Extruder problem  

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lars.n
(@lars-n)
New Member

In recent days, my dear Prusa I3 MK2S has had some occasional problems with printing. It seems like the problem lies in the extruder and now all my latest prints have failed. It seems that the extruder motor starts to stutter and there is no steady flow of filament to the hot end. So the print becomes very uneven and porous. I updated to the latest firmware without it helping.

Does anyone have any tips for further troubleshooting or what might be wrong?


I have taken two pictures of the latest prints that clearly show the problems on the printed parts:



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Posted : 15/02/2020 8:39 am
jshidisky
(@jshidisky)
New Member

This looks like a print that I just made. What I found was that my extruder wasn't at the temperature the display said it was. A lot cooler running PLA. (Used an old military IR thermometer which is off by about 5° C, but still reads only about 160° when I pointed it at my nozzle.) My problem seems to be the thermistor, as sometime in the past the little grub screw worked its way out, and even though I did find it (and stuffed it away somewhere I can't remember where!) I had no idea where it came from. Until last week. I noticed my thermistor was coming out. But perhaps because it was loose and vibrating for a while, I don't think it's working right anymore. I have a new one on order; not in yet. But I just built a MK3S and guess what! There's a spare grub screw in one assembly! Haven't tried it yet, but I think it fits. With my thermistor out of the hot end, the temp (on the thermometer) rose up to well above where it should have been for PLA, so that's why I believe it's bad. Check your nozzle temp and don't rely on the display. I hope a new thermistor will cure my problem.

Posted : 08/03/2020 11:11 pm
donald.s
(@donald-s)
Active Member

Hi. Check this out! I've had my temp sensor come out of the heat block lately. Don't know why.  I think with the sensor out it called for more heat over-temping the block. When it's hot the block rotates separate of the cooling fins? That's where all the globs of filament were oozing out I believe. What exactly did you order? I don't see parts on the Prusa3d web site. 

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Posted : 09/03/2020 4:56 am
jshidisky
(@jshidisky)
New Member

I ordered mine from Filastruder. I buy all my nozzles from them. They're an E3D supplier in the U.S. It's under extruder parts, and it's for a Prusa-specific thermistor, as it comes with the proper cable and connector. Inexpensive, too. Mine didn't arrive yet; due in tomorrow. Then I'll know if it cured my problem. I can't think of anything else it could be. (Except maybe RAMBo, and I don't even want to think that!)

Posted : 09/03/2020 10:48 pm
lars.n
(@lars-n)
New Member

I finally get my printer working again. I first tried to change the extruder gear but that didn’t work. Then I followed the tip here about the hot end temperature. Since the screw was stuck on the hot end, I changed the hot end block and mounted new thermistor and heater. Now it’s working fine again 😊

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Posted : 23/03/2020 3:11 pm
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