3D printing: Gaps between walls and how to fix it

If your prints have gaps between the walls, it may be due to settings in your slicer that aren't set exactly right. Below you can see how to fix it.

Adjust thin wall behavior

Most slicers have a setting that analyzes the model and finds places where there is not enough space to make all the shells and at the same time, infill. Therefore, the setting "Fill thin walls" or "Detect thin walls" can be activated. It may take a little longer to slice your models but it may be worth the wait. You can see where to find this option in the following slicers.

  • SimplyPrint slicer: Inside > Fill thin walls
  • Cura: Custom > Shell > Gear > Print thin walls > Checkbox > Close > Print thin walls
  • Simplify3D: Edit process settings > Advanced > Internal thin wall type > Allow gap fill
  • Prusa slicer: Printer settings > Advanced mode > Layers and perimeters > Quality > Detect thin walls

Change extrusion width

Extrusion width determines how wide the printer tries to make the lines that need to be laid down to build up your print.

If your prints look like the one in the picture, you can also solve the problem by trying different widths of extrusion. If the part to be printed is 1 mm wide like stick number 4 in the picture, you can set the extrusion width to 0.5 mm which can then fill the entire millimeter.

  • Cura: Custom > Quality > Gear > Line width > Checkbox > Close > Line width
  • Simplify3D: Edit process settings > Extruder > Extrusion width
  • Prusa slicer: Printer settings > Advanced mode > Advanced > Extrusion width > Default extrusion width

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Published: Oct 2020, updated: Feb 2021