Slicer Settings and Print Quality
Layer height, walls, infill, speed, flow limits, cooling, retraction, supports and adhesion, with print time and cost worked out.
On this page
- Where to start
- Layer height and line width
- Walls, top and bottom layers
- Infill: patterns and density
- Speed, flow and print time
- Cooling and temperature
- Retraction, stringing and pressure advance
- Supports
- Bed adhesion: skirt, brim and raft
- Seams, ironing and other surface settings
- Starting profiles by goal
- FAQ
Where to start
A slicer offers hundreds of settings, but a handful decide almost everything: layer height (surface finish against time), walls (strength), infill (weight and stiffness), speed and flow (time and quality), cooling (overhangs and small details), supports and adhesion. Start from the profile for your printer and filament, change one thing at a time, and print a small test to see its effect.
Layer height and line width
The nozzle lays a line wider than its opening, because the plastic is pressed flat against the layer below. The two numbers to choose are the layer height and the line width; together with the speed they set the flow rate.
| Setting | Typical value (0.4 mm nozzle) | Notes |
|---|---|---|
| Layer height | 0.12 mm fine, 0.2 mm standard, 0.28 mm draft | Keep between about 25 % and 75 % of the nozzle diameter; thinner layers give a smoother finish at the cost of time |
| First layer height | 0.2 to 0.3 mm | A thicker first layer forgives an uneven bed and sticks better |
| Line width | 0.4 to 0.5 mm | Often 100 to 120 % of the nozzle diameter; wider lines are stronger and faster |
| Preferred layer heights | Multiples of the Z full step (0.04 mm on an 8 mm lead screw) | Avoids rounding errors in Z moves |
The finish is set mostly by the layer height: the cusps on a leaning wall are about layer height × sin(angle from vertical), so halving the layer height roughly halves the visible roughness, and doubles the number of layers and so the print time. Pick fine layers only for the surfaces that matter, or use variable layer height, which prints fine layers where the shape curves and thick layers elsewhere.
Walls, top and bottom layers
The outer shell carries most of the load in bending and tension, so walls (perimeters) are the first strength setting: two walls is the minimum for a good surface, three to four for functional parts. Wall thickness is the number of walls times the line width. Top and bottom layers close the part and cover the infill: use enough that the skin is at least 0.8 to 1.2 mm thick (for 0.2 mm layers, 4 to 6 layers), more where a top surface must be smooth over sparse infill. Walls printed from the outside in give a better surface; printing the inner walls first makes better overhangs and more accurate outer dimensions.
Infill: patterns and density
| Pattern | Character | Use |
|---|---|---|
| Grid, lines, rectilinear | Fast, simple, direction-dependent | Draft parts, large flat areas |
| Gyroid | Smooth curved walls, isotropic, good strength for the weight | Functional parts, good all-rounder; slower to slice |
| Cubic, triangles, adaptive cubic | Strong in several directions; adaptive varies density | Functional parts and large models that need less plastic |
| Honeycomb | Strong and light | Brackets, panels |
| Lightning | Only supports the top layers | Display models: little plastic, little strength |
| Concentric | Follows the outline | Flexible parts (TPU) and shells |
Worked example: what infill costs
- A box 40 × 40 × 20 mm has a gross volume of 32 000 mm³. With 3 walls (1.35 mm) and 0.8 mm top and bottom skins, the hollow core is (40 − 2.7) × (40 − 2.7) × (20 − 1.6) = 25 600 mm³, and the shell is 32 000 − 25 600 = 6 400 mm³.
- At 15 % infill the plastic volume is 6 400 + 0.15 × 25 600 = 10 240 mm³ (12.7 g of PLA); at 40 % it is 16 640 mm³ (20.6 g). Raising the infill from 15 to 40 % adds 62 % material and print time for a core that carries little of the load.
- Adding one more wall (to 4) changes the shell by about 1 220 mm³ and makes the part far stiffer in bending than extra infill does, which is why walls come first (the figure on Strength, Accuracy and Fits shows this).
Rule of thumb: raise the walls to 3 or 4, keep infill at 10 to 25 percent, and only go above 40 percent for parts that will be drilled, tapped or loaded in compression.
Speed, flow and print time
What limits print speed is not how fast the head can move but how fast the hotend can melt plastic. The volumetric flow rate is the volume of plastic extruded per second:
Q = line width × layer height × print speed (mm³/s)
Filament feed speed = Q ÷ (π ÷ 4 × d²) d = 1.75 mm gives a cross-section of 2.41 mm²
Worked example: flow, feed and time
- Flow: 0.45 mm × 0.2 mm × 60 mm/s = 5.4 mm³/s.
- Filament speed: 5.4 ÷ 2.41 = 2.25 mm/s into the extruder.
- Speed limit: a standard hotend melts about 10 to 15 mm³/s of PLA (a typical figure; high-flow hotends manage more). At 12 mm³/s, the highest speed for 0.2 mm layers is 12 ÷ (0.45 × 0.2) = 133 mm/s. Asking for more makes the extruder skip and the part under-extruded.
- Filament length and mass: PLA is about 1.24 g/cm³, so 1 m of 1.75 mm filament weighs 2.98 g, and a 1 kg spool holds about 335 m.
- Print time and cost: a part with 30 cm³ of plastic (walls and infill together, not the bounding box) at 5.4 mm³/s needs 30 000 ÷ 5.4 = 5 556 s, about 1.54 h of pure extrusion. It uses 37.2 g, which costs about $0.74 at $20 per kg.
- The 40 × 40 × 20 mm box above at 15 % infill: 10 240 ÷ 5.4 = 1 896 s, 0.53 h ideal; allow 1.3 to 2 times that for acceleration, corners, retractions and slower outer walls, so plan on 0.8 h.
Use the slicer’s estimate for planning and this calculation to see what the limit is.
| Layer height (0.45 mm line) | Speed that reaches 12 mm³/s | Flow at 60 mm/s |
|---|---|---|
| 0.1 mm | 267 mm/s | 2.7 mm³/s |
| 0.2 mm | 133 mm/s | 5.4 mm³/s |
| 0.3 mm | 89 mm/s | 8.1 mm³/s |
- Thicker layers print faster for the same flow limit, because each pass lays down more plastic. The cost is a rougher surface.
- A larger nozzle (0.6 mm) allows wider and taller lines, so the same flow limit covers more area; fine detail is lost.
- Temperature raises the limit a little, and a longer melt zone or a high-flow hotend raises it more.
- Acceleration and jerk matter on small parts: the head never reaches top speed on short moves (see FDM Printer Hardware).
- Slow the outer wall. Printing the outer wall at 40 to 50 percent of the infill speed gives a better surface at a small cost in time.
Cooling and temperature
Plastic solidifies as it cools, and the part-cooling fan sets how fast. PLA wants the fan on (100 percent after the first layers) so that overhangs, bridges and small details hold their shape. PETG wants 30 to 60 percent, ABS, ASA and nylon 0 to 30 percent because cooling them causes warping and weak layer bonds. Small layers need more time: set a minimum layer time (5 to 15 s) so that the layer has time to cool before the next is laid.
Worked example: a small layer
A 40 mm square outline has a perimeter of 160 mm. At 40 mm/s one wall takes 4 s, so with two walls and a little infill the layer takes about 10 s. A pin 6 mm across has a perimeter of π × 6 = 18.8 mm and a layer time of under 1 s at the same speed: the layer is still molten when the next arrives, and the top of the pin melts and bulges. The slicer slows it to the minimum layer time, or you print two pins together so that each has time to cool.
- Nozzle temperature: use the range on the spool, then tune with a temperature tower (the best surface and layer bond; see Filament Materials and Calibration and Maintenance).
- Bed temperature: PLA 50 to 60 °C, PETG 70 to 85 °C, ABS and ASA 90 to 110 °C, nylon 70 to 90 °C.
- First layer: slow (20 to 30 mm/s), a few degrees hotter, fan off.
Retraction, stringing and pressure advance
When the head travels across an open gap, molten plastic keeps oozing from the nozzle and leaves a hair of string. Retraction pulls the filament back a little before the move and pushes it forward afterwards: about 0.5 to 2 mm on a direct drive, 4 to 6 mm on a Bowden system. Too little retraction leaves strings; too much grinds the filament and causes gaps and clogs. Wiping, coasting and travel speed help too, and drying the filament is often the real cure for stringing.
Pressure advance (Klipper) or linear advance (Marlin) compensates for the elastic pressure that builds in the melt chamber, so that corners do not bulge and line ends are not under-filled. It is set by a calibration pattern, and a typical direct drive value is 0.02 to 0.08 s.
Supports
| Type | Use | Notes |
|---|---|---|
| Normal (grid / snug) | Overhangs beyond about 45° and islands | Easy to generate; leaves marks on the supported surface |
| Tree | Organic shapes with small contact points | Uses less plastic and is easier to remove; can be unstable on large flat overhangs |
| Interface layers | Any support | A dense top layer of the support gives a smoother underside; a gap of one layer height (or a bit more) makes it easy to break off |
| Soluble (PVA, HIPS) with a second extruder | Complex internal supports | Dissolves in water or limonene; needs a multi-material printer |
| Painted or manual supports | Only where needed | Often the best way: place supports where the slicer has found an overhang that matters |
Better than supporting an overhang is not needing one: rotate the part, split it, chamfer a horizontal ceiling, or add a sacrificial bridge (see Designing for 3D Printing). The support gap (z-distance) and interface density control the underside finish: smaller gaps give a better surface and are harder to remove.
Bed adhesion: skirt, brim and raft
- Skirt is a line printed near the part to prime the nozzle: it does not touch the part.
- Brim is a flat band of lines (5 to 10 mm wide) attached to the part’s base: it adds area against warping and is easily removed. Use it for tall, thin parts and warp-prone materials.
- Raft is a thick base under the part: it helps on very uneven beds and with some materials, but it leaves a rough underside.
- Mouse ears are small discs at corners: a cheap anti-warp for sharp corners.
- Surface and glue: a clean build plate (wiped with isopropyl alcohol) and a thin layer of glue stick for ABS and nylon solve most adhesion issues.
Seams, ironing and other surface settings
- Seam position: each wall starts and ends at one point, which leaves a visible seam. Aligning seams to a rear corner hides them; random seams scatter them; “nearest” puts them where the head already is.
- Ironing: after the top layer the nozzle passes again with almost no flow, smoothing it for a flat, glossy top at some cost in time.
- Fuzzy skin: deliberate jitter of the outer wall to hide layer lines and improve grip.
- Vase mode (spiralize): a single continuous outer wall, ideal for decorative containers.
- Arc fitting, adaptive layer height, Z-hop and similar options smooth G-code or protect the part when traveling; use them as needed.
- Scarf seams and wall order (newer slicers) improve the finish of outer walls on curved parts.
Starting profiles by goal
| Goal | Layer | Walls | Infill | Speed (outer wall) | Notes |
|---|---|---|---|---|---|
| Draft (fast, rough) | 0.28 mm | 2 | 10 % grid | 60 mm/s | Check fit and shape; thick layers, large nozzle if possible |
| Standard | 0.2 mm | 3 | 15 % gyroid | 40 to 50 mm/s | Good compromise for most parts |
| Fine (display) | 0.12 mm | 3 | 15 % gyroid | 30 mm/s | Slower: fine layers and cooling, ironing for flat tops |
| Strong (functional) | 0.2 mm | 4 to 6 | 25 to 40 % cubic | 40 mm/s | Orient layers along the load; hotter for layer bonding; see the strength page |
| Flexible (TPU) | 0.2 mm | 3 | 15 % gyroid | 15 to 25 mm/s | Direct drive, slow, low retraction |
Related
- 3D Printing and Additive Manufacturing: the overview of this guide.
- FDM Printer Hardware: why the head never reaches top speed, and what limits flow.
- Filament Materials: temperatures and cooling for each filament.
- Strength, Accuracy and Fits: what walls, infill and orientation do for strength.
- Troubleshooting and Safety: stringing, warping and under-extrusion causes.
FAQ
Why does my print take longer than the slicer says?
Estimates assume the machine reaches its set speeds, but short moves, corners, retractions and travel limit the real speed. Slower outer walls and the first layer add more. A 30 to 100 % increase over the estimate is common.
What does “volumetric flow” mean?
It is the volume of plastic extruded per second (line width × layer height × speed). Every hotend can melt only so much plastic per second, so this, rather than the printer’s top speed, sets how fast you can print.
Is higher infill always stronger?
No. Beyond about 25 to 30 percent, infill adds little strength for a lot of time and material. Walls and orientation matter more.
Which infill pattern is best?
Gyroid or cubic for most functional parts, grid or lines for speed, lightning for models that only need to hold up a top surface.
References
- Slicer documentation: PrusaSlicer, OrcaSlicer, Cura and Bambu Studio (settings and profiles).
- Hotend manufacturers’ published volumetric flow figures (for example E3D, Slice Engineering, Bondtech) for flow limits.
- Klipper and Marlin documentation on pressure advance and linear advance.
Last reviewed: October 2026. Speeds, temperatures and settings are typical starting points: tune them for your printer and filament.