Tools to Facilitate the Production of Accurate Forms.
Year: 1888

page_text: Tools to Facilitate the Production of Accurate Forms.
1, CHARLES SIMEON THOMASON of Indore, Central India, temporarily residing at
61 Abingdon Villas Kensington in the County of Middlesex Brevet Colonel &
Lieutenant Colonel R.E. Bengal do hereby declare the nature of this invention to
be as follows:-
In the Specification of a former Patent granted to William Lloyd Wise No. 12898
dated 27th September 1884 is described an Invention for apparatus for use in grinding
or sharpening cutting tools to facilitate the production of accurate forms, communi-
cated by me to him, and this invention has reference in part to further developments
of or improvements upon apparatus described in the said Specification.
I will first describe the nature of an apparatus according to my present invention
suitable for sharpening drills fluted straight or spirally. The body of a fluted drill
consists of a cylinder grooved on two opposite sides, the intersection of the grooves
with the end of the drill forming two lines, the straight portions of which should be
parallel with each other and at a distance apart equal to about one eighth of the
diameter of the drill and leading from the circumference a little past the axis; they
are curved backward in a direction opposite to that of the rotation of the drill, and
again touch the circumference at a distance of rather more than a quadrant from the
starting point, as well understood.
The angle of clearance of the lips is obtained by the shape to which the end
surfaces of the drill are ground, and the straight part of the intersections of these end
surfaces with the grooves forms the cutting edges. The most efficient shape for these
end surfaces can best be determined by considering that the surface of the metal
being cut is in the form of a hollow cone truncated a certain amount, depending on
the thickness of the web of the drill. The cutting edges of the drill will touch this
hollow cone in straight lines. Now, if a portion of a conical surface be made to
coincide with this hollow cone, and then to be rotated about one of these straight
lines through an angle of, say, 5°, a uniform and similar clearance throughout will be

page_text: produced, and the most perfect clearance possible will be obtained; and it is therefore
the object in shaping the end of a twist drill to approximate to this degree of per-
fection. As the two cutting edges are straight lines, parallel to each other, but at a
distance apart equal to the thickness of the web, and as each is produced by the
intersection of a conical surface with one of the grooves of the drill, these conical
surfaces must be selected so that their intersection with each other will produce a
proper form of chisel point, and so that they will approximate as nearly as possible to
the surface of the hollow cone.
In correctly formed twist drills the apices of the conical surfaces are moved away
from the apex of the hollow cone a sufficient distance to produce, by the intersection
of the surfaces, a proper form of chisel point; the axes are inclined so that the radius of
curvature of the surface at the outer end of the cutting edge corresponds with that
of the hollow cone; and these axes do not lie in the same plane, but in parallel planes,
at a distance apart greater than the thickness of the web of the drill, so that a tangent
to the conical surface will make an angle of 5° with a tangent to the hollow cone at
the outer end of the cutting edge.
Now an arrangement of apparatus according to my invention for facilitating the
correct grinding of fluted drills in accordance with the foregoing well known
principles comprises a block formed of suitable material such as cast iron with two
surfaces each having the shape of. part of a truncated cone the axes of the two
being inclined to each other and arranged at opposite sides of the centre of a hole
formed through the block for the reception of the drill or drill holder. The conical
surfaces correspond to prolongations of the surfaces of a correctly ground drill.
In order that the drill may be readily fixed in place the block may be formed in
two parts hinged together and provided with a fastening device, or the block may
be in one piece; in either case the hole therethrough is adapted to receive a single
tool or a tool holder capable of receiving drills of different sizes and hereinafter
described. When a horizontal grindstone is employed the drill may be correctly
ground by applying each conical surface in turn to a horizontal table or support, the
end of the drill being in rubbing contact with the stone. For a vertically rotating
grindstone a suitable arrangement of tail rest on the grindstone table or support and a
tail or groove on the block may in some cases be provided to enable the block to be
readily and correctly moved for imparting the proper form to the tool. Or the block
may be provided with two projections or pins having their axes coincident with those
of the part cones of the block. The projections or pins are adapted to take into a hole
or into a slot formed in a back rest or frame that serves to carry the block whilst a
tool is being ground and which may be hinged or pivotted to the grinding table Or
the block may be formed with holes instead of projections or pins and the back rest or
frame may be provided with a corresponding projection or pin adapted to enter the
said holes and support the block in the position for correct rotation. In another
arrangement of apparatus, suitable for use when grinding fluted or other drills the
drill holder is secured in a frame which is journalled to a bracket or standard that is
hinged or pivotted to a suitable support. The axis of the drill holder and the axis about
which the frame whereby it is carried turns are arranged at an angle with each other
but they do not intersect, being in different planes. To this end the frame is formed
with a slot in which is secured a spindle mounted in the bracket or standard. Stops
are provided to prevent the frame being turned through too great an angle for correct
grinding of the drill. It will usually be found advantageous to so arrange one of the
stops that at the commencement of grinding a drill, a cutting edge thereof will be in a
plane at an angle of about 7° with the plane containing both the axis of the grindstone
and the axis about which the frame carrying the drill holder moves. To enable this
angle to be varied according to the cutting angle of tool required, the tool holder may
be provided with a stop pin carried by an adjustable ring encircling the holder and
fixed in any desired position by a screw collar. To ensure even wear of the grindstone
the bracket or standard may be pivotted in a slide rest that may be moved towards or
from the stone; or it may be arranged to slide or roll along a suitable table. In
order that several drills may be simultaneously ground I provide at one or both sides

page_text: of the grindstone a frame with projecting spindles each adapted to carry a rest or
grinding table fitted with a grinding apparatus that may be of the kind just described
or of other suitable construction adapted for the tool to be ground.
To ensure the correct presentation of the drill to the grindstone I provide the double
conical block of the apparatus herein before first described, or the drill holder, with a
removable perforated disc, the opening through which is in the form of a slot with
rounded ends and of a size corresponding with the drill to be ground. Thus by
providing a number of discs with slots of different sizes one block or holder may be
used for drills of many different sizes. Or in lieu of perforated dises the drill holder
may for the same purpose be provided with a pair of projecting studs carried by spring.
arms and adapted to take into the grooves of a drill under the action of an adjustable
collar. These studs, which are of a form adapted to enter the grooves and guide and
hold different sizes of drills, may be serrated or roughened to ensure a better hold.
For the purpose of imparting accurate cutting edges to tools such as gouges a guide
block having a conical surface corresponding with the bevilled surface of a correctly
ground gouge is employed, the block being formed with a hole in which the tool is
fixed. Considering the gouge as a portion of a hollow cylinder the form of cutting
edge will depend upon the position of the axis of this cylinder in relation to the axis
of rotation of the conical blocks. Thus if the two axes coincide the cutting edge will
be circular as in a carpenter's gouge, if parallel, a portion of a parabola as in a hand
turning gouge, and if inclined, a portion of an ellipse as may be necessary in some
forms of slide rest tools.
In order that guide blocks and tool holders of various kinds may be adapted to hold
tools of various sizes and that the tools may be readily fixed in and removed from the
block or holder, the hole in the block or holder may be made of tapering form into
which takes a spring clamp of corresponding exterior shape and fluted internally to
adapt it to hold the tool to be ground.
The arrangement is such that if the clamp with a tool therein be forced within the
block or holder parts of the clamp will be sprung or forced against the tool thereby
holding the same firmly within the block whilst if the clamp be moved in the opposite
direction the tool will be released. A convenient arrangement of clamp for this
purpose is made of hollow rectangular form in cross section of two pieces of metal
arranged at a short distance apart and fitted together at one end, the end of one piece
being made to overlap the other so as to admit of the clamp being driven into the
block without straining where they are connected.
Dated this 3rd day of May 1888
W. LLOYD WISE,
46, Lincoln's Inn Fields, London, W.C.,
Agent for the Applicant.

page_text: '
Improvements in Apparatus for Grinding or Sharpening Cutting
Tools to Facilitate the Production of Accurate Forms.
1, CHARLES SIMEON THOMASON of Indore, Central India, lately temporarily
residing at 61 Abingdon Villas, Kensington, in the County of Middlesex Brevet
Colonel and Lieutenant Colonel R.E. Bengal 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 :-
In the Specification of a former Patent granted to William Lloyd Wise No. 12898
dated 27th September 1884 is described an invention for apparatus for use in grinding
or sharpening cutting tools to facilitate the production of accurate forms, com-
municated by me to him, and this invention has reference in part to further
developments of or improvements upon apparatus described in the said Specification.
I will first describe the nature of an apparatus according to my present invention
suitable for sharpening drills fluted straight or spirally. The body of a fluted drill
consists of a cylinder grooved on two opposite sides, the intersection of the grooves
with the end of the drill forming two lines the straight portions of which should be
parallel with each other and at a distance apart equal to about one eighth of the
diameter of the drill, and leading from the circumference a little past the axis, they
are curved backward in a direction opposite to that of the rotation of the drill, and
again touch the circumference at a distance of rather more than a quadrant from the
starting point as well understood.
The angle of clearance of the lips is obtained by the shape to which the end
surfaces of the drill are ground, and the straight part of the intersections of these end
surfaces with the grooves forms the cutting edges.
The most efficient shape for these end surfaces can best be determined by consider-
ing that the surface of the metal being cut is in the form of a hollow cone truncated
a certain amount, depending on the thickness of the web of the drill. The cutting
edges of the drill will touch this hollow cone in straight lines. Now, if a portion of
a conical surface be made to coincide with this hollow cone, and then to be rotated
about one of these straight lines through an angle of, say, 5°, an uniform and
similar clearance throughout will be produced, and the most perfect clearance
possible will be obtained; and it is therefore the object in shaping the end of a twist
drill to approximate to this degree of perfection. As the two cutting edges are
straight lines, parallel to each other but at a distance apart equal to the thickness of
the web, and as each is produced by the intersection of a conical surface with one
of the grooves of the drill, these conical surfaces must be selected so that their inter-
section with each other will produce a proper form of chisel point, and so that they
will approximate as nearly as possible to the surface of the hollow cone.
In correctly formed twist drills the apices of the conical surfaces are moved away
from the apex of the hollow cone a sufficient distance to produce, by the inter-
section of the surfaces, a proper form of chisel point; the axes are inclined so that
the radius of curvature of the surface at the outer end of the cutting edge corresponds

page_text: with that of the hollow cone; and these axes do not lie in the same plane, but in
parallel planes, at a distance apart greater than the thickness of the web of the drill,
so that a tangent to the conical surface will make an angle of 5° with a tangent to
the hollow cone at the outer end of the cutting edge.
Now an arrangement of apparatus according to my invention for facilitating the
correct grinding of fluted drills in accordance with the foregoing well known principles
comprises a block formed of suitable material such as cast iron with two surfaces,
each having the shape of part of a truncated cone the axes of the two being inclined
to each other and arranged at opposite sides of the centre of a hole formed through
the block for the reception of the drill or drill holder. The conical surfaces correspond
to prolongations of the surfaces of a correctly ground drill.
In order, that the drill may be readily fixed in place the block may formed in two
parts hinged together and provided with a fastening device, or the block may be in
one piece; in either case the hole therethrough is adapted to receive a single tool or
tool holder capable of receiving drills of different sizes and hereinafter described.
When a horizontal grind stone is employed the drill may be correctly ground by
applying each conical surface in turn to a horizontal table or support, the end of the
drill being in rubbing contact with the stone. For a vertically rotating grindstone a
suitable arrangement of tail rest on the grindstone table or support and a tail or groove
on the block may in some cases be provided to enable the block to be readily and
correctly moved for imparting the proper form to the tool.
In the accompanying illustrative drawings Figs. 1 and 2 illustrate a block
constructed according to this part of my invention Fig. 1 being a vertical section
through one of the truncated cones and a tool holder carried thereby, and Fig. 2 a
plan or top view of the complete block.
In Fig. 1 the block is shewn as supported upon a horizontal table, the twist drill
secured in the block being applied to the upper part of a vertical grindstone.
hole 1.
The block is formed with a central hole 1 therethrough for the reception of a drill
or of a tool holder 2 as shewn and comprises two parts 3 and 4 hinged together at 5
and provided with a catch or fastening device 6 whereby they may be partly separated
from each other when necessary for the purpose hereinbefore mentioned. The parts I
and 2 are each in the form of part of a truncated cone the conical surface of which
corresponds to a prolongation of the surface of a correctly ground tool clamped in the
The axes
1 is a bush or lining secured within the hole by a set screw 1°.
of the two conical parts are inclined to each other as shewn in Fig. 1 and are on
opposite sides of a centre line passing through the centre of the hole 1 as shewn in
Fig. 2.
is part of a vertical grindstone and 9 is part of a horizontal table upon
which each of the part cones (1) and (2) of the block is caused to roll (in turn).
through part of a revolution for grinding the two end surfaces of the twist drill 10
which is clamped within the block or in the tool holder and has its end arranged to be
in rubbing contact with the upper surface of the grindstone as shewn in Fig. 1.
a fixed tail rest on the table 9 and 12 a corresponding groove in the block for the
purpose hereinbefore mentioned. The block may be provided with two projections or
pins 13 and 14 as shewn the axes of which are coincident with the axes of the part
cones 3 and 4 of the block. These pins may be adapted to take (in turn) into a hole
or into a slot formed in à back rest or frame (not shown) that serves to carry the
block and permit the same being partly turned round whilst a tool is being ground
and which may be hinged or pivotted to the grinding table. In this case the block is
not directly supported by the table. Or the block may be formed with holes instead of
but corresponding in position with the projections or pins 12, 13 and the back rest or
frame may be provided with a corresponding projection or pin adapted to enter the
said holes in turn and serve as a journal to support the block in the position for
correct rotation for grinding the drill.
11 is
This arrangement is not shewn in the drawings but will be readily understood
from fig. 1. In another arrangement of apparatus, suitable for use when grinding
fluted or other drills the drill holder is secured in a frame which is journalled to a
bracket or standard that is hinged or pivotted to a suitable support.

page_text: The axis of the drill holder and the axis about which the frame whereby it is
carried turns are arranged at an angle with each other but they do not intersect
being in different planes.
To this end the frame is formed with a slot in which is secured a spindle mounted
in the bracket or standard.
Stops are provided to prevent the frame being turned through too great an angle
for correct grinding of the drill.
It will usually be found advantageous to so arrange one of the stops that at the
-commencement of grinding a drill, a cutting edge thereof will be in a plane at an
angle of about 7° with the plane containing both the axis of the grindstone and the
-axis about which the frame carrying the drill holder moves.
To enable this angle to be varied according to the cutting angle of tool required,
the tool holder may be provided with a stop pin carried by an adjustable ring
encircling the holder and fixed in any desired position by a screw collar.
To ensure even wear of the grindstone the bracket or standard may be pivotted
in a slide rest that may be moved towards or from the stone; or it may be arranged
to slide or roll along a suitable table.
In order that several drills may be simultaneously ground I provide at one or both
sides of the grindstone a frame with projecting spindles each adapted to carry a rest
or grinding table fitted with a grinding apparatus that may be of the kind just
described or of other suitable construction adapted for the tool to be ground.
Figs. 3 and 4 are elevations at right angles to each other, and
Fig. 5 a plan or top view illustrating apparatus constructed according to this part
of my invention.
Figs. 6, 7 and 8 are detail views of parts of such apparatus. In this arrange-
ment however the necessary checks against overgrinding being otherwise provided
for, the superfluous portions 3 and 4 of the cone shewn in figs. 1 and 2 are dispensed
with.
15 is a frame for carrying the tool holder 2; it is provided with a spindle 16
journalled in a bracket or standard 17 that is pivotted at 18 to a slide rest 19. This
slide rest is mounted upon a support 20 provided with a screw 21 by means of which
the slide rest may be reciprocated and a drill carried in the drill-holder caused to
traverse across the stone for the purpose herein before mentioned. The axis of the
drill holder 2 and the axis of the spindle 16 about which the frame 15 is capable of
turning, are arranged at an angle with each other and do not intersect being in
different planes as shewn in accordance with the principle herein before set forth.
In order that the distance apart of the axes may be adjusted for the purpose of
varying the length of chisel point imparted to a twist drill, the hole in the frame 15,
in which the spindle 16 is secured, is in the form of a slot. The arrangement of the
tool holder 2 and frame 15 are such that assuming a drill to be secured in the said
tool holder and that it is applied to a grindstone, then if the frame be turned about
the axis of the spindle 16 alternately in opposite directions, a correctly formed
cutting edge and surface will be imparted to the end of the drill. Then by loosening
the drill turning it through an angle of 180° in the tool holder clamping it therein,
and again operating the frame 15 as before, the other cutting edge and surface may
be correctly ground and the grinding of the tool completed. In the example shewn
the bracket or standard 17 serves as a stop for limiting the rotary movement of the
frame 15 in both directions; a special stop may however be provided for this purpose
if desired.
Fig. 6 illustrates in central longitudinal section, part of an adjustable tool holder
adapted to enable a twist drill held therein to present its cutting edge at any desired
angle with the plane that contains both the axis of the grindstone and the axis of
the spindle 16 if change be desired to meet requirements of straight fluted drills or
special flutings for various cutting edges. For this purpose the tool holder is pro-
vided with an adjustable ring 22 adapted to turn about the exterior thereof and
to be clamped in any desired position by a screw collar 23. The ring 22 is provided
with a pin 24, which, when the tool holder is inserted into the cylindrical portion 15"

page_text: of the frame -15 in the manner shewn in figs. 3, 4 and 5, takes into a corresponding
groove or recess 25 formed in the adjacent end of the said cylindrical portion. 26.
is a thumb screw for fixing the tool holder in the cylindrical portion 15 of the
frame 15.
An adjustable ring 22 is shewn applied to the tool holder 2 secured in the double.
conical block 3-4 (fig. 1).
27 (figs. 3 and 4) is a frame provided with a series of projecting spindles 28 each
adapted to carry a rest or support fitted with a grinding apparatus as shewn. By
means of this frame of which there may be one at each side of the grindstone several
drills may be simultaneously ground. To ensure the correct presentation of the drill
to the grindstone I provide the double conical block of the apparatus hereinbefore
first, described, or the drill holder, with a removable perforated disc, the opening
through which is in the form of a slot with rounded ends and of a size corresponding
with the drill to be ground.
Fig. 9 is an end view of a drill holder fitted with a perforated disc 29 constructed.
according to this part of my invention, and
Fig. 10 shews the perforated disc detached.
The disc is formed with a slot 29ª of the form shewn and of a size corresponding to
the drill to be ground, which is caused to project through said slot. This disc is.
adapted to be secured in one end of a tool holder which is recessed to receive it as.
indicated in fig. 8. For this purpose each disc is formed with notches 30 adapted to
receive corresponding projections 31 on the tool holder when it is inserted in place.
32 is a sleeve mounted to revolve upon the end of the tool holder to which the
perforated disc is applied; it is formed with projections 33 over which the notches 30.
of the disc pass, when they are in line with the projections 31, but which when turned
to one side as represented in fig. 9, serve to retain the perforated disc in place. 34,
34 are pins that pass through slots 35 (Figs. 7 and 8) in the sleeve 32 and screw
into the tool holder; they serve to retain the sleeve in place endways and to limit.
rotary movement of such sleeve. 36 is a removable collar secured within the opposite
end of the tool holder by a removable cap 37; it serves to hold one end of the drill
centrally in the tool holder. Thus by providing a number of discs 29 with slots 29ª
of different sizes and also a number of collars 34 one block or holder may be used for
dills of many different sizes. Or in lieu of perforated discs the drill holder 2 may
for the same purpose be provided with a pair of projecting studs 36 (as shewn in..
Fig. 1) carried by spring arms 37 and adapted to take into the grooves of the drill to:
be ground under the action of an adjustable collar 38. These studs which are of a
form adapted to enter the grooves and guide and hold different sizes of drills may be
serrated or roughened to ensure a better hold.
a
For the purpose of imparting accurate cutting edges to tools such as gouges,
guide block having a conical surface corresponding with the bevelled surface of a
correctly ground gouge is employed, the block being formed with a hole in which the
tool is fixed. Considering the gouge as a portion of a hollow cylinder the form of
cutting edge will depend upon the position of the axis of this cylinder in relation to
the axis of rotation of the conical block. Thus, if the two axes coincide, the cutting
edge will be circular as in a carpenter's gouge, if parallel, a portion of a parabola as
in a hand turning gouge, and if inclined, a portion of an ellipse as may be necessary
in some forms of slide rest tools.
Figs. 11 and 12 are respectively a sido elevation and a plan or top view illustrating
a guide block constructed according to this part of my invention carried by a pivotted
back rest and shewn with a gouge secured therein.
Fig. 15 is an end view of the gouge, and a carrying plate with a clamping device
for securing the two together. 38 is the guide block in the form of a truncated cone
By ineaus
having a bole 9 therethrough and provided with a tubular extension 40.
of this tubular extension the guide block may be revolved in a corresponding hole
drilled or formed at a suitable inclination in a tail rest 41 which is pivotted to a table
or support in order that the end of a gouge 42 carried by the block may be properly

page_text: applied to a grindstone. Or the tail rest unpivotted may be simply provided with a
groove arranged at a suitable angle in a vertical plane and in which groove
the tube may be revolved thereby securing true presentation to the stone.. 43 is
a plate secured to the guide block, part of which is cut away to. receive it as
shewn.
To this plate the gouge 42 of hollow cylindrical form, is secured by a screw clamp 44
in such a manner as to be held within the guide block and the tubular extension
thereof.
In the example shewn, the axis of the gouge is held parallel to the axis of the
block, so that when the gouge is being ground it will have imparted thereto a
cutting edge of parabolic form suitable for a land turning tool. If the plate 43 be
arranged to hold the gouge with its axis coincident with the axis of rotation of the
block, a circular cutting edge may be imparted to it. To impart an elliptical cutting
edge to the gouge the plate 43 must be set at an angle to the centre line of the guide
block. In order that guide blocks and tool holders of various kinds may be adapted
to hold tools of various sizes and that the tools may be readily fixed in and removed
from the block or holder, the hole. in the block or holder may be made of tapering
form into which takes a spring clamp of corresponding exterior shape and fluted
internally to adapt it to hold the tool to be ground. The arrangement is such that
if the clamp with a tool therein be forced within the block or holder parts of the
clamp will be sprung or forced against the tool thereby holding the same firmly
within the block whilst if the clamp be moved in the opposite direction the tool will
be released. A convenient arrangement of clamp for this purpose is illustrated in
central longitudinal section in fig. 14 and in cross section in figs. 15 and 16. Fig. 14
shews the clamp applied to a guide block 45 formed with facets and suitable for
grinding facet tool as set forth in my said former specification. The clamp which is
made of hollow rectangular form in cross section as shewn comprises two pieces 46, 47
of metal arranged at a short distance apart and fitted together at one end, the end of
one piece being made to overlap the other as shewn so as to admit of the clamp
being driven into the block without straining the parts where they are connected.
48, 48 are pins screwed into the piece 46 and extending into holes formed in the
adjacent part of the piece 47. The clamp is made of tapering form in the
direction of its length and the hole in the guide block, which may be lined with
metal as shewn, is made of corresponding form so that assuming the shank of a tool
to be inserted into the clamp and this be driven into the block the parts 46 and 47
will be caused to approach each other and firmly grip the tool.
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. The construction and use of an apparatus to be employed in grinding or
sharpening cutting tools to facilitate the production of accurate forms with a hole to
receive a drill or drill holder and with two surfaces each having the shape of a
truncated or part cone, these being arranged with their axes inclined to each other
and at opposite sides of the axis of the said hole in such a manner that the conical
surfaces correspond to prolongations of the surfaces of a correctly ground drill
substantially as hereinbefore described.
2. Providing an apparatus such as referred to in the preceding claim either with
projections or pins having their axes coincident with those of the part cones and
adapted to be supported by a back rest or frame, or with correspondingly arranged
holes each adapted to receive a projection or pin carried by the said back rest or
frame substantially as hereinbefore described for the purpose specified.
3. My improved apparatus hereinabove referred to as a guide block for use in
grinding twist drills constructed and arranged substantially as hereinabove described
whether in one piece or as shewn in figs. 1 and 2 of the drawings annexed.
4. The construction and arrangement of apparatus shewn in and described with

page_text: reference to figs. 3, 4 and 5 of the drawings annexed for the purpose specified whether
the bracket or standard 17 be pivotted to a slide rest or to a table arranged to slide or
roll..
5. In apparatus for grinding or sharpening twist drills as set forth a tool holder
provided with an adjustable ring such as 22 substantially as herein before described
with reference to and shewn in fig. 6 of the drawings annexed for the purpose
specified.
:
6. The multiple apparatus for use in grinding or sharpening tools substantially as
hereinabove described with reference to figs. 3 and 4 of the drawings annexed.
7. The use with a drill holder or block such as hereinabove referred to of the
means described with reference to figs. 7 to 10 inclusive of the drawings annexed for
ensuring the correct presentation of drills of different sizes to the grinding surface.
8. The use with a drill holder or block such as hereinabove referred to of the
means described with reference to fig. 1 of the drawings annexed for ensuring the
correct presentation of drills of different sizes to the grinding surface.
9. Apparatus substantially as described with reference to figs. 11 to 13 inclusive of
the drawings annexed for the purpose specified.
10. My improved tool clamp described with reference to figs. 14 to 16 inclusive of
the drawings annexed.
Dated this Eleventh day of December 1888.