FDM Print quality problems

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.

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