Barrel arbor slipping

[espenbd]

Hi,

I’m trying to replace a mainspring in a watch, but the barrel arbor is not catching the new spring. I tried to make the spring opening smaller with a tweezer, but no luck. Any tips?
 

See the pictures. Is the barrel arbor looking ok? I’m fairly new in this game, but have not had problems with mainsprings before.

Thanks,

-Espen

 

[watchweasol]

Hi reform the spring center and set it sightly off center so when the arbor is turned it picks up the anchor point.  Make sure the spring is in the right way round  for it to contact the anchor point. When done check the locking of the spring by fitting in a pin  vise and rotating the arbor and watch the arbour pick up the spring,  then fit the barrel lid carefully.

[yankeedog]

well there should be a little hook on the arbor that engages the mainspring. look at it under magnification.you will see it . one side will be a ramp, the other a 90 degree angle. it should engage. if it does not my first instinct would be that the spring has been installed upside own..I have done this myself..

[espenbd]

Thanks, will try to reform the spring center! I took a picture before i removed the old spring. I think it’s installed the right way. Tale a look at this picture from before, compared to the one in my first post:

[yankeedog]

That solves that. 

[jdrichard]

You can also carefully file the catch so the bite angle is deeper.


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[vinn3]

does everyone have  SET of jewelers' files.?    vin

[saswatch88]

Jewelers files are a must have in watch repair but i really don’t think its needed in this case since the problem lies in the MS and not the arbor itself. The catch looks fine and I have never came across a slipping arbor in which the arbor was the culprit.

[vinn3]

the main spring hook may be soft and bent. file the hook anyway.  vin

[Nucejoe]

Will you disclose the caliber.

Regards

[espenbd]

It’s a CAL. 2750. Still having trouble to reform the spring center. Either the spring get’s too small for the arbor to fit, or it’s too wide. I don’t have jeverly files, so can’t file the hook.

Any tips with tools to form the spring?

[watchweasol]

Hi  I normaly use a pair of round nose pliers to avoid kinking the spring and have had no problems.  I would check that the anchor point will actually fit in the spring slot if not no amount of re forming will make it fit, In such a case the answer is to open the spring slot with a jewelers file or needle file.

[watchweasol]

Hi   The caliber is 2750  whats the make of the movement ?.

[espenbd]

Thanks for all the help so far! It’s a ETA 2750. Will try to reform the spring again tomorrow, just have to pick up a pair of round nose pliers.

The anchor point fits the spring, just checked it

[watchweasol]

Hi thats  good , just a case of getting the spring to grab, I have attached the tech sheet for your interest.   

496_ETA2750,1,2,6,4.pdf

[Nucejoe]

7 hours ago, espenbd said:

It’s a CAL. 2750. Still having trouble to reform the spring center. Either the spring get’s too small for the arbor to fit, or it’s too wide. I don’t have jeverly files, so can’t file the hook.

Any tips with tools to form the spring?

You can,t  re-bend that spring end too many times, breaks easy.

A bit tight would have worked.   

[saswatch88]

 You need a pair of beading pliers like these they wont break the spring