Jon,
it was a suggestion, not patronizing. I saw the need to say to you about strengthening the gantry at glance. But plus that, i spend 2 hours at least thinking about your problem, your machine strength and making calculations, comparing your alu profile data and transferring that data to find the comparative steel profile, then i started calculating deflection and so on...

If you feel i am not right, just ignore what i said, anyway its not an attack or anything personal