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Extruder clogged

Discussion in 'Troubleshooting' started by bgraham111, Sep 10, 2013.

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  1. bgraham111

    bgraham111 New Member

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    Does anyone know a good way to unclog an extruder head?

    My first print went fine. The second print seemed to get all screwed up, and not very much material came out. I tried to run the extruder, and nothing came out. Can't push it by hand, can't get it to budge. Can't get a wire up into the nozzle... nothing.

    Yes - I have the heat on.

    Is anyone else having the head get clogged like this?

    Concerned that I just bought the world most expensive calibration block. :)
     
    #1 bgraham111, Sep 10, 2013
  2. Leon Grossman

    Leon Grossman Active Member

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    I've been printing for months now with zero nozzle clogs. So, unless you were unlucky and there was a burr in the nozzle from the factory, one of a few things could have happened (that I can think of off hand)

    1. You over heated PLA and caused it to crystallize in the nozzle. You would need to remove the nozzle to clean it
    2. You used cheap quality filament with impurities in the plastic. See number one for resolution
    3. You aren't actually heating your hot end but you should be able to to tell that from the display.
     
    #2 Leon Grossman, Sep 12, 2013
  3. bgraham111

    bgraham111 New Member

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    Well, not one to wait, I started trouble shooting on my own. Did some research and started taking it apart to clean it.

    I think the ABS got overheated, and burned up in the nozzle. This caused the blockage.
    Why? - I think the z-axis got out of wack and ended up pressing down on the headed bed too much, which didn't allow the filament to come out. In the future I think I'll leave more room. The bed is horribly aligned and wobbly. I think I'll have to do something about that.

    In addition, as I was taking it apart, I found that the ABS got so packed into the ceramic tube that it can't even be pulled out with forceps. I'm dissolving and picking it out slowly.

    I tried to unscrew the heated nozzle from the ceramic tube - and that's never going to happen in the state it's in. I even tried to warm it up and twist while wearing welders gloves. I think I need to dissolve more ABS out.

    As a design recommendation - the little metal tube inside the ceramic tube seems awful far away from the top. Almost seems like this was going to be a 3mm filament extrude and was changed to 1.75mm with the addition of a metal tube, only the tube is too short. What I mean is, there seems to be an excessive distance from the feeder bolt to the metal tube in the ceramic tube, allowing the filament to buckle. As the radio of Length/Diameter goes up, so does buckling concerns. Just something to keep in mind for future revisions.

    Hopefully this is a one time oops, and I'll be up and running in a few days. Otherwise I may need to talk about a replacement nozzle/ceramic chunk.

    I'll update this space with more info when I can.
     
    #3 bgraham111, Sep 12, 2013
  4. bgraham111

    bgraham111 New Member

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    Update - Acetone is my new friend. It dissolved the ABS really well, and I was able to clean the print head up really well. A little 500F Kapton tape and I'm ready to go.

    I think the print head is... OK. (Not 100% sure, but I'm going to run with that assumption.)

    But the issue seems to be the bed. It isn't flat. I can level the Z-axis across the bed at one given Y location, but that won't be close for another Y location. So it I print something that is 1" by 1", I'm OK. Anything larger and the bed screws me up. It's either so far away from the nozzle that the plastic just goes into space, or (and this is the cause of my clog) it presses up so hard that nothing comes out, and the plastic bunches up in the extruder head.

    This appears to be one of MANY tolerance issues I've found on my machine. Just trying to figure out what to do about them all. The bed levelness / flatness will need to be solved if I want to print anything of substance.

    UPDATE - the bed is BALANCED on two pieces of CARDBOARD! Sigh... maybe I should switch to PLA for a while...
     
    #4 bgraham111, Sep 13, 2013
  5. tesseract

    tesseract Moderator
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    are you printing directly on the the PCB board or do you have glass down as well? If not I would add that as a first step either boro or regular that will help in reducing some of the uneveness and there are bed leveling solutions put forth by many members here as well as quick adjustments for the z axis.

    Most important thing about 3d printing is a level bed
    that said the next is an easy way to make height adjustments

    Mods have been put out to help in both cases

    I actually put one out that seems to work extremely well for bed leveling and there are two good ones in this forum for the z axis

    Bed leveler: http://www.thingiverse.com/thing:125626

    I would also get a good analog dial indicator to check the levelness. I like the analog because you can see the needle swing showing how level things are sometimes it is hard to register the digital number flashing as it moves the needle is easy to see.

    Good luck and post back if you issue is not resolved.
     
    #5 tesseract, Sep 15, 2013
  6. fabrice

    fabrice New Member

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    #6 fabrice, Sep 17, 2013
  7. tesseract

    tesseract Moderator
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    The only thing I would be very worried about is that with something that rigid if you were off angle by ANY amount you could easily enlarge the whole.

    I found at least for ABS that ACETONE soaking and then using a a single strand of simple strand wire like 20-22 gauge seems to work nicely it goes through the hole eventually and has no chance of opening the hole up. Once is get it through (I use a long strand) I actually twist it up into a slight ball shape on the side where the filament comes into the nozzle and then pull it through as the nozzle itself straightens the wire, the wire is grabbing at all the filament in the way and dragging it free of the nozzle sometimes if I think it really needs it I put one end of the single strand against a drill bit and chuck it into my drill the chuck holds the wire against the drill bit and then simply turn press the drill button. It causes the wire to spin around a lot scraping the side of the nozzle and that cleans it out as well

    Just my two cents worth
     
    #7 tesseract, Sep 17, 2013
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