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clogged...but not...  

Geoff G
clogged...but not...

I'm having an issue with my self-built mk4. It used to work great a month ago.This happens with multiple filaments, PET, as well as two different spools of ABS.  The filament is quite dry, as i have a drier in line, feeding the mk4.

When i print, it prints for a little bit, then acts like it has a clog.  Filament simply stops coming out of the hotend.  Sometimes it it just a layer or two, sometimes its 2/3 of the way through the print.

I noted a light dusting of filament inside the body of the nextruder, where the gear is, so I've blown  some compressed air into the nextruder   That cleaned out the filament fluff, but the same problem remains.When i purge filament, sometimes filament comes out, sometimes not.  If I grab the filament while i purge, i can push it through manually.It almost feels like the teeth aren't engaging with the filament consistently.  I have tightened the two screws that house the filament door, to no avail.What else can i look at?


Posted : 04/12/2023 7:22 pm
Trusted Member

This is a weird one.  I wonder if maybe the heater is going out intermittently or maybe the thermistor.  If the hot end is getting cold it would act like a clog.

This post was modified 3 months ago by Altruego
Posted : 09/12/2023 3:10 am
Geoff G
Topic starter answered:
RE: clogged...but not...

Ha!  got it.  Had a few problems at once.  First the idler nut had cracked, invisibly.  It kinda disintegrated in my hand. I printed a new one (thank you mk3), and it still didn't work.


i called support, they said i had overtightened it, which caused the cracking.  they said when i overtightened it, I probably warped the idler arm itself (since i'd been printing a lot of abs recently, i thought this was reasonable.  I mentioned i had some PC, and could print the new idler arm from that.  they thought that was a good idea.

So, i printed a new idler arm.....When i went to replace it, and rebuild the Nextruder. i took off the old one.  and it fell apart. one of the holes had cracked through and fallen off. thats probably what caused the whole thing.

So lessons learned: 1) have a few extra idler arms and nuts. and 2, don't overtighten them. 3) Print the idler parts from a high meltpoint filament....


Thanks for the ideas @altruego. Clearly, i have much to learn about the weaknesses and strengths of the Nextruder...

Posted : 09/12/2023 3:59 am