Many of you don't like the nozzle clogs and blocks, We too. Even the smallest contamination can block the 0.4mm nozzle, You can use a 0.4mm or smaller drill bits to clean up the aperture while the hotend is hot. But sometime (many time) the contamination would come back and block the nozzle. That’s very bad especially when your are in the mid of big prints.

How to clean blocked extruder nozzle of a 3D printer

Nozzle block or clogs can identified via below symptoms,

  • filament are not extruding uniformly
  • extrude very thin filament than usual
  • Or the filament is not at all coming out from nozzle.

From the above symptoms we are sure that the nozzle needs clean up, here are some methods know to work

Cold Pullout Method

PLA filament can be used to remove hard to remove contamination completely out of your nozzle. PLA has a useful property that you can heat it to a temperature between its glass transition and its melting point where it becomes a rubbery solid. When you pull it backwards it stretches and becomes thinner, so it peels away from the walls of the melt chamber and comes out in one piece. Anything in the melt chamber is pulled out with it leaving it completely empty and clean.

Here is how you clean the nozzle as shared by nop head

  1. Heat to extrusion temperature and pull out the filament being used .
  2. Use a 0.4mm drill shank to clear the aperture.
  3. Insert PLA filament (preferably natural so you can see the contamination) and flush through the remaining original filament. You may need to keep clearing the aperture with the drill shank.
  4. Cool the extruder to 80°C with the drill shank in place to ensure the nozzle is clear.
  5. Send M302 command to disable cold extrusion check
  6. Remove the drill and then pull out the PLA.
  7. Inspect the end that comes out to see the culprit contamination.
  8. Send M302 command again to enable cold extrusion check

Of course if you are using PLA you can just do steps 4 and 5. This method of cleaning with PLA is much better than using solvents or burning out nozzles that I often see recommended as it can be done in easily and doesn’t risk damaging anything.

Cleaning with flame torch and acetone

What you need: (It will cost you ₹)

  • Acetone (This chemical don't like your skin, so weare glouse and protection glass)
  • Torch (You can use your gas stove - be careful )
  • Very thin wire

  • Soak the removed nozzle into acetone for about 15 minutes to clean out exterior dirt. Use a tissue paper/cloth wipe clean the nozzle.

  • Place a nozzle on a stone and burn it using the torch for about 1 min. Make sure it is extremely hot until you see slight changes in the colour.
  • Use a very thin wire to clear the hole in the nozzle. If the wire cannot go through repeat step 2 again until the can go through. You do not want to scratch/damage the internal wall of the nozzle. Do not force through the hole with the wire. I use soft copper wire stripped from an unused phone cable.

Note: Please read your user manual before removing it from the block. Some 3D printers require heat to remove and install nozzle.

If everything goes well, the nozzle should extrude nice smooth thick filament.