Stop Printing With Carbon Fiber Nylon

Main Ideas

• Moisture is a major weakness of many nylon filaments. Nylon absorbs water from humid air, which can substantially reduce its stiffness. A part that feels rigid when newly printed may become more flexible after exposure to humidity.
• Flexibility can matter as much as strength. The presenter demonstrates that a moisture-conditioned nylon part flexes noticeably under load, while a PLA Pro example stays more rigid. The broader point is that material performance should be assessed after realistic environmental exposure—not just when a print is fresh and dry.
• The video distinguishes several material properties:
  • Stiffness (Young’s modulus): Resistance to elastic bending or deformation.
  • Yield strength: The point at which a material begins to deform permanently.
  • Ultimate tensile strength: The point at which a material breaks.
  • Creep: Gradual deformation under a sustained load, even when the load is below the material’s yield point.
  • Impact resistance: How much energy a material absorbs during a sudden impact.
  • Layer adhesion: How strongly the printed layers fuse together.
• The presenter’s tests favor some alternatives to common carbon-fiber nylons. In the presenter’s moisture-conditioned comparisons, several tested nylons were less stiff and had lower yield strength than PLA Pro. Two Polymaker nylon variants performed better than PLA Pro on those measures, though one needs annealing to control creep.
• PET carbon-fiber filaments are presented as promising, but not flawless. The tested PET carbon-fiber options were generally stiff and showed very little creep. Their main drawback was lower impact resistance than several comparison materials. Layer adhesion also varied considerably by brand; one option performed notably better than the others in the presenter’s tests.
• Printing constraints affect practical choices. The presenter says that some PET carbon-fiber filament may require a larger nozzle, limiting fine detail, while another may be easier to use with smaller nozzles. The video also cautions that PET carbon fiber is not the same as PETG.
• The recommendations are conditional rather than universal. PLA Pro is described as easy to print and useful for experimentation, but weak in high-temperature environments. A PET carbon-fiber option is presented as a stronger general-purpose candidate for demanding conditions, while a Polymaker PA 612 carbon-fiber option is treated as experimental and dependent on successful annealing. These assessments are based on the presenter’s tests and experience, not a comprehensive evaluation of every filament.

Testing Approach

The presenter describes the following testing methods:

• Compare candidate filaments against PLA Pro as a baseline.
• Condition nylon samples in a wet environment before evaluating them to reflect moisture exposure.
• Measure stiffness and yield behavior with a tensile-testing setup.
• Assess creep by applying a sustained load over multiple days and measuring the resulting deformation.
• Compare impact resistance using an impact-testing machine.
• Evaluate layer adhesion with printed test samples, accounting for factors such as cooling, layer time, print speed, and surrounding temperature.
• Treat results as dependent on test conditions. The presenter notes that some creep measurements were uncertain and that layer adhesion can vary with printer setup.

Speakers and Sources

• Speaker: One presenter/narrator, who describes the tests and interprets the results.
• Sources and materials mentioned: The presenter’s own testing and associated testing paper, along with Polymaker, Bambu Lab, BASF, Atomic Filaments, and other filament products discussed in the comparisons. No additional speakers are featured.