rotatable position, as by the crank
port and associated instrumentalities for suc
head bolt 30. It will be noted that the bracket
,5, cessful and most conveniently operated means 5 is adjustable upon the extension 4 in the usual 5
for the grinding of drill hits such as used in rock‘ manner, as by manipulation of the bolt II. The
drilling or the like, and particularly wherein rel- ‘ table II) is for the convenient support of the work,
atively short drill heads are used on more or
less extended and detachable shanks, so that the
10' head only is necessary for consideration and ma
nipulation during the grinding and sharpening
Such a drill bit is comparatively common in the
art. It is obvious, however, that the cutting face
151 of the bit may be of varied form or shape and still
the convenience of the instant form of work table
or support be equally appreciated and utilized.
One of the principal objects of the invention
is to provide a work supporting table upon which
20 a drill bit head may be most conveniently rotated
manually while being sharpened.
Another object of the invention is to provide
selective and dependable setting means for pre
determining the angle of the ultimate sharpen
25,, mg of the bit.
Referring now to the accompanying drawing,
forming part of this application, and wherein
like reference characters indicate like parts:
Figure 1 is a front elevation of a portion of
a common bench grinder having one embodiment
of the invention applied thereto.
Figure 2 is an enlarged elevation, at right an
gles to that shown in Figure 1 of the grinding
angle gauge.
Figure 3 is an enlarged plan View of the free
end of the table supporting bracket.
In the drawing, l represents a common elec
trically operated bench grinder usually equipped
with a grinding wheel upon either end of the
40 armature shaft thereof, and in this instance I
have illustrated but one end and secured there
to a V-shaped grinding wheel 2 suitable for the
purpose intended, the same being protected by
the adjustable guard housing illustrated at 3
45 and common in the art.
Such guard housing
usually carries an angularly depending projec
which, in this instance, is illustrated in dotted
lines at 12 as being a drill head bit and for con
venience in illustration is shown as one having 10
arcuate cutting edges to be ground with inclined
outer surfaces indicated at [3. It is apparent
thus far that in order to sharpen such an in
clined surface the bit head will have to ap—
proach the grinder while in upright position and 15
horizontally and with the plane of its cutting
face materially above the lower circumferential
edge of the grinding wheel, and the distance
above such lower point will determine the angle
of the grinding.
Now in order to provide a gauge for such pur
pose, prior to the initial operation of the grind
ing and to insure subsequent operations being
uniform, I have provided a gauge carried upon
the guard housing 3' of the grinder and pivot 25
ally attached concentrically coincident with the
axis of the armature of the grinder upon which
the grinding wheel is attached, such connection
being accomplished as by the pin or stud I4 be
ing screw-threadedly applied to the housing for 30
pivotal support of the gauge plate l5 externally
of which the jam nut I6 is screw threaded upon
the pin l4 so that by the slacking oif of this nut
the gauge plate may be selectively rotated and
again held securely in any desired position by 35
the nut. Also upon the outermost end of the
pin or stud I4 is screw threadedly mounted the
sleeve nut I‘! having a diametrically disposed
through hole just outwardly of the outer end
of the pin after the nut I‘! is mounted there 40
upon, and through which hole is adjustably car
ried the pointer stem I8, the adjustability of
which is accomplished by the thumb screw l9
being mounted within the bore of the nut l1
and engageable with the stem I8 when in the
nut. The stem I8 is ?attened somewhat as at
tion 4 provided with a tool rest not shown, but
to which projection I have shown attached a
bracket 5, the extreme free end of which is of
50 somewhat L-shape as at 6 (see Fig. 3) and which
free terminal is split as at l and provided with
an internally screw threaded hole 8 at the in~
ner termination of the slot 1, into which hole is
screw threadedly mounted the stem 9 of the work
of by the thumb screw I9.
The operable condition of the gauge plate 15
is obviously at an angle as shown in Figure 2
which may be set in various ways hereinafter
described, and is provided with a plurality of
screw threaded holes as indicated at 2|, each
hole carrying ‘adjacent thereto numerals indi
55 table It); The object of the bifurcated portion
cating various angles at which the grinding of 55
20, longitudinally thereof for ?rm holding there
the wheel may be accomplished upon a drill head.
Common to all of the holes 2| is provided a
thumb and ?nger manipulated pin 22 having‘ a
screw threaded end applicable to or from any
one of the holes, this pin being for the pur
pose of limiting the movement of the pointer
stem or arm which carries upon its extreme
free end the pointer 23, it being adjustable back
and forth in preferably the same manner as the
10 arm is adjustable in the sleeve l1 and such ad
justment obviously being for the accommodation~
of different shaped and diametered grinding‘
wheels. This gauge apparatus, including the
pointer, arm and plate, may be set in the follow
15 ing manner: Assuming that it 'is desirable to
sharpen the outer wall of the cutting face of
a bit head at an angle of 45°, and that the gauge
plate I5 is loose upon its supportingv bolt l4 and
carrying the pin 22 within the hole designated
20 at 90, which represents the angle of the line to
the angle of grinding, the arm 18 may be swung
on its pivotal support up to a 45° position from
the vertical, as for example indicated by the line
24, and which will swing the‘ center line of the
25 plate I5 somewhat above said 45° line 24, when
the attachment of the plate i5 may be tightened
as by the nut l6 upon the pin or stud l4 so that
it will remain in such position. The pointer 23
being swung concentrically with the extreme pe
30 ripheral edge of the grinding wheel 2 will, when
reaching its limit of movement against the pin
22, indicate at said peripheral edge the point or
height of the plane of the cutting edge of the
bit to be ground. If the plane of the cutting
edge of the bit as at 25 is brought to such point,
indicated at 26, and forced, against the grinding
wheel, subsequent of course to the return of the
pointer to inactive position as illustrated in Fig
ure 2, the grinding operation of the wheel will
40 be conducted as indicated by the line 21, the
same being at an angle of 45° to the axis of the
bit, and 90° to the axis of the pointer arm which
had established such point, so that the holes
within the gauge plate I 5 are numbered in re
. spect to the angle of the grinding operation to
the axis of the pointer arm. It will be noted
that the guard housing 3 on the grinding unit is
rotatably adjustable as by the clamping bolt 29
and suitable nuts therefor, so that it is imma
terial at just what angle an operator cares to
accomplish the desired functioning of the de
vice, as the setting mechanism will function
equally as well.
Furthermore, it will be noted that, if preferred,
the plate l5 may be initially set for the proper
functioning of the gauge instead of the arm l8
itself, and the arrangement of holes 2| in said
plate may be positioned as desired for the work
By this most convenient and simple attach
ment, an operator may grind a bit having a cut
ting face of almost any form, the accuracy of
same apart from the positive setting of the angle
of the grinding depending wholly upon the skill
of the operator.
Having thus described my invention, what I
claim and desire to secure by Letters Patent, is:
l. The combination with a grinding wheel hav
ing a guard housing partially surrounding the
same,. of a vertically adjustable work supporting
table adjustably mounted upon said housing, and 20
a gauge for predetermining the angle at which
work supported upon said table and moved hori
zontally thereupon toward said wheel will be
2. The combination with a grinding wheel hav
ing a guard housing partially surrounding the
same, of a vertically adjustable Work supporting
table mounted upon said housing, and a gauge
for pred‘etermining the angle at which work sup
ported upon said table and moved horizontally 30
thereupon toward said wheel will be ground, said
gauge comprising a plate having a plurality of
openings therein, a pin engageable within any
of said openings, and a pointer swingably mount
ed and coincident with the periphery of said 35
wheel and limited in its movement in one direc
tion by said pin.
3. The combination with a grinding wheel hav
ingv a guard housing partially surrounding the
same, of a vertically adjustable work supporting 40
table mounted upon said housing, and a gauge
for predetermining the angle at which work sup
ported upon said table and moved horizontally
thereupon toward said wheel after removal of
the gauge will be ground, said gauge being piv 45
otally mounted upon said housing coincident with
the axis of said wheel and the free end‘ of said
gauge being swingable in a path coincident with
the periphery of said wheel.
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