My router is roughly 4 feet x 4 feet, and I am concerned about racking in the x axis. Will having two motors and two lead screws eliminate any possible racking, and binding? My gantry rides on 6 bearing blocks, with continously supported guides, made from 80/20. Thanks for any help, and ideas!

Driving the gantry from both sides should eliminate racking, provided you don't stall a motor. That's why you see so many machines driven from both sides.

Binding can be caused by other things, like misalignment, so there's no guarantees there. :)

Thanks, thats what I was thinking. You seem to have all the answers.. :)