3d Printing Troubleshooting Guide- Under Extrusion

Print Layers Look Uniformly Thin/Weak (Under-Extrusion)

What’s the problem?

Under-extrusion often leads to thin layers, unwanted gaps, and even missing layers.

Why is it happening?

There are several possible causes of this issue. The diameter of the filament used may not match the diameter set in the slicing software. The amount of material being extruded may be too low owing to faulty slicer software settings. Alternatively, nozzle blockage may impair the flow of material.

3D Printing Troubleshooting

Check the Filament Diameter

Identify the filament diameter (typically on the box) and check the slicer settings to ensure they match.

Measure the Filament

If filament flow is still an issue, use a set of calipers to double-check the filament diameter as the listed value may be slightly off. Use this measurement to update the diameter setting in the slicer software.

Check Hot End for Debris

Check that the nozzle is clear from built-up filament and dirt.

Set the Extrusion Multiplier

If there is no mismatch between the filament diameter and the software setting, then the extrusion multiplier (or flow rate/flow compensation) may be too low. Increase this value in increments of 5% until you the problem no longer occurs.

Print Looks Melted/Deformed

What’s the problem?

The print layers seem uneven but are actually melted together. Additionally, holes may be printed unevenly with melted material affecting the shape.

Why is it happening?

This is typically the result of an overly hot end or high temperatures. 3D printing requires a fine balance between melting the filament to ensure adequate flow and allowing the filament to set quickly so that the next layer can be applied to a solid surface.

3D Printing Troubleshooting

Check Recommended Material Settings

Check that the correct material settings have been input into the print software. Filament temperatures can range from 180 to 260 ℃, so it is somewhat common to forget to update temperature settings.

Decrease Hot End Temperature

Decrease the hot end temperature. Depending on the severity of overheating, decrease the temperature in 5 ℃ intervals.

Increase Print Speed

Slightly increase print speed and check whether the filament is setting sufficiently between layers.

Adjust Fans

Check that the cooling fans are directed at the hot end in the correct position. If possible, increase their speed to increase airflow over the filament.

Pits and Hollows in Top Layer (Pillowing)

What’s the problem?

The surface of the print shows bumps or holes.

Why is it happening?

This often occurs due to improper cooling of the top layer or an overly thin top layer.

3D Printing Troubleshooting

Check the Fan Position

Check that the fans around your hot end spin consistently throughout the print, particularly toward the end of the print. If they appear to be functioning fine, then the issue may be that they are not directing sufficient airflow over the print. Many 3D printable mods are available to alter your print airflow.

Set Fan Speed in G-Code

Another cooling issue occurs when each successive top layer of molten plastic is applied. As it covers the inner support structure, it requires rapid cooling to avoid falling into the holes between the supports. Fan speed can be adjusted in the G-Code.

A common G-Code for Fan On is M106 and that for Fan Off is M107. With those control lines, set the fan speed to maximum for top layers.

Increase Top Layer Thickness

Most applications will enable you to increase the thickness of the top layer in the advanced section, using the “Bottom / Top Thickness” setting.

Typically, 6 layers of material is desirable, with up to 8 being recommended for smaller nozzles and filament. If your layer height is set to 0.1 mm, set the “Bottom / Top Thickness” setting to 0.6 mm. If the effect of pillowing remains, increase it to 0.8 mm.

Filament Size

Pillowing can affect all 3D printers; however, it is far more common when using 1.75 mm filament. If this problem persists, switch to 2.85 mm filament.

Web-like Strings Cover the Print (Stringing)

What’s the problem?

There are unsightly strings of material between parts of the model.

Why is it happening?

When the print head moves over an open area, some filament drips from the nozzle causing strings to develop.

3D Printing Troubleshooting

Enable Retraction

Retraction settings affect how the filament is moved back into the nozzle before the head moves to avoid molten filament from trailing behind the head, causing thin strings or scars to develop.

Most applications like Cura offer one-click activation. If the standard settings are still producing minor stringing, fine tune the settings for your specific print.

Minimum Travel (mm)

Reduce the minimum travel in 0.5 mm increments until stringing has stopped.

Cut Strings

If the strings do not heavily influence the overall quality or structure of the print, wait for the print to be completed and simply remove the strings using a small blade.

Print Has Lost Dimensional Accuracy

What’s the problem?

Linear components of the print are not aligned, holes are inconsistent, or symmetrical components are not the same.

Why is it happening?

A disparity in set units (such as mm, cm, or in) between the printer and slicer software can cause accuracy issues.

Issues with dimension measurement in the model software may also be to blame. Disparities between connective pieces can also cause this problem.

If the issue is not associated with problematic modeling decisions or unit disparities, axis balance, bed leveling, and printer configuration are likely culprits.

3D Printing Troubleshooting

Check Working Unit of Measurement

In your 3D printing application, check that the correct, real-world dimensions (e.g. mm or cm) are selected.

Check Measurements

When designing connective components, double check your measurements and use a digital caliper.

Over-Scale Screw Holes

When printing screw holes, create a virtual 3D M5 screw with a diameter that is slightly larger than it should be to create a Boolean subtraction from the point in the model at which the hole should be.

Increase Polygon Count

Reducing the polygon count of your models can cause issues by inducing slightly flattened edges. Keep polygons under a reasonable number for smoother gradients and better fit.

Test Printer Accuracy with Test Cube

Print a calibration cube to check the X, Y and Z dimensions of your print and ensure that the printer is functioning well. If minor adjustments are needed, level the bed and check the print head before attempting to print your model again.

Check Nozzle Temperature

Melted material over holes can produce the appearance of dimensional accuracy problems. Try reducing your print temperature if stray extrusion is observed inside the holes of your model.

Check Belts and Rails

Check the belt tension and ensure all components are correctly aligned.