Hi Leadhead,

there are two good priced ones that I use:

Gwizard from CNCCookbook.com expensive but will allow you to buy a life long license

And

FSWizard: http://zero-divide.net/index.php?page=fswizard ( The website version is free but materials are limited)

The latter also has an Android app that costs around £12.

To be honest, I cross check between the two to be sure things do not go south.

Some CAM programs will do the calculations for you too but again, double check.

Regards

George