Sounds like my design are similar for the gantry, I will have one main gantry upright bolted to X axis bearings, Back of this another RHS at the top length to suit Z axis 12 mm aluminium plate , Z Linear Rails will be mounted on 2 more RHS placed horizontally across behind the vertical uprights these rails will be approx 300 mm apart ,and this setback will go towards centre of gravity of the whole gantry , the 2.2 kw Spindle is quite heavy. I invisage the Z axis linear rails to be around 230 - 250 mm apart , does that sounds about right or should they be more or less , thats where I am unsure. Thanks Kit Regards Gordon .