German HAC L28 almost done but......

Discussion in 'General Clock Discussions' started by turboflyer, Apr 9, 2020.

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  1. turboflyer

    turboflyer Registered User

    Feb 17, 2016
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    I have done a search but can’t find what the beat rate should be. Hopefully someone will know, I sure don’t. The l28 I found on an offering on an auction site but not sure if it’s exact. No marking anywhere on the plates.

    51140E77-81E9-4889-9089-47B26693F74C.jpeg E4D8B6A6-6BB4-4008-A4CB-897BC40FCB0B.jpeg 40D55D99-6441-4A8A-A985-D550901A710A.jpeg
     
  2. brian fisher

    brian fisher Registered User
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    Jan 20, 2017
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    hmmm....a good pic of the back of the movement would be amazing....just sayin'.... :0)

    i've looked pretty closely at your pics to the best of my ability. it's difficult to tell what you have there, but i would guess judging by the pendulum, the way the movement appears to look from the sides, the way the dial looks, and the way the chime block looks, i think that you have a pendule de paris movement. i've never seen one of these in a wooden cabinet like that. i might venture to guess that this is a french crystal regulator movement in a well made wooden cabinet ala ("in the style of") someones back yard work shop. if it is indeed a frenchie, i can say that the beats per minute will vary(widely) based on how many teeth are on the escape wheel. that movement did indeed come in many variations.

    my suggestion would be to get it close. ie: within about 5 or 10 minutes per week. then it should be pretty easy to surmise the actual number.
     
  3. Anvil2k9

    Anvil2k9 Registered User

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    #3 Anvil2k9, Apr 10, 2020
    Last edited: Apr 10, 2020
    No marking no HAU/HAC, maybe a Junghans selling the ashes from.

    A personal opinion from what I can gather of the given pics though -
    I'll go with Brian, drive it even further, a nice decoration for
    laypersons living room not running it.

    The ratio of dial, wood and pendula space is very disturbing.
    Case loveless not to speak cheapish.
    Equal dye allover suggests 1960+ industrial aging.

    Polished spring case does not fit the front and indicates rather
    an overrestored movement i.e. reckless destruction of patina for
    sales reason.

    Hope it wasn't that pricy.
     
  4. turboflyer

    turboflyer Registered User

    Feb 17, 2016
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    The movement was already identified as HAC. Yes it has the cross arrows on the back plate. No there are no marking indicating beats or pendulum length. The pendulum bob is French. I used in place of the damaged original. I like the way it looks. The L28 model designation I provided thinking some might know the correct beats for that movement. It runs just fine and was completely dissembled and “ over restored” by me. It will look fine even in a “layman’s living room” thanks.
    The case is original. Over restored:coolsign: Please Anvil do post you most recent restoration so I can see how to improve. No I purchased at a fair price, could be pricy now.
    Thanks Brian for your constructive comments.
     
  5. fbicknel

    fbicknel Registered User

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    I never thought of that: there must be a formula for that: given the number of teeth on each wheel from escape to -- I'm guessing -- center wheel, one should be able to calculate the bpm, yes?

    If you could calculate the effective pendulum length, just the teeth on the escape and knowing the period from the length it should be possible. That's probably not practical, as knowing exactly where the center of mass when hung is probably pretty hard to measure.
     
  6. fbicknel

    fbicknel Registered User

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    Technically correct, but as I look at it, it's quite a nice clock.

    Hey... it's definitely one of a kind! :)
     
  7. Anvil2k9

    Anvil2k9 Registered User

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  8. turboflyer

    turboflyer Registered User

    Feb 17, 2016
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    I have another bob kinda similar. I have considered turning one but not up to that level yet. May practice on aluminum stock first.
    I will play with getting the time right, they check the beat rate and gladly post it. thanks again
     
  9. shimmystep

    shimmystep Registered User

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    I've seen a few of these on my bench, same case and movement. I don't have pics of them, but there are pics online of the same clock, so you can see what the pendulum bob looks like as original, though the regulator bob looks good in that case if you can get it to regulate, why not! I've seen many 'mock mercury' regulator bobs in German Clocks. Junghans went on a good run with them at the turn of the century.
    Don't think you've over done the case, looks great, I can still see warmth in the wood.

    Here's a couple of links that may be helpful...

    http://www.nawcc-index.net/CalcPendulumChange.php

    Tap for Beats Per Minute BPM
    HAC.jpg
     
  10. Kevin W.

    Kevin W. Registered User
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    Apr 11, 2002
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    Thats a nice clock Turbo. Nice job restoring. I have a few HAC clocks and i do like them.
     
  11. fbicknel

    fbicknel Registered User

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    There we go... Had to be out there somewhere.

    Come to think of it, balancing the pendulum outside the clock should give you the COM, then add the length from suspension to hanger + hanger to COM and you should get the length for that formula. Should put you in the ballpark, if you weren't already there.

    Of course, Brian's empirical method in post #2 will get you real close, too. It just takes longer.
     
  12. turboflyer

    turboflyer Registered User

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    Thanks for positive to all. That’s a great formula tool. Saved to my favorites. Now I just have to figure where the center mass if of an object is who’s center will change when I lay it down to balance due to the floating mercury.
     

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