Summary of "Did They Actually Fix PETG?"

Overview

This summary covers testing of Polymaker’s new PETG, which claims PLA-like print speeds while restoring equal strength across XY and Z directions (fixing PETG’s typical layer-adhesion weakness). Tests focused on volumetric flow (speed), tensile strength (XY vs Z), practical printability, and heat/softening behavior, with comparisons to several other filaments.

Context and claim tested

Problem: PETG prints are anisotropic — stronger along layers (XY) than through layers (Z), so parts often fail along layer lines. High-speed PETGs historically traded strength for flow (speed). Claim: Polymaker’s new PETG prints as fast as PLA while maintaining equal strength in both directions (i.e., fixing layer-adhesion weakness).

Key technical concepts

Volumetric flow rate (VFR): the meaningful metric for “speed” — mm^3 of filament extruded per second — not just mm/s nozzle speed.
Layer adhesion / anisotropy: tensile strength differences between XY (along layers) and Z (through layers) determine whether parts split along layer lines.
Material behavior: flexibility vs. brittleness tradeoffs; surface finish (matte vs. glossy) affects visibility of imperfections; heat softening temperature matters for applications exposed to heat (e.g., automotive).

Test methods

Speed: CNC Kitchen “vas mode” / volumetric flow ramp test at 250°C and 270°C, using a standard 0.4 mm nozzle and a high-flow nozzle to find maximum reliable VFR.
Mechanical strength: tensile tests with six samples per filament, printed flat (XY) and standing (Z); results averaged.
Practical printability: filament dried to spec; printed a standard test basket (overhangs, start/stops, honeycomb) and a temperature tower.
Heat resistance: heat/softening test with a 50 g load to find softening/failure temperatures.
Hardware examples noted: Bambu AMS printer with stock PGHF profile and high-flow nozzles.

Filaments compared

New Polymaker PETG (subject)
Old “Polylight” PETG (Polymaker legacy)
Bambu Lab PLA Basic
Bambu Lab PETG HF (high-flow)
“Rapid PETG” (viewer-recommended alternative)

Quantitative results (highlights)

Volumetric flow (mm^3/s):
- Old Polylight (standard nozzle): ~19 and 26 (two test temps).
- New Polymaker PETG: matches old Polylight on standard nozzle; with a high-flow nozzle reaches ~32 and 45 (nearly double old Polylight at high flow).
Tensile maximum load — XY orientation (along layers):
- Old Polylight, Bambu PETG HF, Bambu PLA Basic ≈ 330 kg.
- Rapid PETG ≈ 352 kg.
- New Polymaker PETG ≈ 376 kg (highest).
Tensile — Z orientation (through layers; layer adhesion):
- Old Polylight ≈ 173 kg (very weak).
- Bambu PETG HF ≈ 142 kg (weaker than PLA).
- Rapid PETG and New Polymaker PETG ≈ 300 kg (close to XY strength; much improved).
Heat / softening (50 g load):
- Bambu PLA Basic: failed just under ~60°C.
- Old Polylight PETG: held significantly better than PLA.
- New Polymaker PETG: softened ~10°C earlier than old Polylight (still better than PLA, but less headroom).

Practical printability observations (New Polymaker PETG)

Prints as fast and as easily as PLA; no enclosure or filtration required.
Low stringing and clean surfaces; consistent out-of-the-box results using the stock PGHF profile on a Bambu AMS.
Temperature tower showed a wide usable temperature range, making it robust to dial-in.

Pros and Cons

Pros

Restores layer adhesion at high speed — removes the speed vs. Z-strength tradeoff.
Very high tensile strength (best in this test set).
High volumetric flow capability (real high-speed performance).
Easy to print, low stringing, works well on modern high-speed printers.

Cons / Weaknesses

Glossy surface finish highlights tiny print imperfections (some users prefer a matte finish).
Different flexibility profile — less flexible than classic PETG, more intermediate toward PLA; may absorb impacts less well than classic PETG.
Lower heat resistance than old Polylight PETG — softens ~10°C earlier, reducing advantage over PLA for high-heat use cases; consider ASA if heat resistance is the priority.

Recommendations

Choose the new Polymaker PETG if you want fast, strong, easy-to-print PETG and care more about mechanical strength and high-speed capability than maximal heat resistance or classic PETG flexibility. It runs on stock profiles (e.g., Bambu AMS PGHF).
If heat resistance is critical, prefer ASA (or the older Polylight PETG if your own tests confirm better heat performance).
Rapid PETG is a noted cheaper alternative with good mechanical performance.

Tests, guides and tutorials referenced

CNC Kitchen speed test (vas-mode / volumetric flow ramp).
Tensile testing protocol: six samples per filament, XY and Z orientations.
Practical tests: dry filament to spec; standard test basket; temperature tower; 50 g heat-softening test.
Hardware notes: high-flow nozzles; Bambu AMS with stock PGHF profile.

Sources and main speaker

Speaker / creator: Nels — Perspective3D (video).
Test/method source referenced: CNC Kitchen.
Products tested: Polymaker (new PETG and old Polylight), Bambu Lab PETG HF, Bambu Lab PLA Basic, and a viewer-recommended “Rapid” PETG.