Second Moment of area

I did some calculations to work out which shape of beam would be most useful for the gantry design. I looked at three main shapes: circular tubing, square tubing and I beams. I used the same rough dimensions for each shape.

The results were:

Circular tubing with diameter 300mm and thickness 20mm

10.83x10^6 mm^4

This value would be the same for all directions

Square tubing with diameter 300mm and thickness 20mm

24.56x10^6 mm^4

The square tubing is double times stronger than the circular tubing, however this is only at right angles to the faces.

I beam with 300mm height, 20mm thickness and 260mm high post with 30mm thickness.

201x10^6 mm^4

This is 8 times the strength of the square tubing but this is only in the vertical direction.