High-Speed Printing and Its Limits
A faster speed setting only helps until the hotend cannot melt plastic any faster, and only on moves long enough to reach that speed. Find your volumetric flow limit first, then raise acceleration only as far as input shaping keeps ringing and smoothing acceptable, then tune pressure advance last because it depends on the other two.
Four separate limits
Real print speed is set by whichever of these runs out first. Raising a speed number in the slicer does nothing once one of them is the bottleneck.
- Melt rate. The hotend can only melt so much plastic per second. This is the volumetric flow limit.
- Acceleration. The head needs distance to reach a speed. On short moves it never gets there.
- Vibration. Quick direction changes shake the frame and leave ringing on the walls. Input shaping cancels some of it, at a cost.
- Extruder pressure. Plastic pressure in the nozzle lags behind speed changes, which shows as blobs and thin spots at corners. Pressure advance compensates.
The basics of each setting are in Print Speed and Acceleration. This page is about pushing them.
Limit 1: volumetric flow
Prusa defines max volumetric speed (MVS) as the maximum amount of plastic, in cubic millimeters per second, that the hotend can reliably melt. The slicer uses it as a cap: if the speed you ask for would need more flow than that, the slicer slows the move down. It never speeds anything up.
Turned around, the fastest speed a line can run is the flow limit ÷ (line width × layer height). Example: a 0.45 mm wide, 0.2 mm tall line at 100 mm/s asks for 0.45 × 0.2 × 100 = 9 mm³/s. PrusaSlicer uses a slightly rounder (stadium-shaped) cross section, so its number differs a little from this rectangle.
Because flow is width times height times speed, a thicker layer or wider line hits the limit at a lower speed. Prusa notes that wider or taller extrusions get slowed more.
Prusa lists typical MVS figures Rule of thumb. They vary a lot by hotend and by material:
| Hotend or material | Typical MVS from Prusa's list |
|---|---|
| Standard all-metal hotend | 8 to 12 mm³/s Rule of thumb |
| Prusa Nextruder (MK4, XL) | 15 to 20 mm³/s Rule of thumb |
| High-flow hotends | 25 to 40 mm³/s Rule of thumb |
| PLA | 12 to 20 mm³/s Rule of thumb |
| PETG | 8 to 15 mm³/s Rule of thumb |
| TPU | 2 to 5 mm³/s Rule of thumb |
Use these only to sanity-check a number. Your own limit comes from a max flow test on your hotend with your filament Measure it. Prusa gives the signs that MVS is set too high: extruder clicking, under-extrusion at high speed, and poor layer adhesion. If you see those only on fast features, lower MVS before touching anything else. The volumetric flow calculator on the Calculators page checks a line width, layer height and speed against a limit.
Filament makers also print a speed range on the technical data sheet for some products. When it exists, it is that maker's figure for that filament Maker spec; stay inside it.
Limit 2: acceleration and short moves
A high top speed is reached only on moves long enough for the head to speed up and slow down again. Small parts, infill in narrow areas and detailed walls are made of short moves, so raising the speed setting changes little there.
Speed in mm/s and acceleration in mm/s², starting from a stop. The head needs the same distance again to stop, so a move must be about twice this long to touch top speed at all. Example: reaching 300 mm/s at 5000 mm/s² takes 300² ÷ (2 × 5000) = 9 mm, so a move shorter than about 18 mm never gets there.
That is why, on small parts and short moves, acceleration often decides print time more than the speed setting does. It is also what causes ringing, so it cannot simply be turned up.
Slicers let you set acceleration per feature. OrcaSlicer's documentation describes outer wall acceleration as usually lower than normal printing for better quality, inner walls higher to save time, travel higher still, and top surfaces low like the outer wall. That split keeps the visible surfaces clean and spends the speed where nobody looks.
Limit 3: ringing and input shaping
Klipper's documentation explains ringing as mechanical vibration from quick changes of print direction. It shows as faint repeats of an edge or a letter on the wall after it. See Ghosting and Ringing for the symptom.
Input shaping is a firmware feature that shapes motion commands so they cancel the printer's own vibration. Several firmwares and printer makers ship a version of it; check your printer's documentation for whether it has one and how it is calibrated. Klipper's guide makes these points:
- Fix the machine first. A weak frame, loose belts, misaligned parts or heavy moving mass should be checked and fixed before tuning. If the measured ringing frequency is very low, Klipper recommends stiffening the printer or reducing moving mass instead.
- Measure the frequency. Print the ringing test tower and count the ripples. If those printed measurements come out unreliable, Klipper suggests measuring with an accelerometer instead.
- Shaping smooths the print. As acceleration rises, so does smoothing: fine details and sharp corners soften. Some shaper types smooth more than others.
- Pick max acceleration from both effects. Find the acceleration where ringing is acceptably small, find where smoothing becomes too much, and use the lower of the two. In Klipper's own worked example that came out at 3000 mm/s² Measure it; your printer will be different.
- Re-measure after changes. Tightened belts, a new toolhead or a different bed can shift the frequencies.
Klipper also notes that input shaping itself has almost no effect on print time. The time saving comes from the higher acceleration it lets you use.
Limit 4: pressure advance
When the head speeds up or slows down, the pressure in the nozzle lags behind, so corners bulge and the start of a line runs thin. Klipper's pressure advance pushes extra filament in during acceleration and pulls it back during deceleration. It does not change the path or the total amount extruded.
The faster and harder the printer accelerates, the more this matters. Klipper's guide points out:
- The right value depends on the extruder, the nozzle and the filament. Different brands and even pigments can need very different values Measure it.
- Tune nozzle temperature and extruder calibration before pressure advance, because both affect it.
- Pressure advance may need retuning after input shaper changes.
- A high value combined with high acceleration can make the extruder skip. If that happens, lower acceleration or the pressure advance value.
The test and how to read it are in Pressure Advance.
The order to tune in
- Mechanical check: belts, frame, loose parts.
- Temperature tower and extruder calibration for the filament.
- Max volumetric flow test. Enter the result as the filament's MVS Measure it.
- Input shaping calibration, then choose max acceleration from ringing and smoothing.
- Pressure advance.
- Flow ratio. If it changed a lot, run a quick pressure advance check again; First Print Check explains why flow comes after pressure advance.
- Print a real part at the new settings and compare walls, corners and layer bonding against your old profile.
This order follows Klipper's notes: tune temperature and extruder calibration before pressure advance, and retune pressure advance after input shaper changes. Change one limit at a time. If you raise speed, acceleration and MVS together and the print gets worse, you will not know which one did it.
- Max volumetric speed Prusa Research
- Resonance Compensation Klipper
- Pressure advance Klipper
- Acceleration OrcaSlicer
Last reviewed 2026-11-05