Quote Originally Posted by Zorbit View Post
Pippin is correct. That's why a piece of box section steel is stiffer than the same amount of steel in solid rod form. It's a cube law - the stiffness is proportional to the cube of the thickness.

Beware of mixing materials with such differing properties, you may end up with a structure that performs worse than either would on their own.
Did you not read the OP's post "The frame will be epoxy granite and a welded laser cut steel skeleton inside" you would not cast an epoxy granite frame then clad it outside with steel Box section Box section was not questioned totally different build.
Come on!!!

Take a look at this project: https://www.model-engineer.co.uk/for....asp?th=139042

Phill