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Waltham 8 day mainspring engineering

4thdimension

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Oct 18, 2001
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I service a lot of these and have come to the conclusion that the barrel hook connection was under-engineered. The majority of the failures involve the outer terminus of the spring being ripped off. I have frequently made a new hole end in order to save the customer a few bucks. I thought that was what I was going to be doing today when servicing a CDIA clock and was surprised to find the springs were fine but both barrel hooks ripped out! I was almost pleased because I have more barrels than springs. Just a pointless whine I guess, but I will add it seems crazy to have to dismantle a CDIA to the last screw just to replace mainsprings? -Cort

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DeweyC

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Feb 5, 2007
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I service a lot of these and have come to the conclusion that the barrel hook connection was under-engineered. The majority of the failures involve the outer terminus of the spring being ripped off. I have frequently made a new hole end in order to save the customer a few bucks. I thought that was what I was going to be doing today when servicing a CDIA clock and was surprised to find the springs were fine but both barrel hooks ripped out! I was almost pleased because I have more barrels than springs. Just a pointless whine I guess, but I will add it seems crazy to have to dismantle a CDIA to the last screw just to replace mainsprings? -Cort

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Waltham had continuous financial problems and no one expected these clocks to last 100 years anyway (look at the winding wheel posts; THAT is what I frequently replace). I always replace the springs with new Swiss springs. These springs have braces with solves the problem of the hole tearing out. Never had a customer refuse the quote because of the cost of new springs. Reusing the old blue steel is asking for trouble.

I have come up with a process for replacing the missing end of the stem. The major impediment is if the sliding pinion is missing. Even had dials reprinted.
 
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Karl Burghart

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Jan 30, 2012
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I've found that filling the slot on the inside to a taper allows the spring to seat more securely in the barrel hook. Not sure if that helps the hook from breaking or not but it does hold it tight.
 
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