March 1998

Timepieces:Education & Repair


by David A. Christianson, certified master watchmaker

Timepieces can be damaged during a routine battery change. Does your staff know how to avoid it? In the second of a series of watch repair columns, David Christianson explains how

In many jewelry stores and jewelry departments, the task of changing watch batteries is delegated to the sales staff. To help the staff with this common task, we'll first examine removing casebacks.

Removing Snap-on Caseback
The snap-on caseback is usually removed by inserting a thin-bladed knife into a notch located between the back and the frame. The knife blade is rotated to lever the back away from the frame. This is usually a very easy procedure. Still, observe these precautions:
1. Do not brace your knife blade on one of the case lugs when prying off the caseback. You may break the lug. Use a lifting motion.
2. Do not allow the knife blade to slide under the caseback and into the watch movement inside.
3. Be sure your knife blade is firmly in the notch before prying. Otherwise, the blade will skip off the edge of the caseback and gouge the back.
4. On the rare occasions when you can't get a good grip on the back with your knife blade, quit! Refer the problem to a professional watchmaker.
5. Specially designed snap-on caseback opening systems virtually eliminate many of these problems. Most major watch brands offer their own systems. Or contact your watch supply center.

Removing Screw-on Caseback
The screw-on caseback is removed using a wrench, either hand-held or bench-mounted. A few precautions:
1. The jaws of the case wrench must line up with the notches in the caseback. Apply firm downward pressure to the wrench as the back is unscrewed. If you don't the wrench is likely to slip and gouge the back of the watch, and maybe your hand.
2. Many screw-on casebacks are so tight you'll need to hold the watch in a special case vice when using a hand-held wrench. (Case vices are available through any major watch supply source.) Your hand may be strong enough to hold the case, but the torque applied while unscrewing such a tight caseback will cause the watch to twist in your hand and break the watch band where it attaches to the case.
3. Using a bench-mounted screw-on case opening system will eliminate these problems.

Replacing the Caseback
Even after cleaning with a brush, a ring of contamination may remain around the case opening. Wipe this away with a cloth or a sharpened pegwood stick, keeping the case opening perpendicular to the bench top and rotating it so the contamination falls away from the case and not into it.

When replacing casebacks, carefully remove the caseback gasket, brush the edges and lubricate the gasket with a silicon sealant. This assumes the gasket is not stiff, cracked or broken. If it is, tell your customer it would be best for your watchmaker to replace the gasket.

Snap-on casebacks can often be replaced with finger pressure, but keep fingers off the crystal, which can break under pressure. Align the stem notch in the back with the stem or the back will not go on properly.

If finger pressure won't snap the back on, use a case or crystal press. Align the watch in the press so there is no pressure on the crystal. If you don't have a press, refer your customer to a professional watchmaker.

With the screw-on backs, it's important to tighten the caseback about half a turn after you feel the caseback tug on the gasket. Too much tightening will cause the gasket to stretch and curl, reducing the effectiveness of the gasket.

Next Month: Battery Basics

David A Christianson owns Christianson Jewelry, Kendallville, IN, and is a director and first vice president of the American Watchmakers-Clockmakers Institute.

Copyright © 1998 by Bond Communications.


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