Ideas for reducing friction

Discussion in '400-Day & Atmos' started by KurtinSA, Jun 30, 2019.

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  1. KurtinSA

    KurtinSA Registered User
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    Nov 24, 2014
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    In this specific case, I'm working on a Kundo miniature, the one with the oval dome...it also has the additional arbor in the train. I can't get the clock to run more than a month at a time. I can wind the clock another click, but it will only run for a month or so. I've been into the clock 2-3 times, and just finished a second round of polishing pivots and burnishing the plate holes. I think my trouble is the center arbor. Doing the test with the main train in place without the anchor, it takes 3-4 clicks to get the escape wheel to turn well. On the individual spin tests of each arbor, the center arbor has the least movement to when I try and spin it with a finger. I don't see any fit-up issues when I do the tests with individual pairs of arbors up the train.

    Nothing appears obviously wrong with the center arbor pivots. I don't have a spare arbor to substitute. What can I do to improve this situation? How can I determine if the pivots are not out of plane in any way? I can chuck it up in my lathe, but that's only as good as my chucks will hold the arbor. I don't see how to isolate the pivots to check for true. Do I do an aggressive burnish on the plate holes...especially the larger front plate? I wouldn't use a cutting broach, but would a smoothing broach be gentle enough but yet open the hole up some? The issue there is that you can't put metal back if needed!

    Bottom line, I can't really tell what's wrong with the arbor in order to find a way to fix it.

    Kurt
     
  2. Harry Hopkins

    Harry Hopkins Registered User
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    Nov 16, 2011
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    Kurt,
    Of all the torsion clocks I have worked on the miniature Kundo has been the most problematic. I have one just like yours that I also tore down about 3 times because it would not run more than about a month. I wish I could tell you what I did to finally make it run longer but I cannot and even now it only runs about 6 months. The center wheel most probably spins less due to its larger front bearing surface but still could be causing your problem. I think the miniatures in general are a bit more finicky and require more attention to small details. The wheels higher in the train have very small pivots and can be very easily bent during reassembly.. even the slightest and almost undetectable bend in a pivot will cause a problem. I don't always rely on spinning a wheel between the plates to detect a bent pivot... If I suspect a problem with one I will chuck up each pivot in a collet in my lathe and turn the spindle my hand while watching the opposite pivot. If there is any bend whatsoever you will find it this way and be able to correct it while it is in the collet. When truing one up I put a center in my tailstock and run it right up to the opposite pivot and keep making very small adjustments to the arbor until it runs true. Good luck!
     
  3. KurtinSA

    KurtinSA Registered User
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    Nov 24, 2014
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    I did what Harry suggested. I chucked up the small pivot end and turned the arbor by hand. I could see the larger pivot (the one through the front plate) moving out of round. I did some light "adjusting" and reduced that movement. I put the arbor back between the plates and the individual spin seemed a bit better. I put the train back together less the anchor and got EW movement in 2-3 clicks, so a little improvement. I assembled the clock, set the beat, and it's been running for a while now. The true test will be if it's running a couple of months from now!

    Thanks...Kurt
     
  4. KurtinSA

    KurtinSA Registered User
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    Nov 24, 2014
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    Oh, well...spoke too soon. Clock stopped about 30 minutes ago with the minute hand at 0:45. Maybe not enough power to raise the hand. The main spring was replaced a while back, so it's not sacked. I'm thinking that the locks are too deep, so that will be something to look at later on.

    Kurt
     
  5. GaryT

    GaryT Registered User
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    Oct 26, 2011
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    What are you using for mainspring oil?
    Did you "run in" the mainspring by winding and unwinding it a few (5? times) in a mainspring winder?
    Wipe oil on shaft before slowly winding, unwinding.
     
  6. GaryT

    GaryT Registered User
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    Oct 26, 2011
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    Try running with hands off or loose?
    Remove face and run with out the intermediate gear, others, spacer spring?
    If it runs may not be the problem could be you just reduced the friction enough ;-(
     
  7. zygo

    zygo Registered User

    May 29, 2008
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    Might be worth examining the barrel teeth under a glass - once a month is about the time it takes to rotate.
     

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