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

1. Glossy surface finish highlights tiny print imperfections (some users prefer a matte finish).
2. Different flexibility profile — less flexible than classic PETG, more intermediate toward PLA; may absorb impacts less well than classic PETG.
3. 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.