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Replacing acrylic glass with tension ring


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Hello - searched the forum a bit for a resource for choosing a replacement glass - see my Ebay find attached.  The Swiss department store house brand "Mirexal" has no info that I can chase down on Google, so I went through the Sternkreuz catalog and came up with a couple options.  Based on measuring the existing glass, and looking at the tension ring mounting arrangement (see sketch), and the approximate profile, I found these be an approximate match for OD, ID (on the tension ring, which sits ON the dial face), and inner dome height for hands clearance:

- Mikado 4G 3009 - SK# XAC 300.615

- Seiko - SK# XAC 301.621 

- Seiko - SK# XAC 301.640

Only one is stocked on Cousins, although the Mikado can be ordered.  And if I order a 30.1mm crystal with tension ring, and the ID of the case measures 30.0mm, will I struggle with pressing the crystal into place?  Seems like a lot of interference to me.

This feels like a lot of guessing and approximations.  Is there an alternate approach?

PS - under that cracked crystal was a near-mint, lovely blue dial and an ETA 2789 movement in great shape.  Until i pinged the Date Jumper Spring into the ether a while ago...

Ebay Original.jpg

Existing crystal.jpg

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I'd try a standard Sternkreuz armoured tension ring type. You can adjust the OD with wet-and-dry sandpaper if it's too tight.

I can't comment on the internal height, but it's not been a problem for me with any other watches using this crystal type before. 

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