While changing extruder and firmware I crashed my hotend into the bed twice. I later found out the cause was a negative Z value in my gcode, as the stl file was now "on top" of the bed in the first place. My bad.
I am not sure if all the firmwares are equally happy about going to the "negative" side of the axis, but as I am using MIN endstops it is not mechanically possible to go to negative coordinates. But what is worse is that my printed did not honor in that case the endstop (as after homing the endstop was already pressed). This happened to me using the Marlin 1.0 beta.
I wonder if this is the standard behaviour of the firmwares, as I think it should be safer not to allow negative coordinates in the first place.
Any thoughts?
misan