So you're saying always use a sharp knife?
Well, the thing about doing it yourself at home is that it’s typically easy to get the back off. But often it’s getting them back ON that can be problematic. Many watch backs are pressure backs, and require a watch “press” to reinstall the back. You attach the appropriate die to each side of the watch case, and press them together in a machine that puts even and equal pressure around the perimeter of the watch back. The die that goes on the front of the watch is carefully chosen so as to not crack the crystal once force is applied using the press machine.
Many watch backs can simply be snapped back in with your fingers, but the ones that don’t are literally impossible to get back together without a watch press.
In addition, some watches have a reset procedure when replacing the battery, where the circuit must be shorted in a specific way to prevent problems.
Then there’s the issue of many watches having “straps” that screw down on top of the battery. If you think the screws that hold eyeglasses together are small, you should see the screws used in watches. They are a fraction of a millimeter, and the straps are often “spring loaded”, so when you unscrew the microscopic screw, the battery strap launches the screw into oblivion. Then you’re screwed, because sure you can install a new battery, but you don’t have anything to hold the battery strap down with. The strap must make contact with the battery to complete the circuit. Jewelers have a selection of replacement battery strap screws.
Not only that, but almost all watches have very tiny gaskets that prevent moisture from getting into the watch. It’s not much thicker than a few human hairs. The gasket is often torn when the back is removed, or is flattened or stretched out due to normal use/aging, and must be replaced with a new one.
You’d be surprised how many people bring watches in a ziplock baggie, after they’ve given up trying to work on it at home. We call them butcher jobs, because it looks like they took a dull butter knife and tried to butcher the watch to pieces. The butchering can get so bad that it damages/chews up the case and the back no longer properly mates with a flat surface. It can also chew up where the gasket seats, compromising the integrity of the gasket seal.
If you just take it to a proper jeweler, they have all of the proper tools, all of the proper gaskets, etc. It is $10 well spent (and free lifetime replacement if you purchased the watch from us).
I’m not saying it can’t be a perfectly successful DIY job, but things can go very sideways at which point you’ll need a jeweler or watchmaker to sort it out anyways. No reputable/trustworthy jeweler tries to “gouge” people on watch battery replacement. We’re just happy to provide a service and out a smile on your face. We give away tons of free battery replacement coupons, don’t charge veterans and active duty military, free batteries to new customers, lifetime replacement on watches purchased from us, etc.
