Installing a Superfit® Shank Using Torch Methods

Knowing how to professionally install Superfit shanks for enlarged finger joints demonstrates another aspect of quality in your shop.

Having mechanical shank-device solutions for arthritic or enlarged finger joints adds another professional and profitable dimension to your service department. For previously published information on a variety of enlarged finger joint mechanical shank-device solutions, see Professional Jeweler, November 1998, pp. 97-100.

This article describes a bridge-type installation of a Superfit mechanical shank, a high-quality and easy-to-use device manufactured by Superfit Inc.

>14k yellow gold diamond ring size 7 requires a mechanical shank to accommodate an enlarged finger joint. The ring is 7.5mm wide at the top and 3.3mm at the bottom.

>It’s 6mm wide at the “half-shank” location.
14k yellow gold Superfit mechanical shank size 7 is 6mm wide, which is the width of the “half-shank” part of the ring.

>Superfit stylus is designed to depress the latch of the Superfit shank.

Inspection and Preparation for Installation

Steece Hermanson of Galloway & Moseley, Sumter, SC, thoroughly cleans the ring and inspects the stone for damage or other characteristics not recorded on the job envelope.

Next he assesses the structure and design of the ring to determine the best method of installation. The standard half-shank assembly (illustrated in A) joins the top of the customer’s ring to the bottom mechanism of the Superfit shank. This is ideal for most rings, but when the overall shank is not substantial or features an open design (as in this example), it’s best to use a bridge-type installation (shown in B).

Preparation Steps for Preliminary Installation

1. Hermanson measures down from the top of the diamond ring with dividers and marks it slightly above the half-shank location on each side.

2. Next he saws below the line and files the ends flat. The diamond ring stands up when placed on a bench block and doesn’t lean or tip over.

3. He marks the hinge and latch of the Superfit mechanical shank with a fine-point Sharpie. From these marks, he locates and scribes the exact center of the top of the Superfit shank.

4. He lays out the top using his dividers. He will remove a 2mm strip from the central part of the top. The piece removed is 3mm to 4mm above the hinge and latch.

5. He uses needle files and a tapered cylinder bur to flatten and shape the inside of the central part he cut away.

6. Then he centers the top of the diamond ring alongside the top of the Superfit mechanical shank and scribes its placement. Each side of the ring shank termination is marked 3mm or more above the hinge and latch.

7. Next he scribes a line about 1mm down from the top of each side of the Superfit mechanical shank. The overall depth of the shank is 2mm.

8. He removes and fits the top using a saw and files.

9. To spread the 6mm top of the Superfit mechanical shank, he places flat-nose pliers into to central part and forces them open. He spreads the top to 7mm wide, being careful not to distort the hinge and latch.

Assembly and Soldering Procedure

10. After filing, fitting, prefinishing, cleaning and inspection, he places the assembly into head-and-shank tweezers.

11. He attaches one of the leads from his ABI Tack II welder to the head-and-shank tweezers. He tacks 14k easy yellow solder beads (from Stuller) onto the solder joints using 25 to 30 volts on the low energy setting. (For best results, tack the solder beads before firecoating.)

12. Next he firecoats, preheats, fluxes the joints then solders the ring top onto the Superfit mechanical shank.

13. He allows it to air-cool then quenches all but the gemstone in mineral oil. This helps the Superfit mechanical shank keep the required tension.

Finishing Procedure

14. At this stage, the ring assembly is 7.5mm wide at the top and 6mm wide at the bottom. He files to taper the ring down to 5mm at the bottom. It’s 5.5mm at the hinge and latch area. He’s careful to remove an equal amount from each side.

15. After tapering, he uses his ABI Pulse Arc Welder to arc-weld the hinge pin on both sides.

16. Using various files and abrasive sanding sticks, he cross files the assembly. Then he finishes the ring inside with an assortment of fine abrasive wheels.

17. He determines the tension is slightly loose and the lower part of the Superfit mechanical shank is out of round. He uses ring-bending pliers with a copper sleeve over one side to bend the bottom of the shank outward (method B).

18. After finishing, polishing, cleaning and inspection, he oils the hinge and latch for smooth operation.

Procedure Summary

This bridge installation procedure required 2.5 hours.

– by Mark B. Mann
Technical contributions by JA® Certified Master Bench Jeweler Steece Hermanson, shop manager for Galloway & Moseley, Sumter, SC

For questions related to this process, contact Steece Hermanson by e-mail at shermanson@FTC-I.NET.

Superfit Inc. provided material for this demonstration. The company manufactures mechanical shanks measuring 2.5mm to 10mm wide in yellow ad white gold and platinum. For questions related to Superfit shanks or for a list of distributors call Gina Alulis at Superfit Inc., (800) 765-7111.

Superfit® Shank Installation

A. The ring and mechanical shank portion are true and round. The shank opens and closes easily.

B. The hinge operates smoothly, and the overall assembly has ample tension. When the mechanical shank is closed, there’s an audible click.

C. There are no visible solder joints between the original ring and the Superfit shank.

D. The original ring retained its dimension, appearance and design.

E. The taper is even and removed equally from each side.

F. There are no visible tool marks, and the polish is even and smooth.

G. There was no stone damage through the installation process.

Potential Problems to Watch for
The ring was installed poorly onto the Superfit shank. Its alignment is off-center and out of round
Too much metal was removed from the Superfit shank’s original thickness during installation of the ring. The hinge doesn’t operate properly, the latch is inoperable and the tension is too weak for normal wear.
The tension was not adjusted properly, and the opening tab doesn’t close.
Too much heat was applied during the soldering process, and no “joint” protection such as yellow ochre was used. The shank is frozen closed.

– by Mark B. Mann

This series is sponsored in part by Jewelers of America, (800) 223-0673

Published by Professional Jewelery, January 2003

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