International / IBM Master Mainsprings

Discussion in 'Electric Horology' started by JDToumanian, Feb 20, 2018.

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  1. JDToumanian

    JDToumanian Registered User
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    Apr 28, 2008
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    Hey Group, I have a couple questions about International / IBM mainsprings...

    My 17-7 master clock has the small torsion mainspring. I recently saw a nearly identical (but incomplete) movement on eBay, the only difference I could see was that it had the coil type mainspring instead. It occurred to me afterward, if I had bought that other movement, would the complete main wheels, with their corresponding mainsprings and ratchets, have been interchangeable? It rather looks like they would. Maybe this was even done by IBM when the clocks were overhauled? Besides being more easily obtained if replacement is necessary, I believe the coil spring offers considerably longer run time during a power failure...

    My other question relates to the attached picture of the winding ratchet spring mount... It looks to me like maybe it has been bent outward in order to provide more ratchet spring tension and thus more winding power. I'm wondering if it's supposed to be that way? Or maybe this was an 'official' field modification in order to improve winding action?

    I also attached a picture of the torsion type mainspring for anyone not familiar with it. It's a very 'soft' spring, it's amazing to me that it has enough power to keep the heavy pendulum moving.

    Regards,
    Jon

    045.JPG 046.JPG
     
  2. paradise

    paradise Registered User
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    Jun 24, 2007
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    There are several differences between the style of spring and their functions. In addition the mainshaft is different. along with other functions. All in all its probably better to just buy a complete works with the newer winding setup. They pop up in ebay from time to time. Maybe make mention of it here and someone with a spare will contact you.
    Paradise
     
  3. JDToumanian

    JDToumanian Registered User
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    Thanks for the info... I wasn't necessarily looking to switch to the other mainspring, but I've been looking for a spare spring (and contacts!) for my clock 'just in case' I ever need it. I've never seen a movement for sale with the torsion spring, and when I saw the coil version it made me wonder.

    I found one other picture of a movement where the ratchet spring mount was visible, and it was bent like mine so I'm inclined to leave that alone.

    Jon
     
  4. Scot Traffis

    Scot Traffis Registered User
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    I have International master clock movements with both type springs. Haven't been able to tell if the springs are from different time periods or for different pendulum types. will have to do some research on the movements I have. I do know that Standard Electric used the same torsion springs on there movements.So it makes me think that the torsion springs are on earlier movements. Several of my movement also have bent brackets. Will do some more checking and then post what I find.
    Scot
     
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  5. Scot Traffis

    Scot Traffis Registered User
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    After looking at about a dozen International movements it appears that the torsion springs were used on earlier movements. All the movements I saw with torsion springs had the earlier plastic mounting bracket for the contacts.
     
  6. JDToumanian

    JDToumanian Registered User
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    Thanks for the info! Did you notice if there was a consensus of tension spring brackets bent outward like the one in my pic?

    I've got the movement completely taken down to bits and I've been cleaning and inspecting. There's no noticeable wear, so that's good. I'm almost ready to put everything back together. This clock's walnut case had been completely painted over with white paint by the school or whoever the owner was. I spent many days meticulously scraping the paint off and now I'm refinishing the shellac per Craig's tutorials here. I'm about ready to start final polishing, so the case and movement should be finished and come together soon... I'll update the original thread about the overall clock when it's all done...

    ITR - IBM model 17-7 Master Program Clock

    Regards,
    Jon
     
  7. Scot Traffis

    Scot Traffis Registered User
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    Looked back at the movements and about half of them had the brackets bent like yours and the rest were straight. Must have been done if more tension was needed.
     
  8. Scot Traffis

    Scot Traffis Registered User
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    Just changed out the torsion spring for a regular clock type mainspring. Just changed the whole shaft, spring, and ratchetwheel assembly. Everything worked fine.
     
  9. JDToumanian

    JDToumanian Registered User
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    That's great, thanks for the info! I really appreciate you following up on that. Now I kinda wish I had bought that incomplete movement, but I suppose there will be others. Also if my torsion spring broke, I know of a guy with "about a dozen International movements". :whistle:

    Jon
     
  10. Scot Traffis

    Scot Traffis Registered User
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    If you need parts let me know. I have several incomplete movements for parts
     
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