Thanks guys, I'm using the gecko 540 with nema 23 sm from cncrouterparts. I will look at your build Jeff as I may revise the gantry slightly. I'm not too concerned about possible gantry twist as the gantry is driven from both sides, I personally think this will eliminate any possible problems. You should look at the designers video and work produced with this machine, it's highly impressive with excellent travel speeds and tolerances. I'll post some pics as the stuff arrives.

Thanks again for your time, the advice is invaluable as it's my first build :)