US1329372A - Art of polishing diamonds - Google Patents

Description

UNITED STATES PATENT orrion.

CLYDE J. COLEMAN, OF NEW ROCHELLE, NEW YORK, ASSIGNOR TO STERN-COLEMAN" DIAMOND MACHINE COMPANY, INC., OF NEW YQRK, N. Y.

ART OF POLISHING DIAMONDS.

No Drawing.

1' b all whom it may concern Be it known that I, CLYDE J, COLEMAN, a citizen of the United States, residing at New Rochelle, in the county of Westchester and State of New York, have invented certain new and useful Improvements in the Art oi Polishing Diamonds, of which the following is a specification.

My invention relates to the art of cutting and polishing diamonds or the abrasive treatment thereof, and relates more particularly to the holding of the diamond during the cutting and polishing operations or during the polishing operation.

In polishing diamonds, it is the practice at the present time to hold the diamond in the polishing tool by partially embedding it in a body of metal in a semi-molten state, contained in a small brass basin or dop, the diamond being held in position by the metal after the metal has cooled. This method suffers from the disadvantage that it is necessary from time to time to soften the metal and readjust the diamond to eX- pose a different part thereof for polishing, as itis not possible to expose at one time all parts of the diamond 011 one side of the girdle line; It is also common practice to lock the larger stonesin a clamping device, I

but this device is very difiicult to adjust so as to hold the diamond at the correct angle.

The difficulty in holding diamonds during the polishing operation, as distinguished from other precious stones, 1s due to the ex treme hardness of the diamond which ne- 7 cessitates applying great pressure, with re sultant great friction and generatiton of great heat; Diamond polishing is particularly a difiicult operation and unlike other lapidary work because with all other gems there is something harder than they are, which will easily abrade them andnot require any special speed or pressure to polish them, but the diamond being the hardest known substance, it must be polished with its own dust. This requires great lap speed,

great pressure and also a precise'grain presentation to the direction of movement of the lap, with the result that a high tempera-- ture is generated and often an. almost instantaneous risefrom low. red heat towh1te heat is developed when a hard spot is encountered Specification of Letters Patent.

Patented Feb. 3, 1920.

Application filed. December 22, 1913. Serial No. 808,280.

and then a dropping normal red heat. Therefore a cement must possess resistance against the disintegrating effect of great enough to resist the heat of polishing, must be strong and adhesive to resist the pressure and strain and must have substantially the same coefficient of expansion. or a requisite degree of thereof, so that its adhesion will not be de stroyed or impaired by expansion or contraction due to such temperature changes.

The object of the invention is to provide an improvedmethod for holding diamonds in position for polishing, so as to avoid the disadvantage of the prior methods, and in particular to make it possible to polishall faces of the diamond on one side ofv the girdle line without reclamping or resetting the diamond in its holder, thereby avoiding back suddenly to the vibration, must be refractory.

elasticity which is equivalent the troublesome adjustments, calling for skilled manipulation, heretofore necessary. To these ends the invention contemplates may be polished without resetting or reclamping the diamond to thearbor.

I'liave discoveredthat an excellent cement for this purpose may be formed with a clay base or a base of clay and graphite compounded with salts of metals, such as nitrates of metals, and specifically nitrate of lead and nitrate of antimony, and a boron'com-v pound, such as boracic acid or borax. These compounds are made into a thick paste, and for this purpose the addition of a .suflicient quantity of water has-been found suitable.

This paste is applied between the stone and the'arbor, preferably being applied in'con siderable body so that it will be anchored in the arbor and will'form a stemwithin thefarborfor adhesively holding the dia mond, and it is baked'with the parts to a cement having,

gether at a high temperature preferably in a non-oxidizing environment, as by inclosure in a retort containing carbon monoxid or hydrogen gas. The heat is first applied at a low temperature to dry the material, and then at a high temperature. I have found that a temperature of 1800 Fahrenheit is suitable for this purpose although a temperature as low as 800 F. may be used. The total baking operation usually requires from twenty-five to thirty minutes. 'When thus heated and set the diamond will not be loosened from the cement by the polishing operation on the diamond.

Specifically the cement which I have found to give the best results contains a base consisting of a material known as Dixons stove polish, this material being apparently composed of clay and graphite, and I have at times replaced this stove polish by a mixture of clay and graphite, about 60% of clay and d0% of graphite and if desired somewhat more clay may be added. This base is compounded with the following materials in the following proportions by volume: base, parts; nitrate of lead, 10 parts; nitrate of antimony, 15 parts; boracic acid, 20 parts. A convenient way of mixing these materials is as follows: Take 50 parts by bulk of Dixons stove polish, selecting that which is dense, hard, and of good body and not friable, crumbly, sooty or of a dirty nature, and 50 parts by bulk of pure, white, soapstone clay such as the talcum and steatite' varieties, and 20 parts by bulk of borax or boric acid, and 10 parts by bulk of nitrate of lead, and with these in finely divided condition mix them thoroughly. The nitrate of antimony is preferably used in the form of concentrated solution prepared by allowing strong nitric acid to act on an excess of antimony for about ten to sixteen days, and this solution diluted by adding about an equal amount of water. The powdered mixture is then made into a thick creamy paste with a suificient amount of this nitrate of antimony solution. This paste is allowed to stand for twenty-four hours or longer, and then it is made again into a similar paste with water. The paste or cement is then applied between the diamond and arbor and baked as above described. 7

While my present invention is intended more particularly for use in polishing diamonds, it may also be advantageously employed for the preceding roughing out or bruting operation, thereby obviating the necessity of the present practice of having to remove the diamond from the arbor employed in bruting and to attach and re center it on another arbor for polishing.

It is obvious that various modifications may be made in the herein described specific embodiment of my invention, as by varying the proportions or by substituting chemical equivalents for one or more of the ingredients, within the scope of my invention.

I claim:

1. The improved cement for holding diamonds during the polishing thereof, by adhesive action, which cement has the physical characteristics that it does not disintegrate or soften under the heat of the polishing operation, and has such a degree of elasticity that the diamond during the polishing may be rigidly held in place by the. cement applied to the diamond on one side of the girdle, so that substantially all the facets on one side of the girdle may be polished, without-- resetting or reclamping the diamond to the arbor.

2. The improved cement for holding diamonds during the polishing thereof, by adhesive action, which cement has the physical characteristics that it does not disintegrate or soften under the heat of the polishing operation and has such a degree of elasticity that the diamond during the polishing may be rigidly held in place by the cement.

3. The improved cement for holding diamonds during the polishing thereof, by adhesive action, which cement has the physical characteristics that upon baking it in con.- tact with the diamond it will rigidly adhere thereto and does not fuse or soften under the heat of the polishing operation and has such a degree of elasticity that the diamond during the polishing may be rigidly held in place by the cement applied to the 100 diamond on one side of the girdle, whereby substantially all the facets on one side of the girdle may be polished without resetting or reclamping the diamond to the arbor.

4. The improved cement for holding diamonds during the polishing thereof, by adhesive action, which cement has the physical characteristic that it will rigidly hold the diamond during the polishing operation by adhesion thereto, and which contains clay and graphite as a principal base and a binder, in the nature of an enamel.

5. The improved cement for holding diamonds during the polishing thereof, by ad hesive action, which cement has the physical characteristic that it will rigidly hold the diamond during the polishing operation by adhesion thereto, and which contains clay as a principal base and graphitic material and a binder.

6. The improved cement for holding diamonds during the polishing thereof by adhesive action, which cement has the physical characteristic that it will rigidly hold the diamond during the polishing operation by adhesion thereto, and which contains graphitic and refractory material and a binder.

7. The improved cement for holding diamonds during the polishing thereof, by ad hesive action, which cement has the physical characteristic that it will rigidly adhere to the diamond on baking with such tenacity as to hold the diamond during the polishing operation by adhesion thereto, and Which contains clay, graphitic material and a binder.

8. The improved cement for holding diamonds during the polishing thereof, by adhesive action, Which cement has the physical characteristic that it will rigidly hold the diamond during the polishing operation by adhesion thereto, and Which contains clay, graphitic material and a binder formed of a combination containing nitrate of antimony and a boron compound.

9. The improved cement for holding diamonds during the polishing thereof, by adhesive action, Which cement has the physical characteristic that it Will rigidly hold the diamond during the polishing operation by adhesion thereto, and Which contains clay, graphitic material, a boron compoimd and a binder formed of a solution containing a salt of antimony in proportion such that, upon baking, the cement Will rigidly hold the diamond.

10. The improved cement for holding diamonds during the polishing thereof, by adhesive action, Which cement has the physical characteristic that it Will rigidly hold the diamond during the polishing operation by adhesion thereto, and which contains refractory and graphitic material and a boron compound and a binder containing salts of antimony and lead.

11. The improved cement for holding dia-' 60% clay and 40% graphite, 10 parts nitrate of lead, 15 nitrate of boracic acid.

12. The improved cement for holding diamonds during the polishing thereof, by adhesive action, which cement has the physical characteristics that it does not disintegrate nor soften under the heat of the polishing operation and has such a degree of elasticity as to rigidly hold the diamond during the polishing operation, by adhesion thereto, and Which contains clay and carbon as the principal ingredients, and a binder in the nature of an enamel.

In testimony whereof I have afliXed my signature in presence of two Witnesses.

CLYDE J. COLEMAN.

antimony, and 20 parts M. M. ALcoRN.