Lignes, 16ths, 18ths, crystal magic Yeah right!!

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February 22, 2015 at 1:40 pm #49468
namonllor1953
Participant
Hey guys,
I purchased a most beautiful RR grade (grade 4) Elgin for my son Ansel’s 16th birthday. He loved it!! Checked it’s accuracy everyday in the morning and BAM, dead-nuts on, everytime…that is, until he dropped it on the tile floor in his room a couple of days ago. Heart broken, and terrified he came and told me what had happend and he showed it to me. Balance staff is broken, as is the crystal, everything else seems to be okay (for now).
I found a Grade 4 PW with a good balance/staff and was looking today for the crystal. I’ve gone over my notes three times at least, trying to wrap my head around the Lignes system of picking a crystal. I took 6 measurements (from 12 to 6 on dial) and divided by six and got the average diameter of 43.5612 mm. How the he** do I convert this to Lignes???
Also, I measured the crystal seat opening and not the bezel opening and yes, I know I’ll need to order the next size up so as not to have to cement the crystal in place.
Any other suggestions welcomed…
Thanks for the help…
February 22, 2015 at 2:22 pm #61845
chris mabbott
Participant
Ren my brother, crystal sizing is the reason I have no hair, I pulled it out because of them 😆

Whenever possible I use mm, I measure the inside of the bezel where the edge of the crystal fits. for an open face you need a thick type, which resist a drop/shock more so than the medium thick kind. also, nothing wrong with using a little glue.

Just to mention it, crystals were sold with only three significant figures, the last digit being tenths of a mm. So, there is a 437 (43.7 mm or 19 6/19 L) and a 438 (43.8 mm or 19 7/16 L). Confused? I know I am

Maybe you should consider putting and unbreakable lens in there knowing how active 16-20 yr olds can be, it’s an option, then at a later date you can change it to glass..

Remember for an acrylic that you need to go slightly larger, as they are compressed into place, slightly.

Hope this helps
February 22, 2015 at 4:24 pm #61846
namonllor1953
Participant
‘k bro’,
I read that I should also go one size larger on the thick glass, then heat the bezel so that it expands, then drop in the crystal and it shouldn’t slip out of the bezel. Sound right??
The watches bezel can’t be measured, so I measured the i.d. of the crystal seat. It measured 43.5612mm so I’m thinking, order a 43.6 mm crystal??
February 22, 2015 at 6:17 pm #61847
david pierce
Participant
Ren,
I have found that glass needs a final grinding to fit the bezel. Plastic crystals can be compressed a bit but glass needs to fit properly and should not be forced. One thing you might try is to make a wooden fixture (a piece of wood cut out to hold the oversize crystal) and secure it in a lathe chuck. Then take a wooden plug covered with rodico or a piece or rubber and hold the cryatal in the fixture with the tailstock. Center the oversize crystal in the fixture. After the crystal is centered machine the glass with a diamond sharpening plate that can be obtained from Harbor Freight for a low cost. Grind and measure until you have the desired diameter. Make sure the ways of the lathe are covered so they don’t receive a coating of ground glass.
david
February 22, 2015 at 8:51 pm #61848
chris mabbott
Participant
@namonllor1953 wrote:

‘k bro’,
I read that I should also go one size larger on the thick glass, then heat the bezel so that it expands, then drop in the crystal and it shouldn’t slip out of the bezel. Sound right??
The watches bezel can’t be measured, so I measured the i.d. of the crystal seat. It measured 43.5612mm so I’m thinking, order a 43.6 mm crystal??

Yes, heating the bezel, VERY CAREFULLY, can be done. I use a hair drier to accomplish it 😆

Any particular reason why the bezel can’t be measured Ren?

Are you ordering a new crystal or a NOS type? The reason I ask is that many of the old style are not exactly what they state on the size label 😯 yeah, I know, as if it wasn’t tricky enough already, we have to compensate for variations in manufacturing accuracy, but only sometimes 🙄

You can also use David’s method to remove a little material, but when grinding you have to have an eye not to remove the beveled edge that fits into the bezel seat/lip. Take a look on cousins UK site at their crystal profile chart to give you an idea of the edge shape.

Here is a decent company that provide a wide range of plastic/glass crystals and offer some good info on their site. I’ve ordered from them before and they’re pretty helpful..

http://www.gssupplies.com/plastic_watch.html
February 23, 2015 at 12:29 pm #61849
arutha
Participant
Have you seen this post Chris? – http://www.clockrepairtips.com/forum/viewtopic.php?f=5&t=1593&p=13011#p13011
Paul.
February 23, 2015 at 3:10 pm #61850
chris mabbott
Participant
Paul, no I didn’t see the post, which makes me wonder where I was 🙄 But I think I know this site from before, the SF location rings a bell because if it’s the same company I’m thinking about, they’re expensive. My PC is away for repair still so my files are floating..
Thanks for the alert brother..
February 24, 2015 at 9:00 pm #61851
digitaltripper
Participant
To those who may not know, gssupplies.com is g s crystals and yes they are still in business!

In the bay area here in California, Otto Frei ottofrei.com carries xtals and watchmaker supplies as well…

Just thought I’d mention these folks in case you did not know…

Take Care

Jim

**** Dangit…I just reread the post and Chris already mentioned g s…..Good job Chris!!! BTW, if you have the GS catalog, I believe that the crystals are shown actual size so that you can compare old xtal to the replacement…
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