Impossible case back

[Thesecondtallestman]

I recently bought an old, non-functioning Zenith Surf thinking it would be my new restoration and repair project. However, the case back has proven impossible to remove. It's a normal looking screw-down case and I've tried using a typical jaxa tool without luck. I tried soaking the backside of the case in GT7, thinking it might have rusted shut, even thought there is no visible sign of rust or water damage elsewhere or on the dial, that didn't do much either. I tried the good old method of using superglue and a nut, putting the case in a caseholder and placing that in a vise. The case back still won't budge, and I ended up breaking the caseholder into pieces. How common is it for a stainless steel case back to be galled shut? And is there anything that can be done about it short of destroying the case? I guess someone could also have glued the case back from the inside, but that doesn't make a whole lot of sense to me. I guess a gasket could also serve as an adhesive, but considering the force I've applied to opening it, I can't imagine that would be it either.

Any sort of tips or possible solutions are most welcome. 

[clockboy]

A picture could help. Some case backs are designed to look like screw back but are in fact snap backs. Looking at this one on eBay I might be correct. Looking at the inner rim of the case back is, what looks like a spring washer. 

https://www.ebay.co.uk/itm/Very-Rare-Zenith-Surf-solid-18ctl-Hand-Winding-Watch-with-cal-2572/274296780437?hash=item3fdd5cb695:g:SSsAAOSwUcteMuQP

[Thesecondtallestman]

I did consider that, but I kinda figured it would move a bit if that was the case. I did try with a caseback knife just now, and it feels like I would just break that tool as well if I apply more pressure. Anywho, adding some pictures. Excuse the obfuscating bolt (the nut broke off, so ended up trying something with a larger surface area to put glue on).

[Thesecondtallestman]

For what it's worth I believe the reference is 01.1291.125, with a cal. 2562, but I obviously haven't been able to verify that.

Edited March 8, 2020 by Thesecondtallestman

[watchweasol]

Hi Judging by the methods used up to now this is a real sticker.  I had a screw back that was cross threaded but it Gave in to the   glue / nut system. I would have thought  if it was a snap back it would have moved a little. It is conceivable that the case back gasket has perished and glued the back on.  The only chance is to soak the back of the watch in some  acetone/spirit in the hope it will soften.  wish you the best of luck on that one           Cheers 

[jdm]

1 hour ago, clockboy said:

Looking at this one on eBay I might be correct. Looking at the inner rim of the case back is, what looks like a spring washer. 

Actually looking at the HR image I can almost see threading. A spring washer does not imply a snap back, it's simply one way to keep the casing ring well pressed. Faking a screw back may be common on today cheapies, not a a nice vintage Zenith.

Now if the case holder broke one has to get with a better one, like two metal blocks screwed on a base. Also try to apply controlled heat around on the case, like "almost too hot to touch". The reason why certain butchers glue casebacks is because they want the customer to come back to them in desperation.

[Thesecondtallestman]

How would you suggest heating it up? I did try to heat it with a hairdryer yesterday, and applied an ice-cube to the back to see if it helped to make the case expand and back retract. Are you thinking something more drastic, or was that along the lines of what you were thinking about? 

[jdm]

A 40w soldering iron with a flat tip would do. Be very careful, don't apply more than 5 seconds to three points around. Ideally check temperature with a multimeter probe, these are very cheap now. 

[vinn3]

heat around the edges. above the threads with a torch.       do you have a  proper tool  ?    is the watch case furmly clamped ?  include them with the photo.    good luck.   vin