LAPIDARY HOLDER AND ATTACHMENT THEREFOR
United States Patent 3688452
A lapidary holder including an attachment for generating different types of cuts or facets on non-circular stones in a semi-automatic manner, such holder including a vertical mast extending upwardly from a base, a body member mounted on the mast for axial movement, a shaft rotatably mounted on the body member and extending outwardly at an angle to the mast, for mounting a stone at its outer end, and a first indexing wheel associated with the shaft for adjusting the circumferential position of the shaft relative to the body member, such attachment including a second indexing wheel on the mast, a cam mounted relative to the body member and a cam follower on the indexing wheel for adjusting the height of the body member on the mast, whereby different cuts may be generated on a stone by coordinating the settings of the two indexing wheels.
US Patent References:
Cutter feeding device
Boening - July 1943 - 2325364
Grinding device for tools
Studler - July 1957 - 2797538
Machine for grinding and polishing gem facets
Collar - January 1957 - 2779138
Machine for grinding and polishing facets of precious stones
Ticino - January 1963 - 3073085
Cutter feeding device
Boening - July 1943 - 2325364
Grinding device for tools
Studler - July 1957 - 2797538
Machine for grinding and polishing gem facets
Collar - January 1957 - 2779138
Machine for grinding and polishing facets of precious stones
Ticino - January 1963 - 3073085
Application Number:
05/051538
Publication Date:
09/05/1972
Filing Date:
07/01/1970
View Patent Images:
Export Citation:
Primary Class:
International Classes:
B24B9/16; B24B9/06; B24B9/16
Field of Search:
51/229
Primary Examiner:
Harold, Whitehead D.
Attorney, Agent or Firm:
Sommer, Weber & Gastel
Claims:
1. A lapidary holder comprising a base, a mast on said base, a body member, means mounting said body member on said mast for axial movement, a shaft rotatably mounted relative to said body member, extending outwardly therefrom at an angle to said mast and having an outer end for mounting a stone on which facets are to be cut, and first indexing means for selectively adjusting the circumferential position of said shaft relative to said body member, by rotating said shaft about its axis to various circumferential positions corresponding to the facets to be cut, wherein the improvement comprises: an attachment for cutting facets of different configurations on non-circular stones in a semi-automatic manner, said attachment being mounted relative to said body member and mast and including a cylindrical cam member surrounding said mast for axial movement therealong and having at its second indexing means corresponding to the first indexing means and including a wheel adapted to surround the mast and to be supported below said cam member, and a cam follower extending axially upwardly from said wheel to engage said cam surface, said wheel being adapted to be rotated about the mast to various circumferential positions severally corresponding to or having a predetermined relationship to the circumferential positions of the first indexing means, while effecting relative movement between said cam member and cam follower to adjust the height of the body member on the mast in accordance with the shape of said cam surface.
2. An attachment for cutting facets of different configurations on non-circular stones in a semi-automatic manner and adapted to be mounted relative to the body member and mast of a lapidary holder including means mounting the body member on the mast for axial movement, a shaft rotatably mounted relative to the body member, extending outwardly therefrom at an angle to the mast and having an outer end for mounting a stone on which facets are to be cut, and first indexing means for rotating the shaft to various circumferential positions corresponding to the facets to be cut, said attachment including a cylindrical cam member adapted to surround the mast for axial movement therealong and having at its lower end a cam surface shaped in accordance with the ultimate shape of the stone being cut, lower end a cam surface shaped in accordance with the ultimate shape of the stone being cut, second indexing means corresponding to said first indexing means and including a wheel surrounding said mast and supported below said cam member, and a cam follower extending axially upwardly from said wheel to engage said cam surface, said wheel being rotatable about said mast to various circumferential positions severally corresponding to or having a predetermined relationship to the circumferential positions of said first indexing means, while effecting relative movement between said cam member and cam follower to adjust the height of said body member on said mast in accordance with the shape of said cam surface.
2. An attachment for cutting facets of different configurations on non-circular stones in a semi-automatic manner and adapted to be mounted relative to the body member and mast of a lapidary holder including means mounting the body member on the mast for axial movement, a shaft rotatably mounted relative to the body member, extending outwardly therefrom at an angle to the mast and having an outer end for mounting a stone on which facets are to be cut, and first indexing means for rotating the shaft to various circumferential positions corresponding to the facets to be cut, said attachment including a cylindrical cam member adapted to surround the mast for axial movement therealong and having at its lower end a cam surface shaped in accordance with the ultimate shape of the stone being cut, lower end a cam surface shaped in accordance with the ultimate shape of the stone being cut, second indexing means corresponding to said first indexing means and including a wheel surrounding said mast and supported below said cam member, and a cam follower extending axially upwardly from said wheel to engage said cam surface, said wheel being rotatable about said mast to various circumferential positions severally corresponding to or having a predetermined relationship to the circumferential positions of said first indexing means, while effecting relative movement between said cam member and cam follower to adjust the height of said body member on said mast in accordance with the shape of said cam surface.
Description:
The present invention relates to a lapidary holder and an attachment therefor for cutting facets of different configurations on non-circular precious stones in a semi-automatic manner.
By way of background, precious stones have facets cut thereon by a lapidary holder which mounts a stone and holds it in contact with a rotating abrasive wheel. For simple cuts such as a "brilliant" cut wherein the various facets are located equidistantly from the center of the circular stone, the conventional holder is quite adequate, inasmuch as the crown facets and the girdle facets are of equal size. However, in cutting a non-circular stone wherein the facets are of different sizes, considerable manual dexterity and skill are required. In the past there was no simple way of cutting the latter type of stone in a semi-automatic manner.
Accordingly, it is the primary object of the present invention to provide a lapidary holder which greatly simplifies the cutting of irregular facets so as to permit them to be made in a semi-automatic manner.
Another object of the present invention is to provide an attachment for an existing lapidary holder which can be used for modifying the machine to provide different sizes of facets in a semi-automatic manner. Other objects and attendant advantages of the present invention will readily be perceived hereafter.
The present invention relates to a lapidary holder, comprising a base, a mast on said base, a body member, means mounting said body member on said mast for axial movement, a shaft rotatably mounted relative to said body member and extending outwardly therefrom and at an angle to said mast, an outer end on said shaft for mounting a stone on which facets are to be cut, and first indexing means for selectively adjusting the circumferential position of the shaft relative to the body member, by rotating the shaft about its axis to various circumferential positions corresponding to the facets to be cut, wherein the improvement comprises: an attachment for cutting facets of different configurations on non-circular stones in a semi-automatic manner, such attachment being mounted relative to the body member and mast and including a cam member having a cam surface shaped in accordance with the ultimate shape of the stone being cut, a cam follower, and second indexing means for selectively adjusting the height of said body member on the mast, whereby by coordinating the indexing of the first and second indexing means irregular cuts may be obtained in a semi-automatic manner, such second indexing means corresponding to the first indexing means and being rotatable about the mast to various circumferential positions severally corresponding to or having a predetermined relationship to the circumferential positions of the first indexing means, while effecting relative movement between the cam member and cam follower to adjust the height of the body member on the mast in accordance with the shape of the cam surface. The present invention also relates to an attachment for an existing lapidary holder which includes an indexing platform for mounting on a mast and cam means adapted to be mounted relative to said body member for selectively changing the elevation of the body member in increments, thereby to convert a lapidary holder having only the above mentioned first indexing means into a holder also having the above mentioned cam member, cam follower and second indexing means.
The various aspects of the present invention will be more fully understood when the following portions of the specification are read in conjunction with the accompanying drawings wherein:
FIG. 1 is a side elevational view, partially in cross section, showing the improved lapidary holder of the present invention;
FIG. 2 is a cross sectional view taken substantially along line 2--2 of FIG. 1 and showing the manner of mounting the cam;
FIG. 3 is a view taken substantially in the direction of arrows 3--3 of FIG. 1 and showing the indexing wheel portion of the attachment which is used for making irregular cuts;
FIG. 4 is a side elevational view of a regularly cut stone of the type which is known as a "brilliant" cut;
FIG. 5 is a plan view of the stone of FIG. 4;
FIG. 6 is a plan view of a stone having a modified marquis shape;
FIG. 7 is a side elevational view of the stone of FIG. 6;
FIG. 8 is a perspective view of a cam which is used to produce the modified marquis cut stone shown in FIGS. 6 and 7;
FIG. 9 is a perspective view of a cam which is used to produce a pendeloque or pear-shaped cut stone;
FIG. 10 is a perspective view of a cam which is used to produce an emerald cut stone; and
FIG. 11 is a perspective view of a cam which is used to produce an oval cut stone.
The improved lapidary holder 8 of the present invention includes a base 10 which may be mounted on a fixed surface 11. A mast 12 extends vertically upwardly from base 10 and a longitudinally adjustable yoke or frame member 14 is mounted for axial sliding movement on mast 12 and is prevented from rotating by spline 15. A hand-operated set screw 16 is threadably received in frame member 14 and engages mast 12 to hold frame member 14 in any desired adjusted position.
A head or body member 17 is adjustably mounted for vertical movement relative to frame member 14 by means of a vernier adjustment which includes an enlarged serrated ratchet wheel 20 having attached thereto a lower screw member 18 extending beyond its lower end and a coaxial screw member 18' extending beyond its upper end. As can be seen from FIG. 1, body member or head 17 has arms or yoke-like portions 21 and 23, each of which is tapped to receive upper screw member 18' and lower screw member 18 respectively. A detent 22a on member 17 yieldably engages ratchet wheel 20 for holding body member 17 in its vertically adjusted position after the ratchet wheel has been turned.
Body member 17 is mounted in the following manner. Screw 13 is received in a tapped aperture in arm 15' and is secured in position by nut 13' so that screw 13 is in abutting engagement with the upper end of screw member 18'. A lower screw 23' is received in a mating tapped aperture in arm 25 of frame member 14 and is held in adjusted position in abutting engagement with the bottom of screw member 18 by means of nut 25'. A contoured interfitting configuration exists between screws 23' and 18 and between screws 13 and 18'. This contoured configuration which may consist of a cone on one member and a conical recess on the mating member provides an interfitting relationship which holds the parts in assembled relationship. It will thus be appreciated that whenever ratchet wheel 20 is turned, the threaded relationship between screws 18, 18' and the tapped apertures in arms 23, 21 will cause body member 17 to move upwardly or downwardly relative to mast 12, this providing a vernier adjustment.
A rocker arm 24 is pivotally mounted relative to body member 17 for movement in a vertical plane. The pivotal connection between body member 17 and rocker arm 24 has not been shown in the interest of simplicity but it will be understood that it can constitute a horizontal screw extending rearwardly from rocker arm 24 which is received in an aperture in body member 17, with a nut on the screw securing the two in any desired adjusted position. Rocker arm 24 is oscillatable through an angle of 90° and is provided at its outboard end with a shaft 26 which is held in any circumferentially adjusted position by means of a ratchet wheel 28 keyed to said shaft, said ratchet wheel being engaged by a ratchet lever 29 which is biased into engagement with the serrations 28' of wheel 28 by spring 31, lever 29 being pivoted on pin 31' mounted on the rocker arm. A precious stone S which is to be cut is mounted at the lower end of shaft 26 by means of conventional dop adhesive, as is well known. An abrasive lap wheel 32 is mounted horizontally on shaft 33 which in turn is rotatably mounted in housing 35, shaft 33 being driven at the desired speed by suitable means (not shown).
Prior to taking a cut, rocker arm 24 is swung upwardly out of the way, and the desired angle of inclination of shaft 26 is preset by adjusting stop 27 along slot 17b of protractor portion 17a of body member 17 in accordance with degree marks (not shown) on the upper arcuate surface of such portion 17a. Stop 27 is secured in place by suitable means (not shown) and rocker arm 24 is lowered until the leading edge of upstanding lug portion 24a thereon approaches the trailing edge of stop 27. As the cut is being made, manual pressure is exerted downwardly on shaft 26 or stone S until the leading edge of lug 24a engages the trailing edge of stop 27. At this point, the desired depth and angle of cut are obtained.
The foregoing described structure can be used to create a "brilliant" cut stone such as schematically shown in FIGS. 4 and 5 (a number of facets being eliminated for clarity of illustration). This stone has crown facets 36 of equal size and girdle facets 37 of equal size. In cutting the girdle facets shaft 26 is arranged in a substantially horizontal position, as shown in phantom lines, by pivotally moving rocker arm 24 relative to body member 17 after presetting stop 27 at 90° (i.e., at the rear or left end of slot 17b ). Thereafter indexing wheel 28, which will be described in greater detail hereafter, is circumferentially indexed in equal increments. The various girdle facets 37 are then cut by lap wheel 32. When cutting the crown facets 36, rocker arm 24 is pivoted so that the shaft 26 is an appropriate angle, following adjustment of stop 27, such as shown in FIG. 1, so as to provide the desired crown faceting by selectively indexing index wheel 28 in equal increments. As will be described hereafter, the indexing wheel 28 is graduated or calibrated so as to permit the desired number of degrees of circumferential movement to be obtained.
The above described operation for obtaining equal crown and facet cuts is very simple because once the attitude of shaft 26 has been adjusted, it is only necessary to index the stone in increments about a single central axis, namely, the axis of shaft 26. However, it is much more difficult to cut non-circular stones, namely, stones which are to have an emerald, oval or marquis cut. In this respect numerous adjustments of the holder, precise visual observation and manual skill are necessary to produce the various different sized facets on the stone while maintaining the desired overall shape of the stone. For example, an odd-shaped stone such as the modified marquis shown in FIGS. 6 and 7 would require many adjustments of the holder and a high degree of skill in properly cutting the facets while maintaining the desired shape of the stone.
As a result of the present invention, the cutting of a stone, such as S 2 shown in FIGS. 6 and 7, becomes semi-automatic. The attachment which constitutes the present invention, consists of a platform 40 which is mounted in sliding relationship on mast 12. Platform 40 includes a keyway (not numbered) to receive spline 15 and a set screw 42 for holding platform 40 at any desired elevation. An indexing wheel 44 is rotatably mounted on the platform and is held in position by means of an upstanding shoulder 41 which encircles indexing wheel 44. It can thus be seen that indexing wheel 44 can be rotated on platform 40 to any desired position inasmuch as it is held on the platform by said shoulder. Any desired position of wheel 44 is maintained by means of a ratchet pin 46 which is biased toward wheel 44 by means of spring 45 bearing against abutment 47' and the head of pin 46. It will be appreciated that if it is desired to change the position of indexing wheel 40, it is merely necessary to pull pin 46 to the left in FIG. 3, by grasping head 46' thereof to thus disengage the head of pin 46 from the serration in ratchet wheel 44. Wheel 44 is then manually rotated, and thereafter head 46' is released and the spring 45 will expand to return the head of pin 46 into engagement with wheel 44. It will be noted that up to this point wheel 28 is identical to wheel 44 in that both have indexing marks, as shown, and serrations on their outer peripheries. HOwever, wheel 44 is provided with an upstanding cam follower pin 47 which is fixedly mounted thereon proximate its inner periphery. Pin 47 engages the surface of a cylindrical cam 48 (FIG. 8) having a reduced sleeve portion 50 extending therefrom which fits around mast 12 and up into the inside of frame member 14, as shown in FIG. 1, sleeve 50 being held in assembled engagement with frame member 14 by means of a set screw 51. At its other end cam 48 is provided with a cam face 52 which is shaped in accordance with the ultimate shape of the stone which is to be cut. A slot 48' in sleeve 50 receives spline 15 to prevent rotation of cam 48.
In operation, once platform 40 has been mounted on mast 12, frame member 14 is adjusted vertically on mast 12 until cam face 52 contacts cam follower pin 47. Indexing wheel 28 is then set so that the reading thereon has a predetermined relationship to the reading on indexing wheel 44. Thereafter the required cut is taken by causing the stone S to be cut by the lapidary wheel 32. After a required amount of material has been removed from stone S, to cut a particular facet, rocker arm 24 is raised, and to set up for another facet having a different radius, screw 16 is loosened, frame member 14 is raised, and wheel 44 is indexed to a new setting. Thereafter the frame member is lowered, to come in contact with the top of cam follower pin 47. This will cause the frame member 14 to come to rest at a different elevation, after which screw 16 is retightened. Wheel 28 is then indexed to give a reading having a predetermined relationship to that on wheel 44, and the next cut is taken. These steps are repeated at the required increments. By means of a cam such as 48 in FIG. 8 a cut of a stone such as S 2 shown in FIGS. 6 and 7 can be obtained. It will be seen that the desired shape of the stone will be maintained as the various facets are cut, there being no need for close visual observation or a high degree of manual dexterity in maintaining the desired stone outline. This is true whether girdle facets or crown facets are being cut because the center about which the stone is rotated will be automatically adjusted by the engagement between the cam surface 52 and the cam follower pin 47.
For example, in cutting the various facets of stone S 2 shown in FIGS. 6 and 7, the girdle facets G are cut first, followed by cutting of either crown facets C or the pavillion facets P, with the table T usually being cut last and not employing the embodiment of the invention. Since the procedure for cutting facets C, G and P is essentially the same, except for the angle of shaft 26, a description of one will suffice for the others.
Thus, cutting of the girdle facets G is selected for illustration, because it is the first operation and the simplest to follow, inasmuch as shaft 26 is horizontal. Assuming that girdle facet G64, which traverses the longitudinal axis X--X of stone S 2 is to be cut first, both wheels 28 and 44 are indexed to position 64 (as shown in FIG. 3, for example). Following cutting of facet G64, facets G7 and G57 are cut next in sequence, it being necessary to index only wheel 28 to these positions, because these facets are equidistant with facet 64 from the center A on axis X--X about which they are cut. Next, facets G17 and G47 are cut in sequence, wheels 28 and 44 first being indexed to position 17 for cutting facet G17 and then wheel only 28 being indexed to position 47 for cutting facet G47, because facets G17 and G47 likewise are equidistant from the center B about which they are cut. Finally, facets G27 and G37 are sequentially cut with both wheels 28 and 44 being indexed first to position 27 for cutting facet G27 and then only wheel 28 being indexed to position 37 for cutting facet G37 because of the equidistance from center D about which these last two facets are cut. The crown facets C and pavillion facets P are then cut in the same manner, with the shaft 26 at the appropriate angles.
As is evident from the foregoing example, the reading or position of wheel 44 always has a predetermined relationship to that of wheel 28 and this relationship is determined by the shape of cam 48. Furthermore, it is apparent that only one side or half of the cam surface 52 need by used because of the symmetry of the stone about its longitudinal axis X--X. At the same time, both sides or halves of cam surface 52 could be used, and identical positions of wheels 28 and 44 employed, if desired. Hence, a full circular cam surface is shown for such convenience. From an accuracy standpoint, however, it is preferred that the number of movements of wheel 44 be minimized, in accordance with the above example.
From the foregoing, it can be concluded that for stones symmetrical about their major horizontal axes, only part of a full circular cam surface need be employed. However, for asymmetrical stones, where no facet on one side of such major axis is equidistant from another facet on the same or opposite side, then wheel 44 must be indexed everytime wheel 28 is indexed either to the same position or to one bearing a predetermined relationship thereto.
In FIG. 9 a cam 54 is shown having a cam surface 56 and a tubular extension 58. The configuration of cam surface 56, all or half of which may be used, will produce a pendeloque or pear-shape cut stone. In FIG. 10 a still further configuration is shown. Cam 60 has a cam surface 62 and a tubular shank 64. With all or half of the cam surface 62, an emerald cut stone can be generated. In FIG. 11 a still further cam 64 is shown having a cam surface 68 and a shank 70. The cam surface 68, or as little as one fourth thereof, will produce an oval cut stone. The cams of FIGS. 9-11 have slots (not numbered) analogous to slot 48' of cam 48.
It will be appreciated that the attachment consisting of the cam and the indexing platform can be used to convert any conventional lapidary holder of the above described type into a semi-automatic machine, or if desired it can be built into the original equipment.
By way of background, precious stones have facets cut thereon by a lapidary holder which mounts a stone and holds it in contact with a rotating abrasive wheel. For simple cuts such as a "brilliant" cut wherein the various facets are located equidistantly from the center of the circular stone, the conventional holder is quite adequate, inasmuch as the crown facets and the girdle facets are of equal size. However, in cutting a non-circular stone wherein the facets are of different sizes, considerable manual dexterity and skill are required. In the past there was no simple way of cutting the latter type of stone in a semi-automatic manner.
Accordingly, it is the primary object of the present invention to provide a lapidary holder which greatly simplifies the cutting of irregular facets so as to permit them to be made in a semi-automatic manner.
Another object of the present invention is to provide an attachment for an existing lapidary holder which can be used for modifying the machine to provide different sizes of facets in a semi-automatic manner. Other objects and attendant advantages of the present invention will readily be perceived hereafter.
The present invention relates to a lapidary holder, comprising a base, a mast on said base, a body member, means mounting said body member on said mast for axial movement, a shaft rotatably mounted relative to said body member and extending outwardly therefrom and at an angle to said mast, an outer end on said shaft for mounting a stone on which facets are to be cut, and first indexing means for selectively adjusting the circumferential position of the shaft relative to the body member, by rotating the shaft about its axis to various circumferential positions corresponding to the facets to be cut, wherein the improvement comprises: an attachment for cutting facets of different configurations on non-circular stones in a semi-automatic manner, such attachment being mounted relative to the body member and mast and including a cam member having a cam surface shaped in accordance with the ultimate shape of the stone being cut, a cam follower, and second indexing means for selectively adjusting the height of said body member on the mast, whereby by coordinating the indexing of the first and second indexing means irregular cuts may be obtained in a semi-automatic manner, such second indexing means corresponding to the first indexing means and being rotatable about the mast to various circumferential positions severally corresponding to or having a predetermined relationship to the circumferential positions of the first indexing means, while effecting relative movement between the cam member and cam follower to adjust the height of the body member on the mast in accordance with the shape of the cam surface. The present invention also relates to an attachment for an existing lapidary holder which includes an indexing platform for mounting on a mast and cam means adapted to be mounted relative to said body member for selectively changing the elevation of the body member in increments, thereby to convert a lapidary holder having only the above mentioned first indexing means into a holder also having the above mentioned cam member, cam follower and second indexing means.
The various aspects of the present invention will be more fully understood when the following portions of the specification are read in conjunction with the accompanying drawings wherein:
FIG. 1 is a side elevational view, partially in cross section, showing the improved lapidary holder of the present invention;
FIG. 2 is a cross sectional view taken substantially along line 2--2 of FIG. 1 and showing the manner of mounting the cam;
FIG. 3 is a view taken substantially in the direction of arrows 3--3 of FIG. 1 and showing the indexing wheel portion of the attachment which is used for making irregular cuts;
FIG. 4 is a side elevational view of a regularly cut stone of the type which is known as a "brilliant" cut;
FIG. 5 is a plan view of the stone of FIG. 4;
FIG. 6 is a plan view of a stone having a modified marquis shape;
FIG. 7 is a side elevational view of the stone of FIG. 6;
FIG. 8 is a perspective view of a cam which is used to produce the modified marquis cut stone shown in FIGS. 6 and 7;
FIG. 9 is a perspective view of a cam which is used to produce a pendeloque or pear-shaped cut stone;
FIG. 10 is a perspective view of a cam which is used to produce an emerald cut stone; and
FIG. 11 is a perspective view of a cam which is used to produce an oval cut stone.
The improved lapidary holder 8 of the present invention includes a base 10 which may be mounted on a fixed surface 11. A mast 12 extends vertically upwardly from base 10 and a longitudinally adjustable yoke or frame member 14 is mounted for axial sliding movement on mast 12 and is prevented from rotating by spline 15. A hand-operated set screw 16 is threadably received in frame member 14 and engages mast 12 to hold frame member 14 in any desired adjusted position.
A head or body member 17 is adjustably mounted for vertical movement relative to frame member 14 by means of a vernier adjustment which includes an enlarged serrated ratchet wheel 20 having attached thereto a lower screw member 18 extending beyond its lower end and a coaxial screw member 18' extending beyond its upper end. As can be seen from FIG. 1, body member or head 17 has arms or yoke-like portions 21 and 23, each of which is tapped to receive upper screw member 18' and lower screw member 18 respectively. A detent 22a on member 17 yieldably engages ratchet wheel 20 for holding body member 17 in its vertically adjusted position after the ratchet wheel has been turned.
Body member 17 is mounted in the following manner. Screw 13 is received in a tapped aperture in arm 15' and is secured in position by nut 13' so that screw 13 is in abutting engagement with the upper end of screw member 18'. A lower screw 23' is received in a mating tapped aperture in arm 25 of frame member 14 and is held in adjusted position in abutting engagement with the bottom of screw member 18 by means of nut 25'. A contoured interfitting configuration exists between screws 23' and 18 and between screws 13 and 18'. This contoured configuration which may consist of a cone on one member and a conical recess on the mating member provides an interfitting relationship which holds the parts in assembled relationship. It will thus be appreciated that whenever ratchet wheel 20 is turned, the threaded relationship between screws 18, 18' and the tapped apertures in arms 23, 21 will cause body member 17 to move upwardly or downwardly relative to mast 12, this providing a vernier adjustment.
A rocker arm 24 is pivotally mounted relative to body member 17 for movement in a vertical plane. The pivotal connection between body member 17 and rocker arm 24 has not been shown in the interest of simplicity but it will be understood that it can constitute a horizontal screw extending rearwardly from rocker arm 24 which is received in an aperture in body member 17, with a nut on the screw securing the two in any desired adjusted position. Rocker arm 24 is oscillatable through an angle of 90° and is provided at its outboard end with a shaft 26 which is held in any circumferentially adjusted position by means of a ratchet wheel 28 keyed to said shaft, said ratchet wheel being engaged by a ratchet lever 29 which is biased into engagement with the serrations 28' of wheel 28 by spring 31, lever 29 being pivoted on pin 31' mounted on the rocker arm. A precious stone S which is to be cut is mounted at the lower end of shaft 26 by means of conventional dop adhesive, as is well known. An abrasive lap wheel 32 is mounted horizontally on shaft 33 which in turn is rotatably mounted in housing 35, shaft 33 being driven at the desired speed by suitable means (not shown).
Prior to taking a cut, rocker arm 24 is swung upwardly out of the way, and the desired angle of inclination of shaft 26 is preset by adjusting stop 27 along slot 17b of protractor portion 17a of body member 17 in accordance with degree marks (not shown) on the upper arcuate surface of such portion 17a. Stop 27 is secured in place by suitable means (not shown) and rocker arm 24 is lowered until the leading edge of upstanding lug portion 24a thereon approaches the trailing edge of stop 27. As the cut is being made, manual pressure is exerted downwardly on shaft 26 or stone S until the leading edge of lug 24a engages the trailing edge of stop 27. At this point, the desired depth and angle of cut are obtained.
The foregoing described structure can be used to create a "brilliant" cut stone such as schematically shown in FIGS. 4 and 5 (a number of facets being eliminated for clarity of illustration). This stone has crown facets 36 of equal size and girdle facets 37 of equal size. In cutting the girdle facets shaft 26 is arranged in a substantially horizontal position, as shown in phantom lines, by pivotally moving rocker arm 24 relative to body member 17 after presetting stop 27 at 90° (i.e., at the rear or left end of slot 17b ). Thereafter indexing wheel 28, which will be described in greater detail hereafter, is circumferentially indexed in equal increments. The various girdle facets 37 are then cut by lap wheel 32. When cutting the crown facets 36, rocker arm 24 is pivoted so that the shaft 26 is an appropriate angle, following adjustment of stop 27, such as shown in FIG. 1, so as to provide the desired crown faceting by selectively indexing index wheel 28 in equal increments. As will be described hereafter, the indexing wheel 28 is graduated or calibrated so as to permit the desired number of degrees of circumferential movement to be obtained.
The above described operation for obtaining equal crown and facet cuts is very simple because once the attitude of shaft 26 has been adjusted, it is only necessary to index the stone in increments about a single central axis, namely, the axis of shaft 26. However, it is much more difficult to cut non-circular stones, namely, stones which are to have an emerald, oval or marquis cut. In this respect numerous adjustments of the holder, precise visual observation and manual skill are necessary to produce the various different sized facets on the stone while maintaining the desired overall shape of the stone. For example, an odd-shaped stone such as the modified marquis shown in FIGS. 6 and 7 would require many adjustments of the holder and a high degree of skill in properly cutting the facets while maintaining the desired shape of the stone.
As a result of the present invention, the cutting of a stone, such as S 2 shown in FIGS. 6 and 7, becomes semi-automatic. The attachment which constitutes the present invention, consists of a platform 40 which is mounted in sliding relationship on mast 12. Platform 40 includes a keyway (not numbered) to receive spline 15 and a set screw 42 for holding platform 40 at any desired elevation. An indexing wheel 44 is rotatably mounted on the platform and is held in position by means of an upstanding shoulder 41 which encircles indexing wheel 44. It can thus be seen that indexing wheel 44 can be rotated on platform 40 to any desired position inasmuch as it is held on the platform by said shoulder. Any desired position of wheel 44 is maintained by means of a ratchet pin 46 which is biased toward wheel 44 by means of spring 45 bearing against abutment 47' and the head of pin 46. It will be appreciated that if it is desired to change the position of indexing wheel 40, it is merely necessary to pull pin 46 to the left in FIG. 3, by grasping head 46' thereof to thus disengage the head of pin 46 from the serration in ratchet wheel 44. Wheel 44 is then manually rotated, and thereafter head 46' is released and the spring 45 will expand to return the head of pin 46 into engagement with wheel 44. It will be noted that up to this point wheel 28 is identical to wheel 44 in that both have indexing marks, as shown, and serrations on their outer peripheries. HOwever, wheel 44 is provided with an upstanding cam follower pin 47 which is fixedly mounted thereon proximate its inner periphery. Pin 47 engages the surface of a cylindrical cam 48 (FIG. 8) having a reduced sleeve portion 50 extending therefrom which fits around mast 12 and up into the inside of frame member 14, as shown in FIG. 1, sleeve 50 being held in assembled engagement with frame member 14 by means of a set screw 51. At its other end cam 48 is provided with a cam face 52 which is shaped in accordance with the ultimate shape of the stone which is to be cut. A slot 48' in sleeve 50 receives spline 15 to prevent rotation of cam 48.
In operation, once platform 40 has been mounted on mast 12, frame member 14 is adjusted vertically on mast 12 until cam face 52 contacts cam follower pin 47. Indexing wheel 28 is then set so that the reading thereon has a predetermined relationship to the reading on indexing wheel 44. Thereafter the required cut is taken by causing the stone S to be cut by the lapidary wheel 32. After a required amount of material has been removed from stone S, to cut a particular facet, rocker arm 24 is raised, and to set up for another facet having a different radius, screw 16 is loosened, frame member 14 is raised, and wheel 44 is indexed to a new setting. Thereafter the frame member is lowered, to come in contact with the top of cam follower pin 47. This will cause the frame member 14 to come to rest at a different elevation, after which screw 16 is retightened. Wheel 28 is then indexed to give a reading having a predetermined relationship to that on wheel 44, and the next cut is taken. These steps are repeated at the required increments. By means of a cam such as 48 in FIG. 8 a cut of a stone such as S 2 shown in FIGS. 6 and 7 can be obtained. It will be seen that the desired shape of the stone will be maintained as the various facets are cut, there being no need for close visual observation or a high degree of manual dexterity in maintaining the desired stone outline. This is true whether girdle facets or crown facets are being cut because the center about which the stone is rotated will be automatically adjusted by the engagement between the cam surface 52 and the cam follower pin 47.
For example, in cutting the various facets of stone S 2 shown in FIGS. 6 and 7, the girdle facets G are cut first, followed by cutting of either crown facets C or the pavillion facets P, with the table T usually being cut last and not employing the embodiment of the invention. Since the procedure for cutting facets C, G and P is essentially the same, except for the angle of shaft 26, a description of one will suffice for the others.
Thus, cutting of the girdle facets G is selected for illustration, because it is the first operation and the simplest to follow, inasmuch as shaft 26 is horizontal. Assuming that girdle facet G64, which traverses the longitudinal axis X--X of stone S 2 is to be cut first, both wheels 28 and 44 are indexed to position 64 (as shown in FIG. 3, for example). Following cutting of facet G64, facets G7 and G57 are cut next in sequence, it being necessary to index only wheel 28 to these positions, because these facets are equidistant with facet 64 from the center A on axis X--X about which they are cut. Next, facets G17 and G47 are cut in sequence, wheels 28 and 44 first being indexed to position 17 for cutting facet G17 and then wheel only 28 being indexed to position 47 for cutting facet G47, because facets G17 and G47 likewise are equidistant from the center B about which they are cut. Finally, facets G27 and G37 are sequentially cut with both wheels 28 and 44 being indexed first to position 27 for cutting facet G27 and then only wheel 28 being indexed to position 37 for cutting facet G37 because of the equidistance from center D about which these last two facets are cut. The crown facets C and pavillion facets P are then cut in the same manner, with the shaft 26 at the appropriate angles.
As is evident from the foregoing example, the reading or position of wheel 44 always has a predetermined relationship to that of wheel 28 and this relationship is determined by the shape of cam 48. Furthermore, it is apparent that only one side or half of the cam surface 52 need by used because of the symmetry of the stone about its longitudinal axis X--X. At the same time, both sides or halves of cam surface 52 could be used, and identical positions of wheels 28 and 44 employed, if desired. Hence, a full circular cam surface is shown for such convenience. From an accuracy standpoint, however, it is preferred that the number of movements of wheel 44 be minimized, in accordance with the above example.
From the foregoing, it can be concluded that for stones symmetrical about their major horizontal axes, only part of a full circular cam surface need be employed. However, for asymmetrical stones, where no facet on one side of such major axis is equidistant from another facet on the same or opposite side, then wheel 44 must be indexed everytime wheel 28 is indexed either to the same position or to one bearing a predetermined relationship thereto.
In FIG. 9 a cam 54 is shown having a cam surface 56 and a tubular extension 58. The configuration of cam surface 56, all or half of which may be used, will produce a pendeloque or pear-shape cut stone. In FIG. 10 a still further configuration is shown. Cam 60 has a cam surface 62 and a tubular shank 64. With all or half of the cam surface 62, an emerald cut stone can be generated. In FIG. 11 a still further cam 64 is shown having a cam surface 68 and a shank 70. The cam surface 68, or as little as one fourth thereof, will produce an oval cut stone. The cams of FIGS. 9-11 have slots (not numbered) analogous to slot 48' of cam 48.
It will be appreciated that the attachment consisting of the cam and the indexing platform can be used to convert any conventional lapidary holder of the above described type into a semi-automatic machine, or if desired it can be built into the original equipment.