Battling the Thin Layers: Understanding and Resolving Under-Extrusion in 3D Printing


Under-extrusion is a frustrating obstacle that can hinder the quality and integrity of 3D prints. It occurs when the 3D printer fails to extrude the expected amount of filament, resulting in thin layers, gaps, and overall compromised print quality. In this article, we’ll delve into what under-extrusion is, explore its root causes, and discuss effective strategies to identify and address this common issue in 3D printing.

What is Under-Extrusion?

Under-extrusion in 3D printing refers to the insufficient deposition of filament by the extruder, leading to weak and inconsistent layers in the printed object. The resulting print may exhibit gaps, poor layer adhesion, and an overall lack of material in certain sections.

Causes of Under-Extrusion:

Clogged or Partially Blocked Nozzle:

A common cause of under-extrusion is a nozzle that is clogged or partially blocked. This obstruction restricts the flow of filament, resulting in reduced material deposition.

Incorrect Extrusion Settings:

Inaccurate extrusion settings in the slicer software or firmware can lead to under-extrusion. This includes incorrect filament diameter settings, insufficient extrusion multiplier, or improper steps-per-millimeter calibration.

Filament Issues:

Low-quality or improperly stored filament can absorb moisture, causing it to swell and jam the nozzle. Inconsistent filament diameter can also contribute to under-extrusion.

Tension Issues in the Filament Path:

Excessive tension or friction in the filament path, such as tight filament spooling or misaligned filament guides, can impede the smooth flow of filament, leading to under-extrusion.

Worn or Damaged Extruder Components:

Components of the extruder, such as a worn-out drive gear or a damaged hobbed bolt, can compromise the grip on the filament, resulting in under-extrusion.

Print Speed and Temperature:

Printing too fast or at incorrect temperatures can affect the melt consistency of the filament. Inadequate heating or excessive cooling can contribute to under-extrusion issues.

Retraction Settings:

Incorrect retraction settings, such as excessive retraction distance or speed, can lead to filament retraction beyond the extruder’s ability to recover, causing under-extrusion.

Strategies to Combat Under-Extrusion:

Check Nozzle and Hotend:

Ensure that the nozzle and hotend are free from clogs or obstructions. Perform regular maintenance by cleaning or replacing the nozzle as needed.

Extrusion Calibration:

Calibrate the extrusion settings in the slicer or firmware to match the characteristics of the filament being used. Adjust the extrusion multiplier and steps-per-millimeter values accordingly.

Verify Filament Quality:

Use high-quality and properly stored filament to minimize moisture absorption and ensure consistent filament diameter. Check for any signs of tangling or knots on the filament spool.

Filament Path Inspection:

Inspect the filament path for any points of excessive tension, misalignment, or friction. Ensure smooth and unobstructed filament movement from the spool to the nozzle.

Extruder Maintenance:

Regularly maintain and inspect extruder components. Replace worn-out parts such as drive gears and hobbed bolts to maintain a reliable grip on the filament.

Temperature and Speed Adjustments:

Experiment with temperature settings to find the optimal range for your filament. Adjust print speed to ensure that the extruder can keep up with the desired material flow.

Retraction Optimization:

Fine-tune retraction settings to minimize unnecessary filament retraction, preventing the extruder from losing grip during the print.


Under-extrusion is a common challenge in 3D printing, but armed with an understanding of its causes and effective mitigation strategies, enthusiasts can overcome this obstacle. By maintaining a vigilant eye on printer components, filament quality, and extrusion settings, users can ensure consistent material deposition and achieve high-quality prints. Remember, troubleshooting under-extrusion is often an iterative process, and patience combined with systematic adjustments will lead to more successful and satisfying 3D prints. Happy printing!

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