Casing effect

[dnhb]

Hello again, people.

Charity shop asked me to get this little (20mm dia movement) pendant watch working. Having done so I found it stops when it is cased. I can't see any obvious reason for this (the flat spot on the rhs of the caseback is the inner part of the indent designed to allow it to be 'popped' off). I'd appreciate suggestions as to what to look for & address to fix the issue.

[AndyGSi]

First thing would be to check the hands against the lens.

Is there no holding ring for the movement?

Edited February 10 by AndyGSi

[dnhb]

3 hours ago, AndyGSi said:

First thing would be to check the hands against the lens.

Is there no holding ring for the movement?

Thanks, Andy: the hands seem fine - but I'll check if the second's hub  could be pressed down any. There is no holding ring present nor does there look to be room for one (see photo). It seems it's only when the caseback is fitted that there's a problem.

[tomh207]

Something has to be getting added friction somehow from the caseback then. The cock that overlaps the balance perhaps?

 

Tom

[AndyGSi]

The balance looks like it's very close to the back.

Is these a gasket on the back?

[dnhb]

On 2/10/2025 at 3:42 PM, AndyGSi said:

The balance looks like it's very close to the back.

Is these a gasket on the back?

Yes it is but it doesn't seem so close as to touch the caseback edge and there isn't a gasket. I'm currently looking to see if I can find a screw with a thinner head than that currently securing the escape lever bridge.

[AndyGSi]

I can't see how pressure on the screw would stop the movement and it doesn't look any different to this.

[Neverenoughwatches]

How accurately can you measure how much of the movement stands above the case rim and compare that to the recess in the caseback.

[dnhb]

1 hour ago, AndyGSi said:

I can't see how pressure on the screw would stop the movement and it doesn't look any different to this.

I've established that pressure on the escape lever bridge screw does indeed stop the movement.

22 minutes ago, Neverenoughwatches said:

How accurately can you measure how much of the movement stands above the case rim and compare that to the recess in the caseback.

Thanks, I'll try that comparison. At the moment I'm seeing if there's an orientation of the caseback that works as it is embossed (see initial photo).

[dnhb]

Thank you for your help, Folks. I managed to solve the problem by attaching the caseback at successive positions 'around the clock' until, thankfully, finding an orientation which allowed the watch to run ok.