I cant see how your going to run the main lead screw, usually the sides are unsupported so that the gantry bottom truss can move the whole length, and the lead screw is attached to the center of it. If you have the sides sitting on the base you cant run that cross member underneath as most gantry routers do. They support only the two ends of the router. Look atr K2's website for examples of classic gantry router design. When I built mine I basically copied their mid size frame and it worked great.