Ordering Crystal Gaskets & Proper Sized Crystals

[BobHadababyitsaboy]

What is the proper procedure when ordering a new gasket to fit a specific size crystal? Say, for instance, I need to fit a new 29.5mm crystal in a watch, but the old gasket has become worn and cracked, requiring a new one. How much larger should the gasket be than the crystal in order to get a good fit?

Also, it seems like a lot of suppliers like Cas-Ker, Esslinger, Jules Borel, etc, don't offer many crystals in increments of .1mm (especially for domed crystals and ones thicker than 1mm) and instead only offer them in increments of .5mm. I've often found this painfully frustrating when I need, say, a domed magnifying crystal of dimensions 34.6mm x 2.0mm. Is there any way to remedy this by perhaps getting a 34.5mm crystal and fitting it with a new gasket? Hopefully I've explained what I'm trying to get at well enough, if not, I can try to clarify.

 

Thanks!!

Edited January 13, 2016 by BobHadababyitsaboy

[bobm12]

The way I do, I measure the case opening for the gasket, then the gasket dimensions which are given as the thickness, diameter (internal and external or can be calculated given one of them) and height. The last measurement has to do with the crystal thickness that you order or the original gasket if replacing with same original crystal thickness. I try to find a crystal with diameter slightly bigger than the internal gasket's one. Most of the time, checking Boley database helps find the right gasket/crystal combination and then the guesswork is trivial...provided suppliers carry them.

[oldhippy]

Do you mean the tension ring in side the glass. All I ever did was take the size of the bezel and order a tension ring glass and stating I wanted chrome or gilt thats if I didn't have one in stock as I used to keep boxes of different glasses.  

[rogart63]

Cousinsuk has mineral crystals with gasket . You only have to measure the inside diameter of the case . Buy 0,1-0,2 mm bigger . That is L-gaskets . Then there is I gaskets . In different heights . 

Edited January 13, 2016 by rogart63

[BobHadababyitsaboy]

Thanks, guys. Whats the difference between L-gaskets and I-gaskets?

[rogart63]

Thanks, guys. Whats the difference between L-gaskets and I-gaskets?

 L and I :) . Sorry but it's in the letter . The L is shaped like an L and the I is ....... 

[BobHadababyitsaboy]

...shaped like an I, yeah I get it (and I did type it right FYI, but an uppercase "i" looks like a lower case L.....I l I l can you spot the difference?). Are there different purposes or specific times in which you would use one type of gasket over another?

[bobm12]

 

Are there different purposes or specific times in which you would use one type of gasket over another?

That's a good question and I'll venture an answer: case design and probably water resistance among other properties. I've found most "I" gaskets in submariners but probably the "L" gasket is used in designs with a pressure ring holding down the crystal like Rolex and Seiko 4205. Just MHO and hoping to be right. By the way, the "I" gaskets are the equivalent in shape to an "I" steel beam...so a little dash is missing on both ends of the "I".  

 

Like these:

 

 

I couldn't find a gasket so beams make a good analogy! Don't use these in watches! :)

 

Cheers,

 

Bob

[BobHadababyitsaboy]

Haha thanks Bob! And yeah when I was typing I-gasket I was pronouncing it like "eye". I'll definitely make a mental note: No steel beams in watches!