Hello guys. Apologize for my bad English. Recently I got Rumba controller from Ebay for my first 3d printer Prusa I3. I flashed it with code found on http://reprap.org/wiki/RUMBA#RUMBA_Firmware_Pin_Configuration Next step I tried to use 1 extruder as second Z axis controller. CONFIGURATION_ADV.h #define Z_DUAL_STEPPER_DRIVERS During compilation I got message Arduino: 1.6.3 (Windows 7), "Arduino Mega or Mega 2560, ATmega2560 (Mega 2560)" In file included from Configuration_adv.h:547:0, from Configuration.h:821, from Marlin.h:22, from BlinkM.cpp:5: SanityCheck.h:75:8: error: #error EXTRUDERS must be 1 with Z_DUAL_STEPPER_DRIVERS. #error EXTRUDERS must be 1 with Z_DUAL_STEPPER_DRIVERS. Without any choice I changed number of EXTRUDERS to 1... but Rumba has native support for 3 extruder's any hints how to use 2 extruders with dual Z mode? Thank you in advance.