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  1. #1

    Inconsistent extruding from nozzle

    Hello all! My name is Niels and i am a 3d printer newbie. I have watched tons of guides and tutorials on 3d printing. I suppose I spent around 20-30 hours doing that while building my printer. I do have some electronics skills and i am sort of handy as well, so i figured i should be able to construct a functional 3d printer. (Heck, i made my own WiFi-controlled LED plant grow light, with adaptive spectrum!)

    I have a problem i can not seem to figure out and i can not really find on the internet. I did have a few other problems which i managed to solve on my own, including filament stripping, underextrusion and not perfectly level X-axis (Horrible noise).

    My setup:
    Prusa i3 - Steel, 12V, NEMA17, igus-drylin bearings, Ramps 1.4SB, DRV8825 drivers
    Wade-style extruder, E3D V6 all-metal hotend (1.75mm), Mk3 aluminium heatbed. 0.3mm nozzle

    Problem:
    I am trying to print my PLA at the reccomended temperature of 220C on painters masking tape (yellow, cheap). The heatbed is at 50C (Worked better for adhesion than 60C). The print itself is a single walled upright bar, with bottom, no top. Layer height 0.2mm, speed 50 mm/s.

    I observe gaps in extrusion, as shown in the picture. I see a nice steady stream of plastic flowing from the nozzle, and then suddenly nothing, and a little later it just continues. (In bad cases, when it continues it curls up at the nozzle and makes a mess, dragging everything along).

    Diagnostics performed:
    Simple extrusion through hotend in pronterface - 10 mm @ 100 mm/s occassionally hear a popping sound and see an irregularity (bump and decrease of flow) in the plastic stream, when extruding @ 10mm/s this becomes more pronounced.
    Simple extrusion without hotend in pronterface - 100 mm @ 100 mm/s, perfectly extrudes 100mm of filament. (I did have to add about 20% steps/mm in Marlin to ~1950)

    Tests:
    Tried temperatures between 200-230 - No real difference
    Tried extrusion multiplier between 100-110 - No real difference
    Cleaned the barrel and nozzle very thoroughly with chloroform twice (Dissolves PLA) and used a toothbrush inbetween the two treatments. - No difference
    Cleaned the hobbeld bolt with a toothpick and compressed air (was some slight grindings from skipping extruder from before) - No difference

    I believe after spending about 10 hours on failed prints and searching for solutions on the net, i can say i honestly dont know what i could do more. (Except for maybe a extra extrusion test WITH hotend, although i did calibrate the extruder with the hotend before.)

    Personally i suspect filament flexing/bending or snagging in the hotend barrel, getting softer/melted after a little while and releasing the pressure allowing for further extrusion. But as far as i know this should not happen.

    Regards,
    Niels

    PS: I have the same question on a different forum, but i later thought this forum might be more appropriate.



  2. #2
    Technologist
    Join Date
    Apr 2016
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    120
    I guess the first question would be if you have assembled the hot end correctly, with the PTFE tubing leading all the way down to the threaded heat break.

    I had these problems with the E3D and this was my issue. The PTFE tubing was slightly too short and was moving up and down in the heat sink, allowing the filament to buckle in the gap.

  3. #3
    Quote Originally Posted by noiseboy72 View Post
    I guess the first question would be if you have assembled the hot end correctly, with the PTFE tubing leading all the way down to the threaded heat break.

    I had these problems with the E3D and this was my issue. The PTFE tubing was slightly too short and was moving up and down in the heat sink, allowing the filament to buckle in the gap.
    This was not possible, the top of the hotend (the heatsink of the hotend) does not seem to allow any insertion of PTFE whatsoever. i.e: the hole was too small.

  4. #4
    Technologist
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    Apr 2016
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    Info on correct assembly here: http://wiki.e3d-online.com/wiki/E3D-v6_Assembly

    Explains it better than I can!!

  5. #5
    Quote Originally Posted by noiseboy72 View Post
    Info on correct assembly here: http://wiki.e3d-online.com/wiki/E3D-v6_Assembly

    Explains it better than I can!!
    It is not possible to insert PTFE tubing in the heatsink.
    I do have PTFE tubing between the hobbed bolt and the top of the heatsink (pictured) though. To be extra clear, i mean that i pictured the top of the heatsink, not the PTFE tubing. (I thought it might be unclear when i read my own message.)
    Last edited by Reaping miner; 07-24-2016 at 10:55 AM.

  6. #6
    Engineer-in-Training
    Join Date
    Sep 2014
    Location
    Brummen, Netherlands
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    265
    You have a full-metal hotend. These are notoriously finnicky to the temperature transition zone between cooling body and heating block, most especially for PLA of all plastics. A simple way to see if this is your problem, you can replace the existing heatbreak (the part that connects the cooling body to the heating block) by a ptfe lined one. They cost very little. If that solves your problem you know it is this issue and then you can concentrate on solving it and returning to the full-metal heatbreak.

    Another possibility is too fast extruding, that is the heating block/nozzle can not melt the plastic fast enough. As raising the temp did not solve your problem, I suspect this is not the case, but I would to see what all your print speeds are.

  7. #7
    Accidentally deleted message so i will keep it short.

    Tried printing between 20-70 mm/s.
    Most, if not all prints shown are at 30 mm/s.

    Unfortunately barrel is stuck in heatsink. If i remove it i am afraid i might break something. Ironically i got the full-metal barrel for the versatility and robustness. (Less likely to damage).

    Edit:
    I will try this
    https://forum.e3d-online.com/index.p...-heatsink.341/

  8. #8
    Staff Engineer printbus's Avatar
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    Never seen or heard of an E3D v6 hot end for 1.75mm that doesn't have a PTFE liner in the heatsink. Is this some form of E3D knock off? Where was it purchased?

    Have you tried another roll of filament, preferably from a different source? "...hear a popping sound..." could be excessive moisture in the filament.

    What is happening with the Wades gears when you run into one of the extrusion gaps? Do the gears keep rotating through it all as they should?

    Are retractions enabled? A single width wall shouldn't be applying retractions anywhere but possibly the layer shift point. If retractions are occurring (look at the gcode layer by layer in a viewer like gcode.ws if necessary to verify), it could be that you're retracting way too much.

  9. #9
    Quote Originally Posted by printbus View Post
    Never seen or heard of an E3D v6 hot end for 1.75mm that doesn't have a PTFE liner in the heatsink. Is this some form of E3D knock off? Where was it purchased?

    Have you tried another roll of filament, preferably from a different source? "...hear a popping sound..." could be excessive moisture in the filament.

    What is happening with the Wades gears when you run into one of the extrusion gaps? Do the gears keep rotating through it all as they should?

    Are retractions enabled? A single width wall shouldn't be applying retractions anywhere but possibly the layer shift point. If retractions are occurring (look at the gcode layer by layer in a viewer like gcode.ws if necessary to verify), it could be that you're retracting way too much.
    I bought the kit (including the hotend) at Orballo printing.

    My PLA (BQ) is fairly new (3 weeks today). I also tried ABS++ (FFF), still saw irregularities in the extrusion stream. (Meanwhile i baked silica beads and am storing my filaments in an "airtight" container now.)

    The gears keep running, no indication of slippage/obstructions anywhere.

    I have had retractions enabled (@ 2.5mm instead of the default 10!), but for most prints disabled (Dont think it mattered in my prints). There are no layer shift points (maybe one, from bottom to wall) i have been printing in spirals.

  10. #10
    Staff Engineer printbus's Avatar
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    Quote Originally Posted by Reaping miner View Post
    I bought the kit (including the hotend) at Orballo printing.
    While the hot end appears to be all metal, I'm not sure that's an e3d v6.

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