Buying SHS and RHS Steel.

[Wal]

Heh, no, you're right. I'm not going to be supporting a great deal of weight. To re-cap:

The frame needs to be built in situ (in my cellar) and will at some point in the future need to be dismantled, so - welding is not really an option.

Bolting it together is very much an option. To avoid issues with rigidity and to give me a reasonably good starting point in getting the frame square, I have decided to build a squat floor level frame (as in the animation at the top of the thread). This means I'm using less metal, but I still need the frame to have a fair bit of heft to it. In it's current theoretical spec the frame alone weighs 110Kg. That's not super heavy, but it's also not that light. A reasonable compromise, I'd say. Using 6mm wall box section not only adds to the weight of the frame, but it also means that I'll have an ample 6mm of thread for the holes that I'll tap. That, to me, is important.



Yes, I could use a screw and a nut through oversized holes, rather than tap into the box, but for now I'm favouring the former (threaded) approach with the screw passing through an oversized clearance hole.

Because box section has a slight curvature across it's profile (exaggerated in the pic below) using section with a thinner wall there'd be more of a danger of distorting it when torquing up the screws - 6mm wall will help to mitigate this.



So while I am over-engineering this a bit, it's for the right reasons: weight and rigidity.

Anyway, it's all drifted a bit off-topic, I just wanted to buy some hollow section steel...!

Seriously, thanks for your posts and advice - it's all really helpful, but I have thought long and hard (well, for my pea-brain) about this, and I'm at the stage of having to go with the courage of my convictions.

(Guaranteed if I changed my mind to 4mm then someone would be along sucking their teeth and telling me how badly it's going to deflect and knock the earth off its axis etc...)

I've been planning this build for well over a year and I still haven't got a frame. It's embarrassing me now.

Cheers.

Wal.