ACME or Ball?

I'm looking at putting together a small mill/drill for PCBs and
doing cutouts of plastic or sheet metal enclosures and front panels
( <= 1/4" thick). The mill working area would be a maximum of about
18" by 18". Traces would be pretty fine, between 0.0125" and 0.01"
and drilling for all the through-hole parts.

Think an ACME screw setup would do ok at this or are ball a must for
this level of precision?

Also, think the small ballscrews would be good here? In the reid
catalog I was looking at the TBS-17 screw and the precision nuts for
them. Would these be strong enough? I just can't see my application
requiring much in the way of brute strength...