I may be calling my X axis my Y and visa versa! What i am calling my X axis runs along the table and my Y axis runs on the gantry, just seemed to make more sense this way round! Yes using the 2 leadscrews is to prevent racking.

Just in the middle of tweaking the design now but I will post some pics later. But the basic configuration is a typical flying gantry machine with two lead screws / ball screws to drive the gantry, this is why i was asking about belt configurations to prevent racking.