FDM Print quality problems

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Print exhibits unexpected weakness and various other print quality issues.

  • Print is weaker than expected, despite appearing satisfactory:
    • This may result from a design comprising multiple separate parts, where a unified shape would yield superior results.
    • Check if the design is not manifold (usually indicated by the slicer software; ensure the design is repaired or that automated repair is successful). Utilize the layer view to inspect the new slicing result.
    • Experiment with a different infill pattern.
    • Increase the extrusion multiplier or the extrusion width.
  • Under-extrusion:
    • Verify the correct filament diameter is used in the slicer; measure the filament diameter.
    • Raise the nozzle temperature.
    • Perform nozzle cleaning.
    • Increase the extrusion multiplier for a solid block of plastic (e.g., when printing a lithophane).
  • Gaps between infill and outer wall: This is rare but may occur with demanding materials:
    • Boost the infill overlap.
    • Initiate a layer by printing the perimeter.
    • Reduce the print speed.
    • Consider printing a bit hotter to enhance the printing of filled filaments.
  • Support or infill fails to print correctly:
    • Check for a partly blocked nozzle.
    • Review slicer settings, particularly fill density.
    • Decrease infill speed.
    • Experiment with a different infill pattern.
  • Dimensional accuracy, a few considerations:
    • Acknowledge that a 3D printer’s dimensional accuracy is at best approximate; ensure there is some space between sliding or turning parts, especially if printed simultaneously. When designing, facilitate easy offsetting of important surfaces and maintain a high polygon count for turning surfaces.
    • Over time, wear will degrade the overall and local dimensional accuracy of the printer. Good maintenance mitigates this issue, but new parts may be necessary at some point.
    • Note that a too-high nozzle temperature can also complicate part fitting.
  • Excellent details not printing correctly:
    • Ensure the machine is in perfect running order.
    • Optimize the layer height.
    • Fine-tune the extrusion temperature.
    • If permitted, use a smaller nozzle diameter.
    • Alternatively, consider using an SLA printer.
  • Support scars disfigure a print:
    • Confirm the necessity of support; try reducing it by enabling bridging or adjusting the overhang angle.
    • If these optimizations prove ineffective:
      • Experiment with a different support pattern.
      • Utilize less dense support.
      • Lower the extrusion temperature.
      • Consider using soluble support.
  • Stringing: the print appears hairy; manually remove as many hairs as possible and use hot air to shrink the remainder. To prevent stringing,
    • Ensure the filament is dry.
    • Enable or increase retraction.
    • Increase speed on non-printing moves.
    • Reduce the minimum travel.
    • Activate avoid crossing perimeters.