Here are some formulas that might help... D = pitch diameter m = module Pd = diametral pitch N = Number of teeth Do = Outside diameter Dr = Root diameter Tstd = Tooth Thickness at std pitch diameter D = m * N Pd = 25.4/m Do = D + 2m Dr = D - 2.5m Tstd = (pi/2) * m Hope this helps you, I can't get the gear C-hook to work with metric data. Jim

Check out Stock Drive Products. Jim.