Help with 1960's Gruen Air Flight Jump Hour Wrist Watch

[Seafood]

Hi, the movement appears to be running great but the dial needs help and also need a crystal.  This watch is really neat, for those that aren't aware of it the watch was very popular with military pilot's in the Vietnam war.  The numbers on the dial change from the normal 12 hour format to military 24 hour format after 1 pm.  

The watch has been stored for a while sans crystal and it appears either mold or something else is on the dial and need advice on how to remove it and also help with the crystal.  I haven't installed a crystal on any watch yet but feel confident I could be capable, but I do know when to stop and hand it off to the pros.

The inside bezel measures approx 33mm, I say approx. because the digital caliper changes with the amount of pressure applied.  The case measures 35mm,  

 

Anyway, just want to clean the dial and get a crystal and I would appreciate any help.

 

Thank You!

[Neverenoughwatches]

12 minutes ago, Seafood said:

Hi, the movement appears to be running great but the dial needs help and also need a crystal.  This watch is really neat, for those that aren't aware of it the watch was very popular with military pilot's in the Vietnam war.  The numbers on the dial change from the normal 12 hour format to military 24 hour format after 1 pm.  

The watch has been stored for a while sans crystal and it appears either mold or something else is on the dial and need advice on how to remove it and also help with the crystal.  I haven't installed a crystal on any watch yet but feel confident I could be capable, but I do know when to stop and hand it off to the pros.

The inside bezel measures approx 33mm, I say approx. because the digital caliper changes with the amount of pressure applied.  The case measures 35mm,  

 

Anyway, just want to clean the dial and get a crystal and I would appreciate any help.

 

Thank You!

That is one cool looking watch seafood . We'd love to see more of your collection matey.

[mikepilk]

Do you know what to original glass should be , acrylic or mineral ?

If it's acrylic - then you get one 0.2-0.5mm larger than the measured 33mm, and you need a claw fitting tool to fit it.

The Bergeon ones aren't cheap. You can buy much cheaper ones, but the one I bought was useless - wouldn't hold the glass properly.  I found a second hand Bergeon one one ebay.

[Kalanag]

Here is a website that might be helpful

https://gruen.watch/?product=1180-gruen-geneve-super-g-422ss-super-g-airman-adjutant

 

Edited July 18, 2022 by Kalanag

[mikepilk]

Looks like a high domed acrylic with step

e.g. https://www.cousinsuk.com/product/domed-high-with-step-sternkreuz-hws

[jdm]

2 hours ago, mikepilk said:

you need a claw fitting tool to fit it.

I think it's right to say that a claw tool is not the only way to fit acrylic crystals. Maybe for this watch it is appropriate,  since it appears to be a front loader. The other way is a crystal press and dedicated dies which compress the crystal. That has the advantage of removing the risk of scratching it. Another way which also work is when the crystal is close in size to the opening, is to fit with it bare hands. Since these crystals will have to be glued anyway, it will normally hold fine. 

The other comment that I have for the OP is that leaving aside that after many decades the mov.t will also need to be serviced, as  is not advisable to wear extensively an unserviced watch (and that is a big problem, because doing that is costly and takes time and effort just to find someone reputable), is about "cleaning the dial". Is the black damage is corrosion, or chemical reaction to the dial paint, there is practically nothing that can be done. and in fact any maneuver can make it worse

 

Edited July 18, 2022 by jdm

[Neverenoughwatches]

7 minutes ago, jdm said:

I think it's right to say that a claw tool is not the only way to fit acrylic crystals. Maybe for this watch it is appropriate,  since it appears to be a front loader. The other way is a crystal press and dedicated dies which compress the crystal. That has the advantage of risk of scratching it. Another way which also work is when the crystal is close in size to the opening, is to fit with it bare hands. Since these crystals will have to be glued anyway, it will normally hold fine. 

The other comment that I have for the OP is that leaving aside that after many decades the mov.t will also need to be serviced, and is not advisable to wear extensively an unserviced watch (and that is a big problem, because doing that is costly and takes time and effort just to find someone reputable), is about "cleaning the dial". Is the black damage is corrosion, or chemical reaction to the dial paint, there is practically nothing that can be done. and in fact any maneuver can make it worse

 

I often fit acrylic crystals with my hands under a microscope. I find that i can bend and manipulate them into place. If done through a scope its very easy to see at which point and how much pressure to apply and when to move around the rim. The only time i use a lift is to occasionally remove a tight crystal that i dont want to risk pushing through from the back. Tighten the lift a fraction at a time until the crystal spins then you are close to lfting it off. Lift with a slight turn backwards and forwards making sure that the lift is not coming free of the crystal. Generally if I've used a lift in the first place i leave it on the crystal if its going back on the watch within a couple of days that way it is all ready set up to put back in place.