But I can! (Help on the aluminium, that is
)
I just built this. (It's meant to be the start of a drill jig that hopefully will allow me to drill straight and parallel rows of holes for my CNC machine!)
The aluminium bar is 10x80 mm^2 (2/5" thick). It is 300 mm long (about 12"). If I press down on the end it flexes several mm! Most of it, perhaps 2/3, is because of the fibre board that the THK rail is mounted to, but it is not difficult to actually see the aluminium plate flex. I was really suprised about this since the plate feels so d*rn unflexible when not mounted
Build with triangles; don't rely on the cross section of the material to give you the stability.
Arvid