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Weird beat rate...

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Evening fellow clockies 

I’ve just spent a long time counting wheel teeth over and over again...

centre 84

third 78 & 7 leaves on the pinion

escape 33 & 7 leaves

...which gives me, I think, 8825.14ish beats per hour!

Does that mean someone’s changed a wheel/pinion in the past? Or did they not really care that there’s no integer beat rate (it’s late 19thC fusee clock from Co. Cork)



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First, I'm not heavy into clock, I've done a few but never thought about the beat rate from the mechanism side.

My logic goes from the other end of the stick.

In my world it's the length of the pendulum which determines the number of beats. The longer the pendulum, the slower the beat, the shorter the pendulum, the higher the beat. The pendulum steers the anchor escapement and therefor the speed with which the power is released and the mechanism tuns. The hands for the time-indication are connected to the mechanism.

Change the length of the pendulum and the clock will beat faster or slower. That's how you regulate the time keeping.

So, which end of the stick is it ? :huh:


BTW, looks like a nice fusee mechanism and with (original?) chain ! I wouldn't mind a picture of the (pub?) clock  :)

Edited by Endeavor

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Yup I’ll post a pic when it’s back together (the case is being de-wormed, poor thing) - not a beautiful clock.

The thing is, regardless of your pendulum length you can’t get a regular number of beats per hour (though you’re making me doubt myself). In reality the .14 is irrelevant - it’s just curiosity. 

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The company that makes TimeTrax timing machines has a clock train tables publication.  So going through the book casually I'm guessing That maybe 50% do not have an even count. Not only do they not have even counts for the most part they're all totally different numbers. Which as already pointed out is totally irrelevant as long as the pendulum matches the gear train and the hands revolve the proper rate it doesn't matter.

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It is the play between gravity and the length of the pendulum which determines the rate. As written, the longer the pendulum, the slower the rate, the shorter the faster. Funny enough, the weight of the bob, in theoretical therms and under ideal conditions, is irrelevant; not in reality though ...

Gravity here on earth is not everywhere the same either, never mind dragging the clock into space :biggrin:

The length of the pendulum can be changed to any desired length and therefor to any desired rate.

Remember, it is not the clock which runs on time and the rest has to follow. It's a mechanism which does its thing regardless "the time" and it is up to the clock-maker to make the mechanism to run such that it follows / indicates the time. He can change the gears such that the clock follows the time, but it's the length of the pendulum and the amount of gravity which are dictating the rate.

The length of the pendulum (and therefore the rate) can change due to outside influences, but that's another topic and than we are talking about complete different clocks (think of Vienna clocks )

Same as with mechanical watches, it's the rate / frequency of the balance-wheel which dictates the rest.


Edited by Endeavor

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