If I set the Z-axis feed rate to less then 1In Per minute, I.e. trying for 1/2" (F0.50)to go r e a l l y slow, either my servo controller or Mach3 isn't interpreting it correctly and it goes faster then a bullet. I darn near blew the servo on the Z-axis due to this. 1In per min is just a wee bit to fast when your using 1/16 and smaller end mills.