Hot End Jam - Filament really stuck.


New Taz 5 owner, 0.5mm hot end option, been printing 3mm PLA flawlessly for a week or so. Last night hot end clogged.

I tried extracting the filament manually (hot end at 205) but it’s completely jammed. The filament just wont budge.

How much force is it safe to use to try and pull the filament out ?

Is it feasible to dismantle the hot end to try and clear it ?


You have the spring loaded idler loose and away from the hobbed bolt and see nothing holding the filament? Are you pulling on the filament with your fingers or pliers and the head is heated up? Never had that happen in the 3 or so months of running my Mini.

I would think if you took one hand and held the carriage in place you could pull it out with the other.

Since the machine is new I would call Support and see what they say.

Yep idler is open/loose and nothing appears to be visibly snagging the filament.
I’ve headed up the HE for a few a few minutes and then held the assembly with one hand and used pliers on the filament. Not budging.

Will ping support.

Sounds like the PLA may have swelled in the hotend from heat creep… How much of the filament is still in the extruder? Any chance you can heat the hotend up past the PLA temp and push a bit of the filament through? Just need to push maybe 10-20mm through the nozzle to clear the swollen filament, and then you should be able to pull the filament out.

Other option is to heat up the hotend, remove the nozzle and push the filament through… I don’t think LB supports this, but its fairly easy to pull the nozzle off. Heat the hotend past 165C, use a wrench to hold the heater block and another wrench to unscrew the nozzle. To reinstall, heat the hotend past 165C and finger thread the nozzle… then wrenches to tighten at a hotend temp of 250C. Keep in mind the brass nozzle is soft, so make sure not to damage the thread.

The root cause of this may be a bad heatsink fan. Check that its running and make sure to point it down a bit so the air is hitting the thicker heatsink near the heat break.

You’re on the right path in contacting support.

On another note, clamping forceps help with gripping the filament if its past the hobbed bolt. Undo the idler, grip/clamp the filament, heat up the hotend, and pull on the forceps. Great for when the filament spool runs out…

I had the same problem with a week old Taz5. I think it was a faulty fan as kc Chen pointed out. Their weekend support tech mentioned they have had many problems with that small fan.

You should contact support before you disassemble anything. In that case, they might just ship you a new toolhead.

I really needed the printer operational so I tore down the toolhead. My filament was swelled and stuck up through the heat sink.

I also discovered the thermistor leads were not crimped to the wiring harness. They were just soldered. One of the leads disconnected and the toolhead had to be sent to lulzbot for examination.

Here is the post I made when I was working on it.

My toolhead is on the way back to me but I haven’t heard from Lulzbot regarding what they found or did to it.

I am wondering where they sourced such a small fan and the motor since it runs all the time should be a ball bearing unit. Small 12v DC fan motors are used all,the time like for CPU cooling fans. True they are larger but some re-design, adding a defector to keep the air flow in the right area. Something to think about.