Dennis,
Arts reply takes care of the crop circles.
Make sure you draw in radius, LT in radius, and Mach Turn in radius!
or Dia...dia...diameter
Trust me, from personal experience ....not good to mix them up
( Yes 12mm / almost a 1/2" is a lot)
To quickly test LT's code I just do a simple stepped shaft reduction and a ball on the end of a shaft and all seems to
be on ( note that for a ball you will get flats since no arc coding is provided yet).
RICH