Sudden issues extruding

Hi,

I'm having trouble with my official E3d v6 on a kossel mini (Think3DPrint3D kit) printing PLA. I had to reseat some wires and did a small print at 180°C to test the connections and that went fine. I powered off my printer, went out for a bit and when I came back to do a larger print the extruder motor started skipping back half a turn and I found the filament was coming out not fully melted, it still had teeth impressions and felt kind of chalky. While trying to fix the issue I found raising the temperature to about 240 made the skipping stop and the filament came out smooth and shiny like expected. I wasn't sure if it was:
a nozzle blockage;
a problem with the motor;
an issue with the ptfe tube coming loose causing the filament to expand in the wrong place;
a temperature issue.

I tried greasing the gears on the motor, reseated the ptfe tube (if anything it's definitely in tighter now) and checked for blockages with a light and a microscope (pictures attached) and it seems pretty clear, there were SOME small jagged bits but I don't know if that's the issue. That said, the problem kept getting worse until I couldn't extrude at all. I got some Taulman nylon filament (I admit I got the wrong type, not 618) and that seemed to return it to the state where it would extrude but only while clicking. On first retraction there was a little singed material where the filament was sitting at the top of the chamber but on successive pulls it came out perfectly clear.

I just got a new K type thermometer and whilst I wasn't able to quite get it to read the same temperature as the printer reported (about 5C lower on the k type than on the printer), it was close enough that I think it's an accurate reading, most of my problem was keeping the probe attached evenly so the reading kept spiking up and down but never quite got to the reported temperature. That said my room thermometer, my IR thermometer, the k type and the printer all reported a room temperature of 23C+/- 0.5 so I think the readings are right.

I'm slightly concerned that somehow the 0.4mm nozzle has become slightly deformed and non circular however I can't quite tell and I can't tell if that's how it's always been as I didn't check it with the microscope when it was new.

Originally the motor would only click on longer extrusions, >10mm but now it seems to do it on any length extrusion. I'm extruding at 5mm/s.

I'm at a loss. The only thing I haven't checked is the hobbed bolt as I have no idea how to do that.

When retracting the filament I notice sometimes the end is very wobbly and other times it's perfectly smooth, sometimes there's a small thin nub that's been in the nozzle, other times that nub is off centre and other times the filament comes out perfectly smooth as if it hasn't gone low enough/has squashed against something. I always cut a point in my filament.

One more thing to note is that I also tried extruding manually by turning the gear by hand. I got all the way from one end of the feeder tube to the hot end but I did find there were some rough spots between the two gears, I couldn't see anything wrong with the teeth on either gear, I couldn't get the filament to come out of the nozzle when turning by hand. The extruder motor is running at 1000ma with a 60% idle current and is fairly heavily heatsinked.

Thanks in advance.

Wow, a lot to take in. Start by verifying the stepper voltage. Fix thermistor mount and verify temps. 180c works great on mine. Make sure you are actually using PLA. You can polish extruder with toothpaste and a .4 drillbit and a dremmil. Good luck.

Your motor shouldn't click at all. When that happens, it means that the motor cannot handle the pressure and clicks to relieve the pressure.

When your nozzle is at print temperature (180-210 for PLA) can you manually push the filament through the nozzle?
If you can push it through with your hands, you should check your emotor and/or your bowden tube if you have one. Try to increase it a bit so your extruder motor has some more current to push the filament through.

If you cannot push it through, there is something wrong with your nozzle. Check how you assembled the nozzle. It is very important that the nozzle is well tightened against the heatblock.

If that all doesn't help, try other filament. I had similiar problems with a specific roll of filament. That same roll worked without any problem in another printer..

Thank you both. I actually just discovered that the problem is most likely due to one of the gears on the motor having lost a few teeth, whether this was because of pressure/blockage issues or something else remains to be seen. Hopefully the advice will prevent future problems though. Thanks again.