How do I 'make' a ballscrew antibacklash nut?

Hi all, I'm kind of a CNC newbie.

I've converted my Grizzly G1006 to CNC (Master5/Mach1 and Camtronics
4 axis servo), but the backlash and lead accuracy stink.

I understand I can get decent/cheap screws (.004/ft) from McMaster-
Carr, and use a pair of taper or angular contact bearings for the
drive end.

What I don't quite get is, how do you make a 'anti-backlash' nut
from two regular ball screw nuts? how do you connect them to the
mills existing mount (two screws)... I've read about using a spring
to pre-load, but I cant visualize how that works.

Also, doesn't anybody sell a reasonably priced screw with .100/rev
like a 'regular' mill screw?

Any advice?

Thanks,

Dave S.