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I didn't have any printer-related problem for the past 6 months, but now all of a sudden my Prusa MK3S stopped extruding during printing.

This is very strange as I can easily load\unload filament and control the step motor via Settings\Move axis\Extruder. When I did so, the filament got extruded normally.

However, when I try to print something or do First Layer Calibration, nothing comes out of the nozzle. I tried changing the Live Z (maybe nozzle too low) and it didn't help. I once managed to extrude something by increasing the temperature and the flow (in the printer's menu) to a ridiculous value of 999. Obviously, this isn't the best way to solve the problem.

Is there an easy way to fix this? I only had this problem yesterday and with some midrange-priced PETG

Edit: I tried different filaments, default slicer profiles, reinstalling slicer (prusa slicer) and drivers. None of these methods really helped.

StLuke5
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4 Answers4

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  1. It doesn't seem to be heat creep. See What are ways to avoid heat creep?

  2. Have you measured the actually temperature of the heater block? You may have a failing sensor (thermistor) or sensor circuitry. Optically is the best way to measure. The least expensive way is with multimeters that come with a temperature sensor, such as a thermocouple (lowest cost about $20 U.S.).

Perry Webb
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I have also been experiencing this issue and found a solution. The problem started with an ABS print that somehow scarred the steel sheet, the ABS plastic was melted on so firmly it was tough to remove and left behind marks that may have ruined the coating (normally it just pops off when cold). Each print after that would leave more marks on the steel sheet, but it was still printing. Then a few prints later, the extruder would not print onto the steel sheet, it would just move around pretending to print (like this question is asking). But the extruder was not jammed, because it could unload easily, or I could force the extruder to work manually after a bad print. So the extruder was fine, but not actually printing. I tightened up the idler screw way beyond what I would normally, and then a print started extruding a little. This is when I realized that the nozzle was so close to the steel sheet that it was not able to extrude, and the nozzle was also damaging or burning into the smooth surface but not enough to really scratch it.

My solution was to run the calibration procedure again, filament immediately started printing onto the steel sheet, and then I adjusted the nozzle Z height a bit closer and now its printing fine again. Somehow the print head / nozzle got out of alignment and I've also damaged the steel sheet as well.

Wayne Piekarski
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As it turned out, rebuilding the extruder actually helped. I took it apart to the point where both fans were loose as well as the extruder motor and the hotend. I didn't find anything wrong after a quick look so I put it all back together.

Then i ran the first layer calibration and for some reason it worked. I know it's neither the most satisfying solution, nor the most informative one, so sorry about that. Either way, thank you for the suggestions, I still have no idea what caused the problem.

That being said, I hypothesize that something was wrong with the hotend. That is because when I had this probem, molten filament wouldn't exit the heated nozzle on its own. Now when I heat up the hotend, the filament comes out (without the motor working)

StLuke5
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I have the exact same issue. I still haven't figured out what is going on, but my next step is to work backwards.

I brought my machine in for repairs at our local shop, and the end result was "heat creep" . It worked for a few prints, then stopped. It jammed on me and in the process of removing the jam, I broke the leads to the heat block. When I decide to go back in, I will see if when I reassembled the extruder, I knocked off enough thermal paste to make a difference... :(

user32677
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