The invention relates to the type of engraving machine disclosed in U.S. Pat. No. 2,562,269. The engraving machine disclosed therein uses a pantograph lever which has a stylus at its lower end and an engraving tool near its mid-portion. The patterns to be engraved are carried on a circular carrier and are disposed in a ring along the perimeter thereof. In using this type of machine, the character to be engraved is positioned by an indexing notch on the perimeter of the pattern carrier that cooperates with a locking member on the machine to hold the character underneath the stylus. A ring to be engraved is held by a plurality of chucks mounted to a rotatable ratchet wheel. The ratchet wheel is rotated and indexed by the movement of a pawl. A connecting rod is secured between the pawl and a slideable lock, in order to simultaneously index the ratchet wheel and lock the pattern carrier into position. After the work piece is indexed and the pattern carrier is locked into position, the stylus of the pantograph lever is utilized to trace the character on the pattern carrier thereby causing a corresponding engraving to appear on the interior surface of the ring.
The type of machine disclosed said U.S. Patent has several disadvantages and limitations. The vertical edges of the workholder slide are mounted within grooves in a pair of vertical plates. The proper sliding fit of the work holder slide is dependent upon the adjustment of a pair of screws within each of the plates. Such adjustment requires a great degree of skill and is extremely time consuming. Therefore, the original assembly of the machine is complicated, as well as any servicing which requires the removal of the workholder slide.
Another limitation of the prior machines is the limited range of ring sizes which can be engraved by the apparatus. This range is limited by the amount of travel of the chucks. The prior art machines are capable of engraving only upon standard sized rings such as wedding bands, and school and fraternity rings. Since modern jewelry is available in a wide variety of sizes and shapes, the prior art machines are incapable of engraving upon a significant portion of available jewelry.