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Expanding a balance spring

Chris

NAWCC Business
Nov 4, 2001
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Ok, I was talking to a gent about ST 103A movements and how they tend to run fast. He pretty much agreed with my other source on suggesting to add weight to the balance to slow it.

He also stated that as they age, the balance springs tend to compress and another way to restore a good rate is to expand the spring so it "breathes" more. Has anyone done this and how have you done it?

For clarification, the movements are clean and the balance springs have not been shortened at all. Thanks, Chris.
 

Larry

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Jul 22, 2002
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Chris,
I've successfully added weight to the balance wheel and brought the movement to time. I've never add any luck experimenting with the spring itself.

Larry
 

soaringjoy

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Feb 12, 2009
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Hi Chris,
what that nice gent means ist to extend the spring.
Or pull it.
Some guys do this with mainsprings, but there are a lot of pros and cons
about this.
With a balance spring this could get tricky and you might ruin the spring!
So what they do is clamp the loose end in a vise and then gently unravel the spring, like you wanted to pull it almost straight. Use a piece of clean cloth to slip the spring between your fingers.
Jurgen
 

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