Clicking sounds and bad extrusion from print head
I've been printing the same model 11 times with no problem. Each was a 6 hour print, perfectly fine. Today I went to do the 12th print of this exact same model (no changes to any settings or calibrations, same filament) and as it was laying down the first layer I started hearing clicks as it moved the print head. The sound did not seem to be coming from any of the motors. Looking at what it had been printing it seemed there were globs of filament randomly along the already printed lines, and the print head was sticking to those as it moved nearby for the next closest layer, causing the clicking sound.
I figured there was something wrong with the filament or maybe some clog in the print head. I UNLOADED filament completely and then loaded it in again. I started up the print and got the same symptoms, clicking and globs. Plus, the first line of filament that it prints at the front of the bed was NOT good, just a thin strip, not the normal line.
I ran the First Layer Calibration several times and although the main lines that it lays down on the bed look fine, the initial line is messy and the rectangle of lines is just a mess. I tried several times and got the same results.
I'm hesitant to start trying to actually DO the Z calibration during the First Layer Calibration, as it's been working fine for so long. SO what might be wrong? Why are there globs and bad extrusions from the print head?
The rectangle of lines for the First Layer Calibration look horrible.
The lines for the First Layer Calibration look fine.
I just tried to do the First Layer Calibration again. The clicking sound occurred even when it was laying down that very first strip of filament, at the front of the print bed. So my thoughts about the clicking being caused by the head impacting on previously laid-down globs of filament doesn't seem to be true, or maybe there are TWO causes of the clicking sounds.
I also notice, in the print head mechanism, that there are times when the gears that feed the filament are rotating (apparently trying to feed the filament to the hot head) but no filament is coming out of the print head. It SEEMS, when I place my finger on the filament leading into the print mechanism, that sometimes filament is indeed moving into it (via the rotation of the feeder gears) but no filament is actually coming out, implying maybe some kind of momentary clog inside the print head???
I've tried to add a video so you can hear the clicking sounds, but it doesn't seem to want to do that. I'm trying to use the Attach File option...
Trying AGAIN to add a video file... It 4 MByte, so it SHOULD upload and insert just fine.
[video width="640" height="480" mp4="https://forum.prusaprinters.org/wp-content/uploads/2020/06/MVI_2220.mp4"][/video]