Every once in a while I come across a screw that just won’t turn. This happens more with older watches of course. This week it was a Rolex that I couldn’t get out of the case because both of the case screws appeared to be frozen in place. This was a different problem than usual because the case screws on a Rolex screw out (loose) against the case.
The first rule in breaking a frozen screw loose, is too make sure you are turning it the right way. In the case of the Rolex one of the screws had already been tightened down and didn’t need to be turned, when I tried to back it out a little bit to free it, it turned with ease. The other one really was frozen in place. Crown wheels, and sometimes ratchet wheels, and an occasional screw for a date wheel will often be reverse threaded, so it is important to know which way it needs to turn before trying to muscle it out — or you will definitely break it.
Once you have determined that the screw is stuck there are a few things to try.
- A bigger hammer (or screwdriver in this case). — if you can use a bigger screwdriver without damaging the surrounding bridge sometimes the extra torque will break the screw free.
- A hammer — tapping on the screwdriver while it is engaged with the screw can sometimes free up a screw
- Oil — Some machine oil, or some penetrating oil can be applied. A good penetrating oil will travel under the head and down around the threads providing some lubrication, or even helping break down the rust. Because of its negative implications I would never use WD-40. I use Kroil “the oil that creeps.” — This did the trick on the Rolex case screw for me this week. Ultrasonic — the vibrations will cause some screws to free up.
- Heating / Cooling — the expansion and contraction of heating and cooling a part will often free a screw.
Always be careful not to damage anything around the screws.
On a modern caliber if the above fail you may have to purchase the part that contains the frozen screw. On vintage calibers you may have to drill out the screw and re-tap the hole for a larger screw thread.