My baby 15" x 15" machine

[D.C.]

tell ya what the stuff you linked upped my order by £15 but.. looking around i found some 25mmx5mm x 3M which is perfect i dont really need 10mm thick, my only concern with doing it this way is if the box section is uneven, then adding an uneven piece of flat bar to the top will make it worse possibly?

True unless you make a way to level the box a bit. There is the self levelling epoxy method or the grind bits off method.

This wouldn't correct a seriously bent or twisted piece but it would level most stuff enough for mounting rails on:

homemade surface grinding machine - YouTube

As long as you are starting out with a fairly straight piece this should sort out hot rolled steel, assuming you already have a variable speed drill press all you need is grinding head and a jig.

But if your steel looks like this abandon all hope now! :)

http://www.brindley-steel-forging.co...x-Section.html


PS - Have you thought about how you are connecting all this together? (welding/bolts/brackets/epoxy etc) It might be worth putting in all of your bolts and brackets or you will have a nasty surprise when you can't tighten the bolts you have bought because another bolt is in the way.