Quote Originally Posted by deannos View Post
Your gantry in particular, is it ali box section
Yep:

Quote Originally Posted by Jonathan View Post
I went to a small local metals supplier and picked up a meter of 80x3mm aluminium box section for the Y rails to mount on
It's mounted with 20mm aluminium plate milled to fit in both ends. It's adequate, but I would advise using something a bit stronger. Since the rails are on both sides of the box section it had to be aluminium since the width of steel box section is not accurate enough. Extrusion is a good option, but quite expensive.