okay on X axis one or two ball screws? Also you might want to put a brace in half way down the X axis rail to help reduce any possible flex (depends on weight of gantry and such). Please remind me of dimensions as have been in the shop all day truing (tuning) the motors and travel. Therefore really not looking back in the thread for the info' (yes I am that mentally tired). Other then that looks like a good solid start.

Michael