# Gear ratio calculations for clocks.

Discussion in 'Clock Construction' started by NeonEviscerator, Sep 5, 2018.

1. ### NeonEviscerator Registered User

Jan 26, 2018
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Hello, I'm trying to make a computer program to model the mehcanism of various clocks for use as a design aid and I was wondering, what do you all consider to be the most important things to be factored into the calculations surrounding gear ratios, pendula, and the speed of the clock and, most importantly, how do you calculate these factors with respect to the overall working of the clock.

Also, I'm new to this and know almost nothing about clocks. As such, can you please keep explanations simple enough for an infidel such as myself to understand.

2. ### Phil Burman Registered User

Mar 8, 2014
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That's a big question.

Phil

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3. ### John MacArthur Registered User NAWCC Member

Feb 13, 2007
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For starters, but the most important thing is that the big hand goes around once an hour, the little hand goes around once in 12 hrs, and the second hand goes around once a minute, at least in a traditional clock. Everything else follows. As Phil implied, there are a lot of ways to get there.
Johnny

4. ### NeonEviscerator Registered User

Jan 26, 2018
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Thanks guys, this is a huge help.

5. ### Jim DuBois Registered User NAWCC MemberSponsor

Jun 14, 2008
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If I understand your original question you are starting with a clean sheet of paper conceptually speaking and want to know some major design parameters for clockmaking? A few major design parameters that most clocks follow includes 1) most wheel to pinion ratios are about 8:1 with cycloidal tooth profiles 2) the sweet spot for a clock gear train is 4 arbors, more arbors cause more friction, less arbors may require going outside the 8:1 recommended gear ratios 3) many escape wheels have 30 teeth 4) generally speaking weight driven mechanisms keep better time than spring driven 5) most pendulum clocks have pendulum lengths between 10.7" and 39.14" , meaning that 1/2 second to 1 second pendulums cover the vast majority of pendulum clocks....of course there are exceptions to all 5 of these recommended parameters, but they offer a good way to start..

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6. ### Paul Madden Registered User NAWCC Member

Apr 24, 2017
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Hi Phil,

Did you create this spreadsheet yourself, or did you find it online? It has some useful information on cable length and winding drum diameter which I find interesting as well.

Best wishes,

Paul.

7. ### NeonEviscerator Registered User

Jan 26, 2018
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Thanks Jim, this is incredibly useful.

8. ### dandydude Registered User

Nov 30, 2014
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Broadly... 1. there is power source. 2. There is a regulating device that spins the wheels at certain speed/time interval. 3.There is a indicating device to show/ indicate the time.
The power source can be a weight or a wound spring. Can even be electricity which i don't wish to talk about.
The regulating device can be a pendulum or a hairspring. The regulating device talks to the clock through what is known as an escapement.
The indicating device can be 'the hour and minute hands' or 'striking mechanism' (sound) or both. It could also be a LCD screen.

I really don't know where to stop.

9. ### Phil Burman Registered User

Mar 8, 2014
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#9
I wrote it myself, it's all very simple math.

Phil

10. ### NeonEviscerator Registered User

Jan 26, 2018
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Thanks, Danny, this gives me a lot to think about. My program will not be designed in any real part around electric clocks as, as I understand it, they operate on an entirely different mechanism.

11. ### NeonEviscerator Registered User

Jan 26, 2018
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Phil, if it's not too much trouble can you explain some of the maths behind your spreadsheet, that would be extremely helpful.

12. ### Phil Burman Registered User

Mar 8, 2014
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Another big question. Here's the answer:

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13. ### Paul Madden Registered User NAWCC Member

Apr 24, 2017
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14. ### NeonEviscerator Registered User

Jan 26, 2018
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Thanks Phil! This is a great help!

15. ### manuelf Registered User

Jun 21, 2015
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Es un tema interesante. Y disculpad mi pregunta donde puedo encontrar la formula para el calculo beats por hora para relojes americanos del tipo Ansonia, waterbury, etc. Gracias.

16. ### fbicknel Registered User

Apr 14, 2017
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#16
Oh, great. Now I have another excuse to make another spreadsheet.

17. ### fbicknel Registered User

Apr 14, 2017
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And there's an answer key! (shouldn't it be upside down? )

18. ### fbicknel Registered User

Apr 14, 2017
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#18
It's a a clock forum. We don't stop.