headed chamber and jamming

Discussion in 'E3D-v6 and Lite6' started by mikgol, May 11, 2015.

  1. mikgol

    mikgol Member

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    Hey there,

    I'm trying to print a large ABS object with a heated bed (100 degrees), 230 degrees on hot end, and inside a chamber to keep the heat in.

    The v6 jammed up good. The fins were quite warm to the touch, which is understandable as the fan is blowing warm/hot air as it's inside the heated chamber.

    Is the v6 no good inside a heated chamber? My retraction is 0.8, and print speed wasn't ridiculously fast (75). I'm wondering if I need to build a tube to feed cold air to the v6 to fix this?
     
  2. elmoret

    elmoret Administrator

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    I use a v6 with the standard provided fan to print ABS in a 300mm x 300mm x 300mm enclosure, with a bed at 110C. No jamming, over 500 prints so far.

    ABS really doesn't jam, no matter how hot the upper part of the hotend is. How do you know it was a jam and not a clog due to debris?

    I'd try a higher output fan first, before ducting in cool air (which will lower the temperature of your enclosure). The stock fan is 4 CFM.
     
  3. mikgol

    mikgol Member

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    I had to disassemble the v6 and use a blow torch to get the stuck filament out, so I'm pretty sure it was a jam.

    I tried printing it again this time without the heated chamber, and it got stuck again, but this time no so much that I couldn't pull it out.

    I'm wondering if this particular filament needs more than 230 degree's. Can too low a temperature cause jams like this as well?
     
  4. mikgol

    mikgol Member

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    I bumped up the temp to 240, and printed without the heated chamber, but still no luck. Filament stopped flowing after a couple of layers (of a large, flat object). This time it wasn't difficult to pull the filament out (I had to disassemble the v6 the first time). Could reducing the speed help? Or perhaps disabling retraction altogether?
     
  5. elmoret

    elmoret Administrator

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    Blowtorching is bad news, is carbonizes the polymer and create soot and other debris. The heatbreak and/or nozzle may be permanently damaged now.

    A better alternative would have been to soak the metal parts in acetone.
     
  6. mikgol

    mikgol Member

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    This forum is about as useful as tits on a bull lol
     
  7. licensed2hench

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    That is not good. The fins should be cool to the touch. Even in a enclosed chamber they should be cooler than the surrounding air.
    Standard Checklist:
    Extruder fan should be on max all times. Not to be confused with the print cooling fan. It usually needs a separate, dedicated 12v supply line.
    Print Temp: E3D mentions that they run ABS a bit hotter in their hot ends. At 240c instead of 230c

    I am running ABS in a enclosed chamber and am having stalled print issues that sound similar to yours.
    Print starts off fine, reaches the 4th layer, right when it starts to do infill, and something goes wrong and the filament stops extruding (the "stall"). The filament in the nozzle hardens and discolors becoming too hard for the extruder to push through later. From what I can tell this "clog" is a result of the "stall", not the cause.

    I have found that I can pull the filament from the hot end so it is not a typical "jam". But it does leave the hardened ABS clog behind in the nozzle. (I have gone over the filament and nozzle with a magnifying glass and have not see any evidence of foreign bodies)

    Initially cleared the clogged nozzle by heating nozzle with stove flame. Then repeatedly soaked everything in acetone overnight and swabbed out with paper towels to remove soot and residue. (I hope I did not damage it)

    After it happened again I found I could clear the "clog" manually by heating the extruder, removing the filament and (Bowden) tubing, and inserting a short length of tubing into the extruder manually shoving a short length of filament into the extruder. I can push harder "by hand" then my extruder can (without striping the filament). If your extruder can handle the force necessary you can probably clear the hardened ABS just by extruding very, very slowly.
    Eventually the hardened ABS extrudes and the nozzle flows clear again. I run a several centimeters of filament through just to make sure any residue is cleared.

    As to why the initial stall occurs? No idea.
    My problem is I have so many variables going on that troubleshooting and tracking down the problem is very frustrating...

    I suspect my problem is a combination of "thermal creep" in my extruder and too much "back pressure" in the tube.
    *Thermal Creep - the filament getting too hot and soft in the extruder to be pushed through
    *Back Pressure - too much force required to push the filament down the Bowden tube causing the gear to chew and grind the filament.
    I did not have jamming issues when I was running with the enclosure lid open. I dialed back the current to the extruder motor so it ran cooler and that seems to have helped. (thermal creep from the steeper motor in the extruder?)
    I have noticed that I get a lot of tooth marks on my filament and "dust" building up in and around it even with normal operations. (too much force needed to feed the filament?)


    For you I recommend making sure you extruder fan is working as it should. Then checking out your extruder for thermal creep. It is normally an issue with PLA so most people don't consider it for ABS.
    One tell-tail is a slick divot in the side of your filament where the gear melts/strips out against it.

    I hope this was helpful.
     

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