Under Extrusion How to Fix it Now

Explore our in-depth guide on solving under extrusion in 3D printing, covering effective methods like the cold pull, precise filament measurement, and more.

by Editorial Staff: We are a team of 3D Printing Enthusiasts who have build a lot of knowledge about 3D Printing the last 8 years. Our aim is to create the knowledge hub for 3D Printing covering all minor and major topics. Providing one source of reliable Information for everybody regardless of Beginner or Expert.

Under extrusion in 3D printing can be a frustrating issue, hindering the quality of prints. To address this, we’ve compiled a detailed guide covering the primary causes and solutions for under extrusion, ensuring that your 3D printing projects achieve the highest quality.

Understanding Under Extrusion: Causes and Effects

Under extrusion occurs when a 3D printer fails to supply the correct amount of filament. This can result from various factors, including a clogged nozzle, slipping extruder gear, or incorrect filament diameter/extrusion multiplier settings in your slicer program​​.

The Cold Pull Method: A Step-by-Step Guide

One effective way to address a clogged nozzle is the cold pull method. This technique is particularly beneficial for slippery, soft materials like Nylon filament. The process involves heating the hotend to the working temperature of the filament, pushing it through until the previous material is cleaned out, and then allowing the hotend to cool down. This process is typically repeated two or three times for optimal cleaning​​.

Precise Filament Diameter Measurement for Optimal Printing

Ensuring the correct filament diameter is crucial. The most common diameters are 1.75 mm and 2.85 mm, each with their specific tolerances. To ascertain the correct diameter, measure the filament with a caliper at several points and calculate the average. This value should be used to adjust the filament diameter or extrusion multiplier settings in your slicer program​​.

The Needle Method: Clearing Nozzle Blockages Effectively

For stubborn nozzle blockages, the needle method can be highly effective. This involves using a small needle, typically an acupuncture or hypodermic needle, to physically remove the blockage. It’s crucial to use a needle that fits the nozzle bore and to avoid using drill bits, which can cause permanent damage. The nozzle should be preheated to the regular printing temperature for this method to be effective​​.

Addressing Slipping Extruder Gear Issues

A common cause of under extrusion is a slipping extruder gear. This issue can be identified by the presence of small plastic chippings from the filament. Solutions include increasing the nozzle temperature by 5-10 degrees to facilitate smoother plastic flow and adjusting the printing speed. Additionally, ensuring the cleanliness of the extruder gear is essential to prevent further slipping​​.

Expert Insights and Tips

Our team, consisting of seasoned 3D printing enthusiasts with over eight years of experience, recommends regularly maintaining and calibrating your 3D printer to prevent under extrusion. Regular checks of the filament quality, nozzle cleanliness, and extruder gear condition can significantly improve the overall printing quality.


What is under extrusion in 3D printing?

Under extrusion occurs when a 3D printer does not supply enough filament, leading to poor quality prints. It can be caused by various factors like clogged nozzles or incorrect filament settings.

How can I perform the cold pull method for clearing a clogged nozzle?

Heat the hotend to the filament’s working temperature, push the filament through, then cool down the hotend. Repeat until the filament comes out clean, usually after two or three passes.

Why is measuring the filament diameter important?

Accurate filament diameter measurement ensures the printer uses the correct amount of material. Use a caliper to measure at several points and calculate the average for precise settings.

What should I do if my printer’s extruder gear is slipping?

Increase the nozzle temperature by 5-10 degrees for easier filament flow and adjust the printing speed. Also, clean the gear to remove any plastic shreds that might cause slipping.

Can I use a drill bit instead of a needle for the needle method?

It is not recommended to use a drill bit, as they can break easily and potentially damage the nozzle. Use a small acupuncture or hypodermic needle that fits the nozzle bore.

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