Hi working on new gantry router design and intended to use 3"x3"x10'
1/4" angle iron spanning 8-10ft between support legs and predict a load
of approx 100lbs. I am concerned with deflection or twist. if secured
to supports diff and or where my load rides on the angle iron would change
the amount of deflection. If I uploaded pic properly it might give an idea of
what I am trying to do.
What accuracy are you looking for. 100 lb on a pair of 10ft L beams is enough to induce noticeable flex. The math for these is simple if you know what you are doing. If not there are some good tables for moment of inertia as well as cantilever beam calculators online. Accurate prediction of deflection is possible, the hard part is determining what is allowable.
Unless your angle is loaded through the 'Shear Centre', it will twist as well as deflect vertically. The amount will depend on how the ends of the angle are supported at the ends - 'simple' or 'encastre', or something in between! You really need to have a chat to an engineer friend, if you have one!