ABS layer adhesion issues

Discussion in 'E3D-v6 and Lite6' started by hielvis, Jan 21, 2018.

  1. hielvis

    hielvis Member

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    Hi,

    since I moved from my stock setup on a Geeetech Aluminum to the Titan extruder with V6 hotend I am having layer adhesion issues (see images of part printed at 240° and 250°). I am using this carriage: https://www.thingiverse.com/thing:2065461

    On my old setup I just disconnected all fans (mk8 extruder fan and part cooling fan) and had way less to no layer adhesion issues at 240°.

    The filament is Aprintapro Printament M-ABS, their spec sheet says to print with 225 - 250° C and 65° C heated bed depending on printer. I am already printing at 250° C and 100° C heated bed (heated bed on 65° C just gave me bad warping on pei sheet) with an improvised enclosure (cardboard box, previous setup worked without enclosure).

    My questions are:
    • Might the heat sink cooling fan draft be the culprit here?
      • If yes, should I try to disconnect the heat sink cooling fan or do you think this would definitely result in a clog/jam by heat creep? The mk8 extruder had no issues with heat creep because of the no metal hotend i guess, ptfe tube all the way ;)
      • Do you use some sort of duct opposite the heat sink fan to divert the air upward or similar?
    • Might the thermistor deliver wrong temps and thus result in bad layer adhesion? Despite multiple runs of PID tuning with and without part cooling fan, my temps seem to vary widely around the target temp (regular jumps of up to 5°)

    Thanks!
     

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  2. Spoon Unit

    Spoon Unit Well-Known Member

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    Do NOT disconnect the heat sink fan for a full print or you will definitely get a block. That's not a risk, it's a guaranteed result as far as I understand. You don't want melted plastic in the heatbreak. Your point about the fan impacting airflow might well be spot on though. There is a duct design to control the air intake flow https://www.thingiverse.com/thing:1680165. I don't have a similar design for the air ejection, though I think that's already being directed upward on mine by hitting a fan enclosure.
     
  3. hielvis

    hielvis Member

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    thanks for the quick reply!

    I'll have to look for a thiner design though, since my fan draws air from the left, so this would most definitely collide with the z axis before hitting the end stop. I would have thought the air intake would be less of a problem than the (probably more directed) stream of air at the outtake side though.
     

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