Filament curling, extruder mystery
I've had my MK2 kit for a few weeks now and I started to notice that the filament tends to swirl, bend to side or attach to the hotend when extruding the first few centimetres manually from the menu. Also when running the V2Calibration the extruded filament on the heatbed is not stable. So it seems like these is a partial clog in the extruder. I used the bundled acupuncture needle to clear the nozzle from below to get the clog moving without any success getting the filament to extrude normally. I've also unloaded and loaded the filament several times to the printer trying to get the clog moving. Then I tried cold pulling the filament out while the nozzle was around 90 degrees when I noticed the strange unloaded filament shape (see attached picture below, tip from the hotend on the left hand side of the picture).
As far as I know, there should not be a thinner part of filament before it enters the hotend in the printer. I repeated this (extrude filament and then cold pull) and got the same result. When unloading the filament (Prusa PLA, 215 degrees) normally I've always had (since first unloading) only the normal size filament out. On the other hand, when I now think, the filament has come out of the printer quite quickly. So has there been always a tip of filament in the extruder after unloading the filament? Is the hotend working correctly or is there a major malfunction?
The kit has been assembled as the manual states, the cooling fan is blowing towards the nozzle (sticker facing towards the nozzle) and I've always let the cooling fan run after printing before shutting down the printer. I've only used the provided Prusa PLA-filament. I haven't touched or opened the hotend nor the extruder.
Thanks already in advance for your replys.
Re: Filament curling, extruder mystery
Just a guess,
very left hand end appears to be the inside of the nozzle and the hot end, the right hand side appears to be un heated filament, and the bit in the middle seems to have stretched whilst trying to remove the filament...
have another go at printing, now that the extruder is clear.
best wishes, Joan
I try to make safe suggestions,You should understand the context and ensure you are happy that they are safe before attempting to apply my suggestions, what you do, is YOUR responsibility. Location Halifax UK
Re: Filament curling, extruder mystery
Quick update,
I shortly realised that the thinner part of the unloaded filament (in the picture) must be the result that at 90 degrees the filament is above its glass-transition temperature and the tip of filament is partly attached to the hotend nozzle. When I'm pulling out the filament it starts to yield before the tip detaches from nozzle. I did this again and let the extruder to cool down. Then I unscrewed the idler screws and measured (from the top of extruder assembly) how deep does the filament go (104 mm). I removed the filament, set the idlers screws back, heated up the extruder, loaded the filament from the menu, extruded, marked the spot again on the filament, and unloaded the filament. The difference between these two measurements was 16 mm (104 mm - 88 mm). So there is a 16 mm long filament in the extruder if I'm unloading the filament normally?
Any of these actions didn't change the extrusion, filament still tends to go up to the hotend. I guess this is just a result of partly jammed nozzle? Should I remove the nozzle for inspection and cleaning?