Sticky hairspring; how to demag and what does the hs alloy do?

[bsoderling]

Should be:

Beat error less than 1ms

Amplitude more than 250 degree

Iphone screw up [emoji37]


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[StuartBaker104]

Its hard to see, but you may need to add timing washers and not just move the screws. If they are free running when turned slightly then you will need washers. If they are still tight-ish, go for half a turn each to start. Remember, just the 2 nearest the arms.

Best to turn with a pin vice to avoid damage, and with the balance removed.

 

Edited June 6, 2018 by StuartBaker104

[ecodec]

On 6/4/2018 at 1:25 PM, rogart63 said:

Looks okay to me. But when i have some trouble with sticky hairspring. I sometimes clean it i acetone . Just a quick rinse will do. Or use a brush and then naptha . As the naptha doesn't remove the old oil properly. 

Yes, I almost always use Acetone on the balance and finish off with Naphtha in the U/S.

[rodabod]

Before jumping in with poising the balance, make absolutely sure that the hairspring is not sticking anywhere or touching anything (especially in the fast position. Then inspect the portion of the hairspring where it sits between the index pins. It should be centred and “breathe” between the two. The gap should be approximately 1.5x the hairspring thickness, ie. it should just fit. 

Once that’s done, you can look at poise and also slowing the overall rate. As Stuart mentions, you can add weight evenly at the arms to drop the rate. 

If it were my watch, I’d look for a new balance complete, unless you fancy a difficult challenge. 

[bsoderling]

Hi rodabod and thanks for the feedback!

After the repinning operation, demag, cleaning etc. I think it’s running correctly (but too fast due to the shortened hs).

I adapted the beatfrequency manually on my timegrapher to get horizontal lines and it looks pretty ok.

Your comment about the hs passing the index pins is interesting and a thing I would like to understand better.

The more ”modern” movements I have worked on often have the hs end re-shaped in a circular fashion to allow the hs to stay centered over the entire adjustment range. The raulhorology link in this thread is a good example.

I very rarely see this implemented on the older movements from the 30’s - 50’s where the hs simply ends along the spiral path which makes it hard if not impossible to maintain that centered position and the hs movement between the index pins over the balance rotation becomes very much of a compromise.

I would appreciate any thoughts over this from the experienced.

I would like to find a complete balance replacement but think this will be a hard find. The shock protection is of unusual kind and I doubt there are many parts out there to find. And besides, I paid less than 10 euro fot the thing to start with so heavy investments are hard to motivate... :-)




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[oldhippy]

I’m not quite sure what you mean. The hairspring between the regulating pins should be free wherever the regulator is between the h/spring it should be able to bounce between the two pins. It should never just rest against the regulator.  

[bsoderling]

Hi Oldhippy,

I was just referring to the fact that I seldom see the more advanced hs endings as in the attached photo on the older watches I tend to spend time on.

One purpose of this elaborate shape must be that it allows for a constant hs radius over the regulator slow-fast span.

Without this shape (as in the older movements) the hs radius will vary slightly over the regulator slow-fast span and make the whole thing much more of a compromize when it comes to the hs position in between the pins.


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[bsoderling]

Hi all,

To wrap this up....

I attempted to loosen the timing screws as proposed and was able to make them turn but can’t see any radial movement, so I guess there’s no real thread on them, just push in.

To have any effect I would have to remove entirely and shim under.

Won’t go there right now (or ever...) and just slowed down as much as possible with the regulator (way outside the scale but no apparent mistreatment of the hs).

Still runs a bit fast but runs and I’m happy with that.

I have attached a photo of the assembled watch for those interested.

Thanks for all help through this process!

/bsoderling



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