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Helvetia cal 81-24 mainspring check

cduke

By cduke
in Watch Repairs Help & Advice

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cduke WRT Addict

cduke

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Hello Friends

i have a newbie question on checking a mainspring on a Helvetia movement. Without getting to the mainspring, is it possible to determine if the spring is broken? Watch will wind (not run) to full resistance. I assumed that if the spring were broken the watch would wind indefinitely. Is this true?  Getting to the mainspring involves quite some work and I am not sure how to diagnose.

thank you all again for the lessons.

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oldhippy Distinguished Member

oldhippy

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If you can wind the watch right up, then the mainspring has not broken. if it had broken as you say you would be able to wind it for evermore. Depending on the movement, sometimes you are able to just remove the barrel bridge to access the barrel and replace the spring. Myself I never liked this way because you will dislodge dirt that can get into the train and it will stop the watch. It is always best to do a complete clean.

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Nucejoe Distinguished Member

Nucejoe

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Hi C     Yes you said it, winds to full resistance. 

Release the reserved power through the click, rewind and  repeat several times, you should get to full wind by same number of smooth turns,  about 20 to 30.

If broken , it turns indefinate as you said or wind some and suddenly discharges the reserved power, depending on the length of broken piece.

 

 

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    • GuyMontag
      1972 Bulova President "E" Sea King 11ACACB movement

      By GuyMontag · Posted

      Yeah, I saw that in the tech sheet but I don't see how it can be adequately cleaned with the friction pinion still in place. I've accidentally pulled the arbor right out of the wheel once when I used a presto tool to try and remove it. Mark shows how he does it with the Platax tool. Those are a little too pricey for me so I got one of these from Aliexpress and I just push down on the arbor with the end of my brass tweezers. That usually gets it most of the way out and then I just grab the wheel with one hand the and the friction pinion with the other and gently rotate them until it pops off. Probably not the best way but it's seemed to work for me so far.    
    • Zedster
      Movement inserted from crytal side

      By Zedster · Posted

      Thanks, Jon Sounds like a plan. Obviously I'll have the face on so do you think gripping with the holder will create any problems, but I will check in the morning to see how feasible it is but I assume it only needs to be lightly held. As for holding the movement instead of the holder won't be possible in this scenario as one hand will be puling on the stem while the other pushes the spring down. That was my initial concern is how the hell can I do this with only one pair of hands. All the other times I've had to remove the stem hasn't been a problem, apart from the force required to release the stem from the setting lever, but now I need to fit the face and hands its sent me into panic mode. If it had the screw type release things would be a lot simpler but that's life 😀       
    • nevenbekriev
      Main spring

      By nevenbekriev · Posted

      Hi Jon, do You think that relation spring torque - amplitude is linear? I would rather guess that the amplitude should be proportional to the square of the torque. I had once idea to check it, but still haven't.
    • ManSkirtBrew
      1972 Bulova President "E" Sea King 11ACACB movement

      By ManSkirtBrew · Posted

      I did not. I thought about it, but I had cleaned it in my ultrasonic, and the tech sheet shows lubricating it in place already assembled, so I figured discretion was the better part of valor. Although since I have to depth the jewels anyway, maybe I pull the pinion off to rule it out 100% as part of the problem. Do you know if there's a safe way to do it? I don't want to use a puller because it would push down on the plane of the wheel, and that seems like a Bad Idea. I thought about using a roller table remover, but I don't think I have a hole stake pointy enough to push it down.
    • oldhippy
      Movement inserted from crytal side

      By oldhippy · Posted

      Before putting it back in the case I would fit the hands and use a pin vice on the stem to make sure the hands were in line. 
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