Thanks for the reply. What's a "charge pump"?
Mach3 generates a 12.5Kc/s pulse onto one of the pins of the PP This is used to enable the bob. When Mach3 starts up. It is used in case there is a software problem or e stop situation the pulse disappears and basically switches the bob off.

Re the drives is is usual for us to have a two to one reduction with a belt drive. I use these AM882 on my mill.
Your mill though is in a league of its own.