Fixed z axis to gantry design

[Robin Hewitt]

See picture which shows all the forces acting.

But the diagram doesn't show the rails being screwed to the bed and the blocks being screwed to the gantry.

The nut should be under the gantry and the screw moving with the bed.

That puts the linear bearings permanently underneath the cutting head.

Looks a bit odd, but if you draw it you will see enormous benefits.