Author Topic: An Excell spread sheet for figuring compound pendulums  (Read 12138 times)

Offline jrbeall

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An Excell spread sheet for figuring compound pendulums
« on: October 01, 2005, 05:12:28 AM »
This is also located under compound pendulums in  "General" but it is so important I thought I should make a special heading to make it easy to find.
Thanks to Rabbit for working it out.  http://www.bealltool.com/cmp_pnd.xls

JayRay_Hughes

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An Excell spread sheet for figuring compound pendulums
« Reply #1 on: October 04, 2005, 04:50:48 AM »
Thanks Rabbit, JR

Offline rabbit

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pendulum period vs. beat
« Reply #2 on: October 04, 2005, 08:01:20 PM »
I got called on my formula for "pendulum period"...
I should have used the term "pendulum beat".  The "period" is one full cycle - a tick AND a tock, or two beats.  (My formula is for one "beat".)
my bad.
I grew up calling a one-meter pendulum a "seconds" pendulum, and I still erroneously call this the period.
- rabbit

Offline millerdlca

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Re: An Excell spread sheet for figuring compound pendulums
« Reply #3 on: July 17, 2006, 06:14:34 PM »
Quote from: "jrbeall"
This is also located under compound pendulums in  "General" but it is so important I thought I should make a special heading to make it easy to find.
Thanks to Rabbit for working it out.  http://www.bealltool.com/cmp_pnd.xls


Is this spreadsheet still available?  The link above fails and the Compound Pendulums topic in the General forum can't be viewed (gives a time-out message).

A compound pendulum with a grasshopper escapement looks like a great combination.

Thanks,
Dennis

Offline rabbit

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An Excell spread sheet for figuring compound pendulums
« Reply #4 on: July 18, 2006, 07:03:19 AM »
i think i can attach a file, now...
- rabbit

Offline millerdlca

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Spreadsheet
« Reply #5 on: July 18, 2006, 09:58:41 PM »
Thanks Rabbit.  Now I'll have to play with the parameters to get a feel for how they affect the results.

Dennis

Offline millerdlca

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horizontal weights
« Reply #6 on: July 20, 2006, 09:35:43 PM »
Looking at Mr Beall's videos there appear to be some adjusting weights on a horizontal rod through the rotational axis on his compound pendulums. I'm wondering about their function and how they might be accommodated in the compound pendulum spreadsheet.

Dennis

Offline jrbeall

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Pendulum balancing weights
« Reply #7 on: July 21, 2006, 04:49:59 AM »
The weights on the horizontal bar are simply to balance the bendulum so that it will be perfectly vertical when at rest.  I don't think they have any affect on the other parameters.

Offline rabbit

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balance weights
« Reply #8 on: July 21, 2006, 07:15:49 AM »
as JR said these weights are how the "poise" of the pendulum is adjusted, but they do affect the pendulum period - possibly significantly, depending on how heavy and how far away from the pivot they are.
in the spreadsheet, they can be treated as aditional weights, and they can greatly impact the moment of inertia.
- rabbit