i found this watch in second hand shop and would like to repair it. The hands are moving but not able to open the case. Also the watch is not working. If anyone knows how to open it please let me know.
I am new to this and collecting vintage watches
I think @oldhippy is right.
From wrestling with hairsprings this is one of the trickiest repairs to do, and when doing it one whish one saved the previous discarded part in the “good to have in the future box”.
When it comes to replacing the teeth the donor piece has to come from a wheel not only with the same diameter but also the same type of teeth and depth on them, this is so you will get the correct amount of freedom for the wheels to rotate in a correct way.
Even small differences like these ones will make the wheels not to run correctly in the length.
Another thing to consider is how to put the new piece in place. One should avoid making a rectangular shape to fit with and instead make a “dove tail” shape with a precision triangular file.
Since the teeth on the wheel is subjected to lateral driving pressures a rectangular shape will eventually cause it to wriggle free and fall out, the solder hasn’t a very good mechanical resistance.
This is just some small tips and tricks to think of when repairing wheels.