40s Omega Crystal Replacement - Help!

Thread: 40s Omega Crystal Replacement - Help!

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  1. #1
    Member
    Join Date
    Feb 2006
    Posts
    553

    40s Omega Crystal Replacement - Help!

    Recently acquired this vintage piece,







    Info from omega.ch:

    Reference number: MI 2318
    Movement
    · Caliber number: 30 T2
    · Created in 1941
    15 jewels
    Dial
    Not available
    Crystal
    Hesalite
    Bracelet
    Leather
    Water resistance
    No
    Case details
    · Stainless steel
    · Press-in
    · Full metal
    Functions
    Subsecond
    More product information
    Case : round (35 mm diameter)
    For leather straps of 18 mm lug-size
    International Collection : 1943-1946
    Swiss retail price (1946) : CHF 93.-


    Too bad they don’t have any pics to go with their info. Anyway, here is a similar looking watch from the omega museum.



    And here are pics of a watch with the same ref. # 2318, from the web.







    As can be seen, my watch came with the wrong type (as can be seen from the distortion on the minute tracks) & size ( the crystal rotates freely when turned, and there are traces of adhesive! on the edges…ugh )

    I tried to get the crystal replaced with a local watchmaker, but unfortunately they don’t have the right size in stock.

    Time for another DIY job.
    I’ve tried searching for the correct Omega replacement from ofrei & borel, but they don’t have it listed for this ref #.

    Am I correct in assuming that a generic Stella ‘LD’ low dome Wedge Ledge would be an adequate replacement?

    The inside diameter of the bezel is 33 mm.

    Is this the right sized replacement?

    "LD" Low Dome Plastic Crystal Size 33, = 33.6 mm

    I am thinking of ordering Sizes 32 2/4, 33, 33 ¼, 33 ½ but need the right start-off point as I’m not sure what ofrei means by 33.6 mm. I’m assuming that it’s the outside diameter including the flange.

    Anybody have any experience with this? Your guidance/comments are appreciated.

    Thanks in advance!

    Bryant

  2. #2
    Member
    Join Date
    Mar 2006
    Location
    Wegberg, Germany
    Posts
    3,645

    Re: 40s Omega Crystal Replacement - Help!

    Hi Bryant,

    no idea how Ofrei is practicing it, but usually crystals are specified by the total (biggest) diameter. The bezel has an undercut of about 0.1mm to hold the crystal, and usually the crystal size is chosen 0.2mm bigger than the inner diameter of the bezel - 0.1mm for the undercut, and 0.1mm for sufficient tension.

    Scarcely the undercut is a little more, asking for a 0.3mm bigger crystal.

    Anyay, if you have no proper replacemet tool, better leave the job to a watchmaker. Many watches in the web have poorly glued crystals because it is almost impossible to insert the right-sized crystal without a crystal tool.

    Regards, Roland Ranfft

  3. #3
    Member
    Join Date
    Feb 2006
    Posts
    553

    Re: 40s Omega Crystal Replacement - Help!

    Thank you sir for the invaluable information!

    Regards,

    Bryant

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