pic: 1648 Painted Frame / teaser 2

[apalrd]

Originally Posted by notmattlythgoe

1x1 tubing with 1/8 walls is actually the same weight per foot as 80-20.

1/8" wall would be stiffer in the directions we are concerned with in a chassis design like this.

Decreasing the wall thickness to match the equivant 80-20 stiffness, it would be lighter.

[notmattlythgoe]

Originally Posted by apalrd

1/8" wall would be stiffer in the directions we are concerned with in a chassis design like this.

Decreasing the wall thickness to match the equivant 80-20 stiffness, it would be lighter.

Would you mind pointing me to the data that backs this up?

[apalrd]

Originally Posted by notmattlythgoe

Would you mind pointing me to the data that backs this up?

I was curious too, so I ran some simulation (using Inventor's FEA tools) and found that 8020 is in fact significantly weaker in torsion and slightly weaker in bending. I can't attach images to a CD-media, so I'll summarize the results:

For bending, I constrained both ends of a 1' beam and applied a load to the top face. For torsion, I constrained one end of the same beam and applied a torque to the other.

100lbf load on top face of section, ends constrained:
0.001536" max deflection 8020 (load split between two top flanges on either side of groove)
0.001614" max deflection 0.063"
0.001006" max deflection 0.125"

200 in-lbf torque at end of section, other end constrained:
0.1311" max deflection 8020
0.01055" max deflection 0.063"
0.006772" max deflection 0.125"

The weight of 8020 vs 0.125" 1x1 box is virtually the same, 0.063" would be roughly half.

[notmattlythgoe]

Cool, thanks for the info.