I have been struggling with serious under-extrusion on my Ender 3 for a while now. I tried changing out the extruder, swapping hotends, new PTFE tubing, cleaning the hotend, new nozzle, and changing the print temperatures by a lot, but nothing seemed to work. I suspected the extruder was not producing enough force, but blindly swapping out parts was not giving good results.





Finally out of desperation I came up with a novel way to measure the force output of the extruder. Basically I pulled the nozzle off the hotend, blocked up the z-axis so it could not move up, and extruded a length of fillament into a scale placed on the bed. From there I can directly measure the extruder force. I combined this test with the new dual drive extruder from Creality and was able to dial in the spring tension to triple the force over the default extruder. That seems to have cleaned up my under extrusion for now. I do think the extruder is only half the issue, the hot end also is poorly designed and tends to clog up.