PLA stuck, can't extrude or retract

Discussion in 'E3D-v6 and Lite6' started by Kamacuras, Sep 8, 2018.

  1. Kamacuras

    Kamacuras Member

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    Hello, I finished a 5 hour print yesterday, which came out perfect. Today, I try to remove the filament, and I cannot get it out, or extrude. I have no idea why it would get stuck, especially after a successful print. I tried doing a cold pull (which I have never really had luck with). Started at 100c, and manually tried to pull out, but no go, so I raised the temp by 10c and tried again, repeating until I got to 170, at which point I started to worry... I tried extruding, no luck either. Went to 190, then 200, then straight to 220, but the filament is completely stuck, as if the thing wasn't heated at all. I put some PLA to the tip of the extruder and it is hot enough to melt.

    I'm not sure what to do... Should I remove the nozzle at temp and try again? This is very frustrating as I just went through a mess with the plastic leaking out of an apparent gap between the break and the nozzle (likely me messing up a nozzle change). It made such a mess that I couldn't clean some of the parts, so just got new ones, so this is basically a new v6, which has done several small test prints and two larger prints, all of which came out perfect. then boom, stuck. This isn't a jam during a print, but a turn the printer on and it's stuck before doing anything.

    Very frustrating, as I can't imagine what happened between the end of the print yesterday, and turning it on today.

    This is with a V6, PLA, been printing at 200 and 205c. Any ideas how to proceed? I don't want to make things worse...

    thanks

    -David
     
  2. Kamacuras

    Kamacuras Member

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    Well, I disassembled the hot end, and all looks clean and proper, no leaks and no plastic where it shouldn't be. I clipped the filament, and put a shorter one in so I could test by hand, and heated it up again. Same issue. It seems like the interior of the heat block is not getting up to temp. I can melt plastic on the tip, but not to the degree I think it should. I got nothing pushing, and I finally, with a lot of pull, go the filament out, but I had to go to 270 degrees to do it. I have an infrared thermometer, but it doesn't work very well on the shiny surfaces.

    The temp (thermistor) reads proper room temp when off, and when turned on, the temp rises at the same steady rate and curve as it always has, nothing different there. All temp changes happen at the same rates and stay steady as they always have. The nozzle is tightened against the heat break and nothing is loose. Is it even possible that the therm is reading right but the nozzle/heat break are cooler by a good margin? Suddenly?

    Ideas?

    Thanks
     
  3. mhe

    mhe Well-Known Member

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    Nozzles can be removed at any temp if mechanically possible but tightening them should be done at temp.

    My guess would be that you either have some kind of debris in the nozzle or you have burned or otherwise degraded filament leftovers in that nozzle. I'd start with a nozzle replace again.

    Look inside the nozzle with a lamp. If you want to be really thorough, place the nozzle into some tetrahydrofuran that can dissolve PLA. But that stuff is highly toxic so beware.
     
  4. Old_Tafr

    Old_Tafr Well-Known Member

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    Test things individually even though they seem right?

    e.g. the thermistor in boiling water would seem like a good start so if room temp and 100oC are good then more than likely it is ok.

    Is there gunge between the thermistor body and the Al block?
     
  5. mhe

    mhe Well-Known Member

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    That might be the case, the only way I could think of to test the discrepancy between thermistor reading and actual temp is to use an IR thermometer and compare the values which you did. However, you said it does not work well on shiny surfaces - many of those thermometers can be calibrated for different surfaces by adjusting what is called the emission value - my meter calls it EMS. Maybe in the manual there is a table that tells you which kind of value to set it to to read from aluminium etc. That might help.

    If your meter doesn't do that, the only thing I could come up with is to hold a second thermistor to the heatblock on the side and heat it up. The only way out of that dilemma would be to go for PT100s which I could recommend in any case.
     
  6. Ramon Panganiban

    Ramon Panganiban New Member

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    Happens to me all the time. What I do is heat the nozzle to 230c and do a gentle push pull. Works everytime. Now, I pull the filament out at the of each job then reinsert it when needed after preheating.
     

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