ok, first attempt using sketchup 8

[deannos]

Ok, i think i'm finally getting there. All plate is 20mm thick ali and also using I-beams. I'm not sure if the screw mounts are ok doing it this way. Would the bearing blocks need spreading out more. All the rails are 20mm with 1610 screws. Some pictures to show my progress and please tell me where i have gone wrong and where improvement can be made

I will have the ballscrew end machining increased from 15 to 30mm as i want to use belts and pulleys.
The RSJ's are 178x102x19mm, would it be better to use a smaller size on the gantry, 127x76x13mm.
Also just realised i haven't taken into account the thickness of the beams