Advice sought on new Mill build

[Boyan Silyavski]

So from the suggestions, I've moved from RHS (rolled hollow section) to a welded plate construction. the rear of the column has pockets to put the E/G mixture into, and to perhaps have another plate bolted on to seal the pockets and act as a torsion box.

Am I on the right track?

Bolted? Forget about bolted. Welded sounds better . If you want to pour later E/G , just make pass holes prior to welding the pieces.

Making all braces same distance is not a good idea vibration wise. Introduce some progression or irregularity, in distance i mean.

What you call a torsion box will not function properly if braces are same thickness as the large plates. Plates should be thicker, or the side braces should extend more. Otherwise instead of torsion box you are creating weak spots.

Beware with that side braces cause they must be braced also between them IMO.