FDM First layer

• In an ideal first layer:
  • Individual strands should be visibly distinct.
  • Individual strands should seamlessly merge with their neighbors.
  • The strands should exhibit a slight flattening.

• Local under-extrusion or no extrusion at all can be attributed to:
  • The nozzle being too close to the bed; prolonged proximity may lead to nozzle clogging.
  • Uneven bed leveling.
  • Failure to prime the nozzle.
  • Inadequate nozzle temperature.
  • Nozzle blockage.
  • Incorrect first layer height.
  • Filament stripping.
  • Depletion of filament supply.

• Issues with print adhesion to the bed (locally):
  • Nozzle positioned too high.
  • Inadequate bed preparation.
  • Uneven bed leveling.
  • Consider reducing print speed.
  • Utilize a brim to increase the print's surface area.
  • Lower print speed (as a last resort, especially for unfamiliar materials).

• Localized over-extrusion (nozzle leaves traces in the printed material):
  • Nozzle proximity to the bed is too close, and the nozzle scraping through freshly laid filament is a concerning sign.
  • Excessive extrusion multiplier.