petermichaux wrote

Ball screws are expensive. Plain and simple. They are made with extream
tolerances and I guess that takes fancy machines and plenty of time.

The idea about building a preloaded nut for a regular lead screw is
interesting and may work well...for a while. I think that there would be a
lot of wear and a lot of friction. But the idea makes sense. It is the same
idea as preloaded ball nuts.

Replacing the worn out lead screws every once and a while wouldn't be very
expensive so it might be worth trying.

I've been thinking about this a lot. I think that if you are only cutting
straight lines in the x OR y direction that extend past the end of the part
then ball screws aren't even necessary. If you approach the cutting line
from the correct side then the end mill cannot pull into the cut by moving
the table. You may have to think about this a bit before you get what I'm
trying to explain. I haven't got a really good way to explain it yet.

Peter