[Talonmotorsport]

I used to weld up 5mtr long stillages on a rotating jig, which after 45 mins of welding 6mm angle and 50x50x4 box would clamp it self around the jig. They used to make one hell of a bang as it hit the floor from 3ft up.
I would say if your planning on using one to finish weld a chassis I would make a removable flat base to clamp it to. Theres alot of unsupported weight in the middle of the chassis and don't forget that welds pull too no matter how careful you are.