Need advice on weird random printing problem (Ender 6 3D)

  • Hey all! I'm hoping someone has run across a similar problem as one I am having, and has some ideas or a solution to fix it. The problem I have is in 2 different models (and with 2 different filaments) I have tried to print, I get a section of the print (about 1.5 inchs wide) that doesn't do a solid print, almost as if it was missing lines in the print. So the result is a band of thin area that is porous and you can see light through. Also the approx. 1.5 inch band is in different locations on the 2 different models, so it does seem to be random. (The 2 models are the "Millennium falcon" and an extendable katana).

    Note: Except for the approx. 1.5 inch band of bad print, the rest of the print was fine.

    My current setup is:

    • fully enclosed Ender 6 3D (with BL-touch, but that shouldn't be a factor)
    • Filament was standard PLA (one Gray and one Black)
    • Slicer is Cura ver. 4.9.0
    • One model was set to .12mm and the other was .2mm
    • Infill was 10% on one and 50% on other
    • Temp on both was 210
    • Print speed was 50

    I've attached a pic of the "Millennium falcon" where you can see the problem area is about 60% of the way up, running completely across the print. (And yes there was also a lot of other stringing, but that's just cleanup, the band is just unfixable. (doh!) )

    So has anyone run across anything similar to this before, or have any suggestions on how to fix it? Since both prints were fairly lengthy (40 hours and 17 hours), it's a real pain to find out the print is bad at the end. 😞

  • @SteveDee Thanks for your thoughts, I think you may be on to something with the z-axis. I had added a stabilizer unit at the top of the z-axis screw, since the screw has a slight wobble when the build plate is towards the bottom (not surprising since the screw is only secured on the bottom). But checking the bracket the stabilizer was connected to, it was just loose enough to move and then not slide back right away, which could explain the random locations of having the problem. So I've removed the stabilizer and will run some tests to see if that was the cause.

    Thanks for the input!

  • @telephasic For your question about the height of 1.5 in, the 2 different models had slightly different sized areas that were having the same problem, but both were more than an inch in height.

  • @Dogberticus Looks like there could be some kind of mechanical issue with z-axis.

    My approach would be to 3D design (or download) a tall test piece that will print relatively quickly (...maybe a hollow tube). Then you can test/modify/test quickly without wasting tons of filament.

  • @Dogberticus haha. well it might not have helped at all to be there when it happens, but some evidence like noises would be good to point you more in the right direction.

    more spitballing:

    • a post-processing script forgotton/left turned on? but since it happens at different heights, that's ruled out.

    • maybe a (partial) clog that gets freed after a while? but different filaments you would think would change that behavior.

    • part cooling fan stopping for some reason? thought maybe the right amount of filament is still being added, but just oozing out of place.. i guess it would not make your model so porous though.

    sort of stumped, but still suspecting the extruder is involved.
    is the height exactly the same 1.5"? that might be a clue.

  • @telephasic Thanks for the suggestions! They are better guesses then anything I could come up with. 🙂 I'll try blowing out the extruder and doing another run at something and see if it happens again (of course this has only happened so far when I'm doing a longer build. 😵 )

    Also you are right, I did stop watching it for a while there. My bad! ha ha ha

  • @Dogberticus i think that's the part where you weren't watching it 😛 but really, that's weird. and a crappy thing to find after 40h...
    shot in the dark, but could it be that filament shavings have been building up in the extruder teeth, keeping it from grabbing correctly, and then getting cleared eventually? or maybe it's loose?

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