How do you increase endshake on a balance staff? I have a watch that will not have any endshake on the balance if the bridge it tightend properly. I did discover that there was a shim under the balance bridge when I got it but I want to fix it not patch it. I can think of a few patches like pushing a jewel out a little but that isnt right either, I dont think. Do I need to get into staffing and turn the staff shorter? What are some other things besides the end to end length to check?

Thanks,

Aaron

My guess is the balance staff is too long...try this...with the watch together....no end shake...remove the cap jewel on the balance cock..take a peek..if you now have some end shake..the staff is too long...if there is no end shake...your jammed on the radii of both pivots...this assumes of course that you have the correct balance jewels installed.

Bent balance arm is also a possibility.

Kenny

Aaron,

What are you working on? If you can provide me with information on the watch, I can tell you how long your staff should be. Shortening the lower pivot of a staff can result in incorrect roller and lever alignments and the balance rubbing against the pallet bridge. Shortening the upper pivot can cause clearance problems between the hairspring and balance cock. There is also the risk of the pivot cone contacting the hole jewel causing excessive friction.

John D. Duvall
Vice President, Education

John, it is a 18s 11j Elgin Key wind. Serial number 1614294. Its amazing it is one minute fast after 24 hours with a loose balance bridge.

Aaron

Aaron,

The total length of your #857 staff should be:

New Style (NS) - 6.10mm

or

Old Style (OS) - 5.97mm

Someone may have used a New Style staff in place of an Old Style staff. This would add an additional .13mm to the overall length or about the width of a single pivot. You can bring the watch with you when you visit and fit check both staffs in your watch.

For those of you that have Elgin staff assortments, here are the abbreviations that you might encounter:

NS - New Style
OS - Old Style Short Hub
LH - Long Hub
SH - Short Hub
DR - Double Roller
SR - Single Roller
CDR - Combination Double Roller
OG - Oil Grooved

Note: Elgin introduced the Long Hub staff so the roller (single type) would be positioned closer to the pallet fork. This allowed for a shorter roller jewel thus reducing the chance of jewel breakage.

John D. Duvall
Vice President, Education

[This message was edited by John D. Duvall on March 08, 2004 at 1:01.]

Assuming the length of the balance staff is correct, the right way to correct endshake problems (in most cases) is to bend the balance cock accordingly (NOT while the balance wheel is still in the watch!).

That might seem extreme, but if the staff and everything else is correct in the watch, and yet the endshake is insufficient, it's a safe bet that someone in the past already bent the balance cock (downward) in order to compensate for a staff that was too short. Returning the balance cock to its original condition is merely rectifying previous bad work.

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Steve Maddox
Past President, NAWCC Chapter #62
North Little Rock, Arkansas
IHC Charter Member 49