Bent balance cock?

Discussion in 'Watch Repair' started by BCMC, Apr 10, 2017.

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  1. BCMC

    BCMC Registered User

    Dec 27, 2014
    203
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    Bought a Waltham 0 size movement to place in a nice case for the wife. Cleaned and serviced it the best I could as a novice. The train ran real smooth without the fork so I think my problem is not in the gearing. I install the fork and balance assembly and it runs great without screwing down the balance cock screw tight. If I take a little off the screw the watch runs. Could this be a bent cock putting too much pressure on the staff? What would be a good fix, shimming etc? Thanks Terry
    PS, the staff looks perfect
     
  2. Skutt50

    Skutt50 Registered User

    Mar 14, 2008
    2,862
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    You might have a bent balance cock or a balance that is a tiny bit too long. It could also be that one of the balance jewels is a tiny bit too thin......

    Before you do anything make sure the balance cock is properly seated. I have had several movements where I need to push the back side of the cock hard towards the mainplate before I tighten it down or the balance jamed the balance.

    I have seen several "fixes" for tight balance arbors. Pig ears in the main plate under the balance cock (I even have a punch made for raising the balance cock by punshing some "holes" in the main plate). Other solutions I have come across are dial washers and even small pieces of paper used to raise one end of the balance cock. I dont feel too comfortable about these solutions!
     
  3. karlmansson

    karlmansson Registered User

    Apr 20, 2013
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    Shimming or pig earing is considered bad practice. Check the things Skutt suggested and see if that helps. If not, measure the staff and post the results here. I think these can vary somewhat in length but others that are better aquainted with these movements will tell you more. If you have the wrong staff, the correct procedure is to fit the right one. If the cock is bent you will have to straighten it. You can check if it is flat by laying it on a bench block and see if it wobbles. For this you have to remove any regulator or cap jewel fittings. With the cock like this you can also put it back in the watch with the balance and see if any staff "pokes through. You can then also tighten the cock all the way down to see if it levels out without fear of cracking a jewel or damaging the staff. The only risk is if the staff is so much over length that the conical section becomes jammed into the hole jewel. Doesn't sound like yours is that bad.

    Best of luck!
    Karl
     
  4. PWfanatik

    PWfanatik Registered User

    Jul 7, 2015
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    BCMC,
    Related to what Karl says,
    It can be possible the balance jewels are not set deeply as they ought to be.
    Check to see if the jewels are set surely into the settings and the settings are in the balance cock and the plate the bottom jewels are in.
    Dave.
     
  5. Skutt50

    Skutt50 Registered User

    Mar 14, 2008
    2,862
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    If the jewels are not seated all the way wouldn't that give you extra clearance? If seated deaper the balance would jam even harder!

    My comment about thin jewel was related to this. A thicker jewel would move an end stone out which would give more room for the balance arbor.
     
  6. RJSoftware

    RJSoftware Registered User

    Apr 15, 2005
    7,647
    9
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    Male
    I tell you don't be tempted to bend it by finger. The temptation is strong...! but don't do it.
    Recently I just busted a pivot thinking I could. Pulled up too far, then had to press back down... tink/click arrrgh.!
    RJ
     
  7. PWfanatik

    PWfanatik Registered User

    Jul 7, 2015
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    Skutt you are right.
     
  8. jacekjot

    jacekjot New Member

    Mar 8, 2012
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    It looks like the balance staff is too long or too thick for the jewels.
    You never know what happen to the movement before you grabbed it.
    Many "talented" watchmakers stuff the movement with inappropriate parts.
    Best regards
    Jack
     
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