ultimaker clog

I had a print fail on the ultimaker last night…the extruder stripped the filament, and stopped extruding at about 80% through. Not sure which came first, the clog or the extruder fail, but the nozzle is pretty well clogged right now. I went through the “atomic method” 4 times with no luck.

Probably time to remove the nozzle and clear it with acetone. Thought I would see if Lorin or anyone has a prffered method for proceeding…


  1. Attach one of the other nozzles. We have a .8, .6, .4, and .25. There are official guides for this (the olsen block), however, it’s pretty easy:
  2. Heat the extruder to 140
  3. Use the little torque wrench on the ultimaker to unfasten the hot tip (don’t be super slow, a plastic wrench will melt, even though I made the inside bits out of high temp PET).
  4. Put in another nozzle, and leave a note on the machine that it currently has X nozzle on.
  5. Folks will need to adjust their slicer settings for nozzle size, but you can now test the machine.1. Verify that the path to the nozzle is clear and filament fits easily. The white plastic “coupler” which is held by a spring to the hot end can warp after a lot of high temp use. It’s premature for this one to be warped, but I check to see that it’s looking healthy (not singed).
  6. You can clean the clogged nozzle any way you wish. I generally use acetone for ABS & PET, and NAOH or KOH for PLA — careful there, you might want to ask your PHD chemist spouse about these ;).
  7. Let me know if anything needs to be replaced. I have spares of most parts that are commonly worn out by use and mis-use.

I took a look, here’s what happened:

The nozzle was not tightened properly. You must heat up a nozzle to 240 degrees before tightening. Use the little wrench to tighten, and make sure it clicks. During the print it came loose from movement and started coming off. This put a slight cant on the nozzle, which creates too much pressure for the extruder (path has to be straight). Then plastic oozed onto the threads.

The Ultimaker’s Achilles heal is the bowden system and feeder. The feeder can gouge filament, and if the path is not perfect through the bowden and out the tip, there will be too much friction for it to push against.

Always change nozzles hot!

It’s undamaged and soaking now. No big deal.

The 0.6mm nozzle is still missing, though.


Awesome! Thanks for fixing and diagnosing it. I was planning to visit hive this evening to remove the nozzle. This way I get a mini ultimaker lesson too. Will keep an eye out for 0.6mm nozzle.


The 0.8mm is currently on there…

Found the nozzle on the floor and returned it to ultimaker. Guessing I probably knocked it off while trying to clean the nozzle yesterday…

Awesome. I’m just happy people are using it.