Another off idea...

[mbele]

I've figured out motors and ballscrews...

Can someone comment on base structure and x/y configuration? I have option to make base out of 30mm or 50mm thick granite slabs. I used gantry stiffness calculator I found here to get rough numbers, and it seems that 30mm would work... I don't know how to upload modified excel file, so here are the params I used:
Length=1500, material 5.00E+04 / 2.7E-06 / 24000
Z load=500 simply supported
X load distance=150mm, 200N
Box section, width=250 height=230 thickness=30
(Young's mod for granite is 10-70GPa, I used 50)
It showed 4um deflection due to 50kg load, and 0.25um tool deflection in torsion. Actual base length will be shorter, depending on the x axis block span, so I expect better results for deflection.
Here are the sketches of granite slabs configuration:

I'm wondering if there's a gain in moving X ballscrew from midpoint between the rails towards the tool/load side, and if the overhang of Y axis bed would be a problem.
Thanks
Mihael