[Chiuso] Frequent Filament Jammed at Extruder  

RE: Frequent Filament Jammed at Extruder

There are several possible causes.  

0) Kit or assembled by Prusa?

1) Insufficient tension on the filament (idler adjust screw/idler shaft/dirty Bondtech teeth)

2) Warm printing environment (room > 25c)

3) Complex part (retractions)

4) Nozzle temperature and control (nozzle flow exceeds extruder limits)

So a picture of a failed part is worth 1000 words.  Be sure to use the LINK TO : MEDIA FILE option when uploading.

RE: Frequent Filament Jammed at Extruder

Hi Mahadar,

I have a similar problem but as tim-m30 said you should provide more information about your setup.
Today I checked my IR sensor under Support -> Sensors and realised that it was flickering instead of a steady signal so you might want to check yours as well by feeding filament manually into the extruder.

Another possible jam reason might be the MMU if you are using it. I'm not quite sure but mine could have locked the filament in place which would as well result in filament grinding inside the extruder and the clicking noise.

RE: Frequent Filament Jammed at Extruder

Hi tim-m30,

Thanks for the reply.

I got the MK3s kit and will check again for your point 1 to  5 once my PTFE tube delivered by tomorrow. It has been damaged by the jammed filament and I have dissembled while waiting for replacement. Hope the attached image of the incomplete printed part will help for rectifying the issue. The printing took 8 hours and the last extruder location was its home position. Don’t seem any messed or stringing filament on the nozzle. But I noticed again the filament jammed once I tried to do First Layer printing, nothing from the nozzle coming out during the print.

RE: Frequent Filament Jammed at Extruder

Hi Timo-c

The IR status is static at 1 and am not using MMU yet. Still learning with single material printing 🙂

Thanks.

RE: Frequent Filament Jammed at Extruder

When you reinstall the new PTFE - triple check - make sure the PTFE collet is TIGHT, firmly pulled up, to lock the PTFE in place.  It is best to use a collect clip to secure the PTFE.  Without the clip it is quite easy for the collect to slip loose when installing the heat sink into the extruder.

You can print one, too:

https://www.thingiverse.com/thing:2585970

RE: Frequent Filament Jammed at Extruder

Hi guys,

I have exactly the same problem. I have the kit of MK3s self assembled 3 weeks ago. First prints were quite flawless after figuring out that correct Z-levelling and resulting perfect first layer is the key to success. With first prints I mean I printed approx. 900g of Prusament orange PETG and 500g of Prusament PLA Galaxy purple without any problems. 
But my last print with Prusament PLA Galaxy purple failed because after 90% printing correctly suddendly no material was extruded anymore.
The filament got clogged and I had to remove it manually (disassembling the extruder) because filament extraction per software would not work.

Now I switched to Colorfabb  PLA-PHA chocolate brown and experienced problems with poor printing results (first layer did not stick). I tried the pre-installed filament profile for Colorfabb PLA-PHA but it did not help. Therefore I tried to print a temp-tower to find at least the best temp settings. But after second level of the temp tower (225°C and 220°C were printed), the print "stopped" at 215°C. It did not really stop but in the middle of this level the extruder stopped extruding filament. I stopped the print then manually because the extruder drove its lines extruding just hot air into the air. This happened the second time now and I don't know why???
(Same happened with Prusament Galaxy purple PLA, so this issue does not seem to be filament related)

I checked the stock 0.4mm nozzle and flamed it out just to be sure everything is clean here. After disassembling the extruder I spotted the problem within the PTFE tube which seemed to be melted down on its tip so the diameter was shrunk and the filament could not pass through anymore. I changed the PTFE tube but the same problem occured right in the very first print after changing the PTFE tube (temp tower for PLA-PHA 225°C down to 185°C). It seems the PTFE tube is clogged again because the diameter at the tip has shrunk down and filament cannot pass through. Why is my PTFE tube suddenly destroyed all the time? What can I try to fix this?

According to TIMs checklist. 

0) I assume I assembled everything correctly because I have already printed a lot of things with PETG and PLA without problems (prints ranging from 20m up to >20h).

1) Tension on the filment seems fine. The experienced "tic tac noise" comes from the shaft unsuccessfully trying to drive the filament through the clogged PTFE tube towards the nozzle.

2) Room temp >25°C 
Yes, here in Germany it became warmer the last days but as I have built myself an IKEA enclosure, the ambient printing temperature is usually above 25°C due to the warming of the heated bed. When printing with PETG, I also always had used the pre-installed slicer settings which use significantly higher temperatures for printing and bed heating and everything has worked perfectly. So I don't see why this should be relevant here?

3) Complex part
As Mahadar already stated, even First Layer Calibration print fails because no filament is extruded.

4) Nozzle temperature and control (nozzle flow exceeds extruder limits)
Ok. PLA-PHA filament recommends printing temp of 190-210°C. But does starting with 225°C lead to exceeding the extruder limits? I do not think so, because the print result of the first two temp-tower levels (225-220°C) do look pretty descent. 

Does anybody has other suggestions what to do or try to find the root cause of this problem, which seems to be deformation of the PTFE tube.

Thanks a lot for your help in advance and best regards,

Patrick

RE: Frequent Filament Jammed at Extruder

If the hot end heat sink collet is not tight, the PTFE is free to rise and be chewed by the Bondtech gears whenever filament is unloaded. That in-turn makes feeding filament more difficult.  Just one of the possibilities.

Printing in an enclosure with high ambient temperatures can also cause issues.  The E-motor runs 30c  higher than ambient. So a 50c ambient will make the Bondtech gears approach 80c ... enough to soften some PLA.

The problem is finding what is causing the issue in a random sampling of very different installations and applications.  It's probably not a single root problem in all cases.

In another thread with this exact issue I am asking for help - asking a few simple question to try to find a common theme...

============

To all of you suffering this filament meltdown with jams in the PTFE tube.  Can I get some survey answers?

Printer: MK3 / MK3S / MK3 MMU / MK3S MMU

Material being printed: PLA / PETG/ ABS / NYLON

Nozzle Temp: 210 / 230 /250 /270 /290+ (pick closest)

Enclosure: Y/N 

IR temp of extruder motor case:  55c / 65c / 75c / 85c+   (if possible)

Ambient air temp around printer:  25c / 30c / 35c / 40c / 45c+

Thank you in advance ...

:

RE: Frequent Filament Jammed at Extruder

Here's for mine.

Printer:  MK3S 

Material being printed: PLA (before this have no issue with PLA and PETG)

Nozzle Temp: 210 

Enclosure:  Yes, I'm using the lack table enclosure (as Mikolas Zuza's article) but I have tested removing the top enclosure, still with same issue.

IR temp of extruder motor case:  55c / 65c / 75c / 85c+   (if possible) Please advice for obtaining this temp. Could not find from the menu options.

Ambient air temp around printer:  at time I measured is about 30c 

Thanks to Tim, I have successfully printed this collate clip (  https://www.thingiverse.com/thing:2585970  ) and will put it on.

RE: Frequent Filament Jammed at Extruder

Hi Tim,

here my data:

Printer: MK3S (MMU will be delivered next week ;-))
Material being printed: PLA-PHA
Nozzle Temp: 210-220
Enclosure: Y
IR temp of extruder motor case:  not measured
Ambient air temp around printer:  35c

Sleeping over my first long statement above, I have to correct that problems ocurred after fully installing the enclosure. I printed in the enclosure before with good result but at that time without plexi windows which were delivered late. 
Today I checked the PTFE again and is was not damaged this time (only clogged). Nevertheless the temp-tower print had severe problems last night printing without extruding. Perhaps the gcode is corrupted because I did a mistake setting up the makro code for the temp-changes? I would like to proof this, printing something else with Colorfabb chocolate brown PLA-PHA. But whatever I did, I could not find a setting which correctly prints this filament. Every time the edges of the first layer lines are delaminating when print direction switches 180 degrees (like in printing a rectangle with meander patterns). This makes me a little nervous because I have 4 more spools with different colors in an unopened box.

Meanwhile I switched to Prusa Silver PLA (which came with the kit). The printer is running for several hours now. I opened the enclosure doors. Inside temp is around 28c.

RE: Frequent Filament Jammed at Extruder

I have a similar problem with frequent filament jams. Since upgrading from MK3 to the MK3s I now get regular filament jams. Diagnosing the issue, it seems to be the PTFE tube works its way loose and moves. On my MK3s, when not locked in place, the PTFE can move about 2-3mm. My speculation is that the movement during a print eventually causes a jam. The PTFE tube must be held tightly in place. I DIDNOT have this problem in the MK3 configuration. I am REVERTING back to MK3. The MK3s is GARBAGE, clearly I'm frustrated, but this is CRAP. My printer now requires regular disassembly and re-assembly every few days.  

RE: Frequent Filament Jammed at Extruder

OK, so let me apologize for my rant. No-one needed it. The MK3 in any form is a great printer. I love it. I am Very frustrated with the very frequent filament jams. I've had to rebuild my hotend 8 times since "upgrading" a couple of months ago. I've been printing for nearly 2 years without major issues and almost never a jam/clog. 

I don't mess with my printer, I print with it. I would be happy if it worked like my inkjet (and just printed). My goal is to make things, not be a 3D printer expert, hence my frustration. I like the stock printer because it is less work to accept firmware updates, software updates, and it prints great. I have friends with Creality printers. They constantly have to mess with them just to have them print even close to my Prusa. 

I'm pretty sure the MK3s issue is the heat exchanger is allowing the PTFE tube to move after it is initially locked in place tightly. 

Potential fix: if the printed part performed the initial guide of filament into the PTFE tube instead of directly into the PTFE tube, the printed part could be used to hold the PTFE tube in place. This would eliminate the need for the locking collar, would prevent movement, and force the PTFE tube all the way down into the heat break.