For the x and y Axis you set the zero point with a limit switch, but how can you get the zero position for the z Axis? You have different thickness of material to mill and when you change the tool, you have also a other z Axis positon. With the Sensor, you can define the zero position of the piece automaticly.

Absolute linear positioning using deBruijn sequences.

The Sphinx has all the components I need, except it will need a taller vertical lead screw, the same length as the horizontal ones. It will also need legs. So I need to start with the Sphinx parts list, then make a few changes.