[Resuelto] Underextrusion  

RE: Underextrusion

There are a few things to check. Do you have 1/4 turn preload on the short PTFE tube? Is the idler tension of the extruder correct? If you remove the bowden tube from the hot end, can you manually feed filament through the hot end without a lot of force at a more normal PLA temperature?

RE: Underextrusion

My Mini finally arrived on Thursday and it worked like a charm for the past couple of days. Until this morning. I tried to print the included whistle to test it out and after roughly the first layer the printer stops extruding and the extruder starts to make loud clicking noises. I tried multiple filaments (all PLA) and none of them work. 

I suspect I have the same issue as in this topic but I can't remove the bottom part of the bowden tube connector near the hot end. Does anyone have any tips? 

RE: Underextrusion

How far did you get with disassembly? Specifically, is the filament already unloaded? If you do the unload procedure and help the filament a bit by pulling on it where it goes into the extruder you can help the extruder grip despite the gear having ground down the filament.

Using the wrench that's part of the kit while holding the heatsink should get it loose (remember, righty righty lefty loosy), unless the person at prusa doing the assembly used more force than was necessary. Then I would use some penetrating oil (for getting stuck bolts loose), apply it and let it sit for a few hours.

RE: Underextrusion

The filament is completely removed. I didn't get far with the disassembly. I just removed the bowden tube. I couldn't find the right size allen key to remove the grub screws on the heatsink 

RE: Underextrusion

I'm also experiencing the loud clicks with signs of underextrusion. I'm guessing that the extruder is having trouble catching the filament.

I just ordered the Bondtech extruder upgrade kit, so hopefully that helps with this issue.

RE: Underextrusion

Posted by: @omari

I'm also experiencing the loud clicks with signs of underextrusion. I'm guessing that the extruder is having trouble catching the filament.

 

I just ordered the Bondtech extruder upgrade kit, so hopefully that helps with this issue.

My problem wasn’t the extruded. Although it seemed like it failed at the extruder I wasn’t able to push pla through the hot end directly. 

I contacted Prusa support for my problem and with their help I was able to get the screw off. My mini is printing at the moment en everything seems to go well but only time will tell 

RE: Underextrusion

My issue has been solved - the issue was that both the installed and spare PTFE tubes were cut short from factory by a few mm.  I found some replacement on Amazon, cut to specified length and reassembled per Prusa knowledge base. 

RE: Underextrusion

Just wanted to thank you all for your excellent fix to my July shipped Mini, so this is still a live issue. @brad.w2 video fixed everything. All three of the grub screws were fully stripped from the factory, but I was able to remove them with a torx bit that was able to get some purchase and raise my hot end which completely solved my issues with the printer (complete failure to extrude anything).  

I replaced the grub screws with M3 4mm Button Screws and was very careful to tighten them but not over tighten them. Totally solved everything and the printer is printing like a dream. Thanks!

RE: Underextrusion

I get this on occasion.  The last time I got it, I used cleaning filament.  

1. Heat the hotend to remove the clogged filament.  
2. Remove the PTFE brass connector from the hotend.
3. Directly feed cleaning filament by hand until it comes out the nozzle.  
4. Wait 2-3 minutes.
5. Feed-in 2-3 inches of cleaning filament.  
6. Unload the cleaning filament.  
7. Load your desired filament and print.  

This works for me.  

RE: Underextrusion

@nvgg-creations

How did you get hold of Prusa to send the new heatbreak? I emailed them last night and have no response. The chat feature seems to be gone from the store, and the time difference between Prague and the U.S. makes it difficult to call. 

RE: Underextrusion

@hamstermann

Heat break is just one possible cause.  

RE: Underextrusion

I hope it's not a problem that I dig out this rather old topic, but I had the same issue and wanted to share my experience in solving the problem.

After assembling my Prusa Mini+ Kit, I printed a small smiley as my first print job. It came out flawlessly and I had no issues at all. The next day, I wanted to print another small object and this is were I started hearing clicking noises from the extruder and having underextrusion problems. At first, I thought the Extruder assembly was the culprit, so I disassembled it, cleaned it and put it back together. I also adjusted the pressure on the filament with the help of the idler.

After trying the print a second time, I got the exact same issue, so I disassembled the Extruder again, cleaned it and made sure that the pulley was securely mounted on the motor shaft, which it was. But this also didn't solve my issue, so I turned to Google and found this thread, which was very helpful. Thanks to everyone who contributed to this thread and shared all the information!

Since I ended up doing things a bit differently, here is my guide:

1. Remove the Bowden connector at the top of the extruder. If filament is still loaded, unload it first.

2. Remove the short PTFE tube.

3. Heat up the hotend to 270 degree and do a cold pull, as described in this article: https://www.help.prusa3d.com/en/article/cold-pull-mini_126399 That way, I got the heatbreak really clean and there were no filament particles remaining.

4. Loosen the three grub screws on the heatbreak and push the hotend up until there is around 1 mm between the threads on the hotend and the heatbreak.

5. Tighten the grub screws while holding the hotend with your other hand.

6. Check that the short PTFE-tube has the correct length (tip: use the diagram on the bag with the spare parts to measure the PTFE-tube). If the PTFE-tube is too short, use the spare one provided in the kit.

7. Insert the short PTFE-tube into the heatbreak and push it down as far as it will go. Don't use excessive force!

8. Tighten the Bowden connector at the top of the extruder. Use the wrench to screw it in.

9. Readjust the height of the MINDA probe according to the assembly manual (Chapter 7).

10. Calibrate first layer (Menu -> Calibrate -> First Layer Calibration).

11. Cross your fingers that everything works!

After wasting a couple of hours on fixing the problem, my Mini is now printing since 45 minutes and no issues have occurred so far. When the problem began, the printer started having issues in the first couple of minutes, so I think this is a good sign.

If you encounter the same problem, I hope this guide helps you to solve the problem. Honestly, I think this is an issue Prusa could resolve with better Quality control. I know that they have many orders on hold and the production is probably running at 110 %, but I would have happily waited a couple more days for delivery instead of having to deal with this issue. Even though it seems like I solved the problem on my printer, I was a bit disappointed, since the printer is one of the more expensive printers in it's class. But now it prints nicely and I will definitely keep it, but maybe this is something Prusa could address in the future. Please understand it as feedback and not as an insult.

Again, thanks to everyone who contributed to this thread!

RE: Underextrusion

Thank you for this!! You saved me so much frustration. Th printer is running spectacularly now.

RE: Underextrusion

I swear to God... The majority of my issues with the MK3S, Mini (Older and Plus versions) and even a Prusa Bear upgrade is that goddamn PTFE that goes into the hot end. I did it the Prusa way for the Mini and it was only until I watched Steam Labs video where they friggen shove the whole hotend upwards did I get the Mini to work properly. Straight up, I got another Mini but have an original Mosquito hotend and I a swear it is plug and play. Have not had a single jam, underextrusion or that goddamn clicking noise.