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Clock balance spring

Questions about stress relieving a spring after winding.

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Sam Stones08/11/2010 06:53:47
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922 forum posts
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Hi Everyone,
 
Winding the balance spring using the wire of a guitar-string, prompts me to ask about the post-treatment. I'll assume the wire falls into the category of MUSIC WIRE.

The 0.008" diameter wire appears to have been hardened, tempered and certainly polished already, but should it be stress relieved after winding around a mandrel?

I have read somewhere that the temperature should be around 200C, but for how long should it soak? Since tempering of steel starts around 290C (ish), I imagine that anything approaching this value should be avoided!? I don't really want a blue finish either.

Your comments would be most welcome.
 
Regards,
 
Sam
Ian S C08/11/2010 10:36:50
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Sam, I would say that by the time the temperature is up to 200C thats it, I'd take it as slow as I could, but at .008"  it will take no time to soak through.
I thought  blue was a fairly normal colour for balance springs.  Ian S C
Sam Stones08/11/2010 22:29:29
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922 forum posts
332 photos
Hi Michael,
 
Once again your advice is proving very useful. Thank you!
I’ll do a stress relieving test on the sample which I’ve already made, just to see if there’s any physical movement.
 
Ian,
 
Thanks for your comments too. I've chosen to avoid bluing the spring because I reckon (straddling 300 degrees C), that would alter the temper, and I’m quite satisfied with the test results.
 
Regards,
 
Sam

Edited By Sam Stones on 08/11/2010 22:30:24

Edited By Sam Stones on 08/11/2010 22:31:35

Sam Stones09/11/2010 05:18:42
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922 forum posts
332 photos
For further information, I've created a new album with a couple of photographs about the progress of the balance-wheel spring for my clock.
 
The `AFTER` picture shows a slightly grotty  result. I pinched a bit of oven-bake paper from my better-half's pantry to sit the spring clear of the baking tray. She told me it would scorch at 200C.
 
It did, and left a grubby piece of wire behind.
 
For the curious, the six spring coils tightened as a result of the stress relieving process.
 
I shall follow Michael Williams' suggestions when making the real one. It will remain unscathed.
 
Thanks Michael !
 
Regards to all,
 
Sam

Edited By Sam Stones on 09/11/2010 05:20:00

Edited By Sam Stones on 09/11/2010 05:23:38

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