First steel diy CNC router build

[Jonathan]

Thank you for your reply, I think I messed up links, the set I was actually talking about was this.

Better, but still a bad choice - go with Irving's advice. e.g these

Whilst it is good to have a large spacing between the linear bearings for better stiffness, you need to consider the 'aspect ratio' (distance between two bearings on rail divided by distance between rails), as if this is too small you'll effectively get lower stiffness due to racking. On what you've designated the Y-axis, this is compensated for by using two ballscrews. However on your X-axis (gantry), the spacing of the rails is large with a small bearing spacing, so when a radial force is applied to the cutter parallel to X, the Z-axis will rotate (or rack/whatever you want to call it).

I'd go with bigger rails if you want to cut aluminium regularly - certainly not less than 20mm. Ideally not round rails, but I realise that's a big increase in cost. Also attach the rails on the Z-axis to the plate which holds the spindle (i.e. the other way round), it's generally stronger due to reducing the overhang.