Professional Jeweler Archive: Installing/Repairing a Figure 8 Safety Clasp

April 2002

Professional Bench/Selling Quality

Installing/Repairing a Figure 8 Safety Clasp

Knowing how to perform this procedure demonstrates another aspect of quality in your shop

Clasp mechanisms come in a variety of designs and configurations to secure bracelets, necklaces, watches and other jewelry. The figure 8 safety catch – with its simple utilitarian design, ease of use and installation – is the primary back-up system in case of clasp failure.

A figure 8 safety catch has the following components:

A. Tube.

B. Figure 8.

C. Ball Catch.

Guidelines for the Manufacturing, Repair and Installation of Figure 8 Mechanisms

Overall dimensions vary with the application. A typical figure 8 with a 4mm-5mm reach generally has these measurements:

A. 4mm-5mm reach between the tube and ball catch.

B. 1.5mm ball.

C. 0.50mm diameter round wire.

D. 2mm length of tube.

E. 1mm grab element.


The tube’s inside diameter should be only slightly larger than the outside diameter of the figure 8 wire. The wire should rotate freely inside. The tube should be long enough that the figure 8 closes and locks easily.

Figure 8 Wire

The length of wire varies with the figure 8’s application. The figure 8 wire and ball catch form the locking mechanism. An alloy of nickel white gold works best. When adjusted properly and depressed over the ball catch, the wire flexes and snaps into place below the ball. Longer distances between the tube and the ball catch require heavier gauge wire.

You also can use yellow gold alloys that have been work-hardened or spring alloys. Traditional platinum alloys make poor springs, though newer alloys work well, including Plat SK available from Hoover and Strong or HTA platinum from Imperial Smelting.

Ball Catch

The ends of the wire are fused together into a ball that serves as the grab element to open the safety clasp (E). The fused ball should be close to the ball catch to minimize the risk of accidental catching. It should not extend beyond the clasp it’s soldered to. This location ensures the required spring action takes place between the ball catch and tube and not near the fused ball where the metal has been annealed from fusing.

Make the ball catch by melting together small pieces of clean metal (B). The diameter of the ball should be about three times the outside diameter of the figure 8 wire.

Constructing the Figure 8 Safety Catch

For this explanation, the figure 8 will be attached to a box clasp. Determine the best location for the figure 8 on your clasp and mark the locations of the tube and ball. File a flat area on the tube. For a curved surface, such as the edge of an oval bangle bracelet, use a round or round joint file to make a slight notch for the tube to fit into. Solder the tube in place (if the tube has a seam, face it into the joint).

A ball made by fluxing and melting together small pieces of gold will have a slight flat shape on the bottom. File the flattened bottom side of the joint and solder it.

Estimate the length of wire needed for the figure 8 and cut to length. If in doubt, bend a piece of brass or copper wire to the approximate shape to determine the length needed.

Insert the wire into the tube and begin bending both sides by pushing with the fingers or pliers.
Squeeze the figure 8 wire midway between the ball and tube with round-nose pliers until both sides meet.
Bring ends together with flat pliers. This will slightly straighten the center.
Squeeze the figure 8 wire midway between the ball and tube with round-nose pliers until both sides meet (1). Adjust so both ends touch. Be sure the wires are the same length and are long enough to form the end (2).
Flux the end of the wire and hold it with cross-locking tweezers so the figure 8 hangs downward. Use a small torch tip with a medium hot flame. The flame should be pointed to the outside of the figure 8 because the ball will form toward the flame. As the metal melts, follow the ball up with the torch, pulling the torch away when the ball reaches the proper point.

You will need to tighten the clasp slightly by squeezing the center with round-nose pliers. Check the operation of the clasp and adjust as necessary. To loosen the clasp, insert the round-nose pliers point into the figure 8 to spread slightly.

The clasp should snap closed and have minimal free play. Remember your customer may not have a thumb nail as strong as yours so adjust accordingly!

Knowing these details will contribute also to your ability to repair and reconstruct existing pieces.

This information is required for the first level of the JA® Bench Jeweler Certification™ program.

Mark B. Mann, Director of Trade Programs, Jewelers of America

Technical Content by Wayne Lenkeit, JA® Certified Master Bench Jeweler,™ Lenkeit Manufacturing, Temecula, CA

© 2002 Jewelers of America
Illustrations by Lainie Mann – Visual Communications

The JA® Professional’s Guide to Fine Jewelry Craftsmanship

Installing/Repairing a Figure 8 Safety Clasp

By Mark B. Mann, Director of Trade programs, Jewelers of America

Professionally Repaired, Manufactured and Installed Figure 8 Safety Clasp

A. The diameter of the figure 8 wire is about one-third of the size of the ball catch and substantial enough to maintain its shape through regular use.

B. The figure 8 wire fits snugly into the tube but swings freely.

C. The figure 8 wire snaps into position over the ball and has minimal free play.

D. The figure 8 wire doesn’t extend past the clasp it’s attached to.

E. The figure 8 wire maintains its tension and isn’t annealed.

Potential problems to watch for

The wire diameter selected for this figure 8 was too small; through normal wear, the mechanism has become deformed. The device no longer locks into position and provides no security for the clasp.
This figure 8 wire was installed onto the clasp improperly and was annealed. It will not lock into position and when readjusted will lose its shape on contact.
This figure 8 wire extends well beyond the clasp; it will catch and open easily.
The ball catch was installed improperly and is flat across the bottom portion. There is no space for the figure 8 wire to lock into.

This information is required for first level of the JA® Bench Jeweler Certification™ program.

For more information about bench jeweler certification, call Jewelers of America at (800) 223-0673 or visit

© 2002 Jewelers of America
Illustrations by Lainie Mann – Visual Communications

Copyright © 2002 by Bond Communications