I've made a program that can do all these calculation and choose the closest diameter smaller and greather than the wanted that's "fitting" the knurling wheel ! The program markes the CLOSEST diameter blinking - some people say "Just take the smaller diameter !" - but you are free to choose - I just programmed it this way ! The program is FREE and can be downloaded from my web site ... BUT ... 1) Your security system must allow you to install programs (EXE/MSI-files) 2) You must have Micorsoft .NET FRAMEWORK installed (download free from Microsoft) 3) Notice where you install it on your machine - you must start it from there OR make a shortcut yourself on the desktop You can download it here: http://kelds.weebly.com/sjov.html Hope you enjoy it !