Has anyone used or incorporated any truss type structures into their designs before now - using steel? I'm meaning more than just a few, or the more obvious, gussets and braces. I know full on tubular trusses are not easy to make, but I was thinking of using angle iron welded to the outside of square box (flange inwards or outwards) as the brace member. I feel gantry stiffness (vs weight) is an area where this could be utilised, but the reason to look at using it may be qualitatively or quantitatively assessed, by which I mean not just static deflection under some X-Y-Z combined loading at a Z-point offset, but modal shape and frequency (vibration) performance, indicating which area of moving gantry type machine as a whole to look at first. The latter is probably more a real machine measurement exercise than modelling, due to complexity of including all the stiffnesses in a model, and the variability of excitation forces. Assuming that increased stiffness is the way to go, what are the areas that should be looked at first?

I think it would be useful to benchmark a gantry truss structure stiffness and weight against the typical shapes as in routercnc's spreadsheet.

P.S. eg. aluminium lighting trusses. Whilst theyare pretty stiff, to use as a basis for incorporating into a design, (I would think) wouldn't have the local material strength to cope with getting forces in and out where required, without careful reinforcement. But obviously, there's different sizes and spec's of off the shelf aluminum trusses around.