Slicing & Settings

3D printing speed, cooling and acceleration: your printer's real limits

A 3D printer's real speed limit is usually how much plastic its hotend can melt per second (its maximum volumetric flow), not the mm/s number in your slicer. Measure that limit, set it in your filament profile, and let cooling and acceleration decide the rest.

7 min read Updated October 2026 Intermediate Slicing & Settings · 4 of 4

In short

Flow = layer height × line width × speed. A volumetric speed test tells you your hotend's ceiling in mm³/s.
Set max volumetric speed in the filament profile 10–20% below that result, and the slicer caps every move automatically.
Cool by material: PLA 100%, PETG 30–50%, ABS/ASA 0–25%, with a minimum layer time so small layers can harden.
Acceleration decides whether you ever reach top speed. Input shaping and pressure advance let you raise it without ringing or blobby corners.

Max volumetric speed: the real speed limit

Volumetric flow is the volume of plastic going through the nozzle each second, in mm³/s:

flow = layer height × line width × print speed

At 0.2 mm layers, 0.45 mm lines and 150 mm/s, that's 13.5 mm³/s. Ask for more than the hotend can melt and the plastic leaves the nozzle half-melted, the extruder starts clicking, and you get under-extrusion and weak layers.

Typical hotend flow ranges

Real numbers depend on the hotend, nozzle, filament and temperature, so treat these as rough classes and measure your own:

Hotend class (0.4 mm nozzle)	Rough PLA flow	Notes
Standard short melt zone (V6-style, many older stock hotends)	About 8–15 mm³/s	Fine up to roughly 100–150 mm/s at 0.2 mm layers
Current "high-speed" stock hotends on CoreXY and fast bed slingers	About 20–35 mm³/s	Longer or more efficient melt zones
High-flow hotends and nozzles (Volcano-style, core-heating nozzles)	About 30–65 mm³/s or more	Bambu Lab quotes up to 65 mm³/s for the H2D's high-flow hotend under its own test conditions

PETG and ABS usually top out below PLA on the same hotend, while "high-speed" PLA blends are formulated to melt faster. A hotter nozzle raises flow too, at the cost of more stringing and more work for the fan.

How to measure your max volumetric speed

Dial in temperature first. OrcaSlicer's calibration guide runs temperature, then max volumetric speed, then pressure advance, flow ratio and retraction.
Print the volumetric speed test. In OrcaSlicer it's under Calibration → Max flowrate; the defaults ramp from 5 to 20 mm³/s in 0.5 mm³/s steps. Raise the end value on fast hotends.
Find where quality breaks down. Measure the height where the walls turn rough or gappy. The result is start value + height × step.
Set max volumetric speed 10–20% lower in the filament profile, for each filament you use.

Free PrintPal toolVolumetric Flow CalculatorTurn layer height, line width and speed into mm³/s and compare it with your hotendOpen tool

Your profile uses 0.2 mm layers, 0.45 mm lines and 300 mm/s infill. The volumetric test says 15 mm³/s, and you've set that as max volumetric speed. What happens?

The infill prints at 300 mm/s anyway
The slicer slows infill to about 167 mm/s
The printer raises nozzle temperature to keep up

15 ÷ (0.2 × 0.45) ≈ 167 mm/s. With max volumetric speed set, the slicer caps every move so the flow never exceeds the limit, no matter what speed you typed.

Part cooling fan speed by material

The part cooling fan hardens each fresh line before the next one lands on it. More fan means sharper overhangs and bridges; too much fan on hot, shrink-prone plastics means weak layers and warping. These values match the material guides on this wiki:

Material	First layer(s)	Rest of the print	Notes
PLA	Off or low	100%	Loves cooling; open the enclosure door or lid
PETG	Off or low	30–50%	More fan for bridges; too much hurts layer bonding
ABS	Off	0–25%	Enclosure strongly recommended
ASA	Off	0–25%	Enclosure strongly recommended
TPU	Off or low	30–100%	Varies with hardness and speed; print slowly
Nylon	Off	0–30%	Must be dry; enclosure helps
PC	Off	0–20%	Heated enclosure

Material details are in the PLA, PETG and ABS and ASA guides.

Minimum layer time

Small layers finish before the plastic below has hardened, so tips of cones and thin towers turn into blobs. Minimum layer time (called slow printing down for better layer cooling or similar in Bambu Studio and OrcaSlicer, and slow down if layer print time is below in PrusaSlicer) slows the printer so each layer takes at least that long. Values of about 4–15 s are typical; Bambu Studio's PLA profiles use 4 s.

Print several copies at once so each layer has time to cool while the nozzle visits the others.
Improve the fan or duct before slowing everything down; it's the cheapest speed upgrade on many printers.
Open the door for PLA on enclosed printers; a hot chamber softens PLA and can cause heat creep.

Acceleration: why you rarely reach top speed

Acceleration is how quickly the toolhead changes speed, in mm/s². The distance needed to reach a speed is speed² ÷ (2 × acceleration):

0 to 100 mm/s at 1,000 mm/s² takes 0.1 s and 5 mm.
0 to 300 mm/s at 5,000 mm/s² takes 9 mm, and as much again to slow down.

On a 20 mm part, that second move barely reaches 300 mm/s before it has to brake. That's why raising acceleration often shortens prints more than raising speed does.

Free PrintPal toolAcceleration Distance CalculatorSee how far your printer travels before it reaches the speed you setOpen tool

Printer class	Typical max acceleration	Examples
Older bed slingers without input shaping	About 500–1,500 mm/s²	Many older Ender-style printers on stock firmware
Bed slingers with input shaping	About 2,000–10,000 mm/s²	Prusa MK4S, MK3.9 and MK3.5; Bambu Lab A1 series; Klipper bed slingers
CoreXY with input shaping	About 10,000–20,000 mm/s²	Bambu Lab X1, P1 and H2 series; Voron; Snapmaker U1

Bed slingers move the whole bed and part along Y, so they hit vibration limits earlier than CoreXY machines, which move only a light toolhead. Bambu Lab lists 20,000 mm/s² for the H2D, for example.

Input shaping

Input shaping measures the frame's resonant frequencies and shapes each move to cancel them, which removes most ghosting and ringing at high acceleration.

Klipper: [input_shaper], tuned with an accelerometer or a ringing test tower.
Marlin 2.1.2 and later: M593, if your firmware build enables it.
Prusa: standard on the MK4 since firmware 5.0, and on the CORE One, MK4S, MK3.9, MK3.5, XL and MINI, with several shaper types (ZV, MZV, EI and others) set via M593.
Bambu Lab: vibration compensation runs as part of the printer's built-in calibration.

Re-run calibration after changing belts, the toolhead, or anything heavy on the moving parts.

Pressure advance

Molten plastic lags behind the extruder like toothpaste: pressure builds while the nozzle speeds up and keeps oozing while it slows down. Pressure advance (Klipper, current Prusa firmware, and Bambu Lab, which calibrates it as flow dynamics) or Linear Advance (Marlin) extrudes slightly ahead of acceleration and backs off before decelerating. The result is sharp corners with no bulges and no gaps after them. It needs a quick calibration per filament and nozzle.

Jerk, junction deviation and square corner velocity

These settings decide how fast the toolhead goes through a corner without stopping. Classic jerk (Marlin, in mm/s) allows an instant speed change; junction deviation (Marlin's newer option, default 0.013 mm) calculates corner speed from the geometry; Klipper's square corner velocity (default 5 mm/s) sets the speed for a 90° corner. Higher values print faster but shake the frame more. Leave the defaults alone unless you're chasing a specific artefact.

Practical speed settings by goal

Starting points for a 0.4 mm nozzle at 0.2 mm layers and about 0.45 mm lines. Your max volumetric speed always wins.

Goal	Outer wall speed	Infill speed	Flow needed	Acceleration
Display quality	40–60 mm/s	80–120 mm/s	About 7–11 mm³/s	1,000–3,000 mm/s²
Balanced everyday	60–150 mm/s	150 mm/s	About 13.5 mm³/s	3,000–6,000 mm/s²
Fast functional (CoreXY, high-flow hotend)	150–200 mm/s	250–300 mm/s	About 22–27 mm³/s	10,000 mm/s² or more

When to print slowly anyway

First layer: slow first layers stick far better; see first layer not sticking.
Outer walls on display parts: slower outer walls show fewer ripples.
TPU and other flexibles: they buckle in the extruder when pushed fast.
ABS, ASA, PC and nylon: moderate speeds and little fan give stronger layer bonds.
Wet filament: slowing down won't fix it; dry the filament.

Frequently asked questions

What limits how fast a 3D printer can print?

Usually the hotend's maximum volumetric flow: how many cubic millimetres of plastic it can melt per second. Part cooling and acceleration set the other limits, and on small parts the printer often never reaches the speed you typed in.

What is max volumetric speed?

It is the slicer setting that caps flow in mm³/s, calculated as layer height times line width times speed. Set it 10 to 20% below the value your hotend reaches in a volumetric speed test, and the slicer will slow any move that would exceed it.

What fan speed should I use for PETG?

About 30 to 50% after the first few layers, with the fan off or low on the first layer. More fan improves overhangs but weakens layer bonding; PLA can take 100%, while ABS and ASA want 0 to 25% in an enclosure.

Do I need input shaping?

If you want high acceleration without ringing, yes. Klipper, Marlin 2.1.2 and later, current Prusa firmware and Bambu Lab firmware all support it, and many recent printers calibrate it at the factory or automatically.

Layer heights, walls and line widths Ghosting and ringing Under-extrusion 3D printer calibration guide