But, in a pinch, you can use a normal vice. I have to warn you though, if you're not careful, you might end up breaking your watch. Don't say you weren't warned. It's not my fault if your watch ends up in 1000 different pieces.
The first step is to find a nice flat piece of metal, this is placed against the back plate. In my case I used a large washer with a small hole in it. You'll then need to find a stiff piece of rubber that pushes up against the front of the watch. I found what I think was a rubber screw on foot from something like an old piece of furniture.
This all gets placed in the vice. Make sure it is centred in the jaws as the whole point of this is to exert a gradual uniform pressure on the backplate to clip it back into place.
|Watch in Vice|
The next step is the one that will make you sweat and is something I can't describe. If you've used a vice a lot you'll get a feel for how much pressure it's exerting by the resistance offered when turning the handle. You want to gradually turn the handle while observing the watch from the side. The gap between the backplate and the front will slowly close and then all of a sudden it will snap back into place.
|Watch Compression Stack|
So yeah, it'll work, but it's high risk. You're better off going to eBay and searching for a watch press. They cost something like $16 Australian delivered from China for a cheap one. It'd be handy to have a die to clamp connectors together too, you know like the old db9 ribbon cable ones.