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Omega 30T1 Bi-Metallic Balance Wheel Advice Needed! 1940

  1. VintageOmegaLove May 7, 2019

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    Hi all,

    As the title suggests, I need some advice on my Omega 30T1 bi-metallic balance wheel. I've posted about this watch previously, but this time I am looking for some help on the correct balance wheel: bi-metallic compensation (Earnshaw cut) with adjustments screws. I understand the part number is 260-1327 (correct me if I'm wrong) however, there have been so many iterations of this part and I am looking specifically for the bi-metallic version.

    Questions:
    1. Can I take the bi-metallic balance wheel from other movements such as the Cal 26.5 SOB, Cal 28, or even from a pocket watch movement?
    2. I know the movements are different sizes, but do the balance wheel size differ as well?
    3. Do the positions of the adjustments screws on the balance wheel matter, or can they be placed accordingly?

    These may seem like silly questions to some, but I'm still learning. Please spare me some leniency ::bleh::

    Or...maybe you would recommend me to replace the entire balance wheel with bridge because of the rust. I'm happy to hear what you have to say, whatever it is!

    I've attached photos below of my movement (first photo), as well as other movements mentioned above.

    IMG_2727 copy 2.jpg


    Cal. 28

    Screen Shot 2019-05-07 at 15.03.19.png

    Cal. 26.5 SOB
    Screen Shot 2019-05-07 at 15.02.57.png

    Unknown Pocket Watch Movement
    Screen Shot 2019-05-07 at 15.02.43.png

    Thanks to all who reply! Hope you have a great day!

    All the best,
    Chris
     
  2. mac_omega May 7, 2019

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    Chris,

    why do you want to replace the balance of your watch - it does not look bad...

    No, the balances from the movements mentioned in your OP will not fit. You will have to find a donor movement if a replacement must be done.

    best
    erich
     
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  3. VintageOmegaLove May 7, 2019

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    Hi Erich,

    In my opinion, the balance is quite rusted. Maybe the photo doesn't correctly represent the state of the balance wheel. I've attached a close-up of it here, not sure if that makes it any easier to see.

    Will it still work in that state? If it does, then good news for me! Then I won't have to replace it.

    Also, thanks for the information! Saves me from spending money on trying those thing out myself. But another 30T1 is just so hard to find these days!

    Screen Shot 2019-05-07 at 18.48.31.png

    All the best,
    Chris
     
  4. mac_omega May 7, 2019

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    Chris,

    also a balance of a 30 T2 would work, it is also bimetallic
     
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  5. Germanicus May 11, 2019

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    The correct balance wheel for hours T1 is from another T1, T2 o the first mother movement: the cal 30.
     
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  6. Deafboy His Holiness Puer Surdus May 11, 2019

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    The location of the screws are important and my guess they are adjusted for every watch for accurate timekeeping.

    The screws on the balance wheel serve two functions:
    1) poise balance the wheel so it is not heavier in one position than another. This reduces positional variations of timekeeping.
    2) the screws are part of the thermal compensation system. The hairspring elasticity varies with temperature so timekeeping also varies with temperature. A compensating balance wheel is cut at the rim near center arm and is bimetallic to aid in reducing the effect of temperature on timekeeping. When the temperature increases the wheel deforms to bring the free ends closer to the center and reduces its moment of inertia. This effect is more pronounced at the free ends of the rim. Having the screws located close to the center arm lowers the temperature compensation, having the screws located away from the center arms increases the temperature compensation.

    upload_2019-5-11_16-10-23.png
    From Hans Jendritzski, Watch Adjustment.
     
    Edited May 12, 2019
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  7. VintageOmegaLove May 14, 2019

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    Thank you to the both of you! Yes, I have been looking for the balance assembly from those movements as well. It is still not the easiest to come by though. I have seen 30T2 parts and movements for sale but with the updated balance.

    I think this is going to be a nice, long hunt!

    All the best,
    Chris
     
  8. VintageOmegaLove May 14, 2019

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    Oh wow! Thanks for the info! The temperature compensation ability is something I didn't know about. Science! Learn something new everyday here!

    Those fine adjustments are definitely something to be left for the pros to deal with.

    All the best,
    Chris
     
  9. connieseamaster May 14, 2019

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    You can thank John Harrison for the invention of the bi-metallic balance. His quest for the Longitude Prize is something Hollywood needs to make a (good) movie about.
     
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  10. VintageOmegaLove May 15, 2019

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    What a journey that would be
     
  11. Fritz genuflects before the mighty quartzophobe May 15, 2019

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    There was a very good movie made, for tv, by the BBC I believe.

    Called... are ya ready for it...

    Longitude.

    I had a copy but it was borrowed and not returned, by a watchmaker no less
     
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  12. connieseamaster May 15, 2019

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    I have the book (by Dana Sobel) it was based off of.
     
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