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Discussion Starter · #1 ·
Among the 30-jewel 2616.1N Poljots that I have, there are two Sekonda-branded ones in steel "Geneve" cases; like the others they are on-going restoration projects. The somewhat discoloured dials - in champagne tints - have been replaced with the correct NOS parts, worn bits of the movements also replaced; just that the tired hands cannot be replaced as no new parts are available anymore, but they sure look smart enough, straddling the critical 1977/1978 period where the de luxe appellation was discontinued as one has the de luxe branding and the other hasn't. I am waiting for new crowns to arrive and then they would be as smart as can be; in fact they have already brought admiring comments from strangers.

So there I was, wearing one of them for two days straight-up, and it stopped on my wrist. It is impossible for an automatic to do that, as wrist movement would keep the rotor moving, topping up the mainspring all the time. After popping the back for a look I found that the silicone gasket has shrunk again, enough to rub against the rotor to stop it from moving, so all along it was running off the power reserve in the mainspring until it was exhausted. I took the gasket out, stretched it all the way around to the original size, put it back in and quickly put the caseback on again. Back on the wrist, it is running properly as the rotor is now charging up the mainspring and it is running happily.b-)

The inside of the case is designed to have a channel for the gasket to sit in: there is a "fence" around it on the inside edge to prevent the inner edge of the gasket from touching the rotor, and the caseback is meant to hold down the gasket so it would not jump over this fence. Of course, the inside of the caseback is never meant to touch the top surface of this fence, so as to allow the gasket to do its job. So it makes me wonder if the tiny gap between the top of the fence and caseback is enough for the shrinking gasket to jump over the fence and slip through.

I did not order replacement NOS gaskets as I thought, being of the same age they would have shrunk a bit as well, it sure seems like "gasket stretching" would be one of the routine maintenance jobs that needs to be done! Some time ago I tried making replacement gaskets out of neoprene foam sheets but I have a feeling that they might get gooey when placed under constant compression so I gave up on that. Only if someone can make replacement die-cut gaskets of a higher quality material like that used in the Komandirskie...
 

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You mean the clear flat gaskets that are used in the two piece casebacks. They feel like vinyl, not silicone.
 

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I've often noticed that when I open a new purchase - of an old watch - it's impossible to get the case back gasket back on the outer ring of the movement. It's as if the gasket is one size too small.

So I either do the best I can - letting the gasket encroach into the movement where it won't hang anything up, like the balance. Or I just leave the gasket off.
 

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The major parts suppliers like Ofrei, Jule Borel, Esslinger, CasKer....

I was lucky,and was able to buy a lot of 5 boxes of flat and o-ring gasket that contained over 1 thousand gaskets for less than $10 from ebay. That was probably one of my best buys on ebay.
 

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Discussion Starter · #6 ·
Itri,

They could very well be vinyl too, the gaskets in both "Geneve" 2616.1N examples feel different, the later one is of a much stiffer material. I'd sure like to know if you have flat ones of the correct sizes for Russian watches in your job lot purchase, somehow I feel apprehensive in purchasing these as there is still a chance that none would be of the right size that I need!
 

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I have the same problem with gaskets in Raketas, and I'm pretty sure they're either vinyl or polypropylene. If I were going to make replacements, I'd probably go for silicone. I considered making a mould and then casting new gaskets from high-modulus silicone sealant, but most commercial sealants produce acetic acid (vinegar) as they cure, and I'm worried that the silicone would continue to outgas acetic acid, which might damage the movement.

Paul
 

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I have avoided this thread for the simple reason that after the age of 40 I have become extremely sensitive with anything containing the words "significant shrinkage". :-d I've regretted selling my lathe here recently because I could've turned a 'hand punch' to punch gaskets out of any thin material I wished.
 
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