Printer stops extruding, Chomps filament

The printer stops extruding sometimes, I find a chomp out bit of filament everytime as well. usually the print will run and finish but only the first few layers will be printed.

Any ideas to for the cause?

See picture below

My money is on either a clogged nozzle or, more likely, heat creep. Is your extruder cooling fan still running?

I just came down with the exact same problem, filament looks the same too. I’m going to be swapping out my extruder in the coming week, hoping it’s a clog in the nozzle, but what is heat creep exactly?

Heat creep is when the filament higher up in the extruder body starts to soften. In other words, heat creeps up the filament. This causes a problem because pressure from the filament being pushed into the extruder causes this softer filament to expand and bind in the print head. As it gets harder and hard to push the filament thru, the hobbed bolt cuts a “mouse bite” in the filament and your print is finished. Different filaments conduct head differently and some will be much more prone to this than others. Hot end design plays a big role too and some hot ends are better than others in regards to this. Coupled with this are print speeds and hot end temperatures as printing too slow for a given temperature will allow heat to creep up. You end up having to find the right balance for a particular printer and filament and I find the hexagon hot end on the Taz 5 and 6 to have a fairly narrow sweet spot though admittedly I have only worked with 3 different hot ends so maybe it’s fairly normal?

The classic signs of heat creep are that (when starting from a cold printer) you can print small objects ok, but larger/longer prints will fail. This is because it takes a bit for the heat to “creep” up the filament and cause problems. If you are getting your mouse bite right away and barely anything is ending up on your bed, you have a clogged nozzle. If your print starts OK and fails, it is probably the creep.

FWIW, I struggled with printing PLA with my TAZ 5. I had the creep bad. I replaced the useless hot end fan with a larger one and found a filament oiler on thingiverse that definitely helped. I can’t find the same one right now, but it sat on the print head right where the filament enters and it had a small little bowl where you would put a bit of cotton ball and add a few drops of oil. I used olive oil which worked well. In the end, I swapped the hot end out for an E3D v6 and haven’t looked back. It seems to have a wider sweet spot and I can print a number of filaments without a lot of fussing and tweaking. I love my Taz printers, but their hot ends aren’t the best.

Thanks for the info on heat creep. I have a print head with Innova 1800 stuck in it. I heat up the head, but no matter how hard I pull, it will not come out.

It was during a long print, so I bet it is due to heat creep.

Going to try heating up for a good long time and turn the fans off. Hopefully the heat will creep all the way up and I will be able to pull it out.

I see in the Cura settings, that the fan is set to a max of 70% for Innova 1800. Maybe I should push it to 100%?

Thanks a lot for the post Joule.

I would also take a look at the clearance of your nozzle to the build plate. If you are too close, you’ll be able to print some amount of the model, but it will eventually back up, and you will get the same results; clog with chomping.

I would make sure you can extrude cleanly for a couple hundred mm or filament in the air. Make sure its really a heat creep issue, not a nozzle proximity issue.

I feel this issue was related to heat creep. I have built myself an enclosure for when I print ABS. After testing a bit, Printing in PLA and Ngen seems to not like the enclosure as much.

Thanks so much for you help!!!