Blobbing on outside walls Bambu PETG Basic, drying issue? - eviltoast

Edit: Setting the max speed for walls to 50 mm/s solved it! I feel like this should be limited when you select the filament, but oh well.

Hey, so I have recently gotten a Bambu A1 and got a roll of PLA and PETG. The PLA is printing very nicely out of the box but the PETG not so much. Since I’m still very much at the beginning of my 3D printing journey, I don’t really have a good way of drying my PETG yet, I just stuffed it in a plastic ziplock bag with all the desiccant bags I got from the rolls and printer and stored it that way. I’m already planning to print myself a filament enclosure, I just haven’t gotten around to buying the bearings, etc for it.

I’ve done some functional prints with no angled (overhanging) walls and they have turned out pretty good. When printing on supports the overhangs are ugly af, but no weird pattern like this.

The issue I’m tracking down seems to occur on ~60+° overhangs, that really shouldn’t be an issue. I’ve done a sliced test print and took some photos, any idea what causes this?
Thanks :)

Bambu A1, standard 0.4mm nozzle
Bambu PETG Basic filament and profile using Bambu Studio
Some settings I played around with was flow rate (0.94->0.95) and layer height (0.2mm -> 0.15mm) but it seems to make no difference.

(note, on some of them the part is photographed upside down.)

  • IMALlama@lemmy.worldEnglish
    2·
    10 months ago

    Is that at the beginning or end of your layer? I betting it’s one or the other. If it’s the end, you have too much coasting. If it’s the beginning you’re likely not priming the nozzle enough. I had this issue… forever ago with Cura. What slicer are you using?

    • Jawa@lemmy.worldOPEnglish
      3·
      10 months ago

      It’s kinda not at the start or end of the layer. The layer starts with the inner wall, which prints fine and then it does the outer wall which doesn’t do fine.

      Which corresponds to the wall here

      What slicer are you using?

      Bambu Studio 1.8.4.51

      • IMALlama@lemmy.worldEnglish
        2·
        10 months ago

        Are you sure that’s not the end of the outer wall? You can find out by going to the gcode preview, using the vertical control on the right of the screen to get to a layer with this issue, and then using the horizontal control at the bottom of tge screen to see the print order.

        Do you have pressure advance? If so, it might be worth a tune.

          • IMALlama@lemmy.worldEnglish
            2·
            10 months ago

            Got them! It seems like you might have found your answer elsewhere. I’m somewhat surprised the underextrusion is so localized, but if you’re off and running then be happy I guess.

            • Jawa@lemmy.worldOPEnglish
              2·
              10 months ago

              well it was less underextrusion and more the printhead just trying to go supersonic at those spots and the material just didn’t flow fast enough :D