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I think YouTube compressed this video too much, but what I was trying to take a video of was the motor continuing to spin, but the filament only feeding during approximately half the rotation.

When I first noticed this happening, the knurl on the motor was filthy with plastic shreddings, so I thought I would clean it off thinking that the knurl just couldn't grip due to the contamination. This made no difference. After cleaning I continue to get alternating thick and thin lines of ABS out the nozzle. See photo attached.

Before I started tearing apart the hot end to merely hope I found the reason (like a jam), I thought I'd reach out here to see if anyone had an idea.

[youtube]https://youtu.be/7tBnjphXq0o[/youtube]

Thanks,

-Matt

I've started to have the same issue and best I have been able to tell it is something with the heat break in the hot end. I think I let it get too hot or tightened it too tight. From what I figured out after tearing it down several times is that the melt is happening too high up in the heat break before the nozzle causing much higher pressure needed to extrude material which in turn causes the extruder to strip or spin on the filament. Attempting to figure out how to replace the hot end with e3d v6 in hopes of solving the issue. Not finding a replacement heat break available for the stock hot end on the website to truly confirm my hypothesis.

So, I did a little more digging. As a note, I have ONLY used ABS on this printer.

This occurred after I started using a less expensive ABS filament from JET. These are the filaments I used, in the order that I introduced them to the printer:

1) $29/kg White ABS from MatterHackers
2) $42/kg Clear ABS "Pro Series" from MatterHackers
3) $10/kg Purple ABS from JET (Amazon sourced)

** Experienced this extruder issue with purple **

4) $29/kg White ABS from MatterHackers was returned to the hot end in order to see if it was simply an issue with the less expensive, purple filament.

-------

I printed many things from the White and clear before I switched to the purple. At some point during the purple, I was messing with the Bowden tube in order to get the hot end wire bundle and bowden tube to coil in a way that wouldn't push out the fabric enclosure I hung from the top enclosure of the printer. ** This is where I suspect I might have made a grave mistake! But I'll get to that in a bit... **

I started taking apart the hot end in stages...

1) Removed the Nozzle. I noted that there was a solid core of white throughout the nozzle, but just a hint of purple just inside the heat break fitting that is screwed into the heat sink. (See image below)
2) Removed the Hot End PTC Adapter (70604) that holds the PCBA to the Heat Sink. It is very clean with no melt, whatsoever.
3) Inspecting the bore inside the Heat Sink, I found that there was a very large amount of what looked like crystallized purple melt at the bottom.
A couple thoughts:

1) I have passed white filament through this hot end and printed ONLY white while still experiencing the same binding at the extruder. So, I have reason to believe the purple, where it is, is staying solid and not melting...
2) I feel as though I shouldn't see melt at this diameter. This leads me to believe that I might have backed the Bowden Tube out of the hot end too far and it allowed the melt to rise up, which then prevents the Bowden Tube from being seated all the way down again where it should be.

So... Ponderings:

1) Who has some wise ideas about this?
2) Can you confirm that my suspicion would cause this issue?
3) Is this or is this related to the "backpressure" issue that others are talking about on these forums?
4) Any ideas how to clear this jam and allow the Bowden Tube to go back down all the way to become fully seated?
5) Is there an issue with mixing the different quality ABS?
6) Is it just the inexpensive ABS? What defines cheap ABS? Where's the cutoff of cheap vs. quality? (I'll tell you the stuff stinks to high heaven and it will actually burn if it's in the hot end for too long at 235C like I do with the higher quality ABS...

Thanks for anyone's contributions!

I came across a very similar issue today as well. I have been printing with black, white, ninjaflex, abs and PLA on my V3 with about 8 days of run time on the printer itself. No issues until now not saying that the new Gold PLA ZIRO brand is the issue, but this is when the problem seemed to happen after about 4 hours into the print. I have had the EZ struder make the clicking noise as it skips on the filament before, but most of the time I was running to cold or on the first layer to low. I pulled the hot end apart as you did and found all the same things, I heated it to 235C with the nozzle removed and used a cleaning filament to push out the backed up stuff, replaced the nozzle and made sure I put the tubing in while hot end was still hot just incase I missed some. seems to be running fine as I have restarted the print and have been running for 8 hours non stop with the same gold that got stuck. how many hours do you have on yours? could it be the temp setting for that product and or color?

I have 53.5 hours of printing on my machine. I always run at 235 on the hot end while printing ABS. I tried inserting the Bowden tube while at 235 on the hot end, but it didn't seem to extrude any more fluid out - that made me think that the purple inside is just solid and not remelting. I'm about ready to just pour some acetone in the top of be hot end and let it sit overnight, but I'm not sure how good of an idea that would be.

Im assuming the cleaning filament simply cleared out a path as big as the filament is and you weren't able to get the build up that goes out beyond the 1.75mm diameter of the heat break?

Thanks for contributing to the troubleshooting, it was looking a bit sparse

i should have been more specific. i first heated a thin wire and broke through, then used a small flathead to kind of scrape the edges to the center from the top, then ran the cleaner through to push the rest through. took 5 or more times till i was happy. and update... my print came out good after running the full 13 or so hours

Thanks for the details, I'll report what I find when I've cleaned it, myself.

You can also use a new/sharp 2mm drill bit. If you don't have one I recommend finding an extra long one. Use a pin vise/handle to turn the bit NOT an electric drill. Then heat up to 200°C and ream the hotend from top to push the bad stuff out the bottom.

I am here to report success! I ran into the issue again when I removed the Bowden tube to calibrate my extruder. I noted that I couldn't reinsert the bowden tube as far as it should be (since I now have the insertion depth marked with laptop tape on the Bowden tube). Sure enough, after 5 or 10 hours of printing after I noted the poor insertion, I started observing pitting and holes in my prints.

I've worked out a very straightforward method.

Tools required:

15mm open ended wrench
1/4" socket wrench
1.5mm (1/16") punch

Steps:
1) heat the hot end to whatever temp you need to in order to back the filament out and then remove the Bowden tube.
2) remove the nozzle using the 15mm open ended wrench and the 1/4" socket wrench.
3) remove two of the towers' arms from the head assembly leaving one attached to avoid laying the head assembly on the print bed.
4) heat the hot end to 150C and apply pressure to the filament visible in the bottom of the heat break with the punch until it breaks free. Use only hand pressure. 5) remove the last tower's arms from the head assembly and flip the head assembly over until the plug falls out the top. You may need to remove the cap that clamps the board to the heat break if the plug is too large. 6) reassemble, ensuring the Bowden tube is inserted to the proper depth (fully down the bore) and continue printing happily!