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  1. #1
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    Default Pendulum Bob weight

    Is there any way to determine, other than just a wild guess, how much weight a pendulum bob should have. I have an Urgos UW 030 movement with a lost pendulum. Someone put on a replacement that only weight 4 ounces. Another nearly identical movement, with original pendulum has a bob weight of 15 ounces. How do manufacturers determine how much weight the pendulum bob should weigh. A clock will run with a wide range of pendulum weight, too light, inacurate timekeeping, too heavy and clock will not run. BUT...where in that range is the ideal weight supposed to be.

  2. #2
    Registered User Kevin W.'s Avatar
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    Default Re: Pendulum Bob weight (RE: ArtFish)

    Good question Artfish perhaps Scottie or someone will have a good answer.If it were me i might just try, the trial and error method.
    One clock at a time. Kevin West
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  3. #3

    Default Re: Pendulum Bob weight (RE: ArtFish)

    AF,

    I think that you answered your own question. :-)

    Somewhere between the extreams you mentioned.

    Willie X

  4. #4

    Default Re: Pendulum Bob weight (RE: Willie X)

    I have used the method of installing a fish scale between the weight and rope or chain and let it stop at some point. It does not have to go all the way put a block to stop the weight at some point and the scale will read the weight that is need to operate the movement.

    I would add just a litte more weight to the number that it reads for the weight, maybe it would also change with different bob's That I do not know.

    I purchase a small fish scale from Walmart I think and used it.

    Good luck.

    Don

    Save them for the next generation.
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  5. #5
    Registered User Scottie-TX's Avatar
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    Default Re: Pendulum Bob weight (RE: Don DeMarcus #0135928)

    I don't know how mfrs. decide bob weight. I suspect little thought is given other than esthetics. For an overpowered, spring driven movement such as yours, bob weight will not be critical and I doubt you'd even detect the difference in accuracy of a heavier one. For me, I'd choose a bob I like. It'll work just fine.

  6. #6
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    Default Re: Pendulum Bob weight (RE: ArtFish)

    Quote Originally Posted by ArtFish View Post
    Is there any way to determine ...
    As you and others have guessed, there isn't.

    Even if it was made with a particular weight, it may not be ideal - just think of a cuckoo clock in a draught.
    Mike - banned member of the throwaway society.

  7. #7
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    Default Re: Pendulum Bob weight (RE: ArtFish)

    Actually, the movement I have, Urgos UW-030 is a Cable driven 3 chime movement, and was trying to determine the weight of a pendulum bob, not the weights to drive the clock as a couple of replies mentioned, so a fish scale won't work, thought it is a great idea for determing the operational weights.

    I started with the replacement pendulum that weighed just under 5 ounces. I started adding weight to the pendulum, trying to keep it centered on the centerline of the existing bob, making an attempt to keep the bob mass at the same point. I stopped adding weight at 32 ounces and the clock was still running, but beat was beginning to shorten. Using a Microset III / computer, and comparing beat etc, the strongest beat was between 12 and 24 ounces, and didn't seem to make much difference at any point in between. I ended up adding lead to the inside of the existing bob to bring the weight up to 20 ounces, and the clock was running well. I spent best part of 2 days changing/adjusting weights, sure would have been nice to have some type of guide or 'rule of thumb' to go by to shorten the procedure.

    Art Fish

  8. #8
    Registered User Scottie-TX's Avatar
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    Default Re: Pendulum Bob weight (RE: ArtFish)

    Yeah! Congrats. Pleasing to know I'm not alone in the world of optima - efficiency, etc. It's a lonely island out here. I've never made the accurate measurements you've made. I haven't the analyzing tools for that, but I do think there may be choices that will optimize performance in all clocks from pendulettes to pinwheels.
    Again, I think mfrs. of clocks' choices are based more on esthetics and profit than performance. I'm excluding makers of precision timepieces.

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