Filament Not Extruding

Filament
1

I’m using a Lulzbot Mini and have followed the instructions here:

https://www.lulzbot.com/unclogging-your-hot-end

But nothing is extruding. What is the next step? Do I need to take the extruder apart?

2

Does filament come out when you manually push it into the hotend? Did you ever run any higher temp material through, like nylon?

3

No filament comes through when I try pushing filament through the hotend. The hotend has had HIPS run through it but I have set the temperature up to 250C. I would think that would be hot enough to get even HIPS through.

4

Does it extrude when the toolhead is above the bed?

5

No, nothing extrudes and the hotend is well above the bed. I’m using the Cura control panel to operate this.

6

Dumb question, but do you have your filament clamp unclamped while you’re manually pushing the filament through the nozzle by hand?

7

Yes, it is unclamped.

8

Hi petrock

I am assuming that your thermistor is reading the temperature you have set!?

Then some possible ideas:

  • Can it be that you ended up with filament melted up into the heat break?
  • Is the fan on the heart break working?
  • is there any chance that the nozzle is clogged with some thing not melting?
  • the filament does not even reach the hot end due to offset between the “filament guide” and the hot end.

I don’t know the official procedures in those cases. especially for the last case I have no good Idea how this can be verified and fixed.
For the first 3 cases I would try to “reverse clean” the nozzle with a .4 to .5 mm drill bit / milling bit
Then I would take the nozzle off and push out the plastic from the hot end.
Only if all the filament way is free, the nozzle is clean and the little fan is working I would reload the machine.

All the Best
Frank

9

Thanks, Frank.

Sorry for my ignorance, but what is a “heat break”? Do you mean the cooling fan? Yes it works. And the hotend does heat up. I’m also not sure what you mean by “reverse clean”.

Are there documents outlining how to take apart the hotend? It seems I will have to do so to see if maybe something not melting is clogging it.

10

Hi petrock

It probably is not your ignorance but more my poor english (non native speaker / writer :wink: )
A lot of my writing is pretty much straight translation and might be not best english wording.

Yes the finned part with the very small fan is the heat break. I was afraid that a not working fan might have given you melted plastic all the way up there. That fan working is a bit less work in trouble shooting.

with “reverse cleaning” I meant to pierce backwards (from below) into the nozzle. You can do the carefully with a hot nozzle. Please be really careful as touching the hot nozzle / hot end really hurts (I have tried, you don’t need to prove that :wink: )

For the Links / Information how to take apart:
I am using this link as my guide how the hotted is assembled / disassembled: https://tamarintech.com/article/hexagon_std_assembly

This link describes how you can remove and install the hexagon hotted from your extruder:
https://ohai.lulzbot.com/project/replacing-lulzbot-mini-hexagon-hot-end/maintenance-repairs/

Here Sebastian has described how to replace the nozzle. Only thing I would add for the Mini:
After you heated up the nozzle switch the Printer off. This is to protect the Controller board from a short cut of the 24V heater supply to the Bed Leveling contact.
https://forum.lulzbot.com/t/howto-change-hexagon-hotend-nozzle/2613/1

Last but not least some cleaning ideas including reverse cleaning with a wire. It is a different extruder / but the ideas work on the mini as well :wink:
http://www.tridimake.com/2012/10/clean-hotend-and-nozzle.html

All the Best
Frank

11

Great, thanks again for taking the time to offer up so much help. Looks like I have some work to do. Will drop a note here once I have given this a shot.