random extruder motor issue
Lately, I've been getting random failures with the extruder motor. It will start clicking, which is a symptom I have seen in several posts here. I actually had this problem when I first assembled the kit back in January and it seemed to be an issue with the tensioning of the idler. I increased the pressure until the issue went away and I've been printing fine for 7-8 months. I had a clogged nozzle a month or so ago and ended up replacing it. I've been printing mostly trouble free, but when this noise started to occur, which corresponds to under extrusion, I assumed it was the tensioning issue. I increased the tension like I did before, but the problem still kept happening randomly.
When it happened again, I tried pushing and pulling the filament, but it didn't seem to matter. It is not a clogged nozzle because it starts working fine as randomly as it fails.
Here's a link to a video.
https://www.dropbox.com/s/772yunrq60drphu/MK2Sextruder.m4v?dl=0
I drew a line on the motor axle (ragged because it was moving), so I could see it turn. As you can see in the video, the extruder isn't really progressing; it just goes back and forth a bit. In this video, it happens to be laying down the bottom layer. I've seen it happen in the middle of a print, as well.
This print is just under 3 hours. I printed this model successfully with no issues. I tried to print a second copy and this problem occurred in the middle of the first layer. I think it may have been after the outside perimeter was complete and the infill was started. I stopped the print and without any power cycle or reset, I simply started the print again and it printed the whole thing without any issues. Totally random.
I don't know what to make of it. I'm using the same micro SD card that came with the printer. I suppose it could be failing? I do notice that the gcode files don't have any checksums to validate the file as it is being read, which seems kind of short sighted. Maybe a loose electrical connection? It just seems weird that it is so random.