Whenever the print reaches a layer with top/solid infill, it bulges out. It is not on the same layer for every print, which rules out Z-binding. Here are things I have tried:

  • Different slicers
  • Updated firmware
  • Smaller K value for linear advance
  • Lower temperature
  • Slower walls and top layers
  • More perimeters
  • Tightened belts
  • Different filaments
  • Different jerk and acceleration values

My problem is similar to what these people are experiencing: https://forum.prusaprinters.org/forum/original-prusa-i3-mk3s-mk3-how-do-i-print-this-printing-help/buldge-when-print-reaches-solid-layers/

These pictures show my problem. The lip in the second picture is supposed to be parallel with the body of the model, not stick out to the right like in the picture. Pic of bulge from an angle

Another angle

  • $\begingroup$ Have you checked if the extruder is over-extruding? With infill there is room to bulge out inwards, but when solid if can only go outwards. $\endgroup$
    – 0scar
    Commented Jun 25, 2020 at 8:23
  • $\begingroup$ @0scar I calibrated my extruder and found I was actually under extruding a little bit. $\endgroup$
    – Carson
    Commented Jun 25, 2020 at 17:42

1 Answer 1


I'm not sure about other slicers, but Cura has an option called Skin Overlap that defaults to 5% and causes excess material to be extruded beyond what actually fits in the skin (top/bottom "solid infill" surface) area. If you only have a few top layers it probably won't push the outer walls out and will just build up a rough top surface, but with more than a couple it's likely to start making the walls bulge out because there's nowhere else for the excess material to go. I've gotten dramatically better print quality since turning this setting off (0) and doing the same for Infill Overlap.

  • $\begingroup$ Unfortunately this didn't seem to fix anything. It was a good suggestion though. The fact that the problem persists between slicers suggests it is not a slicer issue, but it only happens around the transition from top/solid infill to the layers above it and not the same layer every print which is extremely confusing to me. $\endgroup$
    – Carson
    Commented Jun 25, 2020 at 4:24
  • $\begingroup$ Can you view the sliced results and confirm that the bulge isn't actually there in the instructions to the printer? $\endgroup$ Commented Jun 25, 2020 at 5:12
  • $\begingroup$ Yes it's not there in the sliced preview or the model. Do you know of the XYZ cube model? When I print that, the bulges are around the top and bottom of the X and Y. $\endgroup$
    – Carson
    Commented Jun 25, 2020 at 6:34
  • $\begingroup$ Maybe you have loose belts and the position of these lines varies by the slop in the belt depending on which direction the last move was from? $\endgroup$ Commented Jun 25, 2020 at 6:42
  • $\begingroup$ I just tightened the belts, but I'll try printing the test piece at a 45 degree angle. $\endgroup$
    – Carson
    Commented Jun 25, 2020 at 17:44

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