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Glass replacement guides

AshF

By AshF
in Watch Repairs Help & Advice

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AshF WRT Addict

AshF

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It seems that selecting the correct glass is a dark art, one I have no experience with.  I've searched the forum and read 15 or so posts about it.  I've read the Sternkreuz PDFs.  I've watched Marks videos on it...

I'm still clueless as to which glass I need for a watch.  Before I post pictures and bore you all with yet another glass replacement question, does anyone have any other links to guides on the subject?

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cduke WRT Addict

cduke

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I simply identify the required crystal diameter or dimensions using a digital caliper and then find the most appropriate crystal in the G-S supply catalog available online.  This is the easiest part of watch repair for me, hope you have luck too.

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spectre6000 Distinguished Member

spectre6000

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I recently discovered it's not always that easy though. I have a watch I'm working on that has possibly 3 critical dimensions. The OD of the crystal, the ID of the crystal, and the height of the straight section of the ID. The case uses the crystal sandwiched between the front and back of the case as a waterproofing feature (though it completely falls apart at the stem best I can tell), and the case won't even stay together without it. I carefully measured, then called GS and they carefully measured, but still the crystal I got is ever so slightly the wrong size in all dimensions.

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jdm Distinguished Member

jdm

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It's normal to have to slightly grind glass crystals to have them fit well. That is much easier with plastic ones. This is where the repairer/watchmaker ability comes, not just picking parts from websites or catalogs.

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AshF WRT Addict

AshF

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I think my problem is that I'm coming at it as a complete novice.  For example...  I get that high dome is higher than low dome, but I'm looking at the old glass and don't know which it is, I have no reference point. 

For acrylic glass my chooses are...

  1. N, Ordinarily domed
  2. HW, Highly-domed, extra strong
  3. HWS, Highly-domed, with step
  4. HH, Extremely highly domed
  5. M, Slightly domed
  6. NB, Ordinarily domed (Again?)
  7. HB, Highly domed

I suppose the best way would be for me to buy one of each and compare them myself.

Then looking at my case, there is a metal ring, not a tension ring, it has markers on it (reflector ring?) and a plastic gasket(?) but I don't think the glass fit into it, rather sat on top of it.  It's all very confusing.

I guess I've not seen enough watches to work out what I need.  So I'm looking for a document or handy guide to the basics of glass replacement and if I can't find my answers there then I'll have you ask you kind lot of friendly people.

Perhaps I should start a document myself to help the next person that comes along...

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JohnR725 Distinguished Member

JohnR725

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On 7/15/2020 at 9:09 AM, jdm said:

It's normal to have to slightly grind glass crystals to have them fit well. That is much easier with plastic ones. This is where the repairer/watchmaker ability comes, not just picking parts from websites or catalogs

one of the problems with the mystery of crystal fitting at least at the professional level is typically professional watchmaker's if they live the right part of the world do not fit crystals themselves. In the bigger cities at one time the material houses located near to the watch shops were if you needed a crystal you would just physically go the material house hand them a tray of cases come back later you'd have crystal fitted. Why should a professional watchmaker waste their time if there is somebody else could do it for you?

but not everyone has access to a material house that means you're going to have to fit the crystal yourself as soon as you figure out what it is. I've attached the handout they help figure out what it might be

 

 

GS Crystals.PDF

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