Filament stuck in the extrudor  

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patrik.m3
(@patrik-m3)
Active Member

Hi, 

I just received an assembled the mk3s this Saturday. The assembly, calibration and first prints (about 10 prints, 20 hours with different Plas) went without a problem.

But now I got a clogged extrudor 2x in the row.

It was grinded by the gears creating a blob, so it was impossible to pull it out or in. I had to cut the blob and pull the rest of the filament out mm by mm. 

After reloading it worked fine for about 3 hours in to the print and then again the same story. 

I don't think it's a clogged nozzle, as the filament is running nice after removing the blob from the gears. 

Extrudor motor was making the clicking sound after the filament got stuck. 

Coming to the second issue. After the block the printer continued "printing" mid air. Should the filament sensor detect the block (it's a black pla by the way)?

Is my idler to tight? Or to lose? Can it be a filament issue? But why then worked for 3 hours?

Does the sensor have an issue with detecting movement of black filament? 

Posted : 28/05/2019 3:40 pm
joe.m14
(@joe-m14)
Estimable Member

The MK3s only detects the presence of filament, not its actual movement. - Detecting movement was pretty unreliable, so many MK3 owners disabled the sensor. The MK3s sensor should be much more reliable at the cost of capability. Or so the argument goes. Anyway, the grinding and airprinting after a clog is to be expected.

I’m definitely NOT an extruder expert here, but maybe you have a partial blockage? Some pics of the idler tension screw may be helpful here too. Temp might want a bump up, but rule-out a clog first.

When someone asks you if you're a god, you say, "YES!"...
Posted : 29/05/2019 11:44 am
patrik.m3
(@patrik-m3)
Active Member

To give an update to my issue.

I have adjusted 3 things for the next print:

  • lovered the idler tension (it was to tight)
  • lefte the enclosure door open, to  keep the ambient temp down an prevent E motor from overheating
  • changed the filament (to the silver provided with the printer)

and the same G code printet fine. Also next print with enclosure closed printed without an issue.

Changed back to the black spool of Sakata filament... again a jam.

So in the end I figuerd out that aparantely the filament was the issue. After some testing I can print it, but at about 245°C and much lower speed...

 

But its still anoying as the same spool printed fine on my old chinese i3 clone at 210°C

Posted : 01/06/2019 10:16 am
patrik.m3
(@patrik-m3)
Active Member

So, one month in with the Prusa MK3S "worth" 4x of a chinese knock of and it  f... #$@&%*!  cant print PLA with their own optimised G Code and their own f..$%#)"  prusament.

6 Benchys, 2 three frogs with original Prusa G Code + Prusa Filament/Prusament + doesens of different customised PLA prints with all kind of setings and materials fail as soone some retraction is introduced.

I added an Extruder motor coolling fan, replaced the PTFE Tube and the nozzle, tightend/losend bondtech tension, checked/aligned/realigned bondtech, printed remixed idler door,

https://www.thingiverse.com/thing:3706930

https://www.thingiverse.com/thing:3504682

Nothing.

I can print PLA with models where practicaly no retraction is needed and with low speed + extreme Temperatures (240°C +) resulting in ugly, stringy prints

How they can possibly sell a FDM printer which cant print PLA??!

PETG printing works well on the other hand.

I see Im not the only one with the issue. 

One last shot is to replace the heat break with original E3D as suggested in some other threads. If that doesnt work I lost my hope

 

Posted : 03/07/2019 7:56 pm
oleh.k liked
Tim
(@tim-m30)
Illustrious Member

Are parts staying "attached" to the bed, or are they knocking loose?

It is always wise to get more than one opinion......
Posted : 04/07/2019 3:07 am
david.a66
(@david-a66)
Honorable Member

are you in a hot room or is the printer in an enclosure ?

Posted : 04/07/2019 4:29 am
patrik.m3
(@patrik-m3)
Active Member

Parts stick well to the bed. ni issue there.

I have a enclosure, but tried also printing with doors open. Room has 23°C

Posted : 04/07/2019 5:22 am
Tim
(@tim-m30)
Illustrious Member

Benchy, and most of the sample parts don't normally stress the printer to the point of causing the heat break jam.  But if you are having these jams, wait for the next jam, when you hear the clicking, stop the print and UNLOAD the filament.  Post a photo of the filament stub.  If you have calipers, measure the stub, and if it is 2.2 mm your heat break is causing problems (2.0 mm is okay).  

 

It is always wise to get more than one opinion......
Posted : 04/07/2019 7:08 am
patrik.m3
(@patrik-m3)
Active Member

I have measured this already. Will post a picture in the afternoon. 

The stub is just somewhere in between 2.1 and 2.15mm (measurer with cheap calipers...) 

Posted : 04/07/2019 7:25 am
patrik.m3
(@patrik-m3)
Active Member

Pictures

 

 

Posted : 04/07/2019 5:59 pm
Hedo
 hedo
(@hedo)
Active Member

Hello Patrik, I have the same problem since I assembled my kit. Then I contacted the support who recommended using a fan for the extruder motor. I tested this and since it blew on the heating bed at that time, I redesigned it and uploaded it to Thinkiverse ( https://www.thingiverse.com/thing:3706930 ). This helped a bit, the PLA prints performed a little better when there was little retraction and not too long prints. The problem was NEVER solved completely.
ABS has been printing quite well so far, except for a bit of warping. PETG was fine too, but I still have problems with PLA, especially with long prints. Today I have again printed three parts, each about 1 hour, now the Hotend is so clogged that nothing goes through. I'll have to dismantle at the weekend.
I find it very demotivating that a printer for this price causes such problems with PLA. Even cheap printers for 200-300 Euro work with it without problems. I have already tested several PLA varieties that worked with a da Vinci Mini Super, but not with the MK3S for a long period of time. I hope there will be a solution to this problem soon, as it is not possible to print with PLA in the long term.

I hope it will be back, greetings, Olaf

Posted : 04/07/2019 8:45 pm
oleh.k liked
jamalgmayel
(@jamalgmayel)
New Member

I've been battling this problem on/off as well. When it's working the printer is flawless, then every now and then the gears will get gummed up and the PTFE tube clogs. Then those dreaded clicks...

The last time I pulled everything apart (today actually) and when putting it back I noticed the gear that is directly on the extruder motor's shaft had shifted quite a bit. I realigned it and tightened down the grub screw really hard. I also kind of torqued the whole extruder assembly when putting the four mains screws back together in a way that I thought would help prevent the filament from getting stuck right before the PTFE tube.  After that it went did a 4 hour print and was absolutely perfect. I even changed filaments about 8 times during the print just to really put it to the test. I do think the extruder motor gets way to hot, so I'm interested in the fan upgrade that Hedo has come up with. I can't help but think that amount of heat is certainly causing the filament to get gummy even before it makes it to the heatbreak.

 

The last thing I noticed I was doing was tightening the idler tension way too much. I was following their recommendation but this time I made it much looser. When the filament is loaded, almost the entire head of the tensioner screw is above the surface. I know you already tried messing with it but I'm just giving you my thoughts/experience.

Hang in there. It's frustrating but you'll get it figured out.

Posted : 04/07/2019 9:29 pm
Tim
(@tim-m30)
Illustrious Member
Posted by: patrik.m3

Pictures

 

The images do look like the heat break is causing your issues.  An E3D-V6-1.75 heat break is pretty inexpensive, and just a little bit of work to install.  It is well worth trying; and if it stops the jams you will be very happy for the "upgrade" ... just have some heat sink compound on hand to grease the upper threads.

 

https://www.amazon.com/Genuine-E3D-Break-1-75mm-V6-175-BREAK/dp/B077Y2MHW8

This post was modified 1 year ago 4 times by Tim
It is always wise to get more than one opinion......
Posted : 05/07/2019 1:09 am
Hedo
 hedo
(@hedo)
Active Member

Hello jamalgmayel,

you may like to test my cooler version or that of CG-Tech. The engine has become about 20 degrees cooler for me and some PLA grades could be processed better. Not every variety though. For example, with another printer, I've had great results with Janbex PLA, super wound, processed accurately, and will not break as fast as others. But this PLA always causes problems after a few hours of printing.

Nevertheless, your experience will surely help! Possibly there are still optimization possibilities.

Posted : 05/07/2019 7:57 pm
peter.m26
(@peter-m26)
Honorable Member

You could also try ,

keep the doors always open with pla print, also in the winter.

As extra you could try a extra fan to blow in the cold case in the case, i have this for the summer only, test with a table fan, later you could make a pc fan to blow in the case, or even better a temp regulated fan.

 

I had the same,

e3d heatbrake i bought,

install fan on extruder,

extra fan for more cold air,

rebuild off,  tube, heatbrake,  nozzle, etc look for several movies on how to, and on prusa manual, so you have more manuals, do this very precise.

After this i had no problems(i have a mk3 without s)

I would try the above without a different heatbrake, if still not good, replace also the heatbrake.

(also i have now orderd more parts so i do not have to wait on parts, also chinese parts, but also original, at the moment i use only original parts)

Posted : 06/07/2019 7:34 am
patrik.m3
(@patrik-m3)
Active Member

update from my side.

 

Summary:

initial issue was that printing with PLA filament resulted in either extruder clicking or grinding the filament in the gears. PETG on the oposite printed without an issue.

steps taken:

-adjusted idler tensions in multiple positions

-always printed with enclosure doors open

-tried several different PLA filaments 

-different setings in the slicer (temp, speed, retraction)

-installed the silicone sock to the heating block

-changed the PTFE tube (original Prusa)

-changed the nozzle (original from E3D)

-added extruder motor heat sink

-added extruder motor cooling fan -> https://www.thingiverse.com/thing:3553320

-printed and installed idler door remix -> https://www.thingiverse.com/thing:3504682

From all the abowe steps only retraction almost off + hight nozzle temp (240-245°C) and realy slow printing did any difference. but prints came out sh#t.

After searching the forum and learning about the moded prusa heat break, I today gor the original from E3D and installed it ->benchy with Prusa G-code and Prusament just running at double speed, lets wait the result.

But at installing I found another potencial source of my problems:

My (original Prusa) hot end does not have the plastic collet clip to hold the PTFE tube ->just a black collet which moves when pulled

 

on the other hand the e3D instruction mention a plastic collet clip (blue)

 

I have installed the hot end back together and will test it. If the problems wont go away the collet clip issue is my last hope.

https://www.thingiverse.com/thing:3499966

This post was modified 1 year ago by patrik.m3
Posted : 08/07/2019 8:06 pm
patrik.m3
(@patrik-m3)
Active Member

Thank you antimix

Your work has saved my prusa mk3s from being tosed through the window.

https://forum.prusaprinters.org/forum/original-prusa-i3-mk3s-mk3-hardware-firmware-and-software-help/prusa-edition-heat-break-easily-jam-clog-with-pla/

After more than one month of googling and trying all possible solutions (list above) the original E3D heat break seemed to solve the issue

Prusa G Code Benchy from Prusament at 200% speed (slowed down back to 100% for the last half of G code)

This post was modified 1 year ago by patrik.m3
Posted : 09/07/2019 8:41 pm
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