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Pocket Watch Screw Case Back - Cross-Threaded

WillFly

By WillFly
in Watch Repairs Help & Advice

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WillFly Distinguished Member

WillFly

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My Hanilton 23 pocket watch, just back from service, still has one outstanding problem which I'm not sure how to deal with - a problem in two parts.

 

  1. The metal case back is cross-threaded. It starts to unscrew very smoothly then seizes up, with one side slightly higher than the other, and then refuses to unscrew any further. It can be popped back down with pressure but won't come off any further, and is too far down for a case knife to be used. Pocket watch backs of this kind typically just have fine knurling around the rim and can be difficult to grip.
  2. Once I get it off - which I need to do to regulate it slightly - there's the question of possible re-casing. The problem with this is that the chronograph button is embedded in the crown! So it may just not be possible to do anything than live with the existing case.

Any advice welcomed.

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Geo Distinguished Member

Geo

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Regarding question 1.

You say that when you start to unscrew it that one side is raised. Is one side raised when it is closed?

It sounds like the metal has gauled (seized and picked up) at some part of the thread. If this has happened then mare damage will probably result in forcing it to screw off. Unfortunately you have little choice in the matter as it has to come off. Before forcing it any further, try to feed some synthetic oil into the threads with a watch oiler then try working it's back and forth and it may eventually come off. If you get it to this stage it might be possible to save enough of the threads to allow it to be serviceable.

I would be willing to help you out if required.

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WillFly Distinguished Member

WillFly

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Hi Geo - when it's closed there are no gaps at all. It's only when I start to unscrew it that the one-sided gap opens. It starts off nice and smooth - then binds with a slight gap on one side.

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autowind Distinguished Member

autowind

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Just a thought but you might be able to see where it has cross threaded with a loupe,  either the case itself or the back,  and with a small fine file be able to repair the thread.  The advice about trying a small amount of oil on the threads is also sound.  If all else fails then Mark may be able to sort it for you.

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