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Under extrusion

Updated on January 25, 2021

This is usually a sign that your hotend has jammed or there is microscopic debris inside of the brass nozzle causing a blockage. It can also mean that you’re printing too fast at a low temperature or that you’re using low quality filament that is not suitable for our all-metal hotends.

There are a few things you can do to try and fix this:

  1. If the extruder is “skipping” (you can see and hear this if you look at the extruder’s hobbed pulley), then your hotend is jammed. To un-clog it, increase the temperature slightly by 10-20 degrees so the heat creeps up the hotend a bit and push the filament by hand into the extruder while you hold the extruder lever down. After pushing it for a few seconds, pull the filament out of the printer and cut off the tip that has expanded and caused a clog.You’ll also need to clean your drive gear (the toothed gear mounted on the extruder motor that pushes the filament) from any filament debris. After a jam, it’s likely that residue got left between the teeth of the drive gear. We recommend you use a can of compressed air or a nylon brush to clean it. You can use the hex key that was included in the box with your printer to un-tension the set screw in the drive gear so you can take it out for cleaning.Tip: If you can’t pull the filament back out, it may be that it will not get through the push-fit on the hotend. You’ll need to use a 7mm wrench to unscrew the push fit from the hotend’s aluminum heat sink and then pull the filament out.
  2. Check to make sure you are not using some cheap “no name” filament. While you may save a few bucks on some plastic filament, it does not mean that it will print well. We recommend you purchase our filament as we test it on a daily basis on our printers and it’s guaranteed to work.
  3. Make sure you’re not printing too fast for the temperature you set. If you’re printing too fast for the set temperature, the plastic will not have enough time to melt inside the hotend before being pushed out by the extruder. Try increasing the temperature by 5 degrees or lowering your speed by 10 mm/sec. If you set the temperature way too high, the plastic will also clog as the heat will creep up into the cold zone of the hotend (where the fan is mounted).
  4. If you’re printing something small or a part that has a lot of small features, the extruder will retract the filament more often as it travels from one part of the print to another. If it doesn’t have enough time to push out the filament before retracting it again, the hotend will clog. There are two ways to fix this:
    a. Lower the printing speed so retractions are slower, or lower the retraction amount.
    b. Increase the infill. If you’re printing something really small, sometimes it’s just best to print it at 100% infill to make sure enough plastic is deposited to keep the printed object from breaking.
  5. Measure your filament’s diameter at least five times in different spots using digital calipers. For example, if your filament measures around 1.65mm, but in Cura you set it to 1.75mm, your printer will not push enough plastic through the nozzle. Make sure the filament diameter in Cura corresponds to the actual diameter of your filament (the average diameter).
  6. You can also try cleaning your hotend’s brass tip to see if that helps remove any debris. (Remember, keep your filament stored in a dust-free environment or else the hotend will clog!)
    a. Remove the filament from your printer.
    b. Un-hook the hotend platform from all the magnetic arms.
    c. Unscrew the push-fit that holds the filament tube from the hotend (using a 7mm wrench will help).
    d. Heat up the hotend to 155-175 degrees and wait until the temperature is reached while holding it in your hands. (Careful to not burn yourself!)
    e. Push in some PLA filament until you cannot push it anymore or until you see just a bit of filament come out the nozzle and immediately pull it out. You should hear a “pop” sound and you should see some debris on the tip of the filament. It’s a good idea to clean your hotend after using abrasive filaments such as brass, copper or metal.