Hi Clive. Of course your right. Ok. I built it myself, it has an mdf and timber table and has no earth, never thought of that, the rest is steel and aluminium, ball screws and hiwin rails. 4 nema 34 motors, 2 on x-axis and 1-y, 1-z, all motors are belt to ball screw driven, my break out board is an HG08 and stepper drivers CW8060 all from cnc4you, i get ''external ratio requested even when I reference all home, spindle or not, last night it said limit switch triggered but it hadn't, very frustrating, not sure what else to tell you