I think Balsaman had some of the right idea, and what I was referring to as a fixed gantry here :
http://webpages.charter.net/pminmo/rec0.jpg
I think by making the y longer with open ends (i.e. +/- a couple of inches so long pieces could be routed)
Incorporating bearingsetups such as xairflyer and Jer21:
http://webpages.charter.net/pminmo/rec1.jpg http://webpages.charter.net/pminmo/rec2.jpg http://webpages.charter.net/pminmo/rec3.jpg
is there way I would go if starting over.
Pminmo
p.s. I have a simpler driver design I'm going to post when I get a chance.