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Constant unfixable PLA filament stuck

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no despair, we will get you going :smile:

it sounds really like your hotend is not getting warm enough to melt the PLA... only a little and then the extruder tries to force it into the hotend... no chance..... do you have any way in measuring how warm the alu block is actually getting... ?

not that there is a problem with the sensor or the sensor and heat element are not properly held into the alu block ?

you could experiment... and take the 4 long screws out, turn on the hot end with your ultcontroller to 220 degrees....

then holding the hot end away from the main body, try and physically push a little pla in through the top and down...

if its correctly 220 degrees, the pla should come running out like a happy snake... if not then your sensor is not ready things right....

hope that helps...

Ian :-)


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You could point a hairdryer on your hot end, and see if the temperature rises accordingly. Or fully lower your build platform and put a electric kettle on it, or just a cup of boiled water. You know it should be 100°C

As an alternative, can you take out the teflon tube and manually push a new fresh piece of filament through?

You should feel zero friction. If you do feel an edge this could also prevent a proper extrusion and create plugs.

After you clean everything, please make sure when you assemble everything back together everything is tight.

Looking forward to hear about your findings,


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Photographs please. Please photograph your hot end assembled, and also a photograph of the plug that you saw when you took it apart.

You can also set the temp to 110C and put a drop of water on the aluminum block and see if it instantly boils.

The problems mentioned above are both possible and have been reported before:

1) Thermocouple reading the wrong temperature (so block is not hot enough)

2) The PLA getting stuck on a lip or edge


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Maybe its a moisture issue? I keep my filament in a dry box, but every now and then I'll test something with a piece of PLA that has been sitting out for a while. It seems like it will push through fine for a little while, then gets harder to push. Then when I pull the piece out, the stuff in the nozzle starts bubbling back out the top.


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I recently bought rather cheap filament from a new source (because living in switzerland, i wanted to avoid the hassle with customs).

I started having rather similar problems: one print works fairly smooth. then the second, or the third, if it was smaller prints, start underextruding and jamming.

Removing the filament, cutting off the lump, reinserting, heating to 250° and pushing by hand results in first very bad flow, then eventually charred bits in the extruded filament, and sooner or later (later, for the most part...) i get clean material.

Actually to me it seems the material is grainy or something.

Since i use hite filament a lot the charred bits show up clearly.

I found that the filament diameter needs to be measured rather exactly for longer prints, since, obviously, any measuring faults add up over time. And this cheaper filament is very unforgiving.

I also started to retract the filament ratehr far (way out of the hot end, to be on the safe side, after each longer print.

Maybe you have similar issues?


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