I had some little pittman servos that I thought were on the small side - but so far they seem to be about perfect. Using the existing lead screws and belt reduction.
10.16tpi/2.5mm
2.5:1 reduction
Input scale in inches is 50800 - or .000019" / encoder count.
mesa 5i25
cheap bob
amc pwm/dir imput servo amps.
amc 20a20ac for spindle.
pittman servos and 500 line encoders.
https://youtu.be/GrzJKXBsXvM
https://youtu.be/HM3UR5sJ5X8