7750 Balance Wheel Installation Information?

[szvwj]

I'm trying to learn how to remove and reinstall a balance wheel assembly. I've read everything I could get my hands on regarding disassembly and reassembly of a 7750 and have been able to tear one down and put it all back together (I'm really enjoying this hobby). The one thing that seems to be hanging me up (and I can't find any detailed information on) is the Balance Wheel assembly.

What do I need to know in order to successfully remove and reinstall a balance wheel assembly? Are there any special tricks, pitfalls or concerns that I need to know about?

I've been able to remove the Balance wheel and reinstall it (without damaging anything), but I don't think I'm doing it correctly.

Should the pallet fork be in any particular position before installing the balance wheel?

Does the balance wheel spring need to be pre-tensioned before assembly?

Any tips (other than 'take it to a watchsmith') would be greatly appreciated.

[freddy333]

What do I need to know in order to successfully remove and reinstall a balance wheel assembly? Are there any special tricks, pitfalls or concerns that I need to know about?

I've been able to remove the Balance wheel and reinstall it (without damaging anything), but I don't think I'm doing it correctly.

Should the pallet fork be in any particular position before installing the balance wheel?

Position the pallet's tail towards the center of the movement.

Does the balance wheel spring need to be pre-tensioned before assembly?

No. And, in fact, you should never do anything with the innards of a movement when the mainspring is carrying a charge. Always let the spring down (gently) completely when working on it.

Any tips (other than 'take it to a watchsmith') would be greatly appreciated.

Be careful not to get the hairspring tangled in the adjacent wheel as you slip it underneath. Before tightening the cock screw, start the balance & be sure it continues to revolve (freely) as you tighten the cock screw. If the balance slows or stops, back the screw out & find out what is out of alignment before continuing. As long as the balance is revolving freely when the cock screw is secure, the balance should be fine.

Congratulations on completing a 7750.

[szvwj]

Fantastic!! thanks for the reply.

Man, it's tough getting that thing back in place, the balance wheel bounces all over when trying to get it into place. I finally got it back in and the watch is working perfectly (with the exception of a broken Oscillating Pinion, which I have on order... darn those things are small).

Again, thanks for the reply, I very much appreciate it!

[Francisco]

I am finishing a new tutorial and in this tutorial I will post these two videos, where you can see how a A7750 balance wheel is assembled and disassembled. It is not easy, beause the minute counter gear is disturbing.

The thread will show how a balance wheel is repaired.

Hope this helps:

[szvwj]

Francisco, you sure do make that look easy!

Are you installing the balance wheel as the movement is working (not stopped)? If so, is it easier to install it that way as opposed to stopping the movement and then installing the balance wheel?

I really appreciate your tutorials, they give me the confidence to attempt repairs myself. I really enjoy working on watches and the tutorials (and help) I've found on the forums make it possible.

Thanks again!

[Francisco]

Francisco, you sure do make that look easy!

Are you installing the balance wheel as the movement is working (not stopped)? If so, is it easier to install it that way as opposed to stopping the movement and then installing the balance wheel?

I really appreciate your tutorials, they give me the confidence to attempt repairs myself. I really enjoy working on watches and the tutorials (and help) I've found on the forums make it possible.

Thanks again!

I think it is much better assembling the BW when the movement is not hacked, for sure. The hacking is fastening the BW!

Thanks for your comments,

Francisco.