Hi - I hope this is the correct forum for this question... I'm building a camera jib arm - essentially a 1.5" sq aluminum tube, 15' long, with a pivot point in the "middle". A camera goes on one end, and counter weights on the other. I'd like to know the limits of the aluminum so it doesn't eventually bend or break. the tubing is 3/16" wall, 1.5" OD - and the total weight of camera, counterweight and the tubes themselves is about 45 pounds. Can someone direct me to stress and/or load charts for aluminum sq tubing? When assembled, the tubing has a slight downward bow. I just want to know how close it is to breaking. thanks!