The Foldover Clasp
Several areas on the buckles are most problematic: the centre hinge pin and the solid pin that holds the buckle assembly to the six o'clock side of the bracelet. If your bracelet has fallen apart, chances are the buckle centre pin slipped out or the clasp connection pin is bent, broken or missing.
The Hinge Pin
Locate the correct-size replacement centre hinge pin, available from your watch material supplier. Often a standard paper clip can fill the need in a pinch: the wire is often just the correct diameter.
In either case, cut the pin or wire half a millimeter longer than the hinge. Tap one end of the pin with a hammer while the buckle rests on your bench block. If you then cut the wire or pin with nippers, you'll need to hammer the ends to flare them. The end will hold the pin into the buckle. File each end smooth so they don't catch on shirt sleeves or skin.
The Buckle Pin
If this pin is missing, it often requires a new spring bar or solid pin. The end of the buckle on the 12 o'clock side uses a solid pin; the other uses a special buckle spring bar. Get the correct size from your materials supply or watch company. Measure the distance between ends in millimeters and select a pin with a snug fit.
Place one end of the bar in the appropriate hole and grasp the pin with needle-nose pliers or other grip. Flex the opposite wall of the buckle just enough to slip the other end of the solid pin into the opposite hole without distorting the wall.
For the buckle spring bar, which has shorter ends than the normal type of spring bar, insert one end into a hole, retract the other and slip it into the opposite hole.
Sliding Clasp Replacement
Many thinner units, typically used with mesh bracelets, include one locking section and one sliding section. The sliding portion can be replaced with a screw or solid pin with riveted ends. The locking portion sometimes requires a spot weld that's not feasible. It might not even be necessary.
It's unnecessary because many of the locking clasps can be replaced more effectively with a fold-over clasp unit. The unit, sold by any watch material supplier, will make your repair simpler and quicker and will result in a nicer clasp for a mesh-style bracelet.
The new unit eliminates the "tail" of the mesh band - creating a more tailored appearance. These units also provide the clasp with a safety chain. Cut the band more deeply in the centre. Here, the jaws of the new clasp will bite into the band.
The clasps require you to first measure your wrist. Lay the watch and band around the wrist and place the replacement clasp in position on the wrist. Using the inner measurement, mark the ends of the bracelet that need to be cut off. Be sure there's enough bracelet to insert into each side of the new clasp. Use a cutting disc or other cutting tool.
Now, with the cutting disc, cut a slit into the underside of each end of the bracelet, about one-quarter inch from each end. Then deepen these slits into the centre of the mesh or link itself. Be sure this slit doesn't reach the sides of the band so the bracelet retains its strength. This cut provides the area into which the jaws of the new clasp will bite into the band (see illustration above). Complete the clamping procedure into these slits and the new clasp is ready to use.
Reprinted with permission from the Professional Jeweler Magazine. For more information, please visit the American Watchmakers-Clockmakers Institute (AWCI).