Quote Originally Posted by Jonathan View Post
I think if we included the torsional stiffness in the calculation then the results would be a lot worse. Once this 3m gantry is drawn I should be able to do a FE simulation to find how much it twists, rather like the one in this post.
Don't disagree, my point was to illustrate that the bearing sizes were OK for a gantry of that scale. Of course it will need to be stiffer in torsion and I'd consider plates both side of the box section and some perpendicular as well.