PETG combines engineering-grade strength with accessible printing, but it only delivers that result when the 5 factors below are dialed in. If any one of them slips, stringing and warping become the rule.
Temperature: start at 235°C and go up
Every brand has a different sweet spot. Run a temperature tower from 220-250°C and log the best level before producing at scale.
Retraction: less is more
PETG hates aggressive retraction (high viscosity, material separates). Try 2-4mm at 25-30mm/s on Bowden, 0.8-1.2mm on Direct Drive.
gcodeM207 S1.0 F1500 ; retract 1mm @ 25mm/s (direct drive)
M208 S0.1 F900 ; extra prime 0.1mm @ 15mm/s
Bed: PVA glue solves 90% of warping
PEI works for small parts. For long parts (>15cm), apply a thin layer of glue stick with alcohol first: adhesion triples.