Filament stuck in heater block or above

Ok, so I’ve googled and seen videos and instructions on clearing out the nozzle etc. I’ve had no trouble getting the nozzle off and cleaning with acetone. However, I still have a bit of filament broken off at the feeder hole and it is very very stuck.

I have heated up to 250C with the nozzle off, and still cant get the filament to budge, even when pushing down on it from above with a skewer with significant force. The filament seems to have melted/lodged itself somehow in the upper area near the heater block.

Help! :cry:

Hello Bovick,
The first thing we need to know to help you is the type of filament that you are using. I am guessing from your temperatures that you are using ABS. If it happens to be PLA, then you have already had it above the temperature where it will start to carbonize. If it is ABS, then you can raise it up another 20C and then see if you are able to push it through the hot end with something solid, that is 2.5mm in diameter. Please make sure that you do this with the power off. You can heat it up and then turn the power off. If you have already had the nozzle off, then you can carefully push it through the hot end with the nozzle off. It may come out more easily.
If you do get it out, please make sure that your microfan is operating, so that you don’t have heat creep with the filament getting soft in the heat exchanger.
Maybe this will help a bit.

I have seen a few extruders that the softened filament swells at the small notch on the bottom of the brass fitting on the top of the cold end and thus locks the filament from moving up or down. :frowning:

Ok, so that’s where I probably messed up. I was trying an unknown ‘wood’ filament and experimenting with higher temp (235C) when this happened. I have the nozzle off and tried putting a ~2.5mm diameter metal rod up the hot end with it heated to 180C but all I got was a bit of brownish (not black) goop at the end of the metal rod. I can’t seem to be able to budge the stuck filament up or down… it’s really stuck in there. Ideas :question:


You can remove the heat block, then heat break (I think there a set screw on the back of the heatsink). If the filament can be cleared, you may be able to salvage the hotend.

Is there a exploded view or similar somewhere of the print head assembly for reference in taking it apart?

Hello Bovick,

Here is a link for the hot end assembly process.

Please make sure to contact, if the tool head is still under warranty.(which it may not be after removing the nozzle)
If not, you should be able to tell where the filament is jammed, by how high up the hot end the plunger that you are using goes. This will tell you where the clog is. Many times the clog will be in the tube that feeds down to the hot end and it can’t be cleared because you can’t get the tube(where the filament is stuck) as hot as the hot end. I have had individuals tell me that they drill out the filament so that they can save the hot end. You can purchase another hot end for $70.00 and that will solve all of the problems.

The link will show you where the set screw is and how to disassemble the hot end from the feed tube. When you have to put it back together, they are using a nylon tape, but Lulzbot uses a thread locker.
Extreme-Temperature Pipe Sealant & Threadlocker, 4 oz bottle, blue Mcmaster 7604A55(sku)

You will want to be careful with filaments like wood fill as they are a PLA based filament most of the time and they will crystallize above 240C.

I hope this will help, but you may just need to get another hot end.

Hello bovick,

I apologize, I meant to send you this link:

It will have the assembly process for the hot end. The other one was someone modifying the hot end.
This will work better! Sorry about the confusion!

Thanks for the help!


Great guides! That’s the first official guides, I’ve seen from Lulzbot about the hexagon assembly. A few questions:

  • Where can we get the silicone boot for the heater block?
  • The heater block on OHAI looks to be the larger block on the original Hexagon not the AO Hexagon?

Hello Kcchen,

Please note that the first link that I sent was definitely not one of ours. I sent that one while I was looking up some information and copied the wrong address. Sorry about that. The hot end on the OHAI, is one of our V2 hexagon hot ends. I think it is just the nature of the photo that makes it look large.
I couldn’t tell you where to get the silicone boot that he had on the other link. Looks interesting. I would have to do some searching!
For anyone doing a rebuild on their hot end. Please make sure that you are careful with the 30 gauge wires for the thermistor. They will break easily.
I hope this will help.

Thanks for the follow-up, I googled the boot and it definitely is out there… but most likely for the original Hexagon heater block.