Seth Thomas Sonora chime

Discussion in 'Clock Repair' started by TEACLOCKS, Nov 7, 2019.

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  1. TEACLOCKS

    TEACLOCKS Registered User
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    Mar 22, 2005
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    I cant seem to find any book that will tell the size of the main spring for the
    Seth Thomas
    #119 movement
    Sonora chime movement.

    Any help please

    Thank you
    Lloyd
     
  2. kinsler33

    kinsler33 Registered User

    Aug 17, 2014
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    If all else fails, try measuring the old one. Width and thickness are somewhat more important than the exact length. You'll need a micrometer or some similar instrument to get the thickness right.

    M Kinsler
     
  3. R. Croswell

    R. Croswell Registered User

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    #3 R. Croswell, Nov 7, 2019
    Last edited: Nov 7, 2019
    My records from one that I serviced indicate that the Sonora unit spring is 1" x 0.022" x 130". It will put the best spring winder to the test!\

    Timesavers No. 23137 is listed as a replacement for the Sonora spring 1" x 0.022" x 136"

    RC
     
  4. TEACLOCKS

    TEACLOCKS Registered User
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    I did find that there is 2 #s in an old LaRose book.
    1"X.022X136"
    1 7/8X.023X130
    I was trying to find the spring before I tore down the movement.

    thank you all
     
  5. R. Croswell

    R. Croswell Registered User

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    I also have a spring chart (not sure where it came from) that says 1" x .0228" x 130". I believe the 1 7/8" width has to be an error, the barrel isn't close to that wide.

    RC
     
  6. kinsler33

    kinsler33 Registered User

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    Holy smoke. I've heard about the Sonora (here) but know nothing about them. That mainspring sounds like a real champ.

    M Kinsler
     
  7. shutterbug

    shutterbug Moderator
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    Yes, and I'm not sure why. The Sonora is basically just a stand alone chime movement, and shouldn't need any more power than a typical chimer. There must be a reason for that big honkin' spring, but I don't get it.
     
  8. R. Croswell

    R. Croswell Registered User

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    It does seem to require a lot of power. If you look closely at the chime hammer assembly you will see a very short moment arm between the hammer arbor and the chime drum and rather long hammer arms with relatively heavy hammers and the hammer lift is also rather high. Also the hammers are directly lifted by the chime drum instead of by an intermediate lever or lifter. I think that just adds up to a lot of required torque to turn the chime drum. My observation is that it really needs all that power. Thank goodness ST include a gear reduction winder.

    RC
     
  9. kinsler33

    kinsler33 Registered User

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    I'll be. Were the reduction gears for that inside the clock case?

    M Kinsler
     
  10. R. Croswell

    R. Croswell Registered User

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    #10 R. Croswell, Nov 7, 2019
    Last edited: Nov 8, 2019
    Yes. The Sonora winder shaft is at about 3:00 o'clock. The shaft extends to the Sonora unit in the back of the clock and terminates in an open pinion gear that drives a gear to wind that monster spring.

    RC

    Here are a couple pictures showing the Sonora gear reduction winder system. At least ST included a very substantial click.

    sonora-1.jpg sonora-2.jpg
     
  11. R. Croswell

    R. Croswell Registered User

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    Mark, see pictures added to post #10 above.

    RC
     

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