Clicking Extruder, under-extrusion and clogging - MINI

Updated 5 hours ago ​by William Holm

The extruder clicking is the sound of the extruder-motor snapping back, unable to push the filament through the hotend, having clogged.

There are 3 main things to check in case of the extruder clicking or under-extrusion, on the MINI:

  • A clogged nozzle
  • Extruder-idler
  • Hotend PTFE-tube and Heatbreak.
On the mini, what referred to as 'the extruder' is the module with the motor and the gear feeding the filament, located on the Z-axis extrusion.
A clogged nozzle
  • Remove the bowden-tube, between extruder and the heat-sink, and check if filament can be pushed through the nozzle by hand, when pre-heated.
You may need to use the supplied wrench or pliers to remove the fitting

Make sure that filament can pass through the bowden-tube without much force. Too much tension on the idler can deform the filament and cause greater resistance.

You can adjust the tension of the idler on the springed-screw, located right bellow the PTFE-tube, circled in the picture below. With the filament removed, the screw head should be level/flush with the plastic part.

Hotend PTFE-tube and Heat-break.
First of all, make sure the three set-screws on the heat-sink are tight. If any of these are loose it can affect the thermal-properties of the hotend.
  • Remove the bowden-tube and fitting from the heat-sink and carefully remove the PTFE-tube inside the hotend.
The tube should be 43.4 (+/- 0.1) mm long. There is a spare supplied with the printer, if needed.
  • Check that there is no filament in the bottom of the heat-break. Use a light from the top - It should be clean and you should see only metal inside.

If there is any filament visible try the following steps to clear it:

  • Pre-heat the nozzle and push filament in by hand, (without the hotend-PTFE) and quickly pull it out. Residual filament should stick to the filament - repeat if necessary.

Once clean, the proper way to re-install the hotend-PTFE is as follows :

Cooldown! Make sure the nozzle is cold! Don't burn yourself.
  1. Push the PTFE-tube into the heat-break, all the way down.
  2. Loosen the three grub-screws on side of the heatsink and try to push nozzle upwards. You will see the PTFE-tube moving upwards.
  3. Re-attach the bowden-fitting to the heat-sink, tighten it, then loosen it a 1/3 turn.
  4. Gently push the nozzle against the fitting until it stops on the PTFE-tube. Then tighten all three grub screws.
  5. Tighten the fitting for the bowden-tube properly (the 1/3 turn from step 3).

Ideal distance between the heat-block and the heat-sink is roughly 4.8 mm. More distance increases the melt zone length - Less distance could reduce the heater-block temperature too much.



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