Balance Pin why?

[nuno]

Hello, i have buy this watch movement. I view have a depose. But when i see back balance have a long brass pin. Do you know why?

 

[roughbarked]

Your photos aren't the clearest but this is unusual. Is it actually connected to anything? I'd be trying to remove it as the watch is unlikely to run well with it there.
The movement looks like an AS or maybe a Larga. (both the AS anyway)

 

[Dr. Jon]

I can guess at two things this pin for this pin to do:

1) As placed it limits the movement of the regulator. I do not beleive this is its purpose because this can be done more simply
2) it is reduce the chance of the balance spring getting tangled when exposed to a magnet. I have had such tangling happen.

 

[John Matthews]

The photographs are unfortunately not clear. The 'bar' is positioned between the overcoil and the rest of the balance spring. To assist understanding and provide feasible explanations it is necessary to have an answer to the question asked in the post #2 above ...

Is it actually connected to anything?

Unless of course, someone actually knows what it is!

John

 

[SKennedy]

Perhaps a not particularly sensible method of preventing the spring from coming out from between the regulator curb pins?

 

[Bernhard J.]

Perhaps a not particularly sensible method of preventing the spring from coming out from between the regulator curb pins?

This is the solution, I am sure.

 

[gmorse]

In other words, it's a bodge . . .

 

[eric the bully]

It is an Alpina caliber " Standard I " from a Langendorf ebauches. In Germany with the tradmark "Das rote Dreieck". I have not seen others with the Breguet balance spring. I think Seth is right.
Regards enrico

 

[Dr. Jon]

If to keep teh overcoil in place there is and has been a much better way with a "shelf" on the bottom of one of the pins such that it can be rotated away for placement. This form looking like a thin and fat pin has been in wide use.

All of these assume it was put there by someone who ahd an idea of what they were doing.

 

[roughbarked]

A good breguet overcoil shouldn't fall out of the pins. It isn't all that difficult to ensure that this doesn't happen. This pin shouldn't be there. If Langendorf, they would have done it better at the factory.

 

[jboger]

The consensus seems to be that the pin is to hold the overcoil in place. One would think this would be handled by the stud screw on the balance cock. This screw is very typical for U.S. watches--sans pin. On U.S. watches, one can adjust the height of the stud by sliding it up and down before tightening down with the screw. I've adjusted this height by eyeballing the flatness of the balance spring before tightening in position. Perhaps this pin is a guide so the stud is adjusted to the right elevation, thus taking [some of] the guesswork out of where to tighten down with the screw? Whatever the reason, it seems redundant and unnecessary to me.

John

 

[roughbarked]

As to the guide theory. Sounds feasible but after setting the stud, the pin should have been removed should it not?

Unless of course the watchmaker didn't finish the job.

 

[Appa69]

The pins look very loose in the first picture. This may explain why it's there, but why not just tighten the pins?

 

[eric the bully]

The pins must not be tighten, they must limit the phases of contraction and expansion of the hairspring.
Regards enrico

 

[gmorse]

Hi Appa69,

The index pins should also be parallel, which these aren't at the moment, giving rise to possible unwanted variations of rate in positions. If the spring doesn't sit at the right level and centrally between the pins, it's a matter of manipulating the stud and/or the spring itself, a seperate issue.

Regards,

Graham

 

[John Matthews]

The index pins should also be parallel, which these aren't at the moment, giving rise to possible unwanted variations of rate in positions.

Graham

I assume you mean for non-parallel pins acting a non planar spring - as is likely to be the case where there is an overcoil.

If my understanding is correct, is it the case that 'unwanted variations' will also be present if the spring coil is not in the same relative position between the pins throughout their arc of rotation (checked when the balance is stationary)? Again, if my understanding is correct, I think this would lead to greater variation and it would also apply to a planar spring.

John

 

[gmorse]

Hi John,

I assume you mean for non-parallel pins acting a non planar spring - as is likely to be the case where there is an overcoil.

If my understanding is correct, is it the case that 'unwanted variations' will also be present if the spring coil is not in the same relative position between the pins throughout their arc of rotation (checked when the balance is stationary)? Again, if my understanding is correct, I think this would lead to greater variation and it would also apply to a planar spring.

Certainly, it doesn't matter what the spring configuration is, if there's any possibility of the portion of the spring between the index pins moving axially in different positions, (due to staff endshake or gravity for instance), the effective spacing between non-parallel pins will vary and hence may affect the rate.

Regards,

Graham

 

[Appa69]

I understand that the pins shouldn't be "tight", but I was led to believe that both pins should contact their side of the spring at all times and that any air gap was undesirable.

 

[Dr. Jon]

The spacing of index pins is an adjustment. The pins should be parallel. Their separation varies with what the adjuster is trying to do.

My view remains that the mentioned pin is not to locate the over coil but to prevent tangling when the watch is put into a de-magnetizer. This was something wrist watch wearers had done fairly regularly when refrigerators with magnetic door closures came into use.

 

[John Matthews]

Jon

To be clear do you mean that the pin is not normally present, but has been inserted temporarily as a precursor to the watch being demagnetise?

John

 

[roughbarked]

Which brings me back to my comment of, is it connected to anything?

 

[John Matthews]

Exactly!

John

 

[Dr. Jon]

I believe the pin was there permanently. The pin is fixed at one end to the balance cock . It should not touch anything except when the balance spring is dancing around in a de-magnetizer.

 

[roughbarked]

No argument if I can see where it is connected. Which why I asked the question. The OP hasn't answered as far as I noticed. His photos don't actually focus on that point.
Everyone else has had a go at explaining it which is all good but the OP hasn't been back.