Correct diameter for a 'let down' mainspring.

Willie X

Registered User
Feb 9, 2008
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Many beginning clock repairers wind the mainsprings up tight and try to restrain then in that condition, or close to that condition. This can result in many different problems, some of them possibly dangerous.

This came up again a couple of months back and since then I've been measuring all the springs I've restrained and also all of my "C" clip diameters.

Long story short, nearly all American
8-Day springs need to be restrained at a 2 1/4" diameter with wire and 2" for "C" clips. All of my many clips were very close to the 2" mark. The let-down results is more consistent with wire but the clip is good too, if it's positioned so that the loop end isn't sticking out to far.

Carry on, Willie X
 

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