Improvements in Machines for Grinding and Polishing Diamonds, and the like."
Year: 1897

page_text: Date of Application, 15th Nov., 1897-Accepted, 18th Dec., 1897
COMPLETE SPECIFICATION.
Improvements in Machines for Grinding and Polishing Diamonds,
and the like."
We, LEOPOLD HERMAN STERN, Manufacturer, of 63 West 87th Street, and
THOMAS WILLIAM GURKIN Cook, Machinist, of 130 East 23rd Street, both in the
City of New York, United States of America, do hereby declare the nature of this
invention and in what manner the same is to be performed, to be particulariy
described and ascertained in and by the following statement:
-
Our improvements have reference to devices designed for the purpose of
holding a diamond in a stationary position relative to a grinding or polishing
tool such holding tools being termed in the art a "dop".
Our improvements in this regard have special reference to the chuck, or means
for confining the stone in its position and also means for varying the angle of
presentation of the stone while secured in the dop.
To this end we have devised a device which involves the combination of a
stationary drop section, and a movable drop section, the latter carrying means for
holding the stone in position, the former having a supporting stem for sup-
porting the dop from a holding frame. The specific device, hereinafter described,
in which we have embobied our invention comprises a supporting rod adapted
to be secured to a stand or frame usually employed in this art, the supporting
rod carrying a casting forming one section of the dop and which is either fixedly
or detachably secured thereto, and a second dop section provided with a seg
mentally slotted arm movable in a recess formed in the first or stationary dop
section, the second dop section carrying a chuck extending radially from the are
of the slot, or line of movement of the second dop section, which chuck carries
means for confining a diamond therein, comprising a plurality of holding fingers,
which, as a group, are capable of being bodily and simultaneously moved to
or from the stone, and which are also capable, each, of an independent movement
to or from the stone, or seat therefor.
Our invention further contemplates certain combinations of parts hereinafter
described and further pointed out in the claims.
In the drawings forming part of this specification:
Fig. 1 is a side elevation of a dop, with the chuck or stone holding clamp in
position to present the table or collet of the stone to the grinding or polishing
tool, the axis of the chuck or clamp being parallel to the perpendicular axis of
he supporting stem.
Fig. 2, a like view showing the chuck adjusted to present the stone at an angle
o the grinding or polishing tool, for the purpose of grinding or polishing one of
the facets thereof.
Fig. 3 is a sectional elevation substantially on the line x, x, fig. 1.
Fig. 4, is a transverse sectional view through the chuck, substantially on the
ine y, y, fig. 3.
Fig. 5, is a front elevation of the chuck.
Fig. 6, is a sectional elevation through the center of the chuck, one of the
tripping fingers being removed to illustrate the spring; and

page_text: Fig. 7, is an enlarged perspective view of one of the gripping fingers, detached.
Similar numerals of reference indicate corresponding parts throughout the
several views.
Our device is intended to be employed in precisely the same manner as the
original dop long in use, which latter consists of a supporting stem adapated to
be detachably secured to a frame to hold the dop in juxta-position to a grinding
or polishing tool, and a casting having an aperture for the reception of soft metal
to hold the stone, the supporting stem being of malleable metal, capable of being
bent to present the stone in it's various angles to the grinding or polishing tool.
It is our aim to keep as closely to this old fashioned tool as possible, in order
that the workmen's skill in the use of the old fashioned dop can be employed in
the use of our device without (to any material extent) altering their methods
acquired by long practice.
Our device, therefore, embodies the following essential elements:
The supporting stem 1 which may be made of malleable metal, or otherwise,
and of any desired length or configuration, and which is adapted to be secured to
the support or frame employed in this art, a stationary dop section 2, and a
movable dop section 3, the movable dop section carrying a plurality of gripping
fingers movable in the direction of their length, and having a plane of movement
radial to the direction of movement of the adjustable dop section.
With this brief statement of the essentials of our invention we will proceed to
describe the details of construction of the device embodying the same.
The dop section. 2 is a casting of any desired shape, except that it is provided in
it's lower portion with a segmental recess 4 defined by the depending web 5 and
segmental crown-piece 6, the latter only being, of necessity, segmental.
To secure the supporting stem 1 in the dop section 2 we can employ any referred
construction which will allow of the ready detachment of the said section and rod.
However, we consider the following construction especially valuable in this
connection, the same consisting of the circular plug 7 having a vertical aperture
8 passing entirely therethrough which aperture is of greater diameter than the
rod 1, the plug being circular aperture 9 extending transversely into the top or
head 10 of the dop section 2. The head 10 on the reverse side is provided with a
threaded aperture 11, which aperture is in line with the aperture 9 and opens into
the same, in which latter aperture 11 is movable the threaded stem 12 of the set
screw having an enlarged head 13 exterior to the dop section 2.
It is clear that by turning up the screw 12. the plug 7 will be moved outwardly,
carrying with it the rod 1 which passes through aligning apertures in the crown-
piece 6 and the roof 14 of the dop section 1, and which also passes through the
aperture 8 in the plug, pressing the parts of the rod 1, which lie in the said
apertures in the head of the dop section, against the adjacent metal, tightly con-
fining the rod in place; and by a reverse movement on the part of the same the
plug may be loosened allowing the rod to be readily withdrawn.
The second or adjustable dop section, indicated generally by the numeral 3,
comprises a plate 15, the upper edge 16 of which is disposed in an arc concentric
with that of the crown-piece 6 af the section 1 and is provided at one end with a
circular slot 17, of a co-incident arc, and at the other end with a solid projection
18. The plate 15 is adapted to lie snugly within the angular recess formed by
the depending flange 5 and crown-piece 6 of the stationary dop section, so that all
the parts are snugly brought together, it being preferred that the inner end of
the slot 17 should terminate approximately at the vertical axis of the supporting
rod 1 for a purpose hereinafter described.
The extension 18 of the plate 15 is provided with a transverse aperture, shown
in dotted lines, fig. 1, and which receives the stem 19 of the chuck, generally
indicated in the drawings by the numeral 20, a set screw 21, dotted lines, fig. 1,
passing through a threaded aperture in the end of the extension 18 to detachably
secure the chuck stem in position, these parts not being essential, we have not
shown them in full in the drawings.

page_text: The depending web 5 of the section 2 is provided with a transverse aperture 22
adapted to receive the threaded sten 23 of a thumb screw 24, the stem passing
through the slot 17 in the plate 15, the thumb screw having an enlarged head 25
adapted to bear against the outer face of the plate 15. By screwing up on the
screw 23 the plate 15 is held against the depending web 5 of the section 2, holding
the chuck stem in the desired position, and by loosening the screw the plate can
be moved in a circular path about the screw stem 23 carrying the chuck stem
with it in these movements, and then secured in the foregoing manner, holding
the chuck in the desired position of adjustment relative to the grinding tool,
which latter is generally horizontal in relation to the position of the supporting
stem 1.
The chuck is constructed as followe:
At. the lower end of the stem 19 is widened out to form outwardly extending
segments 26, screw threaded as at 27, exteriorly, between which segments and
formed by the same are longitudinal grooves or channels 28, the lower end of the
segments being cone-shaped, as at 29, preferably, and free from any thread.
At 30 is a longitudinal aperture formed in the lower end of the stem 19 and
opening out from the bottom, in which aperture is loosely secured a plug 31 so
as to be capable of a rotative movement with slight frictional contact in the
aperture, the extreme lower end of the plug being slightly flared outwardly, as
at 32, and provided with a conical recess 33 to form a seat for the stone, in which
seat may be secured soft metal to form a yielding abutment or backing for the
stone, the periphery of the plug being provided with small apertures 34 to receive
the end of the tool for the purpose of turning the plug in the aperture 30, which
is accomplished after the gripping fingers, hereinafter to be described, are
released from their grip on the stone, allowing of the stone to be turned or
adjusted in the chuck without removing it, the end of the plug abutting against
the head of the aperture.
At 35 are the gripping fingers, comprising the stem 36 provided with an
enlarged shank 37 on it's outer surface, an inclined shoulder 38 on the same side
intermediate between the ends of the finger, and inwardly projecting gripping
points 39 at one extreme, and an inclined end or shoulder 40 on the same side
as the gripping point 39 at the other end, a channel 41 being formed in the edge
of the finger opposite the shoulder 38 and extending from the points 39 to the
other end of the finger.
At 42 are small wire springs located in the channels 28, affixed by their bent
ends 43 in apertures in the stem 19 and extending outwardly in the channels at
an angle to the stem from their point of securement thereto. These springs are
adapted to lie in the channel 41 formed in the fingers, as shown in fig. 6, the
fingers being movable up and down in the channels 28 and over the springs 42,
each simultaneously, as hereinaiter described, or independent of each other.
At 43 is a cap provided with a conical head 44, the extreme of which is rounded
to form a circular shoulder 45, shown more plainly in fig. 6, the upper end of the
cap 43 being enlarged and provided with a screw thread 46 adapted to engage
the thread 27 on the stem so as to allow of the cap being moved up and down,
the cap 44 being enlarged, interiorly, to allow of a play of the spring and gripping
fingers as hereinafter described. By moving the cap 43° upwardly on the stem
19 the curved shoulder 45 of the head 44 is brought to bear against the inclined
shoulder 38 of the gripping fingers, moving their points 39 simultaneously
towards the seat 33 of the plug 31. By this means the stone, after being adjusted
in it's desired position in the seat 33, can be firmly held therein, the springs 12
constantly tending to press the shoulder 38 of the gripping fingers against the
shoulder 45, maintaining them parallel with the stem.
When thus secured in the chuck or stone-holding clamp, the stone can be given
any desired angle of inclination to the grinding or polishing tool by moving the
plate 15 as before described, the chuck, and therefore the stone, when the axis of
the stem 19 is parallel with that of the supporting stem 1, (in which position the

page_text: table or collet of the stone is being ground or polished) lying closely adjacent the
center of the dop, the end of the lot 17 being close to the stem 23. In this way
the extension of the tool is greatly limited and the parts conveniently com-
pacted together.
A further desirable result flowing from this arrangement is that the stone
being located close to the axis of the supporting rod 1, the leverage exerted on
the rod through the friction between the stone and the grinding or polishing tool,
is reduced to a great extent, owing to the nearness of the stone to the axis of the
rod.
We employ but three gripping fingers located about one half the periphery of
the plug, at suitable distances apart, so as to leave a space at one side of the
gripping fingers, as at a, fig. 2, for the application of the stone, shown therein
in dotted lines, to the grinding or polishing tool.
The independent adjustment of the gripping fingers may be utilized at any
stage of the grinding or polishing operation.
When the stones are in the rough, that is, when the stones are of irregular
shape, it is very desirable, when securing the stone to the seat, to allow of various
degrees of projection of the gripping fingers, in order to take hold of the irregula
surfaces of the stone. This may be done, preferably, when the cap of the chuck
is not in contact with the shoulder 38 of the gripping fingers (although it may
be done when such contact is present), and by slightly forcing in the finger and
moving the outer end outwardly from the plug 31, the rounded shoulder 45 of
the head 44 providing for this, the inclined shoulder 40 will be brought in contact
with the surface of the stem 19, allowing of the inward movement of either of the
gripping fingers to decrease it's amount of projection independently of the others.
The screw 12 being located on the side of the dop, opposite the thumb screw 24.
enables both screws to be operated independently without conflict.
Having now particularly described and ascertained the nature of this invention
and in what manner the same is to be performed we declare that what we
claim is:
1/. The combination with the stationary and movable dop sections, the
stationary section having a perpendicular supporting stem affixed thereto, the
movable section being adapted to be moved bodily in a circular and perpendicular
are upon the other, means for securing the dop sections firmly together in their
position of adjustment, the movable section having a detachable seat for the stone,
and a holding finger adjustable in the direction of it's length.
2/. The combination in a dop, of the stem 1 secured to the dop, an adjustable
chuck or clamp having a stem and a plurality of independently movable gripping
fingers, said fingers being bodily adjustable in the direction of their length, means
for securing said clamp in it's position of adjustment, and a detachable stone
socket secured to the clamp within the plane of movement of said fingers.
3/. In a dop, the combination with a perpendicular stem 1, the dop section 2
secured to said stem, the section 3 bodily adjustable in a circular and per-
pendicular arc on section 2 and independently thereof and of the stem i, a
circular and upwardly projecting slot 17 in the section 3, and a transversely
extending bolt 23 passing through said slot and secured to the section 2 whereby
said adjustment is had, the section 3 having a clamping mechanism for holding
a stone.
4/. The combination with the stem 1 secured to the section 2, the section 3
bodily adjustable in a circular and perpendicular are on section 2 independently
thereof and of the stem 12, and a gripping finger carried by section 3 having a
stem adjustable in the direction of it's length, and securing means for said finger.
5/. In a dop, the combination with the stem 1, the dop section 2 secured
thereto, the section 3, both sections having horizontal faces disposed transversely
to the direction of projection of said stem, and co-acting perpendicular faces,
thereby forming an interlocking guide, a horizontally disposed bolt 23 projecting

page_text: out from the section 2 and passing through an upwardly projecting and segmental
slot 17 formed in the section 3, a nut on the bolt, and a stone clamping mechanism
carried by section 3.
6/. The combination with a dop section having a supporting stem, a second dop
section supported on the first section so as to be vibrated in the plane of an arc of
a circle, a clamp in said rotatable section having a stem movable in the direction
of it's length and normally disposed parallel to said supporting stem and adapted
to be moved into angular relationship therewith, a gripping point on the stem,
a stone socket in the latter dop section within the plane of said point, and means
for securing said clamp stem in position.
7/. The combination in a dop, of a clamp comprising a plurality of shanks
provided with gripping fingers, said shanks being adjustable in the direction of
their length, and means for securing said shanks in their position of adjustment
in said dop.
8/. The combination in a dop, of a clamp provided with adjustable gripping
fingers, and means for securing said clamp and fingers in their position of adjust-
ment in said dop.
9/. The combination in a dop, of a clamp comprising a stem and adjustable
clamping feet extending therefrom, a socket for receiving a stone secured to the
dop within the plane of movement of said feet, and means for longitudinally
adjusting said clamping feet in relation to the socket.
10%. In a dop, the combination with the body thereof, of a clamp comprising
the stem and feet extending therefrom, said feet being adjustable longitudinally
on the stem in relation to each other, a socket held in said body, and means for
securing said feet in their position of adjustment in relation to said socket.
11. In a device of the kind described, the combination of the supporting rod 1,
the stationary dop section secured thereto, and having a segmental recess in it's
lower edge, a movable dop section, a segmental plate provided with a segmental
slot forming part of the movable dop section, means for securing the plate and
stationary dop section together, and a chuck having a plurality of independently
movable gripping fingers movable in the direction of their length, extending
radially from said plate.
12/. In a device of the class described, the combination with the rod 1, the dop
section 2 secured to the rod, a segmental recess formed in the lower edge of said
section, a plate having an upper edge co-incident with said recess, a concentric
slot, and a solid projection opposite the slot, a set screw passing through the slot
and into said section, and a chuck with movable holding fingers extending from
said projection.
137. The combination, in a clutch, of a threaded stem, the movable on the stem,
and a plurality of movable gripping fingers maintained on the stem and moved
by said cap.
14/. The combination, in a clutch, of a threaded stem, a plug having a seat
rotatably secured in the end of the stem, a cap on the stem and movable gripping
fingers adapted to be moved towards said seat by said cap.
15%. The combination, in a clutch, of a threaded stem, a cap movable on the
stem, a plurality of movable gripping fingers, and springs for pressing said fingers
against the cap.
16/. The combination in a clutch, of the stem, and cap movable thereon, of a
plurality of gripping fingers held between the cap and stem and capable of a
sliding movement therein in the direction of their lengths.
17. The combination, in a chuck, of a stem and a cap movable thereon, of one
er more gripping fingers held between the stem and cap, said finger being
movable in the direction of it's length independent of the cap.
18/. The combination in a chuck, of a stem and a cap movable thereon, of a
sliding gripping finger maintained between the stem and cap, and a spring
secured to the stem pressing the finger against said cap.
19/. The combination with the channelled stem, of the cap movable on said

page_text: stem, a gripping finger in said channel, a spring secured to the stem and.engaging
the finger, a contracted head on the cap, and a shoulder on the finger engaging
said head.
20%. The combination with the channelled stem, of the cap movable on said
stem, a gripping finger in said channel having a groove adjacent the stem and
a shoulder engaging the cap, and a spring secured to the stem and resting in the
groove in the finger.
21/. In a clutch, the combination with the stem, of the cap movable on the
stem, a channel formed in said stem, a gripping finger having a groove adjacent
said stem and a shoulder on the opposite edge, a rounded shoulder on the end of
the cap engaging the shoulder on the finger, and a spring on the stem lying in
the groove in the finger.
22. The combination with the chanelled stem, of the cap movable on the stem
over the channel, a spring secured to the stem at one end within the channel,
it's free end projecting outwardly therefrom, a grooved gripping finger engaging
the said spring and movable lengthwise thereon, a shoulder on the finger engaging
a shoulder on the cap, and an inclined shoulder at the inner end of the finger
adjacent the stem.
1
1007
L. H. STERN,
T. W. G. COOK,
per W. H. Beck, Agent.
115 Cannon Street London,