What nozzle size should you use?

0.4 mm: the sensible default

A 0.4 mm nozzle balances resolution and throughput well enough that most people never need anything else. Slicer profiles are tuned for it, part strength is respectable, and fine text or small holes still resolve cleanly.

Go bigger for functional parts

A 0.6 mm nozzle lays wider, taller beads: roughly 50–80% faster prints and visibly stronger parts, because wider extrusions bond with more contact area. Brackets, enclosures, and anything mostly straight walls print better at 0.6. At 0.8 mm you are in draft-and-strength territory — great for large boxes and handles, wrong for anything with small features.

• 0.6 mm — the upgrade most workshops should make for functional printing
• 0.8 mm — large, chunky parts where surface finish is secondary
• 0.2–0.3 mm — miniatures and lettering only; slow and clog-prone

Hardened steel or brass?

Brass conducts heat best and is fine for PLA, PETG, ASA, and TPU. The moment a filament contains fiber — carbon-filled nylon like PA6-CF, glow-in-the-dark, wood-filled — the fiber sands a brass nozzle's bore wider within a spool or two, and extrusion turns inconsistent. Hardened steel costs a little thermal performance and lasts. If a printer runs abrasives even occasionally, fit hardened and stop thinking about it.

Signs the nozzle is the problem

• Extrusion width drifts print-to-print with no slicer change — worn bore
• Repeated partial clogs on filament that used to run clean
• First layer inconsistent across the plate at a correct Z-offset