Box section tube straightness

[EddyCurrent]

You can see here that I welded 10mm thick flanges to the frame and also to the underside of the rail support beams, these were then bolted together with shims between where required.
It was the welding of the flanges to the underside of the rail support beams that spoiled it, it made the beam bend like a banana such that it was about 1 to 2 mm higher in the middle. Bolting it down made it like the Loch Ness Monster in that it developed humps between the flanges, obviously not very big but humps all the same.
http://www.mycncuk.com/forums/gantry...html#post54981

I think that if I had simply bolted the rail supporting beams to the frame flanges, i.e. without welding flanges to the beams, then I could have shimmed it successfully without using epoxy at the end.