3D Printing Tip #3 - Troubleshooting Under Extrusion

May 26, 2020

The 3D printing tip series features different "hacks" you can use to get better 3D prints! Each tip showcases a common problem that comes with 3D printing and offers quick and easy solutions for you to get an edge. Today we're troubleshooting under extrusion.

So you got a printer, and you're getting perfect prints that don't warp off the plate (if they warp, check out Tip #2: Improving Build Plate Adhesion). A few months into 3D printing your objects are looking rougher and rougher; eventually becoming so under extruded you can't even use them. That's okay, this is a normal part of 3D printing and the fix is often quick and easy! 

Most common symptoms of under extrusion:

1. Extruder clicking noise
2. Filament grinding 
3. Incomplete prints
4. Holes and missing features in your parts

When troubleshooting, make sure to change one thing at a time. Changing multiple factors at the same time will make it harder to pinpoint exactly what is causing the under extrusion issue. Here is a table with the most common culprits of under extrusion in the order that you should troubleshoot them:

 

Possible root cause	Action
Filament tangle	Check your spool for tangles; maybe it caught on something or even broke!
Heat sink fan failure or malfunction	Heat up your extruder and inspect the heat sink fan.  Is it working at 100% speed? If not, there may be a loose wire or the fan needs replacement.
Bowden tube is not inserted correctly	Remove the retaining clip and check that the bowden tube is inserted all the way so it bottoms out.
Build chamber overheating and causing the filament to expand in the cold area of the heatsink causing a clog	Remove top cover/front door. Increase exhaust fan speed. Lower build plate temp temperature to lower the build volume temperature.
Incorrect slicer settings	Make sure to follow recommended print settings from the filament manufacturer. Match print speeds, temperature, etc.
Slicer settings don't match the loaded filament	This one will make you go "duh" but we're guilty of trying to print ABS with PLA settings. If you slice for PLA, make sure you have PLA loaded!
Incorrect feeder tension	Check to see that the feeder tension is set to the optimal amount. Sometimes after servicing our in-house fleet; we forget to set it back to the correct tension.
Old filament that has absorbed too much moisture	Try a fresher filament or a brand new filament. If you notice a big improvement with the same print settings. Try drying your old spool with a PrintDry.
Built-up gunk on the driving gear or bearing	Over time, it might be that the extruder gear got gunked up with filament dust. Open up your extruder to inspect and clean it out if needed.
Clogged or semi-clogged extruder	Do a hot pull and then cold pull (also known as atomic pull). This will clear out the nozzle from any carbon build-up that might clog the extruder.  Video on how to do an Atomic Pull.
Worn bowden tube or collets adding resistance to the filament movement	After about a year, bowden tubes become rough and collect introduce play into the system. Replace the tubes and collets!

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