Zenith Espada Chronograph/Movado Astronic HS 360

[Rasputin]

I’m in the process of servicing this fine model. The glass crystal is well scratched up and the crystal gasket disintegrated to a point beyond recognition. I have yet to be able to find a crystal replacement and will see if I can have it polished.. if anyone knows were I can find a crystal replacement let me know. Assuming I can polish or replace it, the rate limiting factor appears to be sourcing the crystal gasket(s). Does anyone know where to source one or at least how it should look like/dimensions so that hopefully I can find something similar aftermarket? Thanks in advance.

[Kalanag]

You should disassemble the case first and measure the OD and thickness of the crystal and the ID of the bezel. Then you might find the right parts at cousinsuk.com. The dimensional overlap between bezel, gasket and crystal should be about 0,1mm to get a tight fit.

Edited June 21, 2022 by Kalanag

[jdm]

3 hours ago, Rasputin said:

will see if I can have it polished.

If needed, as a last measure you can do that yourself quite easily. 

3 hours ago, Rasputin said:

 hopefully I can find something similar aftermarket?

Both glass crystals and their gaskets are made in a large variety of types, and in every possible size. So unless there are very special features on a watch these two items are easily and cheaply replaced. 

[Rasputin]

I had to relegate this to my watchmaker who indicated that this requires a unique kind of crystal gasket that he has not seen on other watches.  Unfortunately he does not know exactly how it should look like as the original one melted away.  Hence I'm hoping someone give me some guidance as trying to find an OEM replacement has been a struggle.

[jdm]

14 minutes ago, Rasputin said:

I had to relegate this to my watchmaker who indicated that this requires a unique kind of crystal gasket that he has not seen on other watches.

Can you post clear pictures of the crystal profile, all its dimensions, and same for the case opening. That is done measuring with a vernier or digital caliper. 

Edited June 21, 2022 by jdm

[Rasputin]

12 hours ago, jdm said:

Can you post clear pictures of the crystal profile, all its dimensions, and same for the case opening. That is done measuring with a vernier or digital caliper. 

Will do!

[Rasputin]

See attached. Hope this helps. 

[jdm]

If you confirm that the difference between the case opening and the crystal major diameter is 0.14mm that makes a gap in between the two of 0.07mm, that is too little for a nylon (or any material) gasket, which start at 0.4mm. It could be that the crystal is to be glued instead. The other possibility would be that the crystal is held on the smaller step, but I doubt that.

[Rasputin]

On 6/23/2022 at 9:47 AM, jdm said:

If you confirm that the difference between the case opening and the crystal major diameter is 0.14mm that makes a gap in between the two of 0.07mm, that is too little for a nylon (or any material) gasket, which start at 0.4mm. It could be that the crystal is to be glued instead. The other possibility would be that the crystal is held on the smaller step, but I doubt that.

Are you sure glue would be used considering it's likely a water resistant case with a screw down crown and case back?

[jdm]

11 hours ago, Rasputin said:

Are you sure glue would be used considering it's likely a water resistant case with a screw down crown and case back?

I am just saying that no gasket will fit and the logical consequence is that it has to be glued. Which if done correctly allows no water to enter. The fact that you found the original gasket disintegrated, as in leaving only small debris is consistent with the above. 

BTW, screw down crown and case back are simply features of quality construction, back then as now normally found in dress watches as well. These in itself do not guarantee impermeability, nitryl gaskets do. And in chronos water has also another major way of entering, from the pushers. 

Edited June 25, 2022 by jdm