so im printing along woohoo. then i go to do my print it heats up just fine, homes and then when it is supose to go back to the dump chamber the z axis just starts going down. and unless i stop the print the bed will bottom out. what would cause this? lol i didnt do anything different except load a gcode profile of a part onto the sd card inserted it into the printer and chose the print to print just like every other time i have printed something. any help would be awsome thank you, KNM.