Module gear`s Help

[lane]

I can and know how to figure out diametral pitch gears. But Module I am lost.
Looks like on the Katrina Lathe project I might have to make some Module gears.
How do you figure out what module you have. Book said .( Module =divide circular pitch by 3.1416 ) But what is the circular pitch. Book said ( Circular pitch = multiply module by 3.1416 ) I do not have the module are the circular pitch how do I find them. All I have is out side diameter and number of teeth. I need to know the module to work this out. OK all you smart people lets have some answers . Bill needs his lathe fixed. This sounds like the chicken and the egg thing.

[AllanR]

Lane
According to my text book (Technology of Machine Tools by Krar and Oswald)
Module can be found by dividing the Outside Diameter by the Number of teeth +2
M = OD/N+2
Hope this helps
Al

[John Stevenson]

25.4 divided by DP

Module is number of teeth plus 2 divided by OD in MILLIMETRES.
DP is number of teeth plus 2 divided by OD in INCHES
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[rohart]

I never thought I'd get the chance to correct the Earl of Nottingham.

John - you've quoted the MOD formula upside down.

MOD = OD (in millimetres) divided by (number of teeth plus 2)

Best get back to laying those flagstones !

[John Stevenson]

I never thought I'd get the chance to correct the Earl of Nottingham.

John - you've quoted the MOD formula upside down.

MOD = OD (in millimetres) divided by (number of teeth plus 2)

Best get back to laying those flagstones !

Isn't Lane Australian ????

Yes you are correct, well spotted, it's been a long day but gear related.
Started off in the workshop at 2:30 today with a 15" length of 30mm steel, drilled it from both ends, reamed it in stages and parted off 30 slices 3/8" thick.

Transferred these in batches of 10 on a mandrel to the hobber and cut 20 teeth on the stick of modified form to give them more strength. Broached a 1/8" keyway in them all and locked up at 5:30 for my tea, not bad for 3 hours work.

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[lane]

Isn't Lane Australian ???? H-ll No Good old US of A . A souther boy to be exact. Thanks all I think get it now .