PETG-CF adds chopped carbon fibre to PETG’s base material. The result is stiffer, lighter, and more dimensionally accurate than standard PETG with a distinctive surface finish that looks intentional on technical parts. It also needs a hardened steel nozzle and a bit more patience to print. This guide covers both sides.
PETG-CF is standard PETG with chopped carbon fibre strands blended into the base polymer during manufacturing. The carbon fibre content is typically 15-20% by weight. The strands are short — measured in hundredths of a millimetre — not the continuous fibres used in high-end composite manufacturing. This makes PETG-CF printable on standard FDM equipment with the right nozzle.
The carbon fibre reinforcement changes the material in three meaningful ways. Stiffness increases significantly. Weight decreases compared to standard PETG for the same volume. And dimensional accuracy improves because the CF content reduces thermal expansion during cooling, which means less warping and more precise final dimensions.
The surface finish is distinctive: a matte, slightly textured appearance with a faint directional pattern from the CF strands. It looks right on brackets, enclosures, and mechanical parts. It looks wrong on anything meant to be decorative.
Stiffness: meaningfully higher with PETG-CF. The CF reinforcement increases the tensile modulus, so the same wall thickness resists bending noticeably better. For brackets, frames, and parts where flex under load is the failure mode, PETG-CF is a real upgrade.
Weight: lower for the same geometry. Carbon fibre is less dense than the PETG polymer it displaces, so PETG-CF prints are lighter than standard PETG at the same settings. Not dramatically so, but measurable.
Dimensional accuracy: better with PETG-CF. Standard PETG has a higher coefficient of thermal expansion than most engineering materials and can drift slightly on large flat parts. The CF content constrains this. Holes print closer to target diameter. Flat faces stay flat.
Impact resistance: slightly reduced compared to standard PETG. The chopped fibres make the material stiffer but also less tough in the impact-absorption sense. PETG-CF is more likely to fracture on sharp impact than standard PETG, which tends to deform rather than break. For parts where impact absorption matters, standard PETG is still better.
Printability: more demanding. Hardened steel nozzle required. Speed must be lower. The CF content increases melt viscosity slightly, which means settings that work perfectly for standard PETG need adjustment.
Surface finish: matte and textured rather than the slightly glossy finish of standard PETG. This is fixed — you cannot polish PETG-CF to a glossy finish without sanding through the surface layer.
This is non-negotiable: PETG-CF requires a hardened steel nozzle.
The carbon fibre particles are abrasive. A brass nozzle printing PETG-CF will show measurable wear within 3-5 hours. The orifice diameter enlarges unevenly as the softer brass wears away, producing wider and inconsistent extrusion lines. The degradation is gradual at first and then accelerates. By the time the quality loss is obvious, the nozzle is already significantly worn.
Hardened steel nozzles (also called wear-resistant nozzles) are widely available for all common hot end types including E3D V6, Volcano, Bambu Lab hotends, and Creality standard hotends. They cost more than brass but last many times longer with abrasive materials. If you plan to print PETG-CF or any other CF-blend filament with any regularity, a hardened steel nozzle is a one-time purchase that pays for itself quickly.
Olsson Ruby nozzles and other ruby-tipped variants offer even greater wear resistance at higher cost, but hardened steel is sufficient for most PETG-CF use.
Nozzle: 240-260°C. Start at 250°C. PETG-CF typically runs 5-10°C hotter than standard PETG to compensate for the increased melt viscosity from the CF content.
Bed: 70-85°C. Same as standard PETG. A PEI sheet with a thin layer of glue stick or hairspray provides reliable adhesion and clean release.
Speed: 30-50mm/s for perimeters. Slower than standard PETG. The increased melt viscosity means fast printing produces more voids and weaker layer adhesion. Infill can go faster at 50-70mm/s. First layer: 20mm/s.
Layer height: 0.15-0.28mm. Fine layer heights below 0.15mm are not recommended — the CF particle size creates inconsistency at very fine heights. 0.20mm is the practical standard for functional parts.
Retraction: 1-2mm for direct drive. Similar to standard PETG but PETG-CF strings slightly less because the CF content stiffens the melt and reduces ooze. You may be able to reduce retraction slightly compared to your standard PETG settings.
Cooling: moderate. More cooling than standard PETG helps with bridging, but full cooling can reduce layer adhesion. 30-50% fan speed is a reliable range.
PETG-CF has a fixed matte surface finish with a slight directional texture from the aligned CF strands. This is the natural surface and cannot be polished to gloss. It does not take paint in the same way matte PLA does — the CF surface is relatively smooth despite the matte appearance, and paint adhesion is inconsistent without significant surface preparation.
For most PETG-CF applications, the surface is used as-is. The matte, technical-looking finish is part of the appeal for functional and mechanical parts.
Sanding is possible but works differently than with standard PETG. The CF particles are harder than the surrounding polymer, so sanding produces a slightly rough, scratchy appearance rather than smoothing to a uniform surface. Use sanding to clean up layer lines on specific surfaces rather than as an overall surface treatment.
If you need a finished surface on a part that requires CF-level stiffness, consider printing the structural core in PETG-CF and the outer shell in standard PETG as a multi-material approach, if your printer supports it.
Structural brackets and frames where flex under load is the failure mode. PETG-CF resists bending significantly better than standard PETG at the same wall thickness, meaning you can use thinner walls for the same stiffness.
Parts that need tight dimensional accuracy. Press-fit connections, gear teeth, and mechanical interfaces that need to hit specific tolerances benefit from the reduced thermal expansion of PETG-CF. Holes come out closer to target diameter than standard PETG.
Drone and RC parts where stiffness-to-weight ratio matters. The lighter weight and higher stiffness of PETG-CF compared to standard PETG is meaningful when every gram counts.
Tool holders and workshop fixtures that see regular load and need to keep their shape over time. Standard PETG can creep slightly under sustained load at room temperature. PETG-CF resists this better.
Anything where the technical aesthetic is intentional. The matte CF surface finish looks appropriate on parts that are meant to look engineered. It looks out of place on anything decorative.
eSUN PETG-CF runs consistently within the settings documented here. The CF content is evenly distributed through the spool, which matters for consistent mechanical properties across a print.
eSUN PETG-CF is available through the eSUN Official Store.
Disclosure: the eSUN link above is an affiliate link. If you purchase through it, we earn a small commission at no cost to you. We only recommend products we use ourselves.
Most OreKo models are designed for PLA. For functional applications that need CF-level stiffness, the same files work in PETG-CF with the settings above.