Print Speed and Acceleration

Speed is set per feature

Slicers do not have one speed. They set a speed for each kind of line: outer wall, inner walls, infill, top surface, supports, travel and the first layer. That lets you spend time where it shows and save it where it does not:

• Outer wall: UltiMaker says printing it slower usually gives a better surface finish; OrcaSlicer adds better layer adhesion, at the cost of time.
• Inner walls and sparse infill: hidden, so usually faster. UltiMaker warns that faster infill may weaken the part.
• Top surface: OrcaSlicer suggests a speed similar to the outer wall; slower reduces surface defects.
• Support interface: slower. UltiMaker says that helps it bond to the model; OrcaSlicer says it improves the surface where support meets the model.
• Travel: UltiMaker says faster travel reduces oozing but can make the nozzle strike printed parts.
• First layer: slow by default for adhesion; Cura ramps up over a set number of slower layers.

Where the settings are called what

What it controls	PrusaSlicer	OrcaSlicer	Cura
Feature speeds	Print settings, Speed	Outer wall, Inner wall, Sparse infill, Top surface (Speed)	Print Speed, Outer Wall Speed, Infill Speed, Top/Bottom Speed
Hotend flow limit	Max volumetric speed (Print settings and Filament settings)	Not confirmed	Not confirmed
Acceleration	Not confirmed	Normal printing, Outer wall, Travel and others (Acceleration)	Enable Acceleration Control
Corner speed change	Not confirmed	Not confirmed	Enable Jerk Control (Marlin only)

Not confirmed means we did not find the name in that slicer's documentation; the feature may still exist. We did not find Bambu Studio's speed and acceleration settings documented on Bambu Lab's wiki, so it is left out of this table.

The real limit: how fast the hotend can melt

Every millimeter per second of head speed asks the hotend to melt more plastic. Past a point it cannot keep up, and you get thin, weak, under-extruded lines no matter what the speed box says (see Under-Extrusion).

Two consequences. Wider lines and taller layers hit the limit at lower speeds. And speeds above the limit do nothing useful. PrusaSlicer's Max volumetric speed is a speed limiter: Prusa says it never raises a speed, only lowers one that would exceed it, and when it is set in both print and filament settings the lower value wins. Prusa adds that print, overhang and layer-cooling limits all apply too, and the most restrictive one sets the speed. OrcaSlicer likewise says every speed is capped by volumetric speed, machine motion limits, acceleration and filament cooling time.

The flow limit depends on the hotend, nozzle, material and temperature. Measure it Use your hotend maker's figure if it publishes one, or measure it with a max flow test, and work out what a given width, height and speed asks for with the calculator below or on the calculators page. UltiMaker also notes that higher speed may need a higher temperature to melt the filament properly; see Temperature and Cooling.

Layer cooling can slow you down too: on small layers the slicer reduces speed so each layer has time to cool, which is why a small part may print slower than its settings.

Acceleration

Acceleration is how quickly the head changes speed, in mm/s². On short moves it matters more than the speed setting, because the head may never reach the set speed before it has to slow for the next corner.

What it costs: Klipper's documentation explains that ringing (ghosting, the faint echoes of edges on walls) is caused by mechanical vibration from quick changes in printing direction, and its ringing test raises acceleration to make ringing more pronounced. Higher acceleration saves time but excites more ringing. Klipper also says the mechanical causes, such as a weak frame or loose belts, should be fixed first, and describes input shaping, a firmware technique that cancels the vibration a move would cause. It warns that input shaping adds smoothing that can blur fine detail, so the maximum acceleration still has to be chosen with care. See Ghosting and Ringing.

• Outer wall acceleration: OrcaSlicer says it is usually set lower than normal printing for better quality; UltiMaker says lower wall acceleration reduces ringing.
• Inner walls, infill, travel: usually higher, to save time.
• First layer: lower, which OrcaSlicer says can help bed adhesion.
• Firmware limits still apply. In OrcaSlicer, setting Normal printing acceleration to 0 leaves acceleration to the printer's firmware, and Orca never exceeds the maximum in the printer's motion settings.

Cura's Enable Jerk Control sets how quickly the head can change speed at corners. UltiMaker says higher jerk shortens print time and reduces corner blobs but increases vibration and ringing, that extreme values can cause missed steps and layer shifts, and that it applies only to Marlin firmware.

What to change first

1. Want shorter prints: raise inner wall and infill speeds, and check the flow they need stays under your hotend's limit. Leave the outer wall alone.
2. Lines go thin or gappy at speed: you are past the flow limit. Lower the speed or the line size, or raise temperature within the filament's range.
3. Ringing on walls: lower outer wall acceleration before lowering speed, and check belts and frame.
4. Bulges at corners or seams at speed: look at pressure advance before changing speeds.