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unexplained underextrusion after clog?  

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Arklan
(@arklan)
Trusted Member
unexplained underextrusion after clog?

Hi all, printer was working wonderfully as you see in the Lance Reddick statue pic. 

Then Friday night it got a clog and was moving around midair, without extrusion. Yay.

So, clear the nozzle with cold pulls and an acupuncture needle, and check the extruder for clogged teeth. All looked good.

Underextrusion remains.

In short, repeated those steps, including taking the nozzle out, using drill bits in a handheld pin vise to clear it, as well as a small torch to burn out the clog. also took apart the extruder and cleared every tooth of the gear. Problem remains. Oh, also replaced the PTFE tube in the hotend as well. nope.

I'd previously printed a whole spool of this filament without problem until said clog. It's polymaker Polyterra PLA. I usually use a different color but it's my go-to filament and I've printed well over a dozen spools of the stuff. I did try adjusting the extruder multiplier as well, just in case, but no good. 

It's the stock Prusa Mini extruder and hotend, except for a hardened steel nozzle.

Any advice? IS it possible the nozzle is just toast and I need to replace it? I don't have another on hand.

Postato : 12/04/2023 2:42 am
mark
 mark
(@mark)
Reputable Member
RE: unexplained underextrusion after clog?

The PTFE tube in the hot end is a wear item and can be damaged with time or a bad clog. There are instructions for replacing it on the Prusa site. A spare came with the printer.

I keep some on hand and replace when things get weird.

Regards,

Mark

Postato : 12/04/2023 2:51 am
Arklan
(@arklan)
Trusted Member
Topic starter answered:
RE: unexplained underextrusion after clog?

I am aware, which is why one of the troubleshooting steps I took is replacing it. It did not change the outcome.

Postato : 12/04/2023 2:52 am
René
(@rene-3)
Reputable Member
RE: unexplained underextrusion after clog?

Could it be that the extruder idler screw is set too loose.

Setting the extruder idler screw

Postato : 12/04/2023 6:41 am
Arklan
(@arklan)
Trusted Member
Topic starter answered:
RE: unexplained underextrusion after clog?

Well, according to that article, the idler screw was actually too tight, by a lot. No wonder inserting filament was so hard. Fixed that. 

Still underextruding. 

That page also reminded me I may not have properly compressed the ptfe tube, so I checked that as well. Turned out I might have had it in backwards, as there was definitely more taper on one side. And, the opposite side had some flashing from where it was cut, so I trimmed that extremely carefully. 

This of course ruined my z height, but that should be ok for the moment.

But uh... yea. Still crap. My only guess at this stage is the nozzle is somehow jacked in a way I can't visually see and I'll just replace it. Sigh. I was wanting to hold off on that until I could afford a revo... The thing that makes me curious is the seeming repeating pattern of the underextrusion. Makes no sense.

Postato : 12/04/2023 6:43 pm
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