Omega 640. It's so small and the case screws are fused and broken...

[rehajm]

What remains of the screws is fused to studs in the case back...

The movement floats inside the case without them making it very difficult to operate the back winder. 

Could I try tapping the studs? If that didn't work I think if there were a bit of a post that protruded into the plate it would help a great deal, too...

 

Edited October 26, 2023 by rehajm

[JohnR725]

I'm not quite sure above your picture? in other words the case back says that 18 karat gold is there any other steel on that case back other than the screws themselves? Because if you only have steel screws you should be able to dissolve them out with alum. Typically you do this with a brass plates were your broker screw off as long as there's no other steel or iron that you would like to keep you could just dissolve them out versus drilling them

 

[rehajm]

Thanks John- Alum powder would seem a good candidate but the fused screws and the design of the ‘case band’ and ‘studs’ makes me think they could be steel. I see no exposed brass but steel would make sense to me as the case band supports the plate and is supposed to take the pull/push pressure of the back winder…given that I thought alum is risky...

I’m also wondering if something could be wedged into the area where the screw head is? With the case snapped shut it might prevent the movement from sliding..

Edited October 26, 2023 by rehajm

[JohnR725]

I was rereading of the image text and yes it's? It's not real clear what some of the components are and if it was just the screws stuck in the gold back that would be fine but it looks like probably that's not what it is

 

[rehajm]

I'm contemplating the alum route, the case screws are around so if the others were dissolved problem solved...but chemistry was not my thing. How would I identify the composition of the retaining ring/studs and what could it do to the case back finish if anything?

[RichardHarris123]

I'm assuming the studs are steel, gold is too soft for threading.  I'm confused by the hole in the case back. 

[rehajm]

4 hours ago, RichardHarris123 said:

I'm assuming the studs are steel, gold is too soft for threading.  I'm confused by the hole in the case back. 

Yes- the ring and studs are the support structure for sure…

…the case back hole is for the stem/crown. It’s a back wind like this…

up front in the photo is where the case screw attaches to the plate

Edited October 27, 2023 by rehajm

[JohnR725]

3 hours ago, RichardHarris123 said:

I'm confused

restricting my normal confusions to just this discussion I'm confused also as the image just isn't revealing enough. 18 karat gold is too soft for typically anything. than the problem with cold case screws is they do use them but the slots usually get messed up and a real pain to get them in and out without damage.

Is looking at the picture and it's hard to tell how this all goes together. But from the description it looks like the stud is pressed into the back and the screws somehow threads into that and then threads into the movement told the whole thing together.

then when I think about this I bet you have those are not hiring screws there probably stainless steel. Who knows what the stud is made out of it might be iron or steel. The problem is I don't think alum will dissolve stainless steel. It only typically dissolves iron alloy's which is why it shouldn't touch the gold but it probably wouldn't touch stainless steel in either. Then because the studs are pressed in I'm assuming they're not considered a casing component and you would have to make something

http://cgi.julesborel.com/cgi-bin/matcgi2?ref=OME_640

 

[rehajm]

3 hours ago, JohnR725 said:

restricting my normal confusions to just this discussion I'm confused also as the image just isn't revealing enough. 18 karat gold is too soft for typically anything. than the problem with cold case screws is they do use them but the slots usually get messed up and a real pain to get them in and out without damage.

Is looking at the picture and it's hard to tell how this all goes together. But from the description it looks like the stud is pressed into the back and the screws somehow threads into that and then threads into the movement told the whole thing together.

then when I think about this I bet you have those are not hiring screws there probably stainless steel. Who knows what the stud is made out of it might be iron or steel. The problem is I don't think alum will dissolve stainless steel. It only typically dissolves iron alloy's which is why it shouldn't touch the gold but it probably wouldn't touch stainless steel in either. Then because the studs are pressed in I'm assuming they're not considered a casing component and you would have to make something

http://cgi.julesborel.com/cgi-bin/matcgi2?ref=OME_640

 

Thanks John and sorry it isn’t clear from the photos 

My poor attempt at a blue arrow highlights the area called ‘blue countersink’ from the service illustration. Basically the movement is screwed down with the broken screws in question then the case snaps into the front part of the watch with integrated strap. Here…like this

so when the movement isn’t attached to the case back it floats inside the case and is difficult to wind and set because you have to pull the set wheel/ crown to set. When the winder has to be pushed back in the movement moves until it contacts the crystal…so the dial will wear and sometimes the stem doesn’t push back in so it won’t wind…

Edited October 27, 2023 by rehajm