I am helping install an Acer vertical mill with a millstar add-on that drives table x and y and the quill as the z. Position feedback is linear scales on the x and y with the z using the encoder on the motor (will most likely swap this to a scale as well).

The system is.... old. The cnc system is running windows 95 which while miraculously still seems to be running fine, probably isn't long for this world. We want to bring the system into this century.

Everything works to my knowledge and I think the current route is to keep the glentek dc brushed servos and glentek drives and then utilize linuxcnc to control it (I'm not super worried about the servos themselves as they most likely have very low hours but just the age of the drives does concern me. Someone mentioned making my own with big SSRs. Is that a viable option?)

I have looked into other systems but the lack of position confirmation via the scales seems to be limiting. The masso g3 for example seemed like a sweet solution until realizing that I would need to create my own control loop because the hardware cannot support it (is this a viable option?)

I suppose the ultimate question is... Does anyone have experience with retrofitting this system and/or what would you recommend we do?

This is a hobby grade setup that we want to learn with primarily. Budget is first, ease of use second and installation complexity last (I'm an EE or at least almost lol)

Secondary question is how do most people deal with a powered quill? Assuming it is switched to a linear scale, is there a fast way to switch from powered to manual feed? On this cnc you must unbolt the screw from the quill via the drive nut which isn't fast by any means. Or would switching the motor to the knee be a good option? (I have read the issue with that is if the knee doesn't raise/lower perfectly vertical then you can't really account for that whereas you can adjust the quill via the head assembly.)