I was thinking for ages last night about ways to increase the rigidity of the bed frame. Came up with all sorts of ways that would probably work, but I had a simple idea this morning.

I've got some 900x600x60mm concrete paving slabs laying around. I'm going to place the cnc on one of them and bracket the frame to that. It surely won't be able to twist and it will add a fair amount of mass to help prevent it bouncing around on fast movements.

Best of all, it's free.