Under Extrusion Help

[PatrickM 0]

I've asked this before and have got no useful help. How do I fix under extrusion? I've tried every method that the troubleshooting guide has to offer, and I've replaced all parts of my hot end. What is my printer's problem? I print PLA at 210 degrees on Ultimaker 2.

[fbrc8-erin 316]

Hi, Patrick,

Have you replaced the bowden tube recently? You can experience wear and tear with it over time, or have debris like ground up filament work it's way into it, causing the filament not to move smoothly.

The first place to look at if all the hardware is good would be your settings in Cura to determine your volumetric extrusion rate. You calculate this by using your nozzle width X layer height X print speed to get your extrusion rate in mm^3/second.

8mm^3/s running PLA at 230 C is considered a pretty healthy extrusion rate for this test. You can download the gcode here, which will automatically set the temperature 230 for this print: https://www.youmagine.com/designs/test-print-for-ultimaker--2

This should give a baseline for how much under extrusion you're seeing, or whether the issue may be related to the gcode.

If you're towards the end of a filament reel and it's very tightly wound, you might also start to see some under extrusion because the printer is having to work harder to unwind it and get it through the bowden tube.

You mentioned replacing parts of the hot end--is your fan shroud touching the nozzle? If it is, it will act as a heat sink, and can cause under extrusion.