no half hour cuckoo

Discussion in 'Clock Repair' started by Jadeskies, Dec 18, 2018.

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  1. Jadeskies

    Jadeskies Registered User

    Dec 11, 2018
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    I have a question about a cuckoo that runs great, keeps fairly accurate time. It cuckoos on the hour.

    On the half hour, it sounds like it’s about to cuckoo, but it never does. It’s a Regula 25 movement. Not sure exactly why it’s doing this,


  2. shutterbug

    shutterbug Moderator
    NAWCC Member

    Oct 19, 2005
    Self employed interpreter/clock repairer
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    On the half hour, the rack should fall only one tooth, because the first tooth is shorter than the others. You may not be getting enough lift to allow it to fall. I did find a clock once (not a cuckoo) where the bottom tooth was not shorter than the others. I had to shorten it in order for it to strike at the half hour.
  3. Willie X

    Willie X Registered User

    Feb 9, 2008
    On the specimens I have, the teeth are all the same length but 25s have a long drop-off of the hook to stop the train at the end of the count. My guess is that something is bent or worn on the long (forked) lifting piece that rides on the two lobe cam on the minute hand shaft. This condition would cause the lift to be a little short, not quite enough to allow the hook to release the rack on the half. The hook should go just high enough to allow the rack to drop against the first tooth on the rack.

    I think the problem will be easily seen when the movement is in hand. With the minute hand installed, apply finger pressure to the strike side chain-wheel while slowly advancing the hand.

    Merry Christmas, Willie X
  4. Chris D

    Chris D Registered User

    Sep 8, 2009
    Coplay, PA
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    Guessing you may have one of the older, smaller gathering pallets. They need to be positioned just right for the 1/2hr cuckoo to work. You don't want the pin on the rack hook to be sitting in the bottom of the pallet. You need to have it as close to the left side as possible with some space underneath like in the 2nd pic. What happens when it's adjusted like the 1st pic is, when it comes out of warning the pallet hasn't rotated enough and the pin falls back down before the pallet can come around and hold it up and allow it to cuckoo. Then on the hour it works fine. If that's the case, you just need to carefully rotate the pallet a hair clockwise.

    15451511704044542901671014148164.jpg 15451512048864931056621703001301.jpg
  5. R&A

    R&A Registered User

    Oct 21, 2008
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    You may have to adjust the tab on the pickup flirt it's not raising enough on the half hour

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