ErikZalm/Marlin — pull request #828 by Bevaz (2014-03-10 20:09:57+00:00)
Title: Calibrate Z-offset via LCD Menu.

Calibrate Z-offset via LCD Menu. At the moment only for auto_bed leveling.
Choose "Calibrate Zoffset" from prepare menu. The head will move home and the printer will start auto bed leveling. Then the head will be move to the center of the platform and lower down to z=0. Now the head is ready for calibration. With encoder it is possible to set z-offset and the head will move up or down accordinly. So find the position when nozzle is 0.1-0.2mm above the platform (the sheet of paper can pass between nozzle and the bed). Push the encoder and new z_offset will be stored in EEPROM. It will be applied after next HOME-AXIS command.
Tested on Ultimaker.