Balance Trouble

[rustycolt]

I'm caught in a project that has been plagued with gremlins. One of those where the moment you sort out one issue, another shows up elsewhere. After winning nearly every battle, I am down to one last fight for which I could use a bit of guidance. 

 

With all repairs complete, the watch runs perfectly - in every position except dial up. In that position, it runs if it is positioned just right and held still, but if not, the balance becomes noisy (rattle) and stops. I do not see any interference, the jewels and pivots appear to be undamaged, and I have adjusted the endshake to what seems to be ideal. (side note, with a larger gap between the jewels, the problem was more pronounced) 

 

I feel like this should be a relatively obvious problem to diagnose, and that I have probably overlooked something. What are the areas of concern that bear closer inspection for this symptom?

 

Thanks 

J

[Marc]

Kind of thinking out loud here as I don't know if my logic is sound.....

 

If the bottom hole jewel, which would be uppermost in DU position, were too big for the pivot, either due to excessive wear (of either jewel,or pivot, or both) or because the original jewel had at some time been replaced with one too big, is it possible that instead of spinning smoothly in the jewel, the pivot might develop a tendency to "riddle" in the jewel hole causing the balance to stop? In DD position this would be prevented by the contact between the end of the pivot and the cap jewel, and in the vertical positions the pivot would lay on one side of the hole jewel, damping any tendency to vibrate so things would run smoothly.

 

What is the side shake like?

[bobm12]

Would a bent pivot cause that? Just like Marc, thinking out loud...

[rustycolt]

Upper pivot hole.

 

For reasons I won't go into here, I had built a balance assy & cock from 2 separate balances. Turns out that the BFG 866 uses (at least) two slightly different arrangements, and to make a long story short, there was a mismatch between the upper pivot and pivot hole. Things appear to be running well at the moment, but I'm not celebrating for another 48 hours or so - gremlins.

 

Thanks for the thoughts. They helped to get my brain headed in the right direction. 

[Geo]

Well thought out Marc! :)

[bobm12]

Excellent Marc! Although not a good advice I'm glad it helped! :)

[Marc]

Fingers crossed for the next 48 hours then Rusty but it sounds like you're on top of it.

[bobm12]

I was rereading my former post, I'm talking about MY advise that didn't help. I should have made a line break...that's what you get when you use a tablet!

[noirrac1j]

Rusty I recently used a pallet from a one jewel Sicura on a 17 jewel Sicura and discovered something I had not noticed before. The safety pin of the pallet sticks up above the pallet fork whereas the safety pin from the jeweled variant is BELOW the pallet fork! Icould not jet my jeweled impulse balance to work with this pallet and I could not figure out why--it would run and stop run and stop. When I looked thatthe two pallet levers side by side, I discoved that Sicura not only uses two diffrent balances as you know, but alsop two different pallets. II happened to have an extra pallet from a 17 Jewel sicura and when I put this one in, the watch strated running and keping time right up until this morning when I left home. I will send you picutres later, but I thought you'd want to know because the balance I sent you is for a non-jeweled movement, and this may be the cause of the probem you are having because your pallet is for a jeweled balance (which I have). More in a bit.

 

Joe

[rustycolt]

Good catch Joe, but I did see that there were differences in the balance and pallet forks on the different movements. I kept my original balance (jewelled) and replaced the balance cock with the one you sent me (from non-jewelled). 

This arrangement gave me the correct spring layout relative to the mount and regulator, and in turn corrected the original problem of having a flat spring mounted where there should have been an offset one. (spring was twisted under torsion) The correct repair would have been to replace my flat hairspring with a good offset one, rather than changing the cock to match the spring. I only went that route because it was a brand new balance assy that I had installed, and it came with the flat spring. 

 

In the end, I was able to bring everything back into union, and it has been faithfully ticking away the minutes quite nicely. I still need to regulate it, but I dare say, the finish may finally be in sight!

 

J 

[Geo]

It might have helped if you had given a bit more of the story to start with J. :)

[rustycolt]

Both true and false at the same time Geo  ;)

I was not seeking a specific solution for a specific problem in this case. That would have benefitted from details description for sure. I knew that the problem would be related to the parts I changed, but I saw it as an opportunity to improve my troubleshooting accumen by leaning to diagnose the problem more specifically than just re-replacing the parts I changed. Hence the "trouble is in this area, and happens under these circumstances - where should I direct my attention" phrasing. Granted I did go into a few more details with Joe, but that was just to bring him up to speed as he was along for most of the ride behind the scenes. 

 

Never ask for just a fish from someone who is able to teach you to be a better angler.

[Geo]

Never ask for just a fish from someone who is able to teach you to be a better angler.

You got the answer from one of the best anglers on the boat........Marc! :)