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How to convert from 64 pitch to 48 pitch spur/pinions?

How to convert from 64 pitch to 48 pitch spur/pinions?

Old 01-02-2011, 07:51 PM
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Exclamation How to convert from 64 pitch to 48 pitch spur/pinions?

How do you convert from using 64 pitch to 48 pitch? Seems like I may have more flexibility with gearing in 48 pitch since I have tons of spurs and pinions collected over the years. But how do you convert from one pitch to another and have a reasonable overall gear ratio?

Of course, the non-scientific way would be to take an existing 64 pitch spur and pinion combination and try to physically match it up a 48 pitch spur and pinion combination so that they are all the same physical size.

Barring that trial and error, is there a scientific / mathematical way to convert from 64 pitch to 48 pitch?

Thanks in advance.
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Old 01-02-2011, 07:56 PM
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Sorry... search is your friend. I think I may have answered my own question. I should have searched using the word "64 pitch" instead of "64P".


I quote Stegger in the post:

"To calculate the equivalent number of teeth in a 64 Pitch gear to 48 Pitch or vice versa. Simply divide the number of teeth by its pitch then multiply by the target pitch to obtain the equivalent number of teeth.

Example: 108 Tooth 64 Pitch Spur = 81 Tooth 48 Pitch Spur.
108/64 x 48 = 81 "

Last edited by M3Armand; 01-03-2011 at 07:37 AM.
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Old 01-02-2011, 08:07 PM
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The easiest way that I know of is to multiply the 64p gear size by .75 to get the equivilent diameter 48p gear.

120 * .75 = 90

120t (64p) = 90t (48p)
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Old 01-02-2011, 09:50 PM
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Remembering that the ratio will be the same like is you have 100S and 25p that's 4:1 So look for a set that fits in that range.
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Old 01-03-2011, 05:16 AM
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Question: I am currently running 48 pitch gears and I know the tooth sizes that perform well in 48 pitch, but I want to change to 64 pitch. How do I convert the the number of teeth on gears from 48 pitch to 64 pitch?

Answer: Good question. The short answer is: take the number of teeth on the 48 pitch gear and divide that number by 1.5 and then muliply that answer by 2. Here's and example:

(81 tooth 48 pitch) 81 1.5 = 54 x 2 = 108.

The answer of 108 will be the tooth size to use in 64 pitch. In that example we get a whole number after converting, 108. Not all of the numbers will work out this cleanly, lets take an 86 tooth gear for example:

86 1.5 = 57.333 x 2 = 114.666.

We need to round this number off to the nearest whole number, 115 (a common 64 pitch spur gear size).
Just reverse the equation to convert 64 pitch to 48 pitch. 108 2 x 1.5 = 81.
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Old 01-03-2011, 06:48 AM
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There is an easier formula to get from 48P to 60P.

48P / .75 = 60P
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Old 01-03-2011, 07:02 AM
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Here's a link to with some useful info.

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Old 01-03-2011, 11:49 AM
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The size of the gears themselves does not matter...as long as they are big enough to mesh...what matters is the gear ratio. Divide the # of teeth of the spur by the # of teeth on the pinion then find a 64 pitch equivalent. For example 75T 48p spur with a 25T 48p pinion would be 3:1 (75/25=3) so you need to find a 64p combination that is the same as 3:1 like say 90T 64p spur with a 30T 64p pinion (90/30=3).
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