FDM Surface defects

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The outer surface could be improved.

  • High details not achieved: Details smaller than the nozzle size or layer height cannot be printed.
  • Pimples: these can be caused by over extrusion, but also by poor retraction settings or delays.
    • Check the extrusion ratio.
    • Increase the retraction.
    • Use an SD card or USB stick to avoid network problems causing delays.
  • Unwanted lines on the print: usually caused by 'oozing' during or after a move without printing of the print head. If you use a standard slicer profile, this should not occur. If you use a new material without a profile, see the all3dp.com article for hints.
    • Use or increase the Z-lift or retraction for non-printing moves.
  • Drooping: caused by over-extrusion and probably an excessive layer height.
  • Infill is visible from the outside, also ghosting:
    • Use thicker walls.
    • Adjust the wall thickness to a multiple of the nozzle width.
    • Print the perimeter first (can cause the print to weaken).
    • It could also be due to poor bed leveling; in that case, the problem should be more visible on one side and less elsewhere on the build plate.
  • Drooping filament below bridges: there is always a maximum gap size, but most printers and many materials allow gaps of at least 5 cm (10 cm is often attainable, 15 cm is sometimes possible).
    • Common causes for problems when spanning smaller gaps are insufficient cooling (increase the fan speed), excessive extrusion speed, high extrusion temperature.
    • Make sure to switch on bridging in your slicer, so it can optimize the settings.
    • If you need a quick fix, just add support.
  • Overhang is messy (almost spaghetti), insufficient or weak, or missing support.
    • Lower the print speed.
    • Reduce the layer height.
    • Use support.
    • Sometimes designing your own support or adding a block to your design to shorten the height of flimsy support can be a solution in hard to solve cases.
    • Printing the design in two or more pieces is always an option, as is repositioning the design to increase the angles with the floor.
  • Ghosting and ringing, visual wavy surface imperfections that are usually not reproducible. These are due to (parts of) the printer that vibrate. Such vibrations are more likely or larger on machines with a heavy printing head assembly. If the bed moves, the combined weight of bed and print will be a factor.
    • Reduce the print speed or optimize exposed acceleration settings.
    • Put the printer on a slab of stone (or a sturdier table).
    • Poor maintenance can exacerbate vibrations.
  • Pillowing, which covers most of the top layer defects.
    • Increase the number of top layers.
    • Use a higher infill percentage.
    • Lower the print speed.