Trouble with Koma Midget

Discussion in '400-Day & Atmos' started by Bates, Jul 2, 2019.

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  1. Bates

    Bates Registered User

    Feb 6, 2013
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    Hi,

    I’m having a lot of trouble getting the pin pallet escapement on a Koma midget to work at all. I don’t think it’s a power problem because with the pallets out the wheels begin to turn on the 2nd or 3rd click of the winding arbor. The suspension spring has no kinks or bends. I’ve tried moving the fork up and down a millimeter or so but to no avail. I’ve tried adjusting the saddle in case it’s just horribly out of beat, but that doesn’t help. I’m probably overlooking something obvious, but I can’t figure out what.

    Attached is a video that I hope will help diagnose the issue. Apologies for the shakiness, but it’s hard to get close enough on this small movement.

    Thanks
     
  2. KurtinSA

    KurtinSA Registered User
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    Nov 24, 2014
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    Hard to tell, but it looks like the escape wheel isn't turning at all. If you said it turned in 2/3 clicks, it must be that there some further restrictions on the escape wheel once it was all assembled. Do you have enough end shake on all arbors? You would need to let all the power down and then manually check each arbor.

    Kurt
     
  3. tracerjack

    tracerjack Registered User
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    Jun 6, 2016
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    The video shows the pallets barely moving Have you tried moving the anchor pin back and forth by hand to see what you get? Midgets are also very sensitive when adjusting the saddle for beat. Most of the time I feel like I just get lucky when setting the beat.
     
  4. MartinM

    MartinM Registered User

    Jun 24, 2011
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    Are you sure it's not horribly out of beat? Can you make the escape wheel rotate if you manually move the anchor pin back and forth? If so, It looks like you'll need to rotate the saddle clockwise a bit (as viewed from above).

    Edit: tracerjack beat me to it.
     
  5. Bates

    Bates Registered User

    Feb 6, 2013
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    Thanks to all for taking a looks.

    Yes, the escape wheel moves fine when I manually move the anchor pin back and forth. As I said, I tried adjusting the saddle in case it’s horribly out of beat, but I guess the best thing to do at this point is to try some more. I seems like no matter where I put the saddle, the pin on the right (in the video) doesn’t engage once the pendulum slows a bit. I can get the escape wheel to drop a cajole times and then that’s it. I’ll give adjusting the beat another try.

     
  6. tracerjack

    tracerjack Registered User
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    Jun 6, 2016
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    The most likely problem is as MartinM says, it’s horribly out of beat. Midgets are very sensitive to saddle movement. I have personally found them tricky to get in beat. I can’t see the saddle position in your video. Start with the upper block perpendicular to the back plate and see what you get. One revolution of the pendulum is more than enough to work with. Seemed like in the video you had two full revolutions.
     
  7. MartinM

    MartinM Registered User

    Jun 24, 2011
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    There are several things left to check. A bent anchor pin. A "too tight" fork to pin connection. Among others. You're looking to balance everything that happens with the pendulum equally from left to tight all the way up to the escape wheel.
     
  8. Bates

    Bates Registered User

    Feb 6, 2013
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    Thanks Martin,

    The anchor pin is straight. I checked the fork to pin connection but I’ll check again. It’s hard to check on a midget.



     
  9. Bates

    Bates Registered User

    Feb 6, 2013
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    Tracerjack, I usually only start with one revolution, but in this case I used two or maybe more because I was trying to show that the escape wheel would move but only if the pins were pushed one way or the other more than they should be.

     
  10. Harry Hopkins

    Harry Hopkins Registered User
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    Nov 16, 2011
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    Be extra careful when rocking the anchor back and forth by hand with a pin pallet escapement... those pins are brittle and fragile and a pain to replace if you break one off.

    I agree with those above that say the clock is out of beat.

    Here is a video I took a few years ago of what I consider a well adjusted pin pallet escapement.. If yours has peep holes you can easily compare.
     
  11. Bates

    Bates Registered User

    Feb 6, 2013
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    Problem solved. Thanks again to all. The problem as several of you noted is that it was horribly out of beat. Rather than starting with the upper block perpendicular, which I was doing, I started with the anchor pin as perpendicular as I could get it. I guess in a perfect world these should be the same, but they were pretty far off on this clock, maybe because the suspension spring is twisted slightly between the upper block and the fork?
    I attached a photo to show how far from perpendicular the saddle/block is now with the clock nearly in beat. And in case you’re wondering, I will be exchanging the large pin for the original. I just find it easier when testing the clock to use a larger pin.

    It’s still stopping on me, but I suspect it’s still just a hair out of beat. If that’s not it I might be back.

    Once again, thanks to all of you for your help and input.

    D5789A2D-8792-485F-B1A3-0545B65EE476.jpeg

     
  12. tracerjack

    tracerjack Registered User
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    [QUOTE="Bates, post: 1289984, member: 54719".... I guess in a perfect world these should be the same, but they were pretty far off on this clock, maybe because the suspension spring is twisted slightly between the upper block and the fork?...
    View attachment 538867 [/QUOTE]

    You're right. A twist between the upper block and fork will do it. Sometimes, I flip the suspension spring over, putting the slight twist down by the pendulum, since a slight twist below the fork doesn't seem to matter much. As for the position of the upper block in your photo, it the clock works, I don't mess with it unless I have an attack of the "gotta be perfect" syndrome.
     

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