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October 12, 2015 at 5:26 pm #49690stevefitzwaterParticipant
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Ok, I have an issue, I know what the problem is, but am unsure how to fix.
I picked up this watch with a broken balance staff, and a few broken jewels, so with a new balance staff, and jewels.. everything the balance staff is too tight when installed, so I used the balance cock from a parts movement and it spins freely…
So I am thinking the balance cock is bent… how do you fix that?
I would ideally like to keep the original watch intact, suggestions pleaseOctober 13, 2015 at 11:06 am #63362Bob TascioneModerator
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This is something you will most likely run across often. A hobbyist or owner of a watch may have pressed the balance cock down hoping to recapture a wobbly balance not realizing a staff pivot and or cap jewel was broken or not fully understanding the reason for the wobble.
If you’re absolutely certain that the balance cock is bent and that the staff pivot isn’t too large or staff too long for the hole and cap jewel then you can usually bend it back into position without damaging anything.
I never bend them back while in the movement but use a homemade fixture/jig for this. It’s important not to do this in the movement so that the screw threads holding the balance down are not stripped out. Also never (just my opinion) try to bend the balance cock back with the balance assembly or balance staff in place as it may fall out of the hole jewel resulting in a bent or broken pivot when the balance cock is released and drops back down on the staff.
For a very simple to make bending jig you can use a piece of steel and drill and tap a few holes for different sized hold down screws. You can then use the jig for different sized balance cocks in the future. You will need to drill clearance holes or slots for the locating pins on the foot of the balance cock but this can be done quickly for each balance cock as the need arises. I also use a washer that fits over the balance cock foot when fastening it down rather than just a screw so that the entire foot is pulled down and is secured to the jig plate. This helps prevent a bend occurring on the foot throwing it off plane with the mounting surface of the pillar plate. Any warping between the two surfaces can make exact re-positioning unpredictable.
Again this can usually be done without damaging the balance cock if the bend isn’t too extreme. Trick is not to rush it. Just bend it a little at a time with tests in between until you get it exactly where you want it and you should be ok.
Good luck Steve,
BobOctober 13, 2015 at 11:56 am #63363willofiamModerator
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Hey guys, thought I would mention the possibility of someone “pricking” the balance cock foot to account for the things that Bob has mentioned. Steve, make sure that and the surface where it mounts is smooth. hope that makes sense, WilliamOctober 13, 2015 at 12:43 pm #63364stevefitzwaterParticipant
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yeah, I have another watch that had that done to it William, where a previous watchmaker took something an created raised points on the bottom plate, to raise the tip of the balance cock.
Yeah Bob that is what I was thinking of, I have stripped the balance cock down and made a few drawings for my son to make a jig for me.
Thanks for sharing your knowledge and experienceOctober 13, 2015 at 12:57 pm #63365aruthaParticipant
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Bob gave a great answer and William points out a common bodge worth looking for!
I also have come accross this issue so just for those who might be reading this who may not be in a position to make a jig, if the balance is too tight i.e the cock is bent down then it is possible to put a shim under the foot of the balance cock to lift it high enough to allow the balance the end-shake it needs. If you dont have any very thin brass then an old piece of thin feeler gauge will do. Make sure you clean up the edges of whatever material you use as burrs are formed after cutting and can add considerable thickness.
I have been working on a few Russian Raketa watches lately and it is not unusual for them to have one and sometimes two shims under the balance cock 😯
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