DIY CNC Milling Machine From Scratch

[Jonathan]

Hmmm yeh true i will add a back the column now, but im not sure on the ribs as if i weld these it may upset my ground face, i may add a couple bars inside to act like rebar.

I don't think adding more than the plate to the back of the column will make much difference, as it's the least stiff parts of the machine you need to target if trying to make it stronger. Intuitively I'd say that's a different part, but hard to say without modelling it, which takes a long time...

I will get some info on the z axis as im not sure weather to make them out of steel or ally for acceleration.

Yes please do. The difference in torque required from using aluminium vs steel is unlikely to be significant, plus steel has better damping properties so I'd prefer steel. Although as Lee has pointed out, there are other ways to solve the damping problem.