Jan 5, 2019

Under-Extrusion (3D Printing) – All You Need to Know

If you're at all familiar with 3D printing, you're most likely, though definitely unwillingly, familiar with under extrusion. It is the bane of makers. With these three easy fixes, however, you can be the bane of it.

What Is Under-Extrusion?

An under-extruded Benchy. Source: 3DBenchy

Under-extrusion occurs when too little filament is extruded during a print. This can result in gaps, missing layers, insufficiently small layers, and even little dots or holes in layers. Print quality and even print strength is compromised when under-extrusion occurs. 

In the following, we take a look at three easy fixes to under-extrusion that should eliminate this annoying problem. 

Tip #1: Increase Extrusion Multiplier

Various extrusion multipliers. Source: Ox7D

If your extruder isn’t pushing enough filament, the most obvious course of action is to increase the extrusion multiplier (or flow) setting in your slicer. By doing so, more filament flows, (hopefully) resulting in satisfactory extrusion.

Tweak this setting by 2.5% until you find the right spot. Note, however, that increasing this setting too much can cause jamming. As a rule of thumb, don’t increase this setting to over 1.15 (or 115%). Otherwise, other problems will pop up.

Tip #2: Increase Print Temperature

A temperature tower. Source: All3DP

If the print temperature is too low, filament won’t be able to flow properly. Therefore, nozzle temperature is an extremely significant factor when trying to fix under-extrusion.

Increase your print temperature by 5-degree increments until you find the proper temperature for your machine and material. You can tweak this setting either by repeatedly printing a test and adjusting the temperature or by printing a single temperature tower, with which you can test several temperatures at once. 

Tip #3: Correct Filament Diameter

Measuring that filament. Source: All3DP

This fix resolves a very common mistake: incorrect filament diameter input. If you tell your slicer that, say, your filament has a 1.75-mm diameter, when, in fact, it’s 3 mm wide, the extruder won’t push the filament at a satisfactory rate.

Use calipers to measure your filament and find its correct diameter. Sometimes, even a .1-mm inaccuracy can cause printing issues.

Extra Tips & Tricks (For No Extra Charge)

Evidence of a nozzle jam. Source: All3DP
  • Speed: If your print speed is too high, your printer may have difficulty extruding enough filament in a shorter amount of time. Try decreasing your print speed by 20 mm/s and observe the result. 
  • Nozzle: If you notice that under-extrusion in your prints isn’t uniform, a likely cause is jamming. Make sure that your nozzle is clean and free of clogs. 
  • Bowden Tube: If your printer is driven by a Bowden-extruder system, you should check the tube. This is a likely origin of under-extrusion, as filament can get caught. 

Hopefully, one or all of these ideas help you fix under-extrusion in your prints. Happy printing!

License: The text of "Under-Extrusion (3D Printing) – All You Need to Know" by All3DP is licensed under a Creative Commons Attribution 4.0 International License.

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