Posted by Steve Chen on February 09, 2006 at 12:26:10:

In Reply to: Re: Odd teeth over pin measurement posted by lbmakem on January 22, 2006 at 15:43:23:

Please try this, when the helical angle is biger, the differance is bigger.

psi/sin(psi+pi/z)=tan^2(beta_M)

M=rMxsqrt(psixsin(psi+pi/z)+2x(1+cos(psi+pi/z)))+dp

where

beta_M helical angle at ball center.

rM distance from ball center to gear axle

Find out psi in fist equation, then put into second equation.