A fast ticket to ridicule, according to some bod trying to do it on YouTube, but what care I? :joker:
I had this notion that 30mm round rail bolted to RSJ's might just be rigid enough. I looked at what was available and went for 230x75 parallel flange channel at 25 kg/meter. The rails are all 50cm long.
Attachment 24719
I machined aluminium blocks to connect rail to RSJ. These fit inside the channel. There's a thin slice of channel draped over one of my blocks in the picture.
The idea is that misalignment is irrelevant, it is twist and flex that must be overcome. Do we agree?