US3844070A - Apparatus for grinding a cabochon or the like - Google Patents

Abstract

An apparatus for moving a gem stone, or other object, in a controlled circular or elliptical path with respect to a grinding wheel or cutting tool, for example for grinding a cabochon. It comprises a rotatable assembly to which the stone or the like is attached. The assembly contains a stem-like driver having a tongue reciprocable in a transverse guide. Also forming part of the assembly and rotating with it, is a part formed with an elongate cam slot disposed at right angles to the transverse guide and engaged by a stationary circular cam. The stem-like driver rotates in a normally stationary sleeve, the position of which is adjustable to predetermine the degree of elliptical movement generated. Provision is made not only to adjust the assembly with respect to the grinding or cutting tool, but also angularly in order to dispose the stone or the like in an inclined position with respect to the grinding wheel for chamfering.

Description

Reed

[ Oct. 29, 1974 APPARATUS FOR GRINDING A CABOCHON OR THE LIKE [76] Inventor: Glen H. Reed, 2536 Torisdale Ct.,

Toledo, Ohio 43611 [22] Filed: July 9, 1973 [21] Appl. No.2 377,636

[52] US. Cl. 511/127, 51/229 [51] Int. Cl 1324b 17/02 [58] Field of Search 51/100 R, 101 R, 101 LG,

[56] References Cited UNITED STATES PATENTS 2,350,234 5/1944 Horton 51/101 R X 2,724,220 11/1955 Shaw 51/229 X Primary Examiner-A1 Lawrence Smith Assistant Examiner-Nicholas P. Godici Attorney, Agent, or FirmMalcolm W. Fraser [57] ABSTRACT An apparatus for moving a gem stone, or other object, in a controlled circular or elliptical path with respect to a grinding wheel or cutting tool, for example for grinding a cabochon. It comprises a rotatable assembly to which the stone or the like is attached. The assembly contains a stem-like driver having a tongue reciprocable in a transverse guide. Also forming part of the assembly and rotating with it, is a part formed with an elongate cam slot disposed at right angles to the transverse guide and engaged by a stationary circular cam. The stem-like driver rotates in a normally stationary sleeve, the position of which is adjustable to predetermine the degree of elliptical movement generated. Provision is made not only to adjust the assembly with respect to the grinding or cutting tool, but also angularly in order to dispose the stone or the like in an inclined position with respect to the grinding wheel for chamfering.

4 Claims, 7 Drawing Figures PATENTEDUBIZSIISM v v SHEEI 20F 4 lllllilllllllllll l APPARATUS FUR GINDING A CABOCll-ION OR THE LIKE BACKGROUND AND SUMMARY OF THE INVENTION I Most apparatus available for generating ellipses are expensive and complicated. It is a desideratum to provide an apparatus of this character which is not only relatively simple and inexpensive, but can be adjusted to produce different ellipses. Although the uses are wide and varied, a large demand exists in the field of grinding cabochons. Many amateurs and professionals working in the lapidary art have a need for a reliable apparatus of this character, which is simple to operate.

The apparatus according to this invention has relatively few parts, and these include a subassembly to which the stone or the like is attached, and which is carried through a path of circular or elliptical form as desired. An operating knob is turned by hand and this motion is transmitted to the subassembly which, through cam elements, travels elliptically as regulated by a simple adjuster plate, the position of which determines whether a round stone or an elliptical stone is to be formed, and, if the latter, the particular elliptical shape desired. As a consequence, all that is required is first to attach the stone in a manner well known in the art, position the adjuster plate in accordance with the shape of stone desired, and then manually turn the operating knob so that the stone will be appropriately turned against the rotating grinder wheel. The only other adjustment necessary is from time to time to advance the stone to the grinder wheel which can be done manually in a very simple manner. In the event it is desired to chamfer the stone, the assembly is tilted to the proper angle and the stone will be moved through the correct path as above indicated.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is a fragmentary front perspective view of the apparatus for grinding a cabochon in circular or elliptical form;

FIG. 2 is a vertical sectional view substantially on the line 2-2 of FIG. 1;

FIG. 3 is a top plan view of the ellipse generating apparatus shown in FIG. 1 with the grinding wheel and associated frame parts removed;

FIG. 4 is a front end elevation of the apparatus showing by broken lines parts of the assembly operative for effecting elliptical movement;

FIG. 5 is a fragmentary elevation of the rear of the apparatus showing particularly the plate for adjusting the elliptical movement generated by the assembly;

FIG. 6 is an exploded view of parts of the subassembly by which elliptical movement is effected; and

FIG. 7 is a perspective view of the driver which is rotated for causing the elliptical motion.

DESCRIPTION OF THE PREFERRED EMBODIMENT The illustrated embodiment of the invention comprises an apparatus for grinding a cabochon, or the like, in a circular pattern or in an elliptical path, means being provided to effect adjustment to handle from a round surface to a relatively long and narrow ellipse. As shown. the apparatus comprises an assembly including a driven circular metal disc 10, having on one side an integral forwardly extending centrally disposed hub 11, formed with a hollow bore 12. Adapted to be mounted in the bore 12 is an adaptor stem 13 which is retained in position by a set screw 13a. On the outer end of the stem is a head M, to which the element to be ground, such as a facitious stone E, is attached. The attachment can take place in any suitable manner, but it is usual to attach the stone by hot glue, affording a secure bond but one which enables easy removal of the stone. Although, throughout the description, reference will be made to a stone, such as a cabochon, to be ground by a grinding wheel G, it is to be understood that the invention is not so limited and has utility for many other uses. It will hereinafter appear that the stone E can be rotated to grind a circular stone, or it can be revolved through an elliptical path to grind an ellipse of predetermined form.

The driven circular disc 10 forms part of an assembly. As shown, it is formed on the inner face with a circular recess 15 concentric to the hollow bore 12. The recess 15 has a flat bottom 16 and passing transversely through the bore 12, and extending from side to side of the recess, is a guide groove 17. Slideable in the groove 17 is an approximately rectangular driving tang or tongue 18, which is integral with a cricular washer 20 forming part of an elongate driver stem 21. The circular washer 20 is approximately of a thickness corresponding to the depth of the recess 15. The outer end portion of the stem is provided with a flat surface 22, and adjacent thereto are screw threads 19. Fitting over the outer end of the stem is a knurled operating knob 23 which contains a set screw 24 engaging the flat surface 22 so that the knob can rotate the driver stem 21. On the threaded portion 19 are lock nuts 25 to insure the retention of the knob in position.

Fitting flatly against the circular driven disc 10 and retaining the tang 18 in the guide groove 17 is a circular metal cover plate 26 which has an elongate slot 27 aligned with the guide groove 17 to enable the driver stem 21 to slide in one direction or another along the guide groove 17 in the operation of the apparatus. Abutting flatly against the cover plate 26 and forming part of the assembly is an inner circular, metal guide plate 28 of approximately the same diameter as that of the cover plate 26 and disc 10, and this plate is provided with a relatively large elongate cam slot 29 which is rounded at opposite ends, and is disposed perpendicularly to the guide groove 17 and slot 27.

The disc 10, cover plate 26, and inner guide plate 28 are secured together to form a rigid assembly in the relative positions shown on FIG. 6, by two oppositely disposed screws 30 extending through holes in the plate 26 and cover plate 26 and are threaded into holes in the disc 10. This assembly also includes the driver stem 21 with a tang 18 in sliding engagement with the guide groove 17., and held in position by the integral washer 20 which is engaged on its outer face by the inner face of the cover plate 26.

Operating in the cam slot 29 is a circular stationary metal cam plate or disc 31 which is secured to an upright support plate 32 by a pair of screws 33. The cam disc 31 is of a dimension that the assembly, including the guide plate 28, can move slidably from end to end of the slot 29, and revolve about it. The screws 33 are arranged on opposite sides of a cut-out, or aperture 33 (FIGS. 2 and 5). The cam disc 31 is formed with an elongate slot 35 generally aligned with the slot 27 of the cover plate 26. The driver stem 21 extends freely through the slots 27 and 35, and rotates in a sleeve 36 (FIGS. 2 and 3), which is rigid with and connected to an adjuster plate 37 which is shiftable for adjustment purposes on the support plate 32. The diameter of the driver stem 21 is slightly less than narrow dimension of the slots 27 and 35 in order to contact the sides thereof and move freely along same. In the plate 37 are curved slots 38 at opposite ends to receive rigid bolts projecting from the support plate 32, and between the slots 38 is a straight up and down slot 38' which rides over a pin 38" on the support plate. Wing nuts 39 on the bolts enable the adjuster plate 37 to be rocked to a desired position and secured in place. Such movement shifts the driver stem 21 to one position or another in an up and down direction with respect to the slots 35 and the guide groove 17, thereby to adjust the apparatus for moving the stone E in a circular path or in a predetermined elliptical path. As shown, the adjuster plate 37 has a pointer 40 which can be moved along a series of calibration 41 indicative of certain ellipses.

In order to operate the apparatus, the control knob 23 at the back is rotated to actuate the driver stem 21. The stem rotates in a stationary sleeve 36. The turning of the driver stem 21 drives the assembly consisting of the discs 10, 26 and 28, through the tongue 18. Movement of this assembly, however, is governed by the stationary cam disc 31. 1f the stem 21 is on dead center, then a rotary circular motion is imparted to the assembly, and, hence to the stone E. However, by adjustment of the adjuster plate 37 to effect movement from dead center of the stationary bearing sleeve 36, elliptical movement is imparted to the assembly with the cam slot 29 moving about the stationary cam disc 31, the tongue 18 moving accordingly in the guide slot 17. The greater the adjustment of the adjuster plate with relation to the calibrations 41, the greater will be the generated ellipse.

The support plate 32 on which the above described assembly is supported is adjustable vertically relative to a mounting plate 42 in order to adjust the stone E toward or away from the grinding wheel G. Connecting brackets 43 and 44 on the support plates 32 and 42, respectively, carry a vertical adjusting screw rod 45. The screw rod 45 has an operating handle 46 which, when it is turned, is effective to achieve the desired vertical adjusting movement. It will be noted that the assembly carrying the stone E projects through an enlarged opening 42' in the support plate 42, which affords ample space to accommodate the assembly and the adjustments. A slide way for the plate 32 is provided by a pair of guide strips 47 on opposite sides and this enables guided adjusting movement.

The mounting plate 42 has on opposite sides angle brackets 48 which are connected to any suitable rigid support S by horizontal bolt and nut assemblies 49. By loosening these bolt and nut assemblies, the entire assembly can be tilted. The stone E can thus be properly positioned for chamfering operations. I

What 1 claim is:

1. Apparatus for grinding a cabochon or the like to a circular or elliptical shape comprising a stonecarrying assembly including a driven member having a transverse rectilinear guide, a driver stem having a part movable in said guide, a second driven member fixed to and movable with said first driven member and having an elongate cam guide perpendicular to said transverse guide, a stationary cam engaged by said cam guide to effect predetermined movement of said cam guide upon turning movement thereof, said driver stem extending freely through said second driven member and said cam, a stationary sleeve bearing for said driver stem, a handle for turning said driver stem, means for adjusting the position of said stationary sleeve relative to said assembly for causing the latter to travel circularly or elliptically, and said adjusting means comprises an adjuster plate on which said stationary sleeve is rigidly mounted, and means for shifting said adjuster plate for altering the position of said driver stem relative to said assembly.

2. Apparatus as claimed in claim 1, in which said adjuster plate shifting means operates to move said driver stem laterally of the axis thereof.

3. Apparatus for grinding a cabochon or the like to a circular or elliptical shape comprising a stonecarrying assembly including a driven member having a transverse rectilinear guide, a driver stem having a part movable in said guide, a second driven member fixed to and movable with said first driven member and having an elongate cam guide perpendicular to said transverse guide, a stationary cam engaged by said cam guide to effect predetermined movement of said cam guide upon turning movement thereof, said driver stem extending freely through said second driven member and said cam, a stationary sleeve bearing for said driver stem, a handle for turning said driver stem, a cover plate interposed between said first and second driven members and having an elongate slot aligned with said rectilinear guide, and means for securing together said driven members and cover plate so as to turn as a unit.

4. Apparatus for grinding a cabochon or the like to a circular or elliptical shape comprising a stonecarrying assembly including a driven member having a transverse rectilinear guide, said driven member comprises a metal plate having a recess provided with a rectilinear groove, and a tongue rigid with said driver stem and slidably engaged in said groove, a driver stem having a part movable in said guide, a circular washer rigid with said driver stem and to which said tongue is secured, said washer being of a thickness approximately equal to the depth of said plate recess, a second driven member fixed to and movable with said first driven member and having an elongate cam guide perpendicular to said transverse guide, a stationary cam engaged by said cam guide to effect predetermined movement of said cam guide upon turning movement thereof, said driver stem extending freely through said second driven member and said cam, a stationary sleeve bearing for said driver stem, and a handle for turning said driver stem.

Claims (4)

1. Apparatus for grinding a cabochon or the like to a circular or elliptical shape comprising a stone-carrying assembly including a driven member having a transverse rectilinear guide, a driver stem having a part movable in said guide, a second driven member fixed to and movable with said first driven member and having an elongate cam guide perpendicular to said transverse guide, a stationary cam engaged by said cam guide to effect predetermined movement of said cam guide upon turning movement thereof, said driver stem extending freely through said second driven member and said cam, a stationary sleeve bearing for said driver stem, a handle for turning said driver stem, means for adjusting the position of said stationary sleeve relative to said assembly for causing the latter to travel circularly or ellipticalLy, and said adjusting means comprises an adjuster plate on which said stationary sleeve is rigidly mounted, and means for shifting said adjuster plate for altering the position of said driver stem relative to said assembly.

2. Apparatus as claimed in claim 1, in which said adjuster plate shifting means operates to move said driver stem laterally of the axis thereof.

3. Apparatus for grinding a cabochon or the like to a circular or elliptical shape comprising a stone-carrying assembly including a driven member having a transverse rectilinear guide, a driver stem having a part movable in said guide, a second driven member fixed to and movable with said first driven member and having an elongate cam guide perpendicular to said transverse guide, a stationary cam engaged by said cam guide to effect predetermined movement of said cam guide upon turning movement thereof, said driver stem extending freely through said second driven member and said cam, a stationary sleeve bearing for said driver stem, a handle for turning said driver stem, a cover plate interposed between said first and second driven members and having an elongate slot aligned with said rectilinear guide, and means for securing together said driven members and cover plate so as to turn as a unit.

4. Apparatus for grinding a cabochon or the like to a circular or elliptical shape comprising a stone-carrying assembly including a driven member having a transverse rectilinear guide, said driven member comprises a metal plate having a recess provided with a rectilinear groove, and a tongue rigid with said driver stem and slidably engaged in said groove, a driver stem having a part movable in said guide, a circular washer rigid with said driver stem and to which said tongue is secured, said washer being of a thickness approximately equal to the depth of said plate recess, a second driven member fixed to and movable with said first driven member and having an elongate cam guide perpendicular to said transverse guide, a stationary cam engaged by said cam guide to effect predetermined movement of said cam guide upon turning movement thereof, said driver stem extending freely through said second driven member and said cam, a stationary sleeve bearing for said driver stem, and a handle for turning said driver stem.

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