Mainspring Arbor Pin Repair

Discussion in 'General Clock Discussions' started by Gourdman, Oct 1, 2002.

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  1. Gourdman

    Gourdman Guest

    I need to repair a broken off mainspring arbor pin on a Seth Thomas 89L movement. What is the proper procedure and what material do I use as a pin.

    The arbor does not appear to be hardened. Is annealing required?

    Any advice would be greatly appreciated. Thanks in advance

    John Barnette
    NAWCC 150650
     
  2. Gourdman

    Gourdman Guest

    I need to repair a broken off mainspring arbor pin on a Seth Thomas 89L movement. What is the proper procedure and what material do I use as a pin.

    The arbor does not appear to be hardened. Is annealing required?

    Any advice would be greatly appreciated. Thanks in advance

    John Barnette
    NAWCC 150650
     
  3. Bob Reichel

    Bob Reichel Registered User
    NAWCC Star Fellow NAWCC Member

    Feb 13, 2001
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    See page 97 in Donald de Carle's book "Practical Clock Repairing". It tells how to replace the stud in a barrel and the process is similiar to a mainspring arbor. I have used a nail tapered to get a tight fit thru the arbor and peened on the opposite side.
     
  4. Cactus50

    Cactus50 Registered User
    NAWCC Member

    Jan 28, 2001
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    manor, Texas
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    Hello John

    I always file the broken pin smmoth with the arbor - apply a drop of ink which is then wiped off. The ink will penetrate around the filed pin so you can see exactly where it is. Use a sharp punch to mark the center and drill out the old pin. To make a new pin I use "pinion" wire that I have turned on the lathe to be .001 larger diameter than the hole. Chill the pinion wire and warm the arbor - the pinion wire should be tight enough to require a help with a small hammer to seat it in the arbor. When the temperatures equalize, that pin will be there until it is intentionally removed. After seating the pin, I use my Dremel with a cutting disk to cut to the proper height and shape as needed. If you do not want to try to remove the old pin, simply file it smooth, rotate the arbor and drill a new hole. Hope this helps.

    David
     
  5. Gourdman

    Gourdman Guest

    Thanks Bob and David for the replies. I have 2 of DeCarle's books but not that particular one.

    This "pin" as I am calling it appears to have been forged out of the arbor itself. There isn't an actual pin there already but a trough from where the factory punched it out. It is that trough that concerns me because it is about 1/4 the way into the arbor. I can rotate it and drill through the solid part of the arbor but I want to be sure that is the right thing to do

    Thanks John Barnette NAWCC 150650
     
  6. Cactus50

    Cactus50 Registered User
    NAWCC Member

    Jan 28, 2001
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    manor, Texas
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    Hi John

    With the type arbor you have you can simply rotate it and drill your hole. The indentation from the original "pin" will not cause any problem. If you are using a drill press you can drill the hole in the dent. Hope this helps.

    David

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    David Arnold
    Austin, Texas
    #0142269
     

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