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Inexplicable heat creep

czkinicz

Hi, I've just run into a problem on my DIY printers E3D v6 hotend. The hotend jammed and I had to disassemble it to clean it up. Turned out that phe plastic (PLA) melted in the heatbreak. So I've unjammed it, cleaned it up, applied a heat paste, reassembeled it and it imediately jammed again (nothing even got out of the nozzle). I've repeated the process twice with the same result. The heatsink is not hot to the touch. Any idea what is causing it?

  • Just my thoughts on what I'd do for my machine (which is different)- not that it will help:

     

    • Give a good look over on your connectors to make sure no wire connections came loose.
    • Put a voltmeter on its power leads to see if it is getting voltage.  A quick google showed you are looking for 24V.
    • If you are not getting voltage, it could be the thermistor is not reporting correctly and so the software is not demanding it to be heated.  I'd look to see what the thermistor is reporting on the display.  If it is showing high when its cold to the touch, its the (very rare) problem.
    • If you do not have voltage and the thermistor looks good, check voltage up the line until you find it and the problem will be somewhere in between.
    • Electrolytic capacitors, if you have any, are always my first inspection point when I troubleshoot voltage back to the board.  If they are bulged and have a thin dark goo on their top or bottom, they need tested.

     

    -Sean

  • in reply to Sean_Miller

    I don't have a problem with heating it. I have 12V on the heater and the thermistor is reporting correctly. The heatblock is at a set temperature, heatsink is cold to the touch but the plastic melts in the heatbreak immediatly after i load it in and jamms the hotend.

  • If the nozzle is clogged with a foreign particle or if it is too close to the bed, the filament can feed into the melt zone faster than it can come out the nozzle, causing the melt to back up until it freezes in the heatsink. You may need to heat the nozzle up and clear it with a wire or a needle.

  • in reply to czkinicz

    If it doesn't have a clog remaining as Doug mentioned, one other thought would be that the feed wheels are slipping.  The shaft of one of my wheels eventually eroded down after 4 years.  It loosened up the feed system enough that it began to slip.  

  • in reply to dougw

    I've already tried clearing it with a wire and it didn't help. I had to replace the nozzle.

  • in reply to czkinicz

    Did the new nozzle solve the problem? Are you using a particularly small nozzle?

    If your nozzle is clear of obstructions you should be able to calibrate the filament feed rate so it doesn't back up into the heatsink:

    https://www.youtube.com/watch?v=lRoCwxRZsvU

  • in reply to dougw

    New nozzle solved the problem, I think that by tring to clean it with wire I just pushed the clog in a bit. Replaceing the nozle did the trick and I calibrate feedrates everytime I load in a new spool of filament.