I am in the planning phase of building a 4th axis for a mill. The Mill uses Baldor servo drivers with UM 3015HS-100 cards. I was looking at using a Baldor MTE-4090 to drive the 4th axis. My first question is with my servo controller what other servo options do I have. Can I use other brands that have encoders and a tach or does that add to much complexity. In my design I was going to use either a 3-1 or 4-1 reduction from the servo to the 4th axis spindle. When I do this how do I calibrate the machine to know that 3 or 4 servo rotations equal 1 rotation of the spindle