Bench-top or welded frame

[Doddy]

Come on, now - you should at least feel a little bit of shame

Nah, not a bit :p

My preference for 4mm over 3mm was partly due to deflection calcs (which I don't understand but can sense that one number is better than another), cost (not much in it) and more chance to hold a thread (although nothing at this stage is tapped). The bit I hadn't done was add the final two horizontal members on top of the bed - very much in keeping with your design to mount the rail. My intent was to measure and order the steel, and spend the next few weeks welding on warm days, and designing the gantry on cold days... but you might guess that much of the gantry would be somewhat familiar (I do like your design).

The bed, and the bracing beneath the bed... the bracing from the maxim that more is good (but you can see that it's at this point I take a step back and wonder if I need to buy shares in a welding or steel supplier) and providing some bed rigidity and also some support for the bed itself. The bed - I haven't thought too much above but imagine a 15mm Ali sheet bolted to the bed frame, shimmed or skimmed, or both.

Plans for more bracing under the centre - top to bottom but I have a strong desire to keep the right bay open for storage - controllers/computer/services and just tool storage.

Painting into a corner?, that's kind of where I was losing confidence with the number of acute angles for bracing - I can see it being a bit of a git to weld all that and it's starting to feel heavy just on screen. And, at the end of the day how much is really necessary. That's when I tried to google about the effects of triangulation and bracing, but I think I'm using the wrong search strings.

Yours, I think you are targeting hard woods, from memory?, or have you done any aluminium? My areas of interest are light alloys and laminate, plastics etc. I'd be interested if you have had success with your design on similar.