Alternate main spring set for this Seth Thomas No. 10 movement

Discussion in 'Clock Repair' started by R. Croswell, Oct 22, 2016.

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  1. R. Croswell

    R. Croswell Registered User

    Apr 4, 2006
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    I have this Seth Thomas 8" octagon wall clock with what appears to be an unmarked Seth Thomas No. 10 movement. It runs fine but even with a wide wing key its a real bear to wind, so I'm finding that I tend not to wind it very often. When I serviced it a few years ago I noticed a lot of wear on the second wheel. This clock has two main springs driving the going train. The springs are 0.024" thick x 5/8" wide and I assume 108" long, which matches the information I have for this movement. In a small clock like this with light weight hands I don't believe all that power should be needed.

    I would like to consider changing the main springs for something a little thinner but the only choice I can find in 5/8" width is 0.013" x 5/8" x 105". Going from 0.024" to 0.013" is quite a step. I'm thinking that a pair of 0.013" springs should power a clock like this but just wondering if anyone out there has tried this, or knows of another alternative to the original monster springs before I spend the time and money to find out.

    RC
     

    Attached Files:

  2. Kevin W.

    Kevin W. Registered User
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    Apr 11, 2002
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    Hi Bob is this clock a week runner. I have a no 10 in my ships clock, and yes not easy to wind it. Its very over powered, maybe just to ensure that it will run a week or is a 15 day runner.
     
  3. R. Croswell

    R. Croswell Registered User

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    I assume that it is a week runner. It won't do quite two weeks. Not sure what it is supposed to do. I don't have Tran's Seth Thomas book.

    RC
     
  4. shutterbug

    shutterbug Moderator
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    Oct 19, 2005
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    I would assume the winding issue is right there in the main wheel. Maybe it's too tight at the staking point, or a bunch of gunk has worked it's way under the click.
     
  5. harold bain

    harold bain Registered User
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    RC, the springs for this clock are listed at 9' x 5/8" x.022" in Tran's book. There are few different # 10's listed from A to J, all showing the same size springs. They are listed as 8 day movements.
     
  6. R. Croswell

    R. Croswell Registered User

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    Thanks for that information, will add to my records.

    When I rebuilt the movement there was nothing "stiff" with the main wheel assembly. It's been a bear to wind from get go. Pretty sure it is the thick springs. They may be needed in some applications where the movement drives large hands but I don't think I need all that power but the next size smaller spring is a lot smaller (in thickness).


    RC
     
  7. Kevin W.

    Kevin W. Registered User
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    I dont see why a smaller spring could not be used, lots of power in those current springs.
     
  8. harold bain

    harold bain Registered User
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    These movements were overpowered so they would last with minimal maintenance. I would guess they would be fine with a lot less power when in top condition.
     
  9. R. Croswell

    R. Croswell Registered User

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    Ironic that the excessive power seems to have also caused excessive wear especially to the second wheel.

    RC
     
  10. Uhralt

    Uhralt Registered User
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    Timesavers has a spring # 16806 with the dimensions 5/8x0.018x96. The spring is a little shorter than the original but should be long enough to provide power for 8 days. This spring would provide 0.56 times the power of a 0.024 thick spring of the same other dimensions (power is proportional to the square of the thickness). So, the spring has about half the power of the original. There is an easy way to test if this is sufficient to run the clock. Just let down one of the springs and disengage the click so the barrel can turn freely. Now, try to run the clock with just the other spring wound. if it runs with 50% of the power, 56% of the power that you get with two 0.018 thick springs should work.

    Uhralt
     
  11. R. Croswell

    R. Croswell Registered User

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    Good point. I will try that next time I find one of those elusive 'round tuits'.
     
  12. Jonas Sandstedt

    Jonas Sandstedt Registered User

    Aug 29, 2016
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    Hello,
    I do not know the order of the chicken and the egg, buth these movements were used to drive time stamp mechanisms in ITR time stamp clocks, see
    https://mb.nawcc.org/showthread.php?136178-Help-with-damaged-escape-wheel-in-Seth-Thomas-no-10-for-ITR-time-stamp-clock&p=1054609#post1054609
    where I asked for help with a damaged Wheel (Eventuelly, I have acquired a spare movment for parts). The driving force of the main springs is required to power the stamp mechanisms in the same way as for the larger wall time recorder clocks where two powerful springs also are used.
    Jonas
     
  13. Willie X

    Willie X Registered User

    Feb 9, 2008
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    Test ... remove one spring barrel and see how well and how long it will run. You may be surprised? If it runs OK you can certainly use a pair of much lighter springs.
    You can make this test by simply letting down one spring. But don't do a sustained run, just test it for 20 minutes or so at different wind positions on the spring in use will tell you what you need to know. If you run it a long time, on one spring, you will be backwinding the other spring, spoiling your test and p osibably unthinking the idle spring.
    Note, the movement loses some effeciency when running with one spring due the unbalanced force on the driven pinion.
    I hope you will report back on your findings. There are a lot of similar clocks that are going unused because of these workhorse mainsprings, which really aren't necessary for timekeeping only.
    Willie X
     
  14. R. Croswell

    R. Croswell Registered User

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    Seems like around here it is always hurry up and wait. Right now I'm in one of those phases where I haven't had much time to do anything for myself. I'll let everyone know when I get around to playing with these springs. I do know that after it runs down and stops sometime after 8 days, I can give it just a couple turns wind on one spring and it starts right up and sound like it is running strong. With both spring full wound it is one loud clock for a balance wheel movement. Sounds like an old John Deere tractor under load. Definitely not a bedroom clock.

    RC
     
  15. Willie X

    Willie X Registered User

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    With that information, I would think that a pair of .014" to .015" springs would be just fine and they could be a couple of feet longer. Probably do two weeks?
    Willie X
     
  16. Jonas Sandstedt

    Jonas Sandstedt Registered User

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  17. Heidenreich

    Heidenreich New Member

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    Hey Jonas, I might be able to help. Pls get in touch if this is still actual...Heidenreich
     
  18. RAK

    RAK Registered User
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    Dredging up an old thread, did anyone ever try putting lighter springs on one of these No. 10 movements to see if it would run for the needed eight days? Just curious as my Akin Flipper Advertising clock has this same movement and it seems like overkill to just run the two hands.

    Thanks in advance,

    Bob
     

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