Calibration and setting Z offset
Next you’ll want to calibrate Robo C2 by selecting UTILITIES on the touch screen, and then select WIZARDS from the list.
From here you’ll select Z OFFSET WIZARD.
Now, the printer will wait to calibrate its home position
Press up and down on the arrow buttons while sliding a piece of paper between the nozzle and the print bed until you feel some resistance against the paper
Note that you will see the offset progress and completion on the touchscreen.