Gantry advice please

[AndyUK]

I been following your build

Thanks! :) I too started with the idea of a steel box section gantry, but then temporarily lost access to the Bridgeport and milling the faces became an outside job. Mild steel isn't near straight enough to mount rails to directly.

Once I did the deformation calcs and realised HD aluminium profile could perform just as well, and was an aweful lot easier to build with, it tipped the balance.