Polycarbonate and PCTG

TL;DR

Pick PC for maximum heat resistance and stiffness, but only if you can control warping (hot bed, draft control/enclosure, strong first layer). Pick PCTG for a tougher, more forgiving “PETG-like” material; dry it well and tune temp/retraction to prevent stringing.

What each material is best at

Polycarbonate (PC) is a stiff engineering plastic that holds up better in heat than most common FDM filaments, so it’s used for brackets, fixtures, and parts that must stay rigid in warm environments. PCTG is a copolyester in the PETG family; it’s usually easier to print than PC and is valued for durable, impact-tough parts with less brittleness than PLA, while typically offering better temperature performance than PLA and often an upgrade in toughness over basic PETG.

PC vs PCTG at a glance

Heat resistance

PC is typically higher; PCTG is moderate-high and often “enough” for warm enclosures, car interiors, and tool parts (depending on brand).

Print difficulty

PC is more demanding: warping, bed adhesion, and layer splitting are common without good heat control. PCTG is more forgiving and closer to PETG behavior.

Warping tendency

PC: high (especially large, flat parts). PCTG: medium (still can lift on big plates or cool rooms).

Layer bonding

Both can be strong when printed hot enough and protected from drafts; PC is more sensitive to uneven cooling and needs better thermal stability.

Best reason to choose

PC: maximum temperature capability and stiffness. PCTG: durable functional parts with easier printing and reduced cracking/warp risk.

Before you buy a spool (capability checks)

• Hotend temperature: confirm your machine can reach and hold the filament’s stated range for that exact PC/PCTG (not all spools are the same).
• Bed temperature stability: PC benefits from a reliably hot bed; unstable bed temps show up as corner lift and inconsistent first layer.
• Draft control: plan for an enclosure or strong draft shielding for PC; for PCTG it’s optional for small parts but helpful for larger ones.
• Drying and storage: both print best dry; moisture increases stringing and can reduce part strength. Have a dryer or drying workflow and sealed storage.
• Build surface plan: verify what the filament maker recommends and whether you need a release layer (some surfaces can grip too hard).

Setup priorities that matter most (what you’re actually controlling)

PC failures are usually thermal-stress failures: the part shrinks as it cools, and if different areas cool at different rates, it pulls corners up or splits layers. Your job is to keep the print environment stable (warm, no drafts) and keep the first layer anchored. PCTG is more tolerant of temperature swings, but it can turn into stringy, blobby extrusion if it’s wet or printed too hot; your job is to keep extrusion clean (dry filament, sane temperature) and use just enough cooling to hold detail without causing lift on large parts.

Quick proof tests before a long functional print

1. First-layer strip: print a wide, single-layer patch. Look for even squish across the bed and predictable release after cooling (not tearing chunks off the surface).
2. Warp coupon: a thin rectangular plate with sharp corners. If corners lift, increase draft control, consider a brim, and revisit bed temp and first-layer Z offset.
3. Layer-bond temperature tower: print a small stepped block at a few nozzle temps to find the lowest temp that still gives strong layer bonding (especially important for PC).
4. Detail sample (holes/overhangs): confirms whether you need more cooling for PCTG or less cooling/more enclosure stability for PC. If PCTG looks fuzzy/stringy, assume moisture or too much heat first.

Common failures and first fixes