Hello,
I'm new in this superb forum, and I first want to thank you for permitting me to post my question.
I recently had the chance to get a wonderful Omega AM 6B/159 56. Which is in my opinion one of the beautifulest military watch.
It's a gorgeous watch... but I need to change the crystal, because the one fitted now is not appropriate : it seems that the previous watchmaker who overhauled it didn't find the proper crystal and put a solid one, but not very beautiful (it's a non-dome version).

I read that it is a special acrylic crystal, with a horizontal lip 'underlayed' inside the case.

Could you give me some informations about this ? I think it could be something like this :

https://www.cousinsuk.com/product/seal-domed-bcl

As I'm not sure, I prefer to ask to you, Omega specialists :

which underlayed acrylic crystal would better fit this watch ?

If you know the size of it, it would be also great !

Thank you very Much

 

I'm guessing a Sternkreuz dome, high or low as appropriate, might work. My watchmaker likes those and I do too on the watches that have them.

Tom

 

I found this online, it might help you choose?

 

thank you for your answer; do you know the size I have to order ?
Best regards

 

It's exactly what I'm looking for.
By the way, this one has been overpolished in my opinion.

 

Your watchmaker is the person to make these ultimate decisions (with your approval).

Tom

 

I opened the watch in order to discover how the acrylic crystal is fitted.
There is an internal tightening screwed ring in the case, which holds the underlayed crystal by the inside.
I had never seen such a system before. This Dennison case is very well thought out, with a beautiful solid stainless steel !
As I don't have the tool to remove this internal ring, I dropped my 6B/159 56 at my watchmaker's.
I will let you know when the crystal will be swapped.
I cannot wait to get it back!
Thank you

 

Fortunately, I have this Longines Marine Nationale that compensates for the absence of my Omega ...

 

Not uncommon at all for watches of this type and era. For example this IWC Mk. XI:



I modified the pins for the Bergeon 5700 case opener, in order to provide the required clearance on the inside of the case, to get deep enough to get to the threaded ring:





Then it's just a matter of carefully unscrewing the ring:







My Vertex WWW had the same system...and I think other variations of the WWW likely had the same.

Cheers, Al

 

Dear Al Archer, Thank you very much for that explanation and these pictures ! Could you indicate me a link where I can buy the proper glass that could fit my watch ? Unfortunately, my watchmaker is unable to find it ! Best Regards

 

Ask Ian Wilkinson in the UK. He will have them. Search for him on the Bay.....good luck ! Kind regards. Achim

 

I sent him an email, I hope he will answer my question.
Thank you very much. Kind regards

 

Thank you a lot for all your advices, I finally found a proper crystal and succeeded in install it (by myself, following Archer's advices) !
Best regards,