Mike, my original design was belt drive, but it ended up being less compact and a lot more complicated and expensive. With direct drive, both X and Y motors stick out less than the original handwheels by about an 1.25". On Y the vice extends farther than the motor so that is the limiting factor on compactness. On X the total table assembly width is about 8.25" narrower than the original set up. If you turn the X motor around and place it along the front of the table (as I did in my first design) then you still need to have the bearings, pulleys and some sort of enclosure at the end of the table which would end up taking up about 3" so you've only saved about 3.5" in total width at the expense of a dirt simple direct drive setup. Just my $.06 (have to account for inflation!).

If designed correctly belt drive systems can have very low backlash, possibly less than a direct drive setup since most shaft couplings have some play. The best couplings for stiffness are the disk type, but they are bulky and expensive.

I did a lot of research on belt drives for the first design. I think I decided that the GT2 type belts were best for this application since they are quiet and have very low backlash. I can't find my cad for the belt drive design, must have thrown it out. Attached are my original belt and pulley selections. Can't remember it those were for stepper or servos.

I think I will to a belt drive conversion at some point, but I don't have time at the moment. I would like to copy Arizonavideo99 internal belt drive design as it is in keeping with my overall KISS approach.

My ENCO has a very nice hardened steel gear train, so yours should too. I think it would have no problem handling a 3600rpm motor. I think my mill is just a little bit newer than yours, though, since it uses a standard 145TC motor and has a 7/8" input to the gearbox.

Kurt

EDIT: Are .docx attachments not supported? I had to save as PDF to get attachment to upload.