Mainsprings

TimeafterTime

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Jun 29, 2016
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Hi folks,

I'm wondering what people's thought are when it comes to mainspring replacement. I don't always like to trust the replacement to the broken spring the clock comes in with. When it comes to Hermle movements we're covered with good information out there as Timesavers and others but what about a movement you really can't identify at least I can't. Does anyone have good information out there when it comes to these type movements, such as french, kitchen, and etc. I have a Fontenoy Westminster 43/110 movement that needs a new chime spring.
 
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HTomas

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Nov 2, 2018
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You have to measure a mainspring (thickness, height) and the barel axis and arbour diameter and there is formula for the correct lenght.
 

R. Croswell

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Apr 4, 2006
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If the original spring is just broken (has not been previously altered or repaired) you best information for selecting a replacement is to measure the thickness, width, and length of the original broken spring.

RC
 

Willie X

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Feb 9, 2008
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"broken"? If it's broken at the outer end, this can be repaired.

Note, many spring sizes are no longer available but there is a place that can make a custom replacement spring.

Willie X
 

Grant Perry

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If it is the quality that you are referring to, there are quality springs available as replacements. I order mine from a supplier in Toronto Canada. They are not cheap, but I can usually get what I need.
 

shutterbug

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Beware of springs made in India. They often break on the first wind!
 

TimeafterTime

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Jun 29, 2016
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If the original spring is just broken (has not been previously altered or repaired) you best information for selecting a replacement is to measure the thickness, width, and length of the original broken spring.

RC
My concern is I don't know if someone else replace the spring before me with the correct spring. I can only trust that they did.
 

R. Croswell

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My concern is I don't know if someone else replace the spring before me with the correct spring. I can only trust that they did.
One can never be sure, but an original spring will likely show some signs of wear, especially if the spring was blued. If the original spring had been broken at the outer end, or a new spring had its length altered, the end hole and end trim cut would usually have a "handmade" look. If it is a barreled spring and the barrel looks "too full" or "too empty" these are also clues that the spring may not be original. Unless there is some compelling reason to believe that the spring is not original, I usually assume that it is either an original or a correct replacement, especially if there is any report that the clock has run OK in recent years. It still doesn't hurt to check if the measured dimensions are close to the calculated requirements.

RC
 

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