On Sun, Dec 4, 2022 at 4:37 PM gene heskett <ghesk...@shentel.net> wrote:
> > It seems to me that 19" of 20x20 square tunbing would have less twist > per NM of applied torque than the same length of 8mm steel shaft, but > IDK. Hence the question. This is a tough question. You are in effect asking to compare the torsional stiffness of two very different beams. It can be calculated, but you don't want to see the math involved (Google "second area of moment" if you do want to see.) Of the two shapes, a thin wall square is dramatically worse than a solid round. But in the calculation, we raise the diameter to the 4th power, so a larger size is very much favored. Do they balance? We don't know the mechanical properties of your epoxy/carbon composite tube and we don't even know the exact kind of steel in the rod. Without knowing more it is a toss-up. I'd say measure it. Wrap string around each end in opposite directions and hang weights on the string. Or place a torque wrench on both and measure. > -- Chris Albertson Redondo Beach, California _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
