How to tell if a balance pivot is bent

J

jteselle

I am working on a small ladies watch. It has been cleaned and oiled. When I install the balance without the lever, the balance oscillates freely when the balance is horizontal. When the watch is turned so that the balance is vertical, though, it stops pretty quickly.

When I examine the balance pivots under a microscope it appears that one pivot may be bent, but it is hard to tell visually. Running the watch in a MicroSet timer with paper tape mode on does not produce the 6-second "S" curve that is characteristic of an out of round balance.

Is it possible that the pivot is bent, even though the timer does not indicate this? Is there any other way to detect if the pivot is bent? I do not have a lathe, so any method requiring that won't work for me at present.

Thanks for any help offered.
 

fuzzuki

Registered User
Dec 11, 2001
367
1
0
If you can put it on a poising tool, you can watch the pivots as they turn.

Can you put it on a poising tool under a microscope?

rob
 

Don Dahlberg

NAWCC Member
Aug 31, 2000
3,425
20
38
If it runs dial up and not dial down, or even if there is a large difference in rate in these two positions, you may have something wrong with one of the pivots and/or jewels. The faster rate is usually the bent or damaged side down. The exception if the pivot is mushroomed, then it may show when it is the top pivot.

Other things can stop a watch dial up or dial down. For example the hairspring may touch the center wheel or balance cock or balance arm in one of the dial positions and not the other. If either the balance staff or lever staff has too much endshake, the match between the two may be off in one position. Especially on a single roller, a bent safety dart can also cause dial up or dial down problems.

Here are 20 dial up-down problems
There are about 20 sources of such errors
1. dirt or thick oil in one or both balance jewels
2. Burred or marred balance pivot(s)
3. End of one balance pivot flat or rough and the other polished and rounded.
4. End of both pivots polished, but not the same shape
5. Pivot bent
6. Hairspring rubbing balance arm or stud. (That is my vote)
7. Hairspring not flat or level
8. Overcoil rubbing under balance cock (This is also my vote)
9. Over coil rubbing center wheel.
10. Balance pivots fitted too close in jewels
11. One pivot having excessive side shake and the opposite fit well.
12. Escape or pallet pivots bent or damaged
13. Balance end stone pitted or badly out of flat
14. Over coil rubbing outside coil, at point where it curves over spring.
15. Balance arm or screw touching pallet bridge.
16. Balance screw out too far, touching bridge or train wheel.
17. Safey roller rubbing dial plate or jewel setting.
18. Fork rubbing impulse roller.
19. Gurard pin rubbing edge of safety roller.
20. Roller jewel long and rubs guard pin.

These are from Kleinlein's book. That should keep you busy for a while. It is not a complete list.

Don
 

Smudgy

Registered User
May 20, 2003
2,874
25
38
Country
Region
The out of round balance will produce a different reading than a bent pivot. The 's' curve is representative of an out of royund balance. The bent pivot is more likely to show as a dramatic positional error, as noted by Don Dahlberg. If the pivot appears bent under magnification it probably is. It doesn't take much to effect the balance action.
 

fuzzuki

Registered User
Dec 11, 2001
367
1
0
Originally posted by Don Dahlberg:
If it runs dial up and not dial down, or even if there is a large difference in rate in these two positions, you may have something wrong with one of the pivots and/or jewels. The faster rate is usually the bent or damaged side down. The exception if the pivot is mushroomed, then it may show when it is the top pivot.

Other things can stop a watch dial up or dial down. For example the hairspring may touch the center wheel or balance cock or balance arm in one of the dial positions and not the other. If either the balance staff or lever staff has too much endshake, the match between the two may be off in one position. Especially on a single roller, a bent safety dart can also cause dial up or dial down problems.

Here are 20 dial up-down problems
There are about 20 sources of such errors
1. dirt or thick oil in one or both balance jewels
2. Burred or marred balance pivot(s)
3. End of one balance pivot flat or rough and the other polished and rounded.
4. End of both pivots polished, but not the same shape
5. Pivot bent
6. Hairspring rubbing balance arm or stud. (That is my vote)
7. Hairspring not flat or level
8. Overcoil rubbing under balance cock (This is also my vote)
9. Over coil rubbing center wheel.
10. Balance pivots fitted too close in jewels
11. One pivot having excessive side shake and the opposite fit well.
12. Escape or pallet pivots bent or damaged
13. Balance end stone pitted or badly out of flat
14. Over coil rubbing outside coil, at point where it curves over spring.
15. Balance arm or screw touching pallet bridge.
16. Balance screw out too far, touching bridge or train wheel.
17. Safey roller rubbing dial plate or jewel setting.
18. Fork rubbing impulse roller.
19. Gurard pin rubbing edge of safety roller.
20. Roller jewel long and rubs guard pin.

These are from Kleinlein's book. That should keep you busy for a while. It is not a complete list.

Don

That's just scratching the surface of things that need to be checked.


rob
 
Last edited by a moderator:
J

jteselle

Thanks for the advice. I will go through this list and check these items.

One thing that eliminates several off the bat is that the balance slows down when vertical even if the lever is removed and the balance is just swinging freely.

Thanks again.
 

Forum statistics

Threads
167,107
Messages
1,456,201
Members
87,311
Latest member
darc
Encyclopedia Pages
1,057
Total wiki contributions
2,914
Last edit
E. Howard & Co. by Clint Geller