Maybe this extra stiffness of the box section is why the likes of axyz and chinese makers use this design for the y axis?
Do they use aluminium or mild steel box section. I bet its steel, stronger and easy to weld plates onto it as well as better stiffness?
what is the main reason diy builders use aluminium, softer so easier to machine, lightness or does not rust?
Any ideas?
I am not American!