Ender 3 severe under-extrusion

• I've been using my Ender 3 for about four months now and it's been working wonderfully. The print quality is amazing and all the prints are very strong. Then about three weeks ago, my entire system crashed while Ultimaker Cura was open and it lost the profile for my 3D printer. I recreated the profile to the best of my ability with other people's working profiles online, but none of them worked right. I've been getting severe under extrusion in all my prints, and they're incredibly fragile. For now, I've just been printing a 1"x1"x1" test cube. I've tried many steps from other people's posts online to fix the problem, including:

1. Raising the print temperature for PLA to 200 °C.

2. Checking the extruder for signs of too little tension or too much tension. I checked, and the PLA has light tooth imprints on it, and no grinding or damage to the filament.

3. Clearing out the extruder. I disassembled the whole extruder assemble, and flushed all the plastic from each part with a heat gun, and metal pick, and then tried reprinting, but it didn't work.

4. Trying a newer Ultimaker Cura version. At the time, I was using Ultimaker Cura 3.1 and hadn't updated because it was working well. I then tried the newest stable release of Ultimaker Cura 3.6, with a few different profiles, and then I also tried the beta version of Ultimaker Cura 4.0, but none of these worked.

5. Increasing the extrusion rate. I incrementally increased the extrusion rate from 100 % all the way up to 130 %. The prints looked a little better and were a lot stronger, but this still didn't fix it.

6. Trying a different slicer. I then downloaded Slic3r and created a new profile in that. The prints turned out a lot better, but there was still significant under extruding.

7. Checking the filament tube for any burns or damage, and ensuring it's inside the extruder assembly all the way.

If anyone can help me figure out what's going on with my printer, I'd really appreciate it!

Here are some pictures of the prints I've been getting:
These were made in Ultimaker Cura with different small changes to the profile made

These were made in slic3r with a flow rate adjusted up to 130%

These were prints I made before I lost all my settings in Ultimaker Cura.

Here's some of the material I read/watched and checked before posting myself:

Edit: Here's my printer profile:

Hi Tinkerman255 and welcome to the 3D Printing.SE! I don't want to rude, but your "good prints" are not that well either. Are you sure it isn't an issue that progressed over time or over the crash? Please do check the filament diameter setting, it fooled me countless times when I changed to a newer Ultimaker Cura version and use both 2.85 mm as 1.75 mm filament intermittently.

I agree with you that the print quality before the crash wasn't the greatest. However, it was very consistent and strong, so I had no complaints. It printed with that quality since the time I got it, so I'm confident it isn't an issue with the hardware. As for the filament diameter, I made sure it's all set correctly, and that hasn't helped either

3 years ago

It is not too rare to create a new machine in Ultimaker Cura to be set to 2.85 mm as this is the default. Also some bugs in the past did reset or assume this diameter unless you manually set it, and unless we know your exact version we can't confirm it is really this.

Underextrusion why?

The 0.55 mm more radius result in an underextrusion due to the pressed through volume, and since $$V=A\times l$$, we need to see the area to see how severe the underextrusion is for one given extruded length. $$A_{1.75}=2.405\text{ mm²}$$ and $$A_{2.85}=6.379\text{ mm²}$$ are rather obvious, so $$\frac {\text{real extrusion diameter}} {\text{calculated extrusion diameter}}=\frac{A_{1.75}}{A_{2.85}}=37.7\ \%$$, so only about 40 % of the needed filament is pressed through the nozzle as the slicer thinks it is almost twice the diameter. This matches well with the 130% still being very spotty, as that'd need a much higher factor to compensate for the underextrusion. A compensating extrusion multiplier would be $$\frac 1 {0.377}=265.25\ \%$$.

Fixing

To fix this, check under filament and set it to 1.75 mm so you force the correct diameter. Remember that filament diameter is not saved in the printer profile but in the material database.

You might need to restart Ultimaker Cura to activate these new settings.

Agreed. It's a classic Cura gotcha.

I created a new printer profile and made sure the filament diameter was set to 1.75". I then made sure the material was set to PLA 1.75". I'm still getting severe under extrusion. Here's my current settings: https://drive.google.com/file/d/10_HiEnVGtU1GS1N-Scy-6KG363BIa31d/view?usp=sharing

None of the settings in this file, or the one on the question, have anything to do with filament diameter.

Also, by my math converting both 1.75 and 2.85 diameters into areas of circular filament cross-sections, 1.75 is less then half the area of 2.85. You'd need 204% extrusion to make up for the incorrect setting.

Finally, there was a bug in Cura where it would _ignore your filament setting_ if you did not have a specific material selected, and revert the default 2.85. I believe this was fixed, but not knowing what version of Cura you have, make sure you actually select a material, and the filament size is set for that material.

@JoelCoehoorn corrected, I messed a factor 2 somewhere...

Okay, I figured out what the problem was and it is twofold: In Cura 4.0 changes to your filament selection don't seem to take effect until you restart Cura. After I did this, the filament diameter was correct and that helped a lot with the print. Secondly, I noticed the lever that controls the feeder pressure was wiggling, and so I tightened that bolt. Those two things combined lead to the atrocious prints I was getting. Now everything is working perfectly!

@Trish BTW, the problem was that you should've divided the area of the 2.85" diameter filament by the area of the 1.75" diameter filament. This would've given you the correct extrusion flow rate of 264.7%. Instead, you have the numerator and denominator flipped.

@Tinkerman255 Beware that it isn't inch ("), but the diameter is in millimeters [mm]. But you loose the unit once you divide the two. (One inch is 25.4 mm)

@Tinkerman255 please do not post files from external websites. If you must, please include the key portions in the question, as the question will not be able to stand the test of time when the file link is removed.