PETG filament stuck; significantly narrowed just above the hot end

[user_2318123692]

Hello everybody, this is my first post here so please be gentle

I am a relative beginner with 3d printing. I read about 3d printing and I watched a lot of youtube videos during the last ~2 years but in terms of actual printing experience I just started a few weeks ago with a P1S and PLA. Everything went fine (about 20 different prints, including some of my own models I created in OnShape) and today I tried PETG for the first time - a spool of Elegoo “Rapid” PETG. Before I tried printing with it I dried it for a few days at 55C and it lost about 9 grams. I am printing with the spool placed in the dryer (the Eibos with the impossible name - Polyphemus or something like that). The spool sits on the dryer roller and it can move really easily. The filament makes it from the dryer to the printer via the second piece of white PTFE tube (4mm OD 2.5mm ID, ~50cm long) that came with the P1S.

I am using Orca Slicer. I started with a temperature tower - from 230C to 260C in 5C steps. It printed fine, although very slowly (compared with PLA). I could hardly notice any differences between the different temperatures so I settled for the middle ground temperature - 245C (Elegoo themselves recommend 230C-260C for the nozzle temperature, this is printed on the spool).

I noticed tiny “pock marks” on the surface, so I’ve read some more on the internet and I found some mentions of tuning retractions. So the next thing I printed was a retraction tower - from 0mm to 2mm. Again, it printed nice and I couldn’t see any differences along the Z axis.

At this point I was ok to continue even with the small pock marks but I’ve read some more again (mainly because I wanted to understand if I could safely speed up the printing a bit) and I found mentions about the VFA (vertical fine artifacts) test. So I gave it a try - from 40mm/s to 300mm/s in 20mm/s steps. Elegoo claim that their “Rapid” PETG can print up to 600mm/s so I thought a maximum of half of that should be safe.

This is where the problem occurred though. The print started fine and after a few minutes I minded my own business. Some 10-15 minutes into the print I heard the printer stopped (it’s right behind me). I looked at it and the X-Touch display I am using said that the filament had run out (!). The spool is essentially still full so on closer inspection I realised that the filament somehow narrowed a lot just as it entered the hot end. I disconnected the PTFE tube and this was immediately confirmed - see the pictures I attached here. I tried to unload the filament, a few times, with no result at all. I tried pulling it out while the nozzle was at ~250C but it didn’t seem to move at all so I didn’t insist to avoid damaging something.

I am stumped and I am hoping someone could point me in the right direction. English is not my native language and I never heard of a situation like this so I don’t even know what terms to search for

Thanks a lot for your attention and help!

When asking for help, please provide as much information as possible about your inquiry.
This will help everyone to better understand your problem, and provide you with the best solution.

• Detailed description of the problem - as above
• Printer model used - P1S
• Slicer settings used - default Orca slicer settings for P1S 0.4mm nozzle standard PETG 260C 1st layer, 245C next layers
• Type of filament used - Elegoo “Rapid” PETG (black)
• Photos that clearly show the problem - attached
• .3mf file (if the file can be shared) - no point, I was printing just the Orca built-in VFA test, as described above
• Any potentially useful information that is related to the problem
  
  
  
  
  
  
  
  
  
  
  

[user_2318123692]

I found out what happened! Not knowing how to get the thinned filament out of the hot end I decided to cut it and respool the ~1m length. While trying to respool it I noticed that it had 2 other sections where it was way thinner than it should have been - see the new attached picture. So a filament quality issue…

Now, does anybody have any idea how I could remove the piece stuck in the hot end? It’s too thin for the extruder to move it and I also can’t just pull it out. I’m wondering if I could pull it out if I manually set the extruder to retract… Let’s see.

[simon14]

@user_2318123692

found out what happened! Not knowing how to get the thinned filament out of the hot end I decided to cut it and respool the ~1m length. While trying to respool it I noticed that it had 2 other sections where it was way thinner than it should have been - see the new attached picture. So a filament quality issue…

Now, does anybody have any idea how I could remove the piece stuck in the hot end? It’s too thin for the extruder to move it and I also can’t just pull it out. I’m wondering if I could pull it out if I manually set the extruder to retract… Let’s see.

Visit this link

Maintenance and How To guides

Follow 2 instructions to remove extruder and hotend to remove clog

[EnoTheThracian]

You should be able to push it out by taking a length of normal thickness, identical filament, heat up the nozzle to print temp using the display, feeding the filament manually to the extruder and the use the display and a little force on the filament to make the extruder grab it and then purge the old filament out.

Otherwise, use the wiki’s hex key cold pull method.

[user_2318123692]

Thanks both for the suggestions. It wasn’t a clog and I could also not insert new filament because of the thin section of filament that was already in there, taking a tiny bit of space.

But my idea worked - I heated the nozzle to 260C and I manually set the extruder to retract, while gently pulling back on the thinned section of filament. It actually came out quite smoothly. This is how the filament that was stuck in the hot end looked like:

And I think I also found the cause of the filament thinning: the bloody dryer. I once read in the comments section of an YouTube video about Eibos dryers that (an older model) was “the best filament destroyer” the poster had, and I’m sad to see that even their current “best” model it still at it.

See the picture I just downloaded from their web site. The orange arrows show the direction of the hot air. I added the straight green line to show the direction of the exiting filament when the spool is full. It touches the metal roller where I circled it in red. And that’s the problem: I used the IR temperature measurement gun I have and it showed that the roller was about 80C (!), even if the temperature I set and the dryer displayed was just 55C (the temperature & humidity sensor is the little white square I circled in blue). So the filament softened quite a lot when it touched the hot metal roller, then, when the P1S extruder pulled on it, it thinned…

I have restarted the VFA test and it is now printing quite nicely and quickly (apart from a brief filament tangle that I managed to catch and save just in time, because it was making a creaking noise), with the dryer OFF.

Thanks again! Now onto printing the Bento Box!

[simon14]

Your circumstance is different than the rest of us. We assumed you use AMS like the rest of us.