[solarchimesam]

I am no expert..but I use threaded rod from hardware store with 2 sizes.
I am on a budget (wife says so) so most of the cnc is parts from here and there.
largest rod is for X....Y,Z are a step down from that one.
My X is larger than stepper shaft...no trouble so far.
Yes mine is slower than a cnc with a "real lead screw" but for now it does the job.
Also the X has a heavy router attached so the wear and tear is a concern on threads.
Balancing your weight is an idea...I had a cable and pulley working on a cnc that
you could lift the Z up and down with a finger tip like it was floating.

Good luck!