Balance wheel not secured to balance staff, what do I need to fix this?

[GregG]

I have a balance that has a bent pivot.  I have a Levin pivot polisher, but when I was moving the bow back and forth, I noticed that the impulse pin wasn't moving, but the rim of the balance was moving.  So the rim isn't held securely to the staff.  I am not 100% sure how to fix this issue.  I think I saw a video of it once, and the guy used a staking set with a domed punch to rivet the wheel to the staff.  Can someone clarify what I should do, and/or what staking equipment I'll need?

Thanks

Greg

[JohnR725]

5 hours ago, GregG said:

staking equipment I'll need

Do you have a staking set?

What it means is that somebody restaffed the watch and didn't test to make sure that they actually had riveted correctly.

 

[mikepilk]

You can do it with a domed punch, but I think you may end up having to put a new staff in. I don't think I've ever managed to straighten a bent pivot (more than a tiny amount),  they've all broken - another one only yesterday !

[JohnR725]

13 minutes ago, mikepilk said:

I don't think I've ever managed to straighten a bent pivot (more than a tiny amount),  they've all broken

Normally my experience would agree with yours until I found this tool and so far it's worked quite nice for pivots. It also looks like Bergeron has revised it in some way. I have the PDF attached for describing how the tool works which as I said actually works quite nicely. But there is a limit of what you can do with a bit pivot and because somebody didn't put the staff in right the first place it might be better just to start over.

7135 7136 tool for straightening bent pivots.pdf

[mikepilk]

Interesting read. I can buy a lot of new staffs for the price of one of those. But, I might try the technique of finding a slightly larger jewel hole and bending bit by bit.

Just a thought - any reason why you couldn't anneal the pivot, bend it straight, then harden it again ?

Edited December 4, 2022 by mikepilk

[nickelsilver]

2 hours ago, mikepilk said:

Interesting read. I can buy a lot of new staffs for the price of one of those. But, I might try the technique of finding a slightly larger jewel hole and bending bit by bit.

Just a thought - any reason why you couldn't anneal the pivot, bend it straight, then harden it again ?

You can do a spot temper, with the staff (or pinion) mounted, but to do a full anneal the steel has to go to critical temperature i.e. red hot then cool slowly. In either case to get back to original hardness will require going red hot again then quenching, then tempering.

 

I love that Seitz tool- as a pivot gage. Don't really like it for straightening pivots. I chuck the part in the lathe and turn the spindle by hand to find the max error, and use Dumont #8 tweezers or well dressed stubby nickel tweezers- that have been heated in an alcohol flame until almost too hot to hold- to coaxe the pivot back.

 

The hot tweezers aren't hot enough to affect the temper, but the heat really does help the metal relax and move. Some pivots are simply bent too far and will never straighten without breaking.

 

Op's staff looks homemade and hokey, it's pretty bent. If it's properly heat treated I wouldn't bet on the pivot getting straight before breaking.

[GregG]

3 hours ago, nickelsilver said:

 I wouldn't bet on the pivot getting straight before breaking.

Yep, precisely what happened...

[JohnR725]

5 hours ago, nickelsilver said:

I love that Seitz tool- as a pivot gage. Don't really like it for straightening pivots.

As I already have one of the gauges I don't need it for the gauge aspect. Then I probably don't exactly use it the way they say basically does Buddha balance wheel in look and see if it's leaned and I just gently start pushing it and go to the smaller and smaller holes and so far it seems to work.

5 hours ago, nickelsilver said:

Dumont #8 tweezers or well dressed stubby nickel tweezers- that have been heated in an alcohol flame until almost too hot to hold- to coaxe the pivot back.

Then when I was in school instructor George had tweezers that had pieces of wood attached to them so we can hear them up is hot is they needed to be and he didn't have to burn his fingers and I can't really put it in his lathe or whether he did it. But in any case he was always able to save a pivot but as an instructor I'm sure he got lots of practice.