Print speed: how fast can I print?
are explained briefly when you hover over or tap them.
Many printers advertise 500 mm/s or more. Even so, a print often takes longer than expected, and anyone who simply turns up the speed gets gaps, rough walls or a clogged nozzle. The reason: the speed in the slicer is only one of several limits, and usually not the decisive one.
Speed and acceleration
The speed in mm/s is the maximum speed the print head may reach along a line. The acceleration in mm/s² determines how quickly it reaches that speed and brakes again.
On small parts with short lines, the head often never reaches the set speed. It accelerates but has to brake again before the next corner arrives. That is why a higher acceleration brings more than a higher speed on small, detailed parts.
For context: the default profiles of fast CoreXY printers work with accelerations around 10,000 mm/s², often half of that for outer walls. Older bed slingers are well below that. How much the design limits this is explained in Bed slinger or CoreXY.
High accelerations create vibrations that become visible as waves on the surface. Input shaping helps against this, more in Ghosting.
The real limit: volumetric flow
The hotend can only melt a certain amount of plastic per second. This amount is called volumetric flow and is given in mm³/s. Once it is reached, a higher speed no longer helps. The filament is no longer fully melted, material is missing and, in the worst case, the extruder slips.
You calculate the volumetric flow of a line like this:
Volumetric flow = line width × layer height × speed
Worked example
You print with a 0.4 mm nozzle, 0.45 mm line width and 0.2 mm layer height:
- at 100 mm/s: 0.45 × 0.2 × 100 = 9 mm³/s
- at 200 mm/s: 0.45 × 0.2 × 200 = 18 mm³/s
- at 300 mm/s: 0.45 × 0.2 × 300 = 27 mm³/s
It also works the other way round. If your hotend manages 15 mm³/s, the maximum speed at these values is 15 ÷ (0.45 × 0.2) ≈ 167 mm/s. At 0.28 mm layer height it is only about 119 mm/s. Thicker layers and wider lines therefore need more volumetric flow at the same speed. More in Choosing the right layer height.
Typical hotend limits
| Hotend type | Volumetric flow (rough) |
|---|---|
| Classic standard hotend | about 10 to 15 mm³/s |
| Current hotends of fast printers | about 20 to 30 mm³/s |
| High-flow hotends and nozzles | about 25 to 40 mm³/s, some more |
These are rough values. The actual volumetric flow depends on the material, the temperature, the nozzle and even the colour. The basic profiles in OrcaSlicer cautiously assume 12 mm³/s for many materials and only about 3 mm³/s for TPU. Manufacturer profiles for fast printers are often considerably higher for PLA. Check the values for your machine in the manufacturer’s documentation or measure them yourself.
Measuring volumetric flow yourself
OrcaSlicer has its own test for this. It prints an object in which the volumetric flow increases with height. You look at which height the surface gets worse, for example matt instead of glossy or with gaps, and work out the value from that. The OrcaSlicer documentation recommends subtracting a further 10 to 20 % from the result. How the tests work is explained in Calibrating a 3D printer.
If you enter the value in the filament profile, the slicer automatically slows down wherever it would be exceeded. That is the safest way to print fast without risking underextrusion.
Not everything at the same speed
The slicer uses its own speed for each line type. There are good reasons for this:
| Area | Speed | Why |
|---|---|---|
| First layer | slow, often 20 to 50 mm/s | better adhesion |
| Outer wall | slower than inner walls | visible surface, accurate dimensions |
| Inner walls, infill | fast | invisible, only volumetric flow counts |
| Overhangs, bridges | slow | material needs time to cool |
| Top surface layer | medium | smooth surface |
As an example: a default profile of a fast CoreXY printer uses 200 mm/s for outer walls and 300 mm/s for inner walls. If the surface matters more to you than time, first lower the speed of the outer wall. That costs little time, because it makes up only a small part of the print.
Putting manufacturer claims in context
The figure “up to 500 mm/s” usually describes the maximum speed the mechanics manage on travel moves or long, straight lines. In real printing, other things set the limit:
- Volumetric flow: At 0.2 mm layer height and 0.45 mm line width, you would need 45 mm³/s for 500 mm/s. Only a few hotends manage that.
- Acceleration: On small parts the maximum speed is never reached.
- Cooling: Material printed faster needs more cooling so that it solidifies in time. See Part cooling.
- Material: TPU, nylon or fibre-reinforced filaments often tolerate only a fraction of this.
A more meaningful comparison value between printers is the maximum volumetric flow of the hotend and the acceleration. In the end, what counts is the print time for a typical part.
How to proceed
- Start with the manufacturer’s default profile.
- Measure the maximum volumetric flow for your filament and enter it in the profile.
- If needed, raise the speed for infill and inner walls, the slicer limits it automatically.
- Keep outer walls and overhangs slow if the surface matters.
- If there are waves on the surface, lower the acceleration or calibrate input shaping.
Continue with: Calibrating a 3D printer.