Resolving 3D Printer Under-Extrusion Issues: 8 Easy Solutions

Resolving 3D Printer Under-Extrusion Issues: 8 Easy Solutions

Under-extrusion is a common problem when 3D printing, and can lead to failed prints and lost time. It occurs when an insufficient amount of filament is supplied by the printer to make the shapes you are trying to create, resulting in gaps or missing layers, or in some cases, little dots or holes appearing in the model. 


 If you have had successful prints in the past with the same setup and have suddenly started experiencing under-extrusion, it would be wise to check the hardware first – replacing the tubing or nozzle may do the trick. However, if you are consistently facing under-extrusion issues, it may help to revisit your slicer settings and calibrate them accordingly. Always make sure to check your settings after tinkering rather than making drastic adjustments too quickly.

Luckily, there are some easy fixes that you can use to eliminate this issue. It’s important to remember that before making any changes make sure you have a preferred calibration cube or test print as a reference point. 

Key Checks to Perform

As previously stated, it is advised to start with the hardware. Let’s look at the first thing you ought to think about.

The Impact of Diameter on 3D Printing Under-Extrusion

Incorrect filament diameter input is a regular occurrence when 3D printers are in operation. Luckily, it does not require any change to the machine itself and instead involves managing the most basic component of the printing setup, namely the filament. To illustrate this problem further, if a 1.75 mm wide filament is fed into a slicer that expects a 3 mm wide filament, there will be too much resistance on the extruder.

Callipers are a great and straightforward way to ensure this is the case. Even though a small inaccuracy of only 0.1 mm might not seem like much, it can cause some major issues with the end result of your print. 

However, when it comes to purchasing filament for your 3D printer, be aware that cheaper products do not necessarily guarantee the same quality that a reliable brand will provide. Even if they may be cheaper, off-brand filament cannot always deliver under specific conditions; very particular temperatures and levels of contamination need to be maintained in order to produce the right material and result. 

Addressing Under-Extrusion Caused by Filament Knots in 3D Printing

Another frequent problem with 3D printing is knots and tangles but luckily, there are ways to avoid them. To fix an existing knot or tangle, it is best to unwind your filament past the origin of the knot and then carefully spool it back up. For future print jobs, using a filament clip can effectively prevent troublesome knots and tangles.

The Nozzle and Hot End Connection: How to Ensure Proper Functioning and Avoid Under-Extrusion in 3D Printing

Under-extrusion can be a nightmare in 3D printing and printers can suddenly start under-extruding without warning. More often than not, the cause of this is a clogged nozzle – a build-up of material blocking the path of plastic going through the printhead. Even just a partial clog can severely diminish quality, so it’s important to keep printheads clean and maintained in order to get the best results for your prints. 

The simplest solution is Cleaning and replacing printer nozzles can quickly negate any potential issues that may arise due to blockage. For minor blockage, a wire brush will do the trick. Additionally, powerful nozzle cleaners are available depending on how bad the clog is, which could help to push out all leftover material from the deep crevices of your printer’s nozzle and reopen its opening.

 Checking the Bowden Tube and Cold End for Under-Extrusion Issues

When you’ve gone through all the usual suspects and you’re still facing under-extrusion issues, it may have something to do with your Bowden tube or cold end. Much like a clogged filter in a car, deteriorated PTFE tubing can essentially create a roadblock between your extruder nozzle and filament. 

It’s simpler than you might imagine removing the clogged filament and a defective PTFE tube from the nozzle. First, take out the collet clip that holds the tube in place. Then, press down on the collet as you pull up firmly on the tube. An optional step to ensure the full dissolving of your filament is heating up your hot end to its typical printing temperature (~200°C). 

However, be aware that this may result in burns should you choose to heat it, so be sure to take extra care when doing this. Furthermore, heating your nozzle will help melt any stuck filament that may remain inside so that it can also slide through the Bowden tube with ease.

Also, accessing the cold end of a printer with a direct extrusion setup is crucial to ensure its printing capabilities. It serves as a gatekeeper, as it ensures that the filament can be pushed through without any blockages.

Troubleshooting Under-Extrusion in 3D Printing: Inspecting the Extruder Gears

Under-extrusion can be caused by many factors, but another common one is uncleaned extruder gears. If you have had a clog before, that leaves residue on the gears which affects its ability to grip and feed the filament. This condition can easily be fixed by doing a quick wire brushing of the extruder gears. Doing this will help ensure the proper gear grip so that filament can be pushed through the nozzle with no issue.

Settings to Adjust 

Boosting Print Temperature

When you are printing with filament, always take into account that the temperature settings may need to be adjusted based on the type of material you are using. It’s common to find discrepancies in the ideal temperature of two different filaments or colours from the same material, so if suddenly your printer stops extruding correctly, your first step should be to tweak your print temperatures. 

To do this slowly and carefully, increase the temperature by 5°C increments until you find a good balance for your particular combination of machine and filament. Test prints can help you identify which setting is best for each one or, alternatively, you can try a temperature tower – one piece that contains several printed sections at different temperatures. This will show you in one go which range works best for your printer.

Optimizing Retraction Settings

Many 3D printing projects can suffer from under-extrusion near their edges, corners and seams. This issue can occur if your retraction settings are not properly adjusted. Too much or too little retraction can cause the extruder to push too little filament through the nozzle. The result is layered which has gaps, bubbles or other imperfections. 

To combat this issue, simply lower your retraction distance by 1 mm and increase the speed of retraction by 5 mm/s until you begin to see it disappear. It is important not to get too aggressive with the adjustment levels as it can cause side effects such as stringing or blobs, so trying to stay within the parameters of 2mm distance and 45 mm/s speed should be used as a rule of thumb.

Enhancing Flow Rate

Fortunately, if all the hardware was properly maintained, yet the settings tips are still not working for you, there is still another solution left to try. This can be done simply by increasing the flow rate (also known as extrusion multiplier) in your printer slicer software. Increasing this setting will push more filament through your nozzle resulting in additional material extruding and fuller prints. 

Tweaking this setting by 2.5% at a time will help you find the perfect spot for your specific filament. Keep in mind that taking the adjustments too far can cause jamming, so it’s best to not exceed 1.1 (or 110%). This holds true for different brands, colours and materials of filament, each of which has slightly different requirements when it comes to the flow rate setting.

It’s important to remember the importance of never adjusting the setting for a successful 3D print if you have successfully printed with the same printer, settings, and materials before. The best place to start when faced with random under-extrusion is checking out any potential hardware issues that may be causing it. 

Gunaseelan Murugesan
Author | Website

Experienced Project Engineer with a demonstrated history of working in the field of Product Design & Development industry in Mechanical Engineering. Skilled in 3D Printing and Re engineering Technologies with CATIA V5 , Materials Science, Finite Element Analysis (FEA), Mimics, ANSYS Workbench and Casting Simulation software. Strong engineering professional with a Master’s Degree focused in Industrial Metallurgy from PSG College of Technology, Coimbatore.

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