PETG vs PLA vs ABS for Functional Prints: What Failed in Real Use

PLA: fastest iteration, limited for heat and stress

PLA is my default for fit checks and geometry validation. First run is always PLA — fast, cheap, and disposable. It fails when a part sees heat over ~60°C or sustained load over time.

Settings I use for PLA drafts:

• Layer height: 0.2mm standard, 0.28mm for rough drafts
• Infill: 15–20% gyroid for draft, 40%+ for stress parts
• Walls: 3 for prototypes, 4–5 for mechanical fits
• No brim needed on most parts with good bed adhesion

PETG: best all-around functional default

PETG is where I land for most production parts. Better heat tolerance than PLA (~80°C), tougher under load, and it takes hardware inserts reasonably well. The tradeoff is stringing and slower cooling requirements.

Settings I use for PETG functional parts:

• Layer height: 0.2mm for most parts, 0.15mm on fine interfaces
• Infill: 40% gyroid or grid for structural parts; 25% for brackets/holders
• Walls: 4–5 for anything with screw holes or press fits
• Brim: 5mm brim when part has thin base footprint or tall narrow geometry
• Cooling: reduced fan speed vs PLA — too much cooling causes layer delamination
• First layer: slightly slower, slightly hotter for adhesion

Common failure mode: layer separation at stress points — usually a cooling or under-extrusion issue, not material choice.

ABS: useful when environment demands it

ABS when parts live in hot environments (car interior, near electronics, anything above ~80°C) or need post-processing (acetone smoothing). It requires enclosure-aware printing — drafts kill layer adhesion fast.

Settings I use for ABS:

• Layer height: 0.2mm standard
• Infill: 30–40% for functional parts
• Walls: 4+ for anything structural
• Brim: always — 8–10mm for larger parts, ABS warps at corners without it
• Enclosure: closed, chamber temp elevated
• Cooling: minimal — ABS cracks with aggressive cooling

Common failure mode: corner lift and delamination — usually draft/airflow issue, not under-extrusion.

Slicer settings that actually changed outcomes

These are the settings that made the most difference on real functional parts, not just benchmark prints:

• Wall count over infill: going from 3 to 5 walls on mechanical parts improved strength more than doubling infill did
• Orientation: rotating a bracket 45° to align layer lines with load direction changed failure mode from snap to gradual flex
• Support interface layers: adding 2 interface layers at 0.2mm spacing made support removal clean and preserved surface quality underneath
• Ironing on top surfaces: useful for flat mating surfaces on PETG where tolerance matters
• Brim gap on PETG: 0.1–0.2mm gap from part edge prevents brim from fusing too hard — makes removal clean without edge damage
• Seam placement: moving seam to back/hidden face on brackets improved surface fit where it counts

My practical default

Prototype in PLA, deploy in PETG unless the environment says otherwise, step to ABS when heat/durability requirements are explicit. The material decision should follow the part's real operating conditions — not habit or what's already loaded in the printer.