Wobblycogs CNC Mk1

[Jonathan]

That looks much better than the initial design. Your steel sheets will help a lot to do the job of the diagonal bracing pieces, but they could cause problems with resonance since it's a large unsupported thin area, but that should be easy to solve by adding some thin strips to them should it be needed.

Are you not having the height of the bed adjustable? It's a pretty big advantage in terms of rigidity, although I doubt it will be moved much...

1800mm for the X-axis is a tricky size for the ballscrews. The cheapest option is just to use RM1610, but due to the critical speed you'll be limited to about 6m/min using the standard bearing blocks and assuming the screw arrives without any bend. To go any faster, without rotating the nut, is going to require a larger diameter screw (e.g RM2510) or larger pitch (e.g RM2020), which gets expensive as you would most likely need Nema 34 motors.