Clearing a jammed / clogged nozzle

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With the extruder heated to operating temperature, press down on the tension lever and manually press filament into the extruder. A clean nozzle should extrude liquid plastic in a straight vertical drop. Any deflection or curling indicates a partially clogged or damaged nozzle. Clogs can be cleared by some of these methods:

Without Disassembling

This procedure covers clearing the nozzle with a "cold pull" of nylon or other filament. In short, you push filament in, it adheres to contaminants and debris, it cools a bit, and you pull it all out leaving a clean nozzle behind.

Also mentioned, a brass or steel wire plucked from a wire brush can be pushed into the tip of the nozzle to dislodge any large foreign contaminants.

With Disassembling

by Katherine Campbell

I would suggest for a jam to do the following (after trying other things to less success):

  • With the heater off, unscrew retaining bolt, taking care to avoid disturbing thermistor wire
  • Take out PTFE tube, inspect. If narrowing or shearing has occurred, you can reshape with tiny files. Check for narrowing by threading cold filament through PTFE tube, it should have low friction.
  • Heat the block once more as it is dangling by the heater wire (goes without saying, but CAUTION: HOT!)
  • Disconnect control software and power off bot
  • Working quickly, disconnect thermistor at board end (to avoid movement causing fatiguing of thermistor wire)
  • Using non-marring pliers (if you have some, otherwise just be super careful), hold the block, and with your other hand, unscrew the nozzle using a 7mm socket
  • Heat the nozzle with a blowtorch to burn out anything clogging it (or you can place it on a paper towel on a ceramic dish in your oven, although the temp required to burn out the plastic will make it stink in your kitchen for a bit).
  • Visually inspect nozzle to make sure it is clear & the brass has not been deformed (by hitting the bed or the leveling screws)
  • Reassemble by reversing pertinent steps except that plugging the thermistor back in should be last.

Burning out the clogged material

Using a burner, hot fan or maybe just a regular gas stove, burn away the material, and pass a thin hard wire through to make sure it's clean of ashes. this is messy, potentially dangerous, and if you are not careful you could deform the nozzle, but sometimes there's little choice left, if the "Cold Pull" method above doesn't work.

https://www.youtube.com/watch?v=6bTfl35zlHE

Solvents

It used to be the case that the only recommended way to clean out the nozzle was to soak the metal parts in acetone. This takes hours and only works on ABS. You may end up with the material becoming just gooey and still need to push it out mechanically.

The materials for dissolving PLA are industrial solvents that may be a little harder to get, look for lye soap, Hexafluoroisopropanol, Tetrahydrofuran (TFA), hot benzene (careful!), Dioxane, Chloroform CHCl3, Dichloromethane CH2Cl2 and Dimethylformamide are mentioned around the web, each has its own health and environmental warnings, so read up before you start playing with them. Also note some of them will require the mechanical help of an ultrasonic cleaning chamber.

(Of course, this being a wiki, If you know of off-the-shelf products that worked for you, please mention them here!)

Drilling the hole with a 0.4mm drill bit

HIGHLY unrecommended unless you have 100% certainty you know what you are doing. Chances are you will be damaging the tip and getting material extruding a-symetrically, and that's the end of that nozzle. You could manually use that drill it to get gunk out of the nozzle when it's hot maybe, but that's pretty All we can recommend.

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