Nozzles, Hotends, and Feeding PET-CF

Use a hardened nozzle

PET-CF contains 15% carbon fiber, which is abrasive. A brass nozzle will wear out quickly and its opening will grow. Use hardened steel, tungsten carbide, ruby-tipped, or another abrasion-resistant nozzle, with an all-metal hotend.

Use a 0.5 mm or larger nozzle

Fibers need room to pass. A 0.5 mm or larger nozzle reduces the chance of clogs. 0.6 mm is a popular choice. See also Nozzles for Pro PCTG, which covers hardened and high-flow nozzles.

Watch tight bends in the filament path

Carbon fiber makes PET-CF stiffer and less flexible than unfilled filament. In independent testing, it passed through a 25 mm bend radius but snapped at 15 mm. Check that the PTFE tube from your spool, dryer, or AMS doesn't make a sharp bend, especially near the toolhead.

See Feeding fiber-filled filaments reliably for more tips.