Fusee mainspring preload

fixoclox

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Apr 4, 2007
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Hello Everyone,

I am rebuilding a couple of Fusee movements.
I am familiar with the Fusee pendulum type preload. On a balance escapement what is the preferred preload. It cannot be the same as the movement is running really fast 10 minutes a day and the regulator is set to slow.

41507487-59A3-4451-B083-5D02E597E538.jpeg
 

bruce linde

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i would suspect balance issues before power issues... all the pre-load does is make sure the mainspring still has enough tension to keep the chain or cord in place when it comes to the end of its run... typically a half to one full turn.
 

gmorse

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Hi fixoclox,
...the movement is running really fast 10 minutes a day and the regulator is set to slow.
What sort of amplitude are you seeing on the balance wheel, and is the escapement in beat?

Regards,

Graham
 

fixoclox

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i would suspect balance issues before power issues... all the pre-load does is make sure the mainspring still has enough tension to keep the chain or cord in place when it comes to the end of its run... typically a half to one full turn.
Yes, I understand, with that much preload on a balance wheel Fusee it runs to fast and cannot be slowed down any further. I preloaded it 3 teeth on the preload ratchet. Now with a full 30 turn wind she is keeping time and the regulator is closer to the middle. Thanks
 

gmorse

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Hi fixoclox,
Amplitude is about 180
How are you defining the 180º, the entire balance excursion or just from the centre to one side? It's low if you mean the latter, (which is the usual way it's defined with balance wheels), and very low if you mean the former.

Love the deer by the way.

Regards,

Graham
 
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fixoclox

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Apr 4, 2007
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Hi fixoclox,


How are you defining the 180º, the entire balance excursion or just from the centre to one side? It's low if you mean the latter, (which is the usual way it's defined with balance wheels), and very low if you mean the former.

Love the deer by the way.

Regards,

Graham
Hi Graham, the whole wheels rotation. I have 50 years working on Chelsea. Ram all I can say is the proof is in the pudding. With a very low preload on a balance wheel fusee the clock is now keeping time and is not adjusted fully to the slow side of the regulator. Pictured is a Sunday afternoon visitor. I love it here

8DB3F2A7-4902-4AA1-870C-9B682C65F150.jpeg
 

gmorse

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Hi fixoclox,

Thanks for clarifying this. A balance amplitude of only 90º, if I understand you correctly, is extremely low, but if the clock is working satisfactorily, fine. At least the balance in a clock doesn't have to cope with all the movement and disturbance that a watch goes through.

We get deer here, but fortunately the bears left several hundred years ago!

Regards,

Graham
 
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