Blockage troubleshooting.  

Re: Blockage troubleshooting.

Thanks for the explanation on how the filament was back so far in the bowden tube. It's always a learning thing with the MMU. Looks like I've got several filament rolls I shouldn't use any more. My white Maker Geeks I started on this thread with trying to get to work, I finally gave up on and got a roll of Hatchbox off Amazon as I needed some white. Now I have three rolls of eSun that don't look like I should be using. I do have a roll of AI0 that hasn't failed me yet. Any filaments you've had good luck with ? Seems I need to go shopping.............................
Thanks Again, I'm sure I'll be back.............Dave in MI

Re: Blockage troubleshooting.

Any filaments you've had good luck with ?

Yeah - but there's always the potential for this to happen with any filaments.

PR (or Plasty Mladeč): https://www.filament-pm.cz/
Fillamentum: https://fillamentum.com
Trček: http://www.plastikatrcek.si/en/

But being EU, they are of little use to you. As I mentioned, I have had issues with 3 rolls of PR (out of maybe 50+ rolls) and 4 rolls of Trček (out of maybe 100+ rolls). Fillamentum works well - if you can get the temperature correct. Spoolworks - I have used about 5 rolls of this with no problems, plus some ColorFabb specials (had huge problems with Copperfill on one printer, printed perfectly on the other).

Peter

Re: Blockage troubleshooting.

Before asking help of Prusa, I did also a factory reset, flashed the fw, also I did a clean install of slicer.

I did the complete calibration, printed the prusa Z code more then once. Then I printed the famous square for better adjusting the Z hight two times.
Then I printed a print of 2 hours. So I was hopefull.

But the next print starts immediately, after the front line laying, with skipping.

I hope Prusa can help me. I am now struggling for more then 4 weeks with the MM getting it running in only single mode.

Anyone advise (see my post before in this Post Blockage troubleshooting)?

Frans

Re: Blockage troubleshooting.

Some filament rolls are wound untidily. I have had issues where the filament comes off the roll. With a significant wiggle. Which can cause jamming too. Regards Joan

Re: Blockage troubleshooting.

Peter, Do you care if I share your gcode for Prusa emblem ? I've got a couple done, and I've got a couple of the supplied gcodes for the gear bearing done, with no jams. Seems some of my filaments were a problem. Thanks for all your help, I'm going to continue to read and learn here........

Re: Blockage troubleshooting.

Peter, Do you care if I share your gcode for Prusa emblem ?

I have no problems with that. The STL files are also attached (they were sliced with KISS).

Peter

Re: Blockage troubleshooting.

Thank you very much !

Re: Blockage troubleshooting.

This is a gread idea! Can you david.c16 or PJR share the KISSliced gcode here in the forum ?
I'm also interested to compare my print with others.

Thanks

Re: Blockage troubleshooting.

This is a gread idea! Can you david.c16 or PJR share the KISSliced gcode here in the forum ?
I'm also interested to compare my print with others.

Thanks

Prusa file Gcode is on page 15 of this thread. Good Luck !

Re: Blockage troubleshooting.

Got it - Thanks! Here is the result:

Re: Blockage troubleshooting.

Well there, here is my progress of the story to discover why my prusa MM blocks.

The case
What happens, is that I was not able to print MM and MM in single mode. A new print with freshly cut filament 45 degrees trints fine, but the next print with the same filament blocks when is starts it's first layer: Big question WHY 😀 \

Friday evening/night I had a chat with Prusa. We went through all 😀 and then they asked me to make foto's of the filament tip after a print. And bingo there was the issue.

The tip of filament was not properly formed. There was a long "hair" and some other nasty smal blubs.

And to my surprise there was a little filament ring 1-2 mm high in the entrance of the PTFE tube. No wonder that the filament can't be pushed through by the next print. The PTFE tube with even such a small obstacle doesn't work.

The origine of this misbehavior is the temperature. While retracting the filament when the print has ended, a small residu comes of the filament and remains on the top of the entrance of the PTFE tube.

I dialed the temperatuur down. From 210 to 205 to 200 to 199 and now I am at 198.

That is 3 degrees higher then the lowest advised temp.

Look at the foto I toke and see how little the debris is.

Moral of the story: don't give up, the forum is a great way the share en ask, and of course the Prusa company with there help, even in the middle of the night.

Now I am ready to think about MM in more color prints.

Frans

Re: Blockage troubleshooting.

Frans

It might be worthwhile having a look at your end G-code section. It should replicate as much as possible to a filament unload. If it does not, then that is your problem (may not be to do with temp, just the unload strategy...)

Peter

Re: Blockage troubleshooting.

Hi Peter,

I checked the unload strategy. The end G code in slicer PR is exactly the same as in the V2MM calibration_PLA code of Prusa and I post it here under.
What suggestions do you have?

BTW again a print of 7 hours runs great, without blockage (MM single mode still)

Frans

G1 E-4 F2100.00000
G1 Z0.5 F7200.000
G1 X245 Y1
G1 X240 E4

G1 F4000
G1 X190 E2.7
G1 F4600
G1 X110 E2.8
G1 F5200
G1 X40 E3

G1 E-15.0000 F5000
G1 E-50.0000 F5400
G1 E-15.0000 F3000
G1 E-12.0000 F2000

G1 F1600
G1 X0 Y1 E3.0000
G1 X50 Y1 E-5.0000
G1 F2000
G1 X0 Y1 E5.0000
G1 X50 Y1 E-5.0000
G1 F2400
G1 X0 Y1 E5.0000
G1 X50 Y1 E-5.0000
G1 F2400
G1 X0 Y1 E5.0000
G1 X50 Y1 E-3.0000
G4 S0

Re: Blockage troubleshooting.

That's a good reason why you are having issues...

There's no pressure before unload. My end G-code:

G1 Z<Z+1.0> E-4 F7200 ; Lift and retract
G1 X0 Y200 F3600 ; move bed for easy removal
G1 E12 F2100 ; unload filament
G1 E-80 F5000
G1 E-5 F3500
G1 E-5 F2400
G1 E-2 F1000
G1 E10 F300
G1 E-10 F300
G1 E10 F600
G1 E-10 F600
G1 E10 F900
G1 E-10 F900
G1 E15 F1200
G1 E-15 F1200
G1 E5 F600
G4 S1 ; pause 1 second
M107 ; turn off fan
M104 S0 ; turn off temperature
M140 S0 ; turn off heatbed
M84 ; disable motors


You will note that the second line extruders 12mm of filament quite quickly (in fact, too quickly) before unloading. This puts colder filament into the hot end so that it unloads relatively cleanly.

Peter

Re: Blockage troubleshooting.

Thanks Peter for this post, it helped me remove some of my initial troubles. I had to cut and taper my PTFE tube, which was too long by a millimeter. After two misprints I got a perfect 4-colour Gears print and a couple of single material tests out. Then it blocked and since then I get jamming all over (reducing retract to 2.5-3mm lets me run most single-material prints). I would next try to re-seat the PTFE according to your procedure, but maybe could look at the attached picture first and give me some feedback? I don't want to go through it if the reason is something else...
It seems to me the filament buffs up right below the PTFE, which seems rather weird (there shouldn't be so much space?). Could this be an improperly seated heatbreak?
Cheers,
Nils

Re: Blockage troubleshooting.

Thanks Peter for this post, it helped me remove some of my initial troubles. I had to cut and taper my PTFE tube, which was too long by a millimeter. After two misprints I got a perfect 4-colour Gears print and a couple of single material tests out. Then it blocked and since then I get jamming all over (reducing retract to 2.5-3mm lets me run most single-material prints). I would next try to re-seat the PTFE according to your procedure, but maybe could look at the attached picture first and give me some feedback? I don't want to go through it if the reason is something else...
It seems to me the filament buffs up right below the PTFE, which seems rather weird (there shouldn't be so much space?). Could this be an improperly seated heatbreak?
Cheers,
Nils

Hi Nils

To get that type of plug on the end of the filament would to me imply that there is melted filament rising up the heat break and solidifying.

Check the extruder fan is working as expected. Maybe reduce temperature by 5 degrees. I would also say reduce retraction, but any more (using Slic3r and no LA) would be too little.

I think I would re-seat the PTFE; it only takes a few minutes.

Does this plug form during a print? Or at the end? What filament are you using (make/type)?

Peter

Re: Blockage troubleshooting.

I'll check the extruder fan, someone mentioned that his polarity was inverted. Maybe I have the same problem.
I tried Prusa PLA filament (silver) and various Ingeo PLA at 210, 205, 200 degrees. Below that I tend to get regular nozzle blockage (which could indicate a problem with the fan as well, I used to be able to go as low as 190), so don't really want to go there for now. The filament diameters are always spot on in this material.
The plug forms during prints and apparently always at more or less the same Z height if I print the same model. If the model needs lots of retracts if happens earlier. It seems to happen more often during color changes, but sometimes it even happens before the first color change.

Re: Blockage troubleshooting.

Try resucing your retraction distance.

Regards Joan

Re: Blockage troubleshooting.

Peter,

I used your end gcode right away, and the tip of the filament is perfect

Thanks for sharing

Another step closer to heaven 😀

Frans

Re: Blockage troubleshooting.

Peter,

I used your end gcode right away, and the tip of the filament is perfect

Thanks for sharing

Another step closer to heaven 😀

Frans

Well, that is good news.

I would suggest that you slow down the feed rate of this line:

G1 E12 F2100

to something more sensible, maybe:

G1 E12 F300

just to see how it goes - it should work just fine without any skipping...

Peter