Ender 3 V2 has started under-extruding on me

After a couple months of really good performance from my new Ender 3 V2, I started getting sporadic under-extrusion in my prints this week. I had ordered a Capricorn Bowden tube a while back and I just installed that this morning; however, that didn’t fix the problem. Here is what the stock Bowden tube looked like:


By the way, when I pulled the cover off the hot end assembly, the cooling fan was free-floating. They used screws that are too short. I replaced those with longer screws:


However, the Capricorn upgrade didn’t fix my problem.

I can see & feel the extruder skipping. What I mean by that is that the extruder stepper turns to feed filament, but the filament slips and doesn’t always go into the Bowden tube. Sometimes the skips are louder and sometimes I don’t hear it at all and can just feel the slip happen.

I was getting ready to order a replacement hot end, but then I noticed this: That spring-tensioner screw in the extruder isn’t supposed to be screwed out like that is it? I assume I should screw it in tight, right?


Yeah, that didn’t work. I tried screwing in that extruder spring screw and the problem is actually worse now. Short Video of the skipping.

Any ideas?

You will probably get far better prints now, as a loose fan has a huge impact on a print. I had my e3D hotend fan being able to rotate 30°, which on first sight does not matter as it cools the same in any position, but the print looked terrible. When the tool head was turning 90° the fan must have bounced and cause a temporal layer shift of 0.1mm just by vibration. I would not have believed it, but after I just locked the fan under the fat heater wire, the next print was perfect. This little thing, just a few grams in weight made such a difference, just by dodging a little left and a little right.

I made sure the heater and thermistor wires are fully seated. Those look ok, right?

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The look OK to me. Have you tried pulling the Capricorn tubing & nozzle, cleaning out the filament channel, then replacing the nozzle with a new one?

Before I installed the Capricorn, I ran the de-clogging wire that came with the printer through the head end all the way out the nozzle. I did it a couple of times cleaning the PLA off the wire tool between each try.

I don’t have a spare 0.4 mm nozzle. The other one that came with the printer must be smaller because the wire doesn’t fit through it.

By the way, today I ordered a Swiss all metal hot end and it will be arriving on Monday. Just continuing to debug this to see if I can get it working to print this weekend. The print that I showed in the video above was completely terrible–there was barely any PLA on the print bed after it had tried to print a couple of layers.

That terrible print was with black Hatchbox PLA. I changed to white Hatchbox PLA and I seem to have it declogged for now. Printing a test print as I type…

I’m still not sure about that extruder spring screw I showed in the original post. Is that supposed to be screwed in all the way?

Unfortunately, the cleaning wire doesn’t really clean out the channel above the nozzle, or even the channel in the nozzle just above the nozzle opening.

To test filement flow I move the hotend to the center of the bed, usually be hand, lower the bed to 100 (in your case, raise the head to 100), connect to the printer over USB, then issue a G91, followed by G1 E100 F200. If the filament flows out easily & smoothly, I continue on to printing. If not, I look into cleaning out the filament path. In fact, I’m working on that today.

Yeah, I think something is still wrong. The BLTouch/Smith3D did its 5x5 bed leveling and then printed this


The best square looks good:


But there were a couple that were starved of filament:


You best square looks, to me, as though the nozzle is just a tiny bit too close to the bed.

BTW, for photos like the one of the entire print bed, you might be interested in utilizing Focus Stacking.

I did the test and it looked like a smooth extrusion to me. Video here.

How does one clean the channel above the nozzle and nozzle opening?

I agree, that filament flow seems to be good. So, then, something is impeding the flow. Hmmmm, maybe the nozzle is too close to the bed?? :smiley: :smiley:

I would try printing a single square, adjusting the Z Offset by +0.05mm 2 or 3 times as the diagonal lines are printed inside the square.

I think it was some kind of clog that finally worked its way out. Before starting my trouble-shooting, this kind of thing was happening:

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That’s 5 layers of printing that is passing light in that photo.

After changing to the Capricorn Bowden tube and fixing that loose extruder screw (??? I’m still not sure whether I was supposed to it in all the way) and fixing my loose fan, matters got worse to the point that almost no filament was making its way out of the nozzle and the extruder was slipping loudly.

But after I changed filament after the terrible print I think the nozzle finally passed its kidney stone and now I’m back in business. I printed these later today and they came out very good.

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The good news is that clog caused me to get the Capricorn upgrade done and got the Swiss all metal hot end ordered. :slight_smile:

Thanks for the help.