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How to Fix Under-Extrusion

How to Fix Under-Extrusion

Are you seeing missing layers, thin layers, or layers that have seemingly random dots and holes in them? You are most likely experiencing an under-extrusion problem. This is a tricky problem to fix because there are multiple causes to the issue. But don’t worry, we have highlighted how to fix under-extrusion, and you will be back up and printing in no time!

Temperature issues causing under-extrusion

The most common cause of under-extrusion in your 3D printer is due to temperature. You could be printing too fast for the temperature it takes to melt your plastic at, and the plastic cannot fully melt by the time it needs to fully extrude.

What you can do:

  • Decrease your print speed.
  • Increase your temperature. Make sure to only increase the temperature in increments of 5 degrees, because you can quickly go from under-extrusion from too low of a temperature to under-extrusion from too high of a temperature.

Filament snag causing under-extrusion

Almost as common as temperature, the next potential cause of your under-extrusion could simply be that your filament is snagging as it is being fed into the system.

What you can do:

  • Tape the loose end of your filament to the edge of your roll so that it doesn’t get under the other filament loops. Has your loose end already snaked its way and gotten tangled? Make sure to untangle your filament roll before you continue printing, otherwise the tangle will just get worse, and it could cause more severe under-extrusion issues.
  • Check your filament guides to make sure that the filament is sliding cleanly between them.

Slicer issues causing under-extrusion

Sometimes you can have the wrong filament diameter listed in the slicer. For example, the profile could have the filament diameter set at 2.75 mm when in fact it uses 1.75 mm filament. This would cause the slicer to think 1 mm of filament was being pushed into the system, when in reality a 1/3 more than that is being pushed in, causing under-extrusion.

What you can do:

  • Make sure your slicer filament settings match the diameter of the filament that your printer actually uses.

Filament feed gear clogging causing under-extrusion

Take a look at your filament feed gear to see if there are a lot of plastic shavings in it or if it is clogged. If this happens, the gear teeth cannot grip the filament correctly to feed it through the system, causing under-extrusion.

What you can do:

  • Clean your filament gear by taking the filament out of the system and then cleaning the gear with an old toothbrush (to reach the nooks and crannies). You can also use compressed air to get rid of the plastic shavings.

Retraction number settings causing under-extrusion

If you have under-extrusion in an area of your model that has a bunch of retractions, your retraction number could be set too high. When your feeder gear is retracting, it is pulling that filament back and forth over the gear, which can cause the filament to be ground down.

What you can do:

  • Reduce grinding on the filament by adjusting your tension on the feed gear. This involves finding the “sweet spot.” If your tension is too high then you will grind away your filament and cause under-extrusion. If you tension is too loose, the gear teeth can’t grip onto the filament to feed it through the system.
  • Reduce grinding on the filament by reducing the length of your retractions.

The problem of under-extrusion is a difficult issue to pinpoint and fix. The first step is recognizing that your model has some under-extrusion, and then working through our tips to correct the issue. The cause could be temperature related or something as simple as your feed gear being clogged. Make sure to check each potential cause individually, and you will be back up and printing in no time.

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