Euramca mini runs less than 8 beats/min.

Discussion in '400-Day & Atmos' started by marylander, Apr 24, 2012.

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  1. marylander

    marylander Registered User

    Sep 9, 2008
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    I got a Euramca mini from local auction last Saturday for $2.
    The back plate is #1088. There are two strange things show up on this little clock.

    1) It takes 64 seconds to finish 8 beats while keeping good time.
    Clock pivots were gummed up originally. After I cleaned and lubed the movement and main spring, I found the clock need 64 seconds to finish 8 beat while the clock is keeping correct time. There is no flutering.
    2) The pendulum is turning 590º with almost 90º overswing each side using the original suspension spring (brass color). When I took out the main spring, I found it uses a very strong main spring. Accoriing to RG, it should have 8 beats/min. The diamond shape ball pendulum is fairly heavy.

    Any explaination will be appreciated.
    Ming
     

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  2. Shayne

    Shayne Registered User

    Dec 17, 2008
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    Ming for $2 its a steal . Heres what I would try let down the mainspring completly give it just 1 full turn of the key and then check the BPM and degree of rotation if it correct then you know that the mainspring is too strong when fully wound.

    What puzzles me with a heavy pendulum 590 rotation 90 overswing the clock should run slow. :cyclops: I am just wondering what the impulse must sound like I am sure you can hear it with the dome on.

    Shayne
     
  3. John Hubby

    John Hubby Principal Administrator
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    Sep 7, 2000
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    Shayne, neither the weight of the pendulum nor the strength of the mainspring have any influence on beats per minute, provided the suspension spring is the correct strength for the pendulum mass to keep time. Also, the amount of rotation does not change beats per minute. A mainspring that is too strong "may" cause flutter, but if not then the result is higher than normal rotation as seems to be the case for Ming's clock.

    Beats per minute for correct time is SOLELY controlled by the train count and escape wheel tooth count. In the case of this clock, I have a notation in my Repair Guide that it has been found two times previously demonstrating 7.5 beats per minute, which is exactly what Ming has described. At 7.5 beats per minute, each beat is exactly 8 seconds, thus 8 beats is 64 seconds. and 7.5 beats is 60.

    In Appendix 96 in the RG, it mentions that two different pendulums are used with this movement. Ming has No. 61, the diamond 4-Ball. The other pendulum is No. 59, which has a flat thin disc on which four button shape weights are mounted. That one has curved slots in the disc that guide the weights in and out to regulate the time. Evidently this pendulum was used in the miniature 4-Glass models, and the one Ming has in the glass dome models. Unfortunately my notes aren't complete, but what I suspect is that the clocks that use pensulum No 61 are all 7.5 beat and the ones using pendulum No. 59 are 8 beat. If any other user reading this has one of the other of these clocks andd sees this post, it will be appreciated if you could post your clock here for comparison and additional discussion.

    Even without further information, there is no question that Ming's clock is designed to be 7.5 beats per minute.
     
  4. Shayne

    Shayne Registered User

    Dec 17, 2008
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    John thank you for reminding me that the pendulum weight does not effect the BPM, in fact I keep borrowing pendulums on clocks that come without them as practice to get it to keep time. Feel a bit silly It did not strike me. Anyway I searched the forum on 7.5 beats and learnt something
    https://mb.nawcc.org/showthread.php?13720-400-day-conondrum/page2&highlight=half+beat+henn

    https://mb.nawcc.org/showthread.php?67157-keeping-time-at-7-5-beats-per-minute-after-wheel-transplant&highlight=BPM

    Shayne
     
  5. marylander

    marylander Registered User

    Sep 9, 2008
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    Thank you John as always for your help and confirmation. This is the first clock I have with 7.5 beats/min.
    Do you have any explaination of close to 590º rotation and 90º overswing. If we know the reason, it will help us to achieve high degree rotation on other clocks especially Kundo standard.
    I believe that part of reason for good rotation is the strong main spring. Most of main springs from our old clocks are set for long time and become weaken.
    Ming
     
  6. marylander

    marylander Registered User

    Sep 9, 2008
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    John, from this clock, I learn that:
    1) the distance between anchor pin and the suspension spring is very short (only 7mm, some other clock are twice as long);
    2) it uses a standard size anchor which is a lot bigger than its counter parts (distance between two pallets are winder);
    3) the main spring is relatively stronger than its count part;

    I think the short distance between anchor pin and the suspension spring make the fork turn larger angle, hence more rotation of the pendulum.
    Because this shorter distance, the anchor pin has less leverage to push the fork, it require a stronger main spring to deliver more power needed to push the fork.
    The standard size anchor (winder distance between two pallets) will give more leverage to rock the anchor pin. This compansate the shorter leverage between pin and s. spring.
    Please correct me if I am wrong.
    Ming
     
  7. MartinM

    MartinM Registered User

    Jun 24, 2011
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    Waiting with bated breath for any epiphanies about this movement's persnickety behavior.
    By far, the hardest to keep running of all that I have worked on.
     
  8. John Hubby

    John Hubby Principal Administrator
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    Ming, you are basically correct on all points. Some while back, 400-Day repair expert Joe Rabushka published an article the Chapter 168's "The Torsion Times" demonstrating that having the anchor pin closer to the suspension spring will increase pendulum rotation, regardless of the type or make of clock. The downside is that it also increases the tendency to flutter and may not work if the mainspring isn't in top condition. By using a standard size anchor, this clock movement offsets the flutter problem but "does" require a stronger mainspring. All the Henn miniatures I've seen have more pendulum rotation than other makes, due to this design.
     
  9. marylander

    marylander Registered User

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    Thank you John for the information. I have a couple standard Kundo clocks their pendulum only turn about 180-200º.
    I may make a experiment on them.
    Ming
     
  10. doug sinclair

    doug sinclair Registered User

    Aug 27, 2000
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    I well remember the first one of these that I repaired, many years ago. I remember the effort I took to get it to beat 8 heats per minute! When I finally succeeded, of course the time was way off. I eventually got it to keep time. At the time, I marked the silhouette in my repair guide, so that has been a great help with several others I have encountered.
     

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