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ronseto
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Prime Numbers

08/03/2009 4:52 PM

Some of you may have noticed that certain items are made using the prime number 7. I have noticed things like automobile wheels and sheriff's badges having 7 points or spokes. Why would anyone choose to divide a circle into 7 equal parts? Take gears for example. The number of teeth is never a prime number. 360° ÷ 7 will never come out even.

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ronseto
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#45

Re: Prime Numbers

08/05/2009 7:05 PM

I just checked the McMaster-Carr catalog for gears and sprockets and was surprised to find sprockets with 7, 11, 13, 17, 19, and 23 teeth ....and one gear with 17 teeth, so I guess my original question goes out the window.

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devitg
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#87
In reply to #45

Re: Prime Numbers

08/12/2009 7:23 AM

Hi Ronseto . at the first sight on your original post , I think in the 127 theeth gear we use here to make metric thread on lathes with 4 thread per inch master screw.

As 12.7mm is half a INCH .

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#46

Re: Prime Numbers

08/06/2009 4:37 AM

It is often advantageous for ay paired gears to have numbers of teeth that share no (or as few as possible) common factors in the number of teeth. Using gears with a prime number of teeth makes this task simple, and therefor common.

If you aren't finding gears with a prime number of teeth, then you must have better things to do than sit around counting gear teeth.

BENBENBEN --- but I cannot comment under my screenname.. help
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saddlechariot
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#70

Re: Prime Numbers

08/06/2009 11:39 AM

Here is an interesting argument on seven being the smallest number of cables which will stabilise an object in three dimensions.

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phoenix911
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#74

Re: Prime Numbers

08/07/2009 12:50 PM

I'm surprise no one mentioned that the freemasons had something to do with it.....

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Kris
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#76
In reply to #74

Re: Prime Numbers

08/07/2009 1:03 PM

They did, but the posts were mysteriously deleted.

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user-deleted-13
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#77
In reply to #76

Re: Prime Numbers

08/07/2009 1:21 PM

I wouldn't be a Freemason now if you went down on your bloody stinking knees and begged me!

If any of you could put in a word for me ..... Masonry opens doors ... if I were a Mason I'd ... sit in the back and ... not get in anyone's way ...

I nearly got in at Hendon!

I've got a second-hand apron!
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Kris
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#78
In reply to #77

Re: Prime Numbers

08/07/2009 3:37 PM

I thought you had to get on bended knees as part of the initition ?

Join the WI, it's far more influential and has more women members

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English Rose
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#90
In reply to #78

Re: Prime Numbers

08/13/2009 4:10 AM

We wouldn't have you! But if you're interesting enough and good enough, we might consider having you as a speaker....

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Kris
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#99
In reply to #90

Re: Prime Numbers

08/13/2009 9:07 AM

if

? I'd much sooner listen in. Here's an interesting (well, 'quite interesting' ) one for you to explore and talk upon. Once upon a day, all the chaps used to meet up and discuss business in pie-shops. This is back in the days when the 'City' was all coming together, and evolved with coffee houses and all that. Anyway, the blokes were all gorging on meat, meat, and more meat, as was their want during those times. Women, wanting a place where men wouldn't possibly want to visit, began to open small places selling only vegetable based foods/meals. This small step developed onward to females gathering in number, women's suffrage, and vegetarianism. The porcine bankers never noticed that the seeds of equality had been planted behind their backs.

That little snippet of a story might be a complete fabrication, poorly remembered, or a good bit of history upon which to base a talk on something. The source of reference completely escapes me right now.

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English Rose
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#106
In reply to #99

Re: Prime Numbers

08/20/2009 10:59 AM

as was their want during those times

wont....as was their wont....spelt with an "o".

History according to Kris S Quirelle is the reference you're looking for, methinks..

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Kris
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#108
In reply to #106

Re: Prime Numbers

08/20/2009 12:35 PM

I'm just being wanton

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JohnDG
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#109
In reply to #108

Re: Prime Numbers

08/20/2009 7:11 PM

That'll be (from Merriam-Webster):

2 a : lewd, bawdy b : causing sexual excitement : lustful, sensual

... or maybe:

Mànmàn chī

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Kris
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#110
In reply to #109

Re: Prime Numbers

08/21/2009 2:48 AM

10/10

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ronseto
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#112

Re: Prime Numbers

09/22/2009 12:29 PM

The answer to my OT may not have been answered to complete satisfaction, but there were many interesting replies. I think it stirred up some grey matter which is definitely a good thing. Thank you all or as they say in my neck of the woods, y'all.

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