Extruder failing sometimes partway through a print
 
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peridot
(@peridot)
Eminent Member
Extruder failing sometimes partway through a print

When I try to print, the extrusion becomes very erratic after consuming a few cm of filament. In the attached picture, the bottom layers should be a nested set of rings. Instead the extrusion becomes erratic; some filament is extruded but not the correct amount. When I stop the print and hit "load filament", sometimes nothing happens and sometimes extrusion is fine. Any idea what might be wrong, or how to fix it?

This started happening after printing nearly two kilograms of PLA, the roll that came with the printer, and a roll of eSUN PLA; both are freshly-opened in the last month and are clean. The only recent change I have made is I re-fiddled the Live Z adjust value, but I came up with almost exactly the same value as I had before.

On the theory that it was a nozzle clog, I have poked around a hot nozzle with the needle that came with the kit, and I have tried a cold pull. I've also opened up the extruder gear/idler thing; it appears to be fine, although the extruder gear does have some plastic in its teeth. When the problem is occurring, "unload filament" sometimes doesn't work, though usually I can run "load filament", and after some extrusion, then "unload filament" works.

The problem is somewhat erratic; some of my test objects don't appear to trigger it, and the ones that do seem to trigger it after a certain point only: perhaps the first Z hop? I'm not re-slicing here, in all cases it's the same g-code on the SD card. In fact I first ran into it with the gear bearing on the SD card, which I had previously printed successfully several times. By contrast I'm printing a 50x100x0.2 mm cube and that seems to do completely fine, as does my calibration cat.

Clearly this is some kind of maintenance issue - nozzle clog? extruder teeth jammed with gunk? extruder gear loose? But I haven't identified it yet.

Posted : 11/06/2017 9:22 pm
iker.e
(@iker-e)
New Member
Re: Extruder failing sometimes partway through a print

Good day,
First I need to tell you that I'm a beginner. I had also some extrusion/retraction problem this days, no so clear as yours, but problem.
Yesterday night the nozzle and block was totally cloged. Also as you say the unloading of filament was not working correctly. Yesterday a dissamble nozzle and block for cleaning and i was thinking why happen this one and from when. I find the next conclusion:
- this one was happening to me from the new firmware/software(slic3r) was installed. The new slic3r is loading for me always as multimaterial with 4 extruders and i change it everytime. I never check how much was the retraction configured, and after checking it was set to 4 mm. Reading the forum i found that it never should be more that 1 mm (around 0.8mm). My conclusion is that with this hight retraction, the filament was cooling inside the block and cloging it.
So, check if you are slicing with the new slic3r, how much mm is set the extrusion.
I'm waiting to come back home for recheking that mine is working now well.

If any "expert" is reading my reply, i will be very grateful if he/she can confirm if I'm in the good way or I've lost the north totally 😉

Posted : 12/06/2017 6:16 pm
peridot
(@peridot)
Eminent Member
Topic starter answered:
Re: Extruder failing sometimes partway through a print

That does sound annoying. Unfortunately it's not the problem I'm having - I'm not using the multimaterial version of slic3r, and anyway the model that first caused problems was the gear bearing that came pre-sliced on the SD card. So it's not a configuration issue. I don't know what it *is* though.

I do notice on that model that the misbehaviour always starts at exactly the same place: the skirt and the first two rings print fine, then the third ring starts with a blob and tapers away to nothing. If I leave it running, I can feel retractions in the filament, and there's some draw to it, but I do hear "extruder skipping" noises from time to time.

Posted : 14/06/2017 12:01 am
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