Well I have attempted to work it all out and this is what I came up with?

Aluminium on gantry 31kg
800mm rails+blocks 5.8kg
400mm rails+blocks 3.6kg
4 blocks on x axis 1.6kg
Z ballscrew+mounts 2.5kg
Y Ballscrew+mounts 3kg
x axis ballnuts 1kg
2 nema23 motors 3.6kg
CapScrews? 2Kg

Total weight 54.1Kg

Does that sound about right? have I missed anything. I suppose I need to look at the calculator now.

Cheers charlie