I know that this is an old topic, but I needed to know and found what works. Here is my start.gcode for S3D to prime both extruders at start: ; **** Duplicator 4 dual start.gcode **** M73 P0 ; enable build progress G162 X Y F3000 ; home XY maximum G161 Z F1200 ; home Z minimum G92 Z-5 ; set Z to -5 ...