so heres the result of some playing around with the drawing-

main changes were thinking how to integrate the rotating ball nut- the idea is to sling it under the x rail ( which will bolt to the side of the table, so hopefully there will be some adjustment on the profiled rails. Ideally they'd sit on another tube to take the weight rather than just be on the bolts- any suggestions?!

i split the y axis and am planning on using 80 x 80 x 8 with the ball screw between the two, fixed to the front and back of y carriage, but this stops any bracing between the 2 rails, do you think this will be a problem?

i extended the z and moved the y upo to give more clearance- now 230mm travel which has meant massive side plates for the gantry-

jonathan, do you think the roating nuts will sit nicely where i've got them or do you think it's hideous-!

anyway- thoughts on this before i start ordering stuff would be awesome