Hi there, I have the original Mini 1, everything is how it was purchased. It’s been years since I’ve just recently started using the printer for serious work. While printing today, it suddenly stop extruding. I found out that part of the hot end stopped working. Please excuse my ignorance about the printer as I’ve only successfully done the printing part but not too familiar with repairing or understanding how each part of the printer works.
The filaments seems to be stuck at the upper portion of the hot nozzle, shown in the picture. I tried pushing the filament through and retracting but it’s completely stuck. Is that part of the hot end suppose to get hot too? I cranked up the temperature but it doesn’t seem to help with pushing or retracting the filament. What is the maximum temperature that I can set the nozzle to?
What steps do I need to go through to fix this? What is that part of the nozzle called?
That part of the extruder is part of the “cold end”. The lower part that the nozzle is connected to is the “hot end” and the two are separated by the thin tube called the “heat break”.
The fan blows on the last part of the cold end to prevent heat from the hot end from creeping up through the heat break. When it fails to do so, it is called “heat creep”.
When the filament gets stuck in the section you have highlighted, one solution is to heat the nozzle and block the fan for 10-20 minutes. The goal here is to purposely cause heat creep to melt the filament in that section of the extruder.
Manually push the filament until it starts moving and then while it is moving, unblock the fan and lower the extruder temperature to a value 10-15 degrees below your normal print temperature for the type of filament. If you have an LCD display or the ability to manually send gcode commands to the printer, you can replace the manual push with using the extruder normally to keep things moving until the nozzle temperature stabilizes.
To minimize “heat creep” in the future, make sure that the fan is working correctly (i.e. it isn’t slowing down from worn bushings/bearings or dust buildup. Use a 5 (or as much as 10) degree lower temperature than you were using before, i.e. the lowest temperature that produces decent prints.
Many have replaced that fan with one with a higher CFM rating, or a different type of fan with a different duct. Search this forum or Thingiverse for examples.
When printing with PLA on my TAZ 6, I used an external fan to blow across the bed at the extruder. This worked when I remembered to turn it off for the first layer or two and turn it on for the rest of the print but after the operator failed to do so multiple times, I added an automated solution.
