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Regulating Mido 0917

GeorgeC

By GeorgeC
in Watch Repairs Help & Advice

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GeorgeC WRT Addict

GeorgeC

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I have a Mido 0917 a friend asked me to overhaul. Having done so, I can’t seem to get the beat adjustment or the regulation to the tolerance I can with standard regulation setups. This model has what is called a floating hairspring.

Any advice on correcting the beat error?

 

 

http://www.ranfft.de/cgi-bin/bidfun-db.cgi?10&ranfft&&2uswk&Mido_0917

 

 

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jdm Distinguished Member

jdm

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17 minutes ago, GeorgeC said:

I can’t seem to get the beat adjustment or the regulation to the tolerance I can with standard regulation setups.

What happens exactly? Any chance of a picture of balance and timegrapher screen?

17 minutes ago, GeorgeC said:

This model has what is called a floating hairspring.

More commonly, free sprung or Breguet HS.

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HSL Distinguished Member

HSL

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We could agree one can call it a free sprung balance.
The thing with these is you regulate the timing with the screws on the balance and the beat error with the regulator arm.
If my memory is correct that small screw on the top is to adjust the distance of the index pins, maybe there is someone with a better memory online who could correct me with this, maybe it was to fintune the beat error.
Just as jdm says it would be interessting to see how you are doing when trying to regulate it.
To correct the beat error you should be able to gently move the regulator arm back and forth.

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GeorgeC WRT Addict

GeorgeC

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Posted (edited)

Yes, I could not see the forest for the trees on this one.

Thanks alot you two.  I did see the obvious movable beat error component and have the beat right now. 

The regulation of timing is performed by the micro adjusting screw.  All balance wheel screws were smooth without slots for adjustment.  I did notice that the hsprg was not shaped appropriately so each time the +- was moved for timing, the hspg would move to be off centered from the pivot.

I have it running much better now - thanks again.

 

This training example is what I have drawn on for correcting the hairspring https://youtu.be/4EYk787sjAM?t=620

Edited by GeorgeC
further example of correcting hspg forming
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CaptCalvin WRT Addict

CaptCalvin

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Posted (edited)

I've never worked on one of these myself, but hearing from people who have they have nothing but complaints. It's called "incastar regulator" if you want to do more research. From what I can work out in my head as well as anecdotes from other watchmakers, the challenge is keeping the hairspring from going out of round whilst you regulate it. Think you'll have better luck if you put the hairspring into round, not touch the regulator, and manipulate the inertia of the balance itself with the balance screws with say a pin vice. All I can say is good luck with this one.

Edited by CaptCalvin
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CaptCalvin WRT Addict

CaptCalvin

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15 hours ago, HSL said:

We could agree one can call it a free sprung balance.
The thing with these is you regulate the timing with the screws on the balance and the beat error with the regulator arm.
If my memory is correct that small screw on the top is to adjust the distance of the index pins, maybe there is someone with a better memory online who could correct me with this, maybe it was to fintune the beat error.
Just as jdm says it would be interessting to see how you are doing when trying to regulate it.
To correct the beat error you should be able to gently move the regulator arm back and forth.

That knob is in fact what you would use to regulate. It turns rollers that tightly pinch the hairspring. Turn it one way the rollers dispense hairspring, turn it the other way they retract.

I think the drawbacks of such a system is obvious.

Edited by CaptCalvin
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