ITR mainspring letdown

CJo

NAWCC Member
Aug 22, 2005
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Need some advice. I have an ITR that I would like to let down the mainsprings so that I can properly clean the movement, but I do not have a letdown key that is that big, approximately 7.2 mm. key size. Does anyone have a suggestion on how to let down the main springs on this movement? I know that I did one sometime back but don’t remember how I got it let down. Any suggestions would be very much appreciate.thank you
 

disciple_dan

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Mar 10, 2016
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If the movement will run you can put the clamps on the springs and let it run until it stops. Maybe by the time you're ready to put it back together you will have found the right key.
Good luck, Danny
 
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CJo

NAWCC Member
Aug 22, 2005
462
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southwest Kansas.
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I will try the socket idea first. The mainsprings are pretty well expanded inside the movement, so the last time it ran, it ran down. But this hasn’t run in years and was stored in outside storage. It might run, but that would be the second thing I would try. Thanks for the suggestions.
 

DTaphorn

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May 22, 2019
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I have a 1932 ITR. And am going to disassemble it for cleaning.
But..
Those mainsprings look like hungry bears. Very powerful.
I was able to wind both springs up enough to slip a 3" round
mainspring clamp on them.
But, I'm still working on taking those springs off the arbors.
I want to put a pair of much lighter springs on the movement.
So far every movement that I have looked at has damaged
gear teeth from the pressure of those springs

I can not find a let down key big enough or even adaptable
to fit into my ollie baker. As of now I'm looking into cutting
off the end of an extra mainspring key and having it welded
to a sawed-off regular letdown key that will fit in my ollie
baker.
I've just acquired this clock and am restoring it. And have
numerous questions that I'll be posting here for help.
 

D.th.munroe

Registered User
Feb 15, 2018
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Just a thought Instead of cutting an existing key, just a 7/16" piece of hex stock should work.
Dan
 

Ed O'Brien

NAWCC Member
Nov 30, 2009
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If the springs are quite run down already, how about using a stainless steel hose clamp to secure them where they are. If you use a slightly large clamp you can continue to let down the spring tension after removal.
 

D.th.munroe

Registered User
Feb 15, 2018
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Just hexagonal rod, maybe even a 7/16" Alan key or impact wrench adapter.
 
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