Vintage wrist-watch crystals, simplifiable?

[MrRoundel]

Greetings all.

Again I find myself in the middle of a rather difficult search for a vintage watch crystal. This, despite it being a round crystal, that should have some GS number that works. This is the second time that I have tried so very hard to order the right crystal the first time and failed. Close, but no cigar. It's also the second time that it is with a Girard-Perregaux wrist-watch that is probably from the late-forties to early fifties. And again it is with the type of case that utilizes a bezel that cinches down over the crystal, which should be a snug fit around the case bottom. I believe that Benrus used this type case, as well as some others.

I don't know if there's a way to do it, but it sure would be nice to start compiling a database that shows brands/types/sizes of cases along with their GS (or other brand) crystal. I realize that there are many types and sizes of vintage cases, but it would be a very convenient database. Perhaps like Dr. Ranfft's movement database? I'm sure it wasn't built in a day. I'm sure that I could add a few at this point. And if a lot of people add to it, it has the potential to save a lot of time and money for professionals and hobbyists alike. Make any practical sense to anyone? Many thanks.

 

[manodeoro]

If your assembly is midcase with rehaut / plexi / bezel then you could the method I use.
1 - measure the outer diameter of the rehaut and the inner diameter of the bezel.
2 - search on cousinsuk a plexi with the closest profile, inner diameter a little too small for the rehaut and outer diameter a little too large for the bezel.
3 - gently sand with 2000 grade the inside diameter of the plexi until you can press it on the rehaut with a tight fit
4 - remove the plexi and gently sand with 2000 grade the outer diameter of the plexi until you can press it inside the rehaut with a tight fit
5 - clean everything
6 - put a tiny bit of grease on the rehaut to help and press the plexi back
7 - put a tiny bit of grease on the bezel and press it over the plexi with a crystal press
Using that method I got good results with even 6 ATM waterproofness.


Envoyé de mon moto g(7) power en utilisant Tapatalk

[MrRoundel]

Thanks. I may end up doing something like that after I try at least one more. I got so close with the first one. Getting it right the first time seems very difficult with these cases. I'll insert an image of a watch that has the same waterproof design case. it's a ladies Perregaux in the old "Mermaid". It is like the forties and early fifties SeaHawks, but smaller. Thanks again for your suggestion. Cheers.

BTW: I found that a PA200 that is for a Wyler watch worked perfectly on this one. There's another GS PA crystal that is near the size I need, and is also said to be for a Wyler. I may end up trying that one. Maybe Wyler and GP were utilizing the same cases? Or maybe I was just lucky on the Mermaid?

 

Edited July 17, 2019 by MrRoundel
Added "BTW"

[MrRoundel]

I couldn't find it originally, but here is the image of the watch with the case apart. As I may have mentioned, it is a GP Amphibian. And as you can see, it has the square case back, which is unusual, but doesn't effect the crystal setup.

[vinn3]

1 hour ago, MrRoundel said:

Thanks. I may end up doing something like that after I try at least one more. I got so close with the first one. Getting it right the first time seems very difficult with these cases. I'll insert an image of a watch that has the same waterproof design case. it's a ladies Perregaux in the old "Mermaid". It is like the forties and early fifties SeaHawks, but smaller. Thanks again for your suggestion. Cheers.

BTW: I found that a PA200 that is for a Wyler watch worked perfectly on this one. There's another GS PA crystal that is near the size I need, and is also said to be for a Wyler. I may end up trying that one. Maybe Wyler and GP were utilizing the same cases? Or maybe I was just lucky on the Mermaid?

 

     that is a wyler style case, yes.  the wyler crystols are unique to this watch AND hard to find.  if you have a lathe,  cut an "aftermarket" crystol to the proper inside and out side to a "press fit" since it is the only thing that holds the watch together.  good luck.  vin

[MrRoundel]

Thanks, vin. I appreciate your advice. Yes, the crystals need to be the proper ID, OD, and really thickness, in order to work. Very temperamental sizing. And yes, that's all that holds the case together. The one I chose would probably have worked, but the ID was slightly large, and didn't allow a strong enough cinching against the back. I THINK it would have worked if the ID was a touch smaller. I may try the Wyler to see if it might work.

I do have a lathe. What would I hold the crystal in while cutting? I have a bezel-chuck (Vintage WW style lathe.). Would that work? I don't have a three or four jaw. Thanks again. Cheers.

Edited July 18, 2019 by MrRoundel

[vinn3]

    I use 3 and 4 jaw chucks, large and small on a "compound lathe".   how does a " bezel - chuck" grab a crystol?  with a 4 jaw,  you invert the jaws and grab the inside so you can cut the outer diameter.   do they make chucks for jewelers lathes?   vin

[MrRoundel]

As you can tell, vinn3, I have a lathe, but so far it's mostly been for decoration.  I was visualizing the bezel-chuck, and was thinking it could be used by placing the crystal in the center, thereby using the bezel-chuck as a "jawed" chuck. My bad.

I do know that the 3-jaw is probably a must for lathe work. I just haven't stepped up to buy one yet. Someday. Until then I guess I'm stuck taking $10 stabs in the near darkness until I get the right size. At least it's not a customer-owned watch. Thanks again. Cheers.

[MrRoundel]

I just tried the fit of the PA370-10 as far as the OD holding the crystal snugly. It does. So the OD is good for the bezel, but the ID is too big for the case back. If the crystal held to the case-back, I think all would be good, as the snug fit would hold the crystal to the bezel well enough, methinks.

Rather than trying to modify a blank, or find the exact crystal, I am considering UV gluing the crystal to the case back. Since it will still be able to be pressed out from the bezel/lug part, it might work. The hang-up will be at some point down the line when I have to service the movement again. However, I might be able to be sparing enough, but strong enough, with the glue to be able to break it free and clean it up with acetone at that point. Comments? Thanks again.

 

[vinn3]

i have got a few of those "glued togethers".   its not cricket.   i have secured a loose crystol with 3 dots of epoxy  rather than smearing other glues all around.  i have a book on how to run a lathe i could post.   for the hobbist,  the UNOMAT  is not that expensive .   vin

[MrRoundel]

Thanks, vinn3. Hmm...Unimat. I forgot about those. I actually do have an SL1000 that I won in a raffle a couple of years ago. I bought the 3-jaw chuck for it. I didn't think of it because I heard that it wasn't considered precise enough for most watch-work. Crystal work is probably not what they're referring to.

So if the 3-jaw on the SL1000 would work, I might be able to do something. Still, I'm not sure of how to order a crystal of sufficient size and thickness to be of use.

Oh, and the epoxy idea sounds like something I could work as well. That way I would just have to break those beads/bonds, remove the movement, and then soak the back to remove the epoxy.