[rthibeau]

I'm thinking on putting in my shop a steel I-beam overhead from one end to the other and using a trolley with chain hoist to pick up and move stuff that's heavier than I can lift by myself. Presently, I'm using a gantry style construction of 4" OD square tube, legs and cross beam, 10' wide. I know that will take at least 2 tons and not bend or flex. I have to move the whole thing to use it on the other end of the shop, which is not easy. The setup I'm thinking of would be about 28' long with the 4" square tube (dismantling the present one) at each end for the legs, I could put a temporary support one third of the way in from either end when necessary. My question is: how much weight will a 28' long run of 3.5" I-beam take? an 18' run? and a 10' run?