Screw down crown issue

[randy]

So,
I’ve been rattling that last two braincells I have…trying to figure out what is causing my watch to stop running when I run the screw down crown tight..Heck, it even happens at times when I only have it screwed down a couple of turns…but the watch runs great when I haven’t screwed it down at all ?
Anyone have a similar experience ?

Oh…and it’s on my Hamilton 921 that’s been recased into a wristwatch…..

[Bob Tascione]

Hey Randy it’s really good to see you up here!

Yeah that’s one of those weird occurrances that throws me for a loop too. Have you inspected the o-ring to see if it’s cracked or deformed? If the stem’s allowed to move in too far it will sometimes stop a watch. You can test this by picking up a running movement and pressing the stem in with a bit of force, or just remove that movement from the watch and manually test it. If it stops easily with little pressure then probably the problem. You probably already know this but for anyone else reading this in the future the crowns shouldn’t be tightened down beyond where a little resistance occurs. That’s sufficient for the o-ring to do it’s job for water tightness. Beyond that and you might run the risk of damaging the o-ring? People tend to crank those screw down crowns way to tight which can cause damage to the o-ring allowing the stem to move in just a bit further. I don’t think this is true for all watches. Pretty sure that some are designed to be tightened down and are stopped within a safe compression range by the two metal surfaces making contact. There are different designs and I’m not sure what you have there nor am I really up on or even remember those different setups. I do remember your watch though. Beautiful!

Bob

[randy]

Hey Bob…How you doing ?

Thanks for the insight. Yes,..some of these can be touchy…I think you’re spot on with your assessment.
I’m going to uncase it tomorrow and start testing out theories…I’ll let you know what I find out.
BTW…I’ve decided to retire on April fool’s day next year..I’ve had enough !!

All the best….be safe !

Randy

[c.kelly]

Hi,
I think Bob has the answer to your issue however I thought I would throw in my 2 cents in about how the screw down crown can be tightened too much. I recently repaired a Ladies Rolex which had a worn crown gasket. To compensate for that the owner tightened the crown up more. Eventually she caused the case tube to break. Half was in the crown and the other half left in the case. The part left in the case was a real bear to get out.
Charles K

[randy]

Thanks Charles.
I think that my issue is with the stem that comes with the Helena-rou cases .
This is from my Hamilton 921 conversion I built up awhile ago.

The shoulder on their stem isn’t as “long”, next to where the threads end alongside the setting detent ?, and I think that it’s allowing the movement to move a bit in the case, as it doesn’t give much support through the edge of the case and the inside of the tube.
The movement ring is also not as good as it could be in regards to really locating the movement in the case, in a repeatable ( snug index ) manner

I’m going to use a standard Ham stem…chase out my theory.
They are also now offering more cases without the screw down crown,….so it could be something in the case design itself.

Thanks for jumping in.
Best

Randy

[Bob Tascione]

Hey Randy I just read your previous post. Congrats on your upcoming retirement!!!

[randy]

Thanks Bob….long time coming brother.
It’ll be almost 39 years,…that’s enough…

Take care !
Randy

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