clock pendulum

Discussion in 'Clock Repair' started by sparkey0151, Apr 19, 2017.

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  1. sparkey0151

    sparkey0151 Registered User
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    Aug 9, 2016
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    horologist
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    Hi this has probable been asked before ? what info im looking for is how do i measure a pendulum to match it to the measurements that are sometimes stamped on a clock movement, i dont seem to be able to find the answer,


    regards john
     
  2. novicetimekeeper

    novicetimekeeper Registered User
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    from what I have read on here these seem to be instructions for a case maker, so it shows the overall length of the pendulum including bob and regulator nut, not what we would usually call the length of a pendulum.
     
  3. Tinker Dwight

    Tinker Dwight Registered User

    Oct 11, 2010
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    Different manufactures used different measuring points.
    Most measured from the suspension post. Some from
    the center arbor and a few even from the bottom of the
    plate.
    If there is a beat count number, that is more useful in
    determining an approximate length.
    Maybe you can give us an idea of the particular problem
    you have.
    If the clock is apart, a tooth count can always get an
    exact beat count.
    Tinker Dwight
     
  4. Willie X

    Willie X Registered User

    Feb 9, 2008
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    If the clock has a case, there are often 'ghost' marks left on the back, sides, or glass, from the old pendulum.
    Outside of that, you are better off to rig up a temporary pendulum and modify it until your clock keeps time. Even then, it's best to make the cut about an inch longer than your test indicate because cutting the excess stick (or rod) off will make your clock run faster. This sounds like a lengthy process but I have found it to actually be the fastest method, as far as hands on time spent. Someone on this list used the words "sneak up on it" pertaining to the final cutoff of a new pendulum stick/rod. ☺
    Willie X
     
  5. sparkey0151

    sparkey0151 Registered User
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    So not that straight forward rely, i dont have any particular clock in mind, i was just tinkering the other day with a working clock and i measured the pendulum to the middle of the bob from its hook on point and it rely did not match up with the figures on the back of the movement, but the pendulum was the one with the clock,

    john
     
  6. Tinker Dwight

    Tinker Dwight Registered User

    Oct 11, 2010
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    I don't believe I've ever seen one that measures from
    the hook. I suppose it could. None, to my knowledge
    measure to the center of the bob. They all measure to
    the rating nut at the bottom of the bob.
    Remember, the number is not there so you can find a
    pendulum that will work with your clock or there to match
    the theoretical simple pendulum length. It is there
    to the cabinet maker can provide enough clearance
    for the pendulum to swing or select the right movement
    for some desired case size.
    Tinker Dwight
     
  7. Willie X

    Willie X Registered User

    Feb 9, 2008
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    The pendulum length, for identical movements with identical numbers can vary up to 5 inches. This is not due to any errors, just differing pendulum construction.
    In my shop the numbers are a source of amusement. The only good and consisent use for the numbers is to order a replacement movement on modern clocks.
    Note, the pendulum number for cuckoos is suposedly taken to the 'center of the leaf'.
     
  8. Tinker Dwight

    Tinker Dwight Registered User

    Oct 11, 2010
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    That makes sense. The case maker needs to know were the
    bob will be for viewing.
    You don't want the bob hanging half way out the bottom.
    Tinker Dwight
     
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