I have tried twice to print the “test” Marvin file, and both time when the printer gets to the key ring loop everything goes bad. The first print the key ring was a gobbled mess,(picture 4) so i tried again, and when the print got towards the top i slowed the print speed to 50% (using pronterface). Any ideas of what to try next? I glued the “ring” portion back on which is the substance you can see in the first 3 pictures. Also you can see a difference in the texture on the backside of the print, maybe the bed is not level?
Can you confirm that you have active cooling on your printer? Is there a fan, blowing onto the print, in the immediate area of the nozzle? I’ve never printed a successful Marvin without cooling. It’s just too small. Even if there’s not much plastic being extruded on each layer, the heat from the nozzle will probably be enough to warm up the print too much. Worth making sure your hot-end insulation is intact.