Filament spreading apart and stringy on first layer

  • I keep having this issue on prints where the first layer has stringy lines that don't stick together.

    I've tried the following things

    • Replaced nozzle and throat

    • Used new filament (to rule out filament that may have absorbed moisture)

    • Printed at 180, 200 (my usual temp), 220

    • Aligned z stop sensor

    • Tried line width of 0.8 (usual 0.4)

    • Slowed initial speed to 30mm/s

    • Increased flow

    • Different Top/Bottom patterns

    My print settings as shown in this pic are the following

    • Layer height: 0.2

    • Line width: 0.4

    • Wall thickness: 0.8

    • Print temp: 200

    • Bed temp: 60

    • Retraction dist: 5.5

    • Retraction speed: 40mm/s

    • Initial layer speed: 30mm/s

    • Cooling at 20% after 0.2mm, 0% until then


    • Prusa I3 (hictop)

    • Cura to slice

    • Printing with PLA

    • Have had years of successful prints, issue started happening after a couple months of not using printer

    • Running marlin

    • Runs auto leveling routine before each print

    Let me know if you think there's other relevant settings to this issue. Any help is greatly appreciated, I've been trying to fix this for days. I've tried different models, large and small, but have the same issue no matter the size

    enter image description here

    This looks like a mechanical or electronical (missing steps) combined with a too close nozzle to the build plate. Also with correct hair spray or specific adhesion spray you won't need the kapton tape at all.

  • KeithS

    KeithS Correct answer

    2 years ago

    I would try two things you didn't mention; a bed leveling (this looks a little close) and an e-stepper calibration. The layer looks thin and under-extruded, and two common culprits are the bed height being too close ("oversquishing" the first layer which reduces flow rate and adhesion), and the e-stepper not feeding as much filament as the slicer's asking for (giving you thinner lines than the slicer expected, so they don't adhere to each other or the substrate).

    I also see problems with that kapton layer. Totally understandable, the stuff is a major pain to lay down bubble-free, however it's also absolutely necessary to do so to avoid first layer issues. That's not your only problem here but it'll keep being a pain after you have filament feeding sorted out.

    Lastly, I'm seeing slicer error; the floor fill is being laid down over the top of the shell layers on the right side of your image. Remember that the wealth of slicer variables in Cura regarding print speeds, flow rate, filament diameter etc ultimately boil down to a single G1 command per line: "move from here to here at this speed extruding this length of filament". So, if the slicer is forgetting where it drew the outline by the time it scripts the floor fill, it's possible it lost the plot on extrusion calculations as well. Alternately, the printer could be the one that lost the plot, either losing track of the steppers or incorrectly interpreting the G-code. Usually you just need to power-cycle the printer, close and reopen Cura and re-slice. Also, if you're printing with a USB cable, try switching to an SD card; there's less to go wrong in the communication between slicer and printer if the slicer tells the printer everything it should do up front.

    I'd look into each of these, then try to print a calibration shape, like a 20mm XYZ cube, before going back to the print you had on the plate before.

    Thank you so much for the insights! I do have the bed autoleveling each time (forgot this one). I'll give the rest of these a try. I did have perfectly smooth kapton the other day, but in trying to calibrate the height, it faced the wrath of the nozzle making contact with the bed :'(

    @Chris consider dumping kapton or other layer in favor of gluestick or gluespray. Much easier to deal with.

    @CarlWitthoft - For some plastics, yes, however if you need a heated bed over about 60*, i.e. ABS printing, kapton's the stuff. ABS adheres well to it, and the tape's own adhesive keeps the layer down on the bed even at 120*C where other bed preps fear to tread. Can't tell you how many times I've had a print pull blue tape right off the print bed, and glue stick/hairspray can both make a real mess of the bottom of your print (which could easily be the top or front of your finished piece) and can lose their adhesive qualities at these higher temps.

    @KeithS Great, complete answer! With 3DLAC or Dimafix spray you do not need Kapton for ABS, they increase to adhere more at higher temperatures. I get even POM to stick using such sprays. Whole lot easier to apply.

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Content dated before 7/24/2021 11:53 AM