Debetto,
It's always very exciting to see a new build start! As for the 6' axis, this can be made to work with 1/2" ACME. However, I strongly encourage you to use 5 start screws, This will reduce your required rotational speed by a factor of 5, which will do a lot to reduce whip. I'd also encourage you to order good screws from McMaster (usually they end up being Nook screws) rather than the crap screws from Enco, which sometimes aren't exactly straight.
Anyhoo, looking forward to your build (and your order
. Good luck, and post some pictures soon if you get a chance!
Ahren
www.cncrouterparts.com