Omega fob watch mainspring....help needed to choose replacement :-(

Discussion in 'Watch Repair' started by PJQL, Apr 4, 2017.

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  1. PJQL

    PJQL Registered User
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    Jun 13, 2011
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    Hi all,

    Could anyone offer some assistance in helping me choose/identify a replacement mainspring
    for this Omega fob watch please?

    What type or reference numbers should I be looking for when choosing the correct replacement ?

    The barrel width is about 1.1cm, and the width of the existing broken mainspring is about 1.1mm.
    There are no helpful numbers etched or stamped into the barrel anywhere.

    Any help would be much appreciated .

    Regards

    Piers
     
  2. Skutt50

    Skutt50 Registered User

    Mar 14, 2008
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    Is this a small pocket watch?

    I usually measure the length, width and thickness of the existing (broken) spring and look for one that is the same.

    The original springs are made of blue steel but today you find white "unbreakable" springs which are a tiny bit harder. When replaceing a blue steel spring with a white steel spring you can go down a hundred or two mm in the thickness of the spring.

    On old Omegas you also need to check which type of attachment there is in the barrel. Some are of a T-type and some folded at the end. (Some barrels can take both! Could be later adjustments!) You seem to have the folded type!
     
  3. PJQL

    PJQL Registered User
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    Hi Skutt50,

    Thanks for that :)

    Yes..its a 29mm diameter movement. When I'm looking on the internet, all the replacement springs seem to have reference numbers etc....so it's a bit confusing. I think it would help if I knew the calibre number.

    Piers
     
  4. PJQL

    PJQL Registered User
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    Hi,

    Anyone know the likely calibre for this one?

    Piers
     
  5. Albert Antonelli

    Albert Antonelli Registered User
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    Jan 8, 2011
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    I agree with Skut, you measure the width, length, and strength of the spring, the only other way would be by finger printing the setting bridge and set lever if you have a parts catalog that is old enough to have that information. My two cents worth, good luck.
     
  6. Skutt50

    Skutt50 Registered User

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    On modern Omegas (wrist watches) the caliber is stamped on a plate visable from the back but on some older movements you can find information stamped on the main plate, under the balance wheel.

    You could also go through these pages to search for the caliber:

    http://www.ranfft.de/cgi-bin/bidfun-db.cgi?10&ranfft&2&2uswk

    You can limit your search by starting with the size of the movement.
     
  7. MrRoundel

    MrRoundel Registered User
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    The big Swartchild catalog from 1951 has a very good section on mainsprings. It shows width as the primary measurement. You then look down the column to find the strength/thickness and length. It's under the Black Shield brand section of mainsprings with a tongue end. But again, you'll need that to provide the thickness, either in Dennison or metric, as well as the length of the spring. With that info someone should be able to find you a part number that will work. Do you have a mainspring gauge or micrometer to take the thickness measurement?
     
  8. PJQL

    PJQL Registered User
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    Thank you Mr Roundel...appreciated.

    Unfortunately my toolkit is very small, and needs a serious upgrade! Your input is very welcome though:)

    Regards

    Piers
     
  9. MrRoundel

    MrRoundel Registered User
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    YW, PJQL. You might try looking for a relatively inexpensive mainspring gauge. It's the one that looks like a 6" ruler made of brass that has sized notches in the sides for measuring width, and a tapered opening slide for measuring thickness. I'll bet Dave's Watch Parts has one for sale. Ah yes, go to WT602 on the link below, and you'll see the tool of which I speak. You should be able to find one on your side of The Pond as well. Good luck.

    http://daveswatchparts.com/Measuring.html
     
  10. Skutt50

    Skutt50 Registered User

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    Did you mean WT2602?
     
  11. MrRoundel

    MrRoundel Registered User
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    Probably. I went by memory, and that can be a mistake. Thanks for the correction.
     
  12. roughbarked

    roughbarked Registered User

    Dec 2, 2016
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    Digital vernier calipers could get you close.
     
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