[Solved] Underextrusion  

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brad.w2
(@brad-w2)
Active Member

I am experiencing underextrusion with prusament pla with default slicer settings. Also the first layer is having trouble sticking. If I lower the nozzle to really squish, it starts curling up. If I raise it up, first layer won't stick. Also extruder is clicking and missing steps.  Anyone else?

Best Answer by brad.w2:

I made a video describing how to fix your hotend if your are having underextrusion and jamming issues.

 

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Posted : 22/12/2019 8:06 pm
einkauf-2 and tracy liked
Bare
 bare
(@bare)
Active Member

Yes, same for me. 🙁

Posted : 22/12/2019 8:53 pm
Oxygen
(@oxygen)
Estimable Member

Which firmware and with what brand of filament (there are some issues with version 4.01 and I've seen issues when other then Prusa filament i used - which could be related to different melting temperatures of the filament or other density or inconsistent diameter)

Mini with FW:4.2.1 + Bondtech Heatbreak...
Posted : 23/12/2019 8:31 am
ed.b
 ed-b
(@ed-b)
New Member

Ditto here.  My mini under-extrudes to the point of where it isn't usable, but I don't know if the cause is the same..  I encountered the same issue on both firmware versions.  Using Prusament worked a little better than eSun.  It does not appear an issue of filament drag in the ptfe tube and the hobbed wheel has ample grip, so it seems that it must be the extruder itself by process of elimination.  Additionally, purging is reluctant either manually or via the controls and cranking up the extrusion percentage just leads to more clicking and skipping.

Posted : 24/12/2019 12:23 am
brad.w2
(@brad-w2)
Active Member

Im using blue prusament filament fresh out of the package. Issues with both firmware. 

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Posted : 24/12/2019 2:13 am
mark.g33
(@mark-g33)
Eminent Member

@brad-w2

Mine under extrudes to the point it stops extruding anything at all after a few layers.  I have only managed one print so far, the whistle.  Prusa are sending me a new heat break so we will see if that helps.

Posted : 24/12/2019 11:45 am
sigfredo.n
(@sigfredo-n)
Active Member

I m having the same issue. I also think that the hobbed wheel has ample grip and pull the filament alright. When I star printing at some point the material get  ‘eat it away’,  this is were a ticking sound can be heard from the extruder. Let us know if a new heat break resolve your issue. 

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Posted : 24/12/2019 4:20 pm
andrew.d44
(@andrew-d44)
Eminent Member

I'm also suffering from an inconsistent under extrusion issue (plus the locked up rotary encoder), to the point at which I cannot figure out what do to next. I've:

  1. Dismantled the extruder to look for contamination - Found a little, cleaned it out.
  2. Cold pulled on the hot end - Came out fine.
  3. Checked all the Bowden tubes for kinks or damage - No damage.
  4. Adjusted tension on the idler - Seems to be feeding OK at the lower tensions.
  5. Played with temps (using Prusament, set 215C) - No difference at +10C.

 

I can't tell if the extruder motor is skipping steps, but that is my final suspect.

To top it all off, my rotary encoder is now completely solid, so I'm unable to play with it anymore. Very frustrating as I had several really high quality prints and was having a great time. Emailed support yesterday, but they must have been incredibly busy.

Posted : 24/12/2019 5:50 pm
miguel angel.p
(@miguel-angel-p)
Active Member

@andrew-d44

Exactly same issue here.. no possible to print ANYTHING...

I have request cancell order and send it back.. not ussable for now

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Posted : 24/12/2019 10:29 pm
bobstro
(@bobstro)
Illustrious Member
Posted by: @andrew-d44

[...] Emailed support yesterday, but they must have been incredibly busy.

FYI - Prusa email support is notoriously bad. For best results, log into the estore and select the live chat option. They're usually pretty good at resolving issues and taking corrective actions. I know this sucks, but at least you've got support!

 

My notes and disclaimers on 3D printing and miscellaneous other tech projects
He is intelligent, but not experienced. His pattern indicates two dimensional thinking. -- Spock in Star Trek: The Wrath of Khan...
Posted : 24/12/2019 10:36 pm
andrew.d44
(@andrew-d44)
Eminent Member
Posted by: @bobstro
Posted by: @andrew-d44

[...] Emailed support yesterday, but they must have been incredibly busy.

FYI - Prusa email support is notoriously bad. For best results, log into the estore and select the live chat option. They're usually pretty good at resolving issues and taking corrective actions. I know this sucks, but at least you've got support!

 

Thanks, I have too unfortunate experience with the email support. Spent over 1 hour each time across several periods during the day on the chat on the 23rd, never got connected. I expect many people are having issues with the Mini and/or are following up on their new printers that they bought during Black Friday.

 

 

Posted : 24/12/2019 10:55 pm
andrew.d44
(@andrew-d44)
Eminent Member
Posted by: @miguel-angel-p

@andrew-d44

Exactly same issue here.. no possible to print ANYTHING...

I have request cancell order and send it back.. not ussable for now

I don’t blame you. What gets me is that I had great success across my first two days and then all of a sudden I’m unable to print anything.

several people have reported that they think it might be the Bowden and the fact that the tubes are so sensitive to minor blemishes/filament inconsistencies. I’m going to try some different Bowden tubes and see if this improves matters. I think Prusa have to up the current on the extruded stepper to give it more oomph when encountering minor snags in the tube.

Posted : 24/12/2019 10:58 pm
miguel angel.p
(@miguel-angel-p)
Active Member

@andrew-d44

Yes, first two prints were fine but I am not able to use printer anymore.. nor to use any filament brands or different materials.

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Posted : 24/12/2019 11:04 pm
jameswilddev
(@jameswilddev)
Eminent Member

Mine has now very suddenly started doing this with all filaments I have after tens of hours of flawless prints. 

Posted : 25/12/2019 1:22 am
brad.w2
(@brad-w2)
Active Member

@jameswilddev

Exactly what mine looks like. 

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Posted : 25/12/2019 1:27 am
jameswilddev
(@jameswilddev)
Eminent Member

Right, so, I have a theory on what the problem is.

My printer makes a lot of plastic straining noises while retracting, which appears to be the filament itself.  Sometimes you can see white stress marks on the filament as it passes between the hot end and the extruder motor.

This seems to be producing a lot of debris in the extruder chamber which is coating basically everything in there in PLA dust, which simply does not grip the filament at all causing underextrusion.  There is mention in the manual of cleaning the extruder wheel under the flap with compressed air, but this stuff is seriously stuck, and there is no way compressed air will shift it, and it shouldn't need to be done this soon.

Prusa need to put a limiter on the amount of torque the extruder produces, because it seems to be damaging filament and the printer as a result.

Posted : 25/12/2019 10:09 am
mark.g33
(@mark-g33)
Eminent Member

@jameswilddev

Well that was my theory too until I took the extruder apart, took photos and sent them to Prusa support.  Although I believe that the idler screw was way too tight as delivered and caused filament dust to get everywhere, Prusa have decided to send me a new heat break.   I am not sure what their thinking is but I do wonder if they know there is a problem in the heat break.

Posted : 25/12/2019 12:24 pm
andrew.d44
(@andrew-d44)
Eminent Member

Took some time this morning to have a look at the heatbreak. I took the PTFE tube out of the heat break, there was a strange piece of what seems like a PTFE shaving at the base (see image I've attempted to add). I've replaced with the spare that came with the Mini. I can't control the printer from the screen/rotary encoder combo, but running a print through Pronterface looks good. I think this has solved it for me.

This post was modified 10 months ago 2 times by andrew.d44
Posted : 25/12/2019 1:41 pm
miguel angel.p
(@miguel-angel-p)
Active Member

@andrew-d44

how do you disassemble the hotend? any guide online from Prusa?

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Posted : 25/12/2019 3:27 pm
andrew.d44
(@andrew-d44)
Eminent Member

@miguel-angel-p

I just unscrewed the brass Bowden connector from the hot end and pulled out the PTFE. There is no guide that I’ve seen on the web yet.

If you are not comfortable with dismantling it, I’d wait until Prusa support is back online.

 

Posted : 25/12/2019 6:21 pm
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