The Core Slicer Settings That Actually Matter

Modern slicers expose hundreds of settings. The overwhelming majority you can leave at default forever. Five settings decide whether a print succeeds or fails, and they’re the five worth understanding before you touch anything else: layer height, wall (perimeter) count, infill, temperature, and print speed.

Everything else is refinement on top of getting these right.

1. Layer height

Layer height is the vertical thickness of each printed slice. It is the single biggest lever on the print-time-versus-detail trade-off.

• 0.12 mm — fine detail, slow. Use for miniatures, organic models, anything with shallow curves where staircasing shows.
• 0.20 mm — the default for a reason. Good balance of speed and quality on a 0.4 mm nozzle. Start here.
• 0.28 mm — fast, coarser surface, stronger in the Z direction because thicker layers bond over more area. Good for functional parts where appearance is secondary.

The practical ceiling is roughly 75% of nozzle diameter. On a 0.4 mm nozzle that’s 0.30 mm; push past it and layer adhesion and top-surface quality degrade noticeably. The practical floor is around 25% of nozzle diameter — below that, print time balloons for diminishing visual return.

If you want layer height to vary automatically across a model, that’s a separate feature with its own trade-offs — see the adaptive layer height guide.

2. Wall count (perimeters)

Walls — also called perimeters or shells — are the concentric loops that form a part’s vertical surfaces. For functional parts, wall count affects strength far more than infill does.

• 2 walls — light or decorative parts only.
• 3 walls — the sensible default for most prints on a 0.4 mm nozzle. ~1.2 mm of solid shell.
• 4–5 walls — functional and load-bearing parts. Adding walls is usually a better strength investment than raising infill density, because walls run continuously along the load path while infill does not.

A useful rule: if a part is failing under load, add a wall before you add infill. Four walls at 15% infill is typically stronger and faster to print than two walls at 40% infill.

How the slicer generates those walls on thin or tapering features is governed by the perimeter generator — see Arachne vs Classic.

3. Infill

Infill is the internal lattice that fills the hollow interior. Two choices: pattern and density.

Density:

• 0–10% — decorative and display parts. The walls and top/bottom shells do the work.
• 15–20% — general-purpose default. Fine for most everyday prints.
• 25–40% — functional parts under real load.
• 50%+ — rarely worth it. Past ~40%, adding walls is almost always the better strength-per-gram and strength-per-minute investment.

Pattern:

• Gyroid — isotropic (similar strength in all directions), no sharp direction changes, good general default for functional parts.
• Grid / rectilinear — fast, fine for non-structural parts.
• Lightning — minimal material, supports only the top surface, near-zero internal strength. Right for display parts, wrong for anything load-bearing. See the Lightning infill guide.

For most people: gyroid at 15–20% covers everyday prints; raise density only for parts that take load.

4. Temperature

Temperature is material-specific and the most common cause of weak or ugly prints when wrong. Typical hotend ranges (always defer to the filament spool’s printed range first):

Material	Hotend (°C)	Bed (°C)
PLA	200–220	55–60
PETG	230–250	70–85
ABS / ASA	240–260	90–110
TPU	220–235	40–60

The right number within a brand’s range varies by spool. Don’t guess: print a temperature tower and pick the temperature that gives the best layer adhesion without stringing or bridging sag. The procedure is in the flow and temperature calibration guide.

Bed temperature matters as much as hotend temperature for first-layer adhesion and warp control, especially on ABS/ASA.

5. Print speed

Speed is capped by physics, not by the number you type. The real ceiling is the hotend’s volumetric flow rate — the mm³/s it can melt and push. Setting a wall speed of 300 mm/s means nothing if the hotend can only melt enough plastic for 200 mm/s at your layer height and line width; the printer silently under-extrudes.

Practical guidance:

• Outer-wall speed slower than inner-wall speed (surface quality is set by the outer wall).
• First-layer speed slow (15–25 mm/s) regardless of everything else — adhesion is decided here.
• Find your hotend’s max volumetric speed with a calibration test, then let the slicer cap speeds to it rather than chasing big numbers.

Most “my fast print looks terrible” problems are a volumetric-speed limit being exceeded, not a quality setting being wrong.

A starting profile

For a generic 0.4 mm nozzle printing PLA, a sane baseline before any tuning:

• Layer height: 0.20 mm
• Walls: 3
• Infill: gyroid, 15%
• Hotend / bed: 210 °C / 60 °C (then refine with a temperature tower)
• Outer wall speed: conservative; first layer slow

From there, change one variable at a time and observe the result. The fastest way to never understand your printer is to change five settings at once and not know which one helped.

Where to go next

Once these five are dialed, calibration is what makes them trustworthy: the flow and temperature calibration guide covers the tests. For choosing a slicer to apply all this in, see the four-slicer comparison.

For material strength testing methodology behind these recommendations, PrintLabGuide ↗ goes deeper, and FDM Desk ↗ covers printer-specific tuning.