Aluminum Box Beam Load Bearing Properties

[Ron Nossaman]

> An aluminum pneumatic rib press.  Two aluminum box beams (upper and lower)
> held together by vertical pieces of aluminum angle "iron" with room for a
> single 2x4 cut into the shaped caul between which the rib, soundboard panel
> and pneumatically operated hose would go.  Nice and light and easily
> storable.  Just trying to figure out how big the box beam needs to be, 1.5"
> wide is all I need in that dimension so the key, as it always is with beams,
> is the height.  The caul would add a bit of stiffness to the assembly as
> well.    
> 
> David Love

Near as I can tell, an 1/8" wall T6 aluminum box would be 
around 150% as stiff as solid maple of the same dimension. I'd 
go maybe 5" on the height.
Ron N