Hey. A couple weeks ago I got my old ender 3 pro out of the basement and have been trying to get a decent print with it ever since. I managed to print out one benchy without issue, but ever since then every print I do would be plagued with awful underextrusion.
I’ve replaced a few parts, including the hot end and the nozzle, and even did this one hack someone suggested where you put a piece of PTFE tubing in the hotend, but no matter what the issue persists. My thought was it might be the creality filament I ordered, so I ordered a spool of hatchbox filament. But the problem ended up being worse on the hatchbox filament. I’ve put both in a filament dehydrator but it’s made no difference. Both spools have tough sections along them that don’t seem to melt as easily when I pull them out of the extruder, so I’m thinking that might have something to do with it.
Turning the print speed down and increasing the flow and temperature yielded better results, but it was still underextruding on every other layer.
I want to know if there’s something I can or should do before I just give in and buy another roll of filament. I’ve probably spent enough at this point to buy a better printer, but I guess that’s sunk cost for ya.
Edit: SOLVED! I just forgot to tighten the extruder tension arm, now it’s working perfectly. Thanks to @brettvitaz@programming.dev
Check the extruder tension arm. If you have the plastic one it may be cracked.
It’s metal, and it seems fine. I’ll try adjusting it for a bit more tension and see if that works.
Edit: nevermind it is plastic. But still, seems fine.
Note that the brass toothed gear can also wear out. Maybe check it to see if there’s a lot of ground-up filament in the teeth? Then check the fitting where the bowden tube goes into the extruder, make sure that isn’t loose (it will be seen moving back and forth during retractions in a print). Also worth checking the bowden tube itself, make sure it’s not causing a lot of drag on the filament passing through it. And for that PTFE mod in the hotend, check the friction there, it’s possible to over-tighten the fitting and partially crush that tubing. You should be able to easily push filament through the hotend by hand once it is up to temp.
I assume you have something other than the stock setup for your filament roll to reduce the drag there so it’s not being pulled into the extruder at a 90-degree angle? There are a number of extension arms you can print to change the angle, but the best methods are either to move the filament spool off to the side (where the filament can enter the extruder in a straight line), or print a roller that uses a bearing for changing the angle in combination with a full bearing-supported roller that the filament spool itself sits on. I still have mine in the stock position on top of the frame but with the combination of bearing objects in the last option I have practically zero friction pulling the filament into the extruder.
Finally, when was the last time you calibrated your E-steps? It’s likely you actually have underextrusion on all layers, but they’re getting smoothed over and are not as obvious on the alternate layers. Never hurts to check this step.
tl;dr: eliminate all friction from the spool to the hotend, calibrate E-steps.
Thank you. I recently replaced that gear as well, and the problem has gotten a bit better. I’ll be sure to check everything you just mentioned.
I tightened the tension arm and now it’s clicking when it reaches a piece of filament that isn’t extruding fast enough. So I think that means it’s an issue with the hotend not heating the filament fast enough. I’ll check the friction of the mod though just to be safe, and I don’t think I ever calibrated my E-steps, so I’ll have to do that.
Adjusting the tension arm seems to have helped a lot, so I think you’re on to something.
Yeah you don’t want the arm TOO tight or you just create another friction issue. I generally find if you have a very consistent under-extrusion then it’s likely the E-steps, but if the issue seems more random (some layers are great, only certain corners are bad, etc) that it comes down to friction somewhere in the line. Good luck!