ABS Jamming!

Discussion in 'E3D-v6 and Lite6' started by ornitech, Apr 8, 2014.

  1. ornitech

    ornitech Member

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    Hi Everyone,

    I recently upgraded my GermanRepRap to an E3D hotend (3mm). Initial installation was very easy, and the first push of the filament through the hotend was very smooth. I've done about 20 hours of printing on the new hotend at speeds ranging from 20mm/s up to 140mm/s with good results. However, it's started jamming now, with no changes on hardware or print settings.

    Quite often it's jamming on the first layer or two, but sometimes it fails mid print. occasionally, it can complete a print with no jamming. I've tried:

    -Super slow speeds (no difference, especially since a lot of failures are happening during solid infill.
    -no retraction (no difference)
    -Wide range of temps 230-260c
    -Different nozzles (0.4mm first, swapped to 0.6mm to see if that would improve things...)

    Here's what the filament looks like just after a jam:



    It starts having trouble, but is able to start moving again a couple times, and the final jam results in the extruder chewing through the filament.

    I also have a 1.75mm hotend, so may swap to that while trying to debug the 3mm...
     

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  2. Eaglezsoar

    Eaglezsoar Administrator

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    If you printed 20 hours with no problems and are now jamming, it sounds as though some of your filament has left debris
    behind which is clogging your heat break and possibly the nozzle. You will need to disassemble the hotend and soak the parts in
    Acetone followed by running a pipe cleaner with ABS on it and pushing it through the heat break a few times. I wish there was
    another way to clean the hotend but the ones I have read about I will not promote because I feel you could damage the hotend.
    Best of luck and let us know how it goes.
     
  3. ornitech

    ornitech Member

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    Solved!?

    I removed the entire 3mm extruder assembly, took it apart, and did the typical cleaning routine... nothing unusual there. Checked the inside of the heatbreak for burrs or machining problems.. some slight rings, but nothing really bad it seems. I ordered some pipe cleaners to polish the inside.

    Meanwhile.... I decided to try the 1.75mm hotend...

    Works great! Nice output, speeds up to 140mm/s, no problem.....for about 12-15 hours! Suddenly, I started having the same mysterious jamming problem. I decided to go step by step:

    1) Proper assembly: rechecked everything, tightened at 300C (and confirmed no leakage between nozzle and heatbreak)
    2) Thermistor: confirmed output with an IR thermometer.
    3) Heater: Aha! I noticed a small gap between the heater and the block. So I foil wrapped the cartridge until it has a nice snug fit in the block. The resulting temperature band is much tighter, but doesn't solve the issue.
    4) extruder gear: cleaned and aligned to filament. many of these failed prints are producing fuzzies that indicate the gear is slipping. after cleaning, no difference.
    5) Printer settings: tried a wide range of speeds, temps, layer heights, retraction, all seem to have no effect.

    At this point I had been watching 10's of failed prints in quick succession, and noticed something..

    The filament was bent away from the center of the extruder gear whenever it jammed. So was this a cause, or effect? was it jamming first, and then as the extruder continues to push, does the filament wiggle under the pressure?

    More observations resulted in this conclusion: The angle of entry to the top of the extruder was causing the filament to work it's way along the extruder gear. This caused increased friction inside the cool portion of the hotend, causing the filament to move further, and eventually be stripped near the edge of the hobbed portion.

    The solution: enforce the location and angle of filament entry into the extruder with a PTFE tube.

    I still haven't switched back to the original 3mm hotend, but will report then I do.
     
  4. Eaglezsoar

    Eaglezsoar Administrator

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    How long have you been printing now without problems?
     
  5. ornitech

    ornitech Member

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    So... new issues...

    After I revised the filament entry, I was able to get a couple decent prints, but there was poor layer adhesion, and bad solid infill, so I decided to recalibrate using the thinwall model. Across a number of prints with speeds ranging from 20mm/s up to 130mm/s and temps from 230-260C, i was having a strange problem.

    About halfway through the print, the filament would start to have gaps. It's strange becouse the first few minutes go just fine, but then it rapidly deteriorates from solid to extremely intermittent extrusion. Did a couple prints with my finger on the stepper, and it seems like it's step loss.

    So my question is, too much, or too little stepper power?
     

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  6. myk68

    myk68 Member

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    Hi Ornitech

    I think this is linked to the issues we are going though here but maybe not to the same extent. I have the same issue you are getting but then the air printing starts.
    take a look-
    viewtopic.php?f=7&t=115

    Mike
     
  7. ornitech

    ornitech Member

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    Hi Mike,

    I have also been following the other threads with interest in the nozzle problem. I fear the fix may not apply for me as I have tried several different nozzles, and both 1.75 and 3mm hotends.

    So far I have tried:

    3mm - 0.4mm, and 0.6mm

    1.75mm - 0.4mm

    Btw, this is the extruder I am using:

    https://shop.germanreprap.com/en/product?info=286

    it has a pretty serious motor on it, and can chew through the filament, so it's pretty remarkable to get step losses. I also have a heated chamber, that is normally kept at 100C (print lots of giant ABS parts) so the nozzle may not be cooling as much as some others.
     
  8. Sanjay

    Sanjay Administrator
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    If your chamber is at 100C the fan is definitely going to have issues keeping the heatsink cool myself and a few others have found 50C to be around the max ambient air temp before things start going wrong - additionally the fan might begin to fail due to the lubricant on the fan gumming up.
     
  9. JuanG_v

    JuanG_v Member

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    The problem is that this hole has disappeared.

    Image (sin titulo)

    The nozzle temperature is not correct. I had the same problem with the thermistor placed in that position.
    I had another e3d v5 with that hole. I use the same body and just change that piece, place the thermistor with the same nozzle and all in the position of that hole.

    thermistor is far from the nozzle.

    Problem solved.

    I teach courses mounting prusa i3, I have assembled 15 e3d with hole and perfect, since I bought the last 20 e3d without that hole, 20 have given failure jamming with different extruders.

    if I take 10 of the last 20 e3d and I put the thermistor in that position (with this piece) all work and no problems.

    Sorry for my english! :)
     

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