Power crisis

[jguitron]

I'm suffering with a power crisis and need help!

I'm working on a vintage diver... it's a cheaper mechanical Sheffield and I actually got a couple of them on eBay in an attempt to rehab one with the extra pieces. 

It all looks great (washed, inspected, re-assembled) until I wind it up. For a few seconds the balance starts swinging in a promising manner only to slow down and come to a complete stop in less than a minute.

At first I thought it was the balance itself, checked, oiled, swings excellent with minimal impulse from the dust blower. Then I noticed the escape wheel wasn't advancing despite full wind. So I removed the train bridge and reassess all wheels and pivots. Minimal pressure on the train results in the balance swinging like a champ.  Finally I looked into the barrel: I noticed that if I held the stem on (meaning the barrel is spun forwards not allowing the click to lock the wheel), the balance swings very nicely, but it slows down to a stop as soon as I relax the stem. 

This made me suspect that the arbor wasn't well lubed, so I lubed it without any change. If I spin the balance and then help the barrel with my peg wood, all looks great, but as soon as I release it, the same thing happens. So that made me suspect that something was up with the mainspring. I removed it, cleaned it and inspected it not finding any anomaly. Looking at the main plate there's no obstruction or abnormality that I can tell. All wheels have appropriate endshakes, gears and pinions are all intact... it just seems that the power generated by the mainspring is not sufficient!! 

Could the mainspring be worn out despite keeping shape and consistency? It looks totally fine to me, but other than that, I can't think of what else could be the problem.

Thank you so much for even reading through this long litany. Any suggestions are more than welcome!!!

Cheers!

[Marc]

Has someone put the wrong mainspring in it before it came to you?

[rodabod]

What is the endshake/sideshake of the barrel like? Does it tilt at all, or are there any signs of wear on it or the plate/bridge from rubbing?

Edited October 15, 2016 by rodabod

[jguitron]

Has someone put the wrong mainspring in it before it came to you?

That's a good thought. It looks like a perfect fit but who knows!? Is there any way to test this? Should I try to find another stronger spring?




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[jguitron]

What is the endshake/sideshake of the barrel like? Does it tilt at all, or are there any signs of wear on it or the plate/bridge from rubbing?

Endshake and sideshake normal, no signs of wear. The barrel is the kind that doesn't have a cap. I made sure to oil the plate where the barrel/mainspring rest. All teeth intact. I'm starting to think it is a replaced mainspring that doesn't have enough power and that's why it was sold for parts/repair?

I got the barrel from the other movement I got. Unfortunately although it's the same "watch" he movement of different, which I believe is a coming thing among the vintage lower end brands. The other mainspring was 0.03mm taller and it killed the endshake when I tried to use it. No such luck.


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[SteveFitzwater]

you need to becareful when swapping out parts, for the sounds of it, it appears that there is a difference with the movements, try using the main plate from the "barrel" and assemble. I would be there is enough sideshake that when the mainspring is wound, it creates a binding with the main wheel, thus stopping the transfer of power.