Pro Tip: Setting a proper volumetric speed limit is more effective than manually reducing speeds everywhere. It ensures optimal speeds for each feature while preventing under-extrusion.
Volumetric Speed Limit
Control the maximum filament flow rate based on your hotend's melting capacity.
What is Volumetric Speed?
Volumetric speed (or volumetric flow rate) measures how much plastic volume your hotend can melt and extrude per second, expressed in mm³/s. It's the true limit on how fast you can print, regardless of the speeds set in your profile.
Formula: Volumetric Speed = Layer Height × Line Width × Print Speed
Max Volumetric Speed
- Parameter
filament_max_volumetric_speed- Unit
- mm³/s
- Default
- 0 (disabled)
- Description
- The maximum volumetric flow rate for this filament. OrcaSlicer will automatically reduce speeds to stay within this limit.
Why Volumetric Speed Matters
- Prevents under-extrusion: If you try to push filament faster than your hotend can melt, you'll get under-extrusion
- Automatic speed limiting: OrcaSlicer adjusts speeds to stay within the limit
- Material-specific: Different materials have different melting characteristics
- Hotend dependent: Upgraded hotends (CHT, Rapido, Mosquito) have higher limits
Typical Volumetric Speed Limits
| Material | Standard Hotend | High-Flow Hotend |
|---|---|---|
| PLA | 12-15 mm³/s | 25-35 mm³/s |
| PLA+ (High Speed) | 15-20 mm³/s | 30-45 mm³/s |
| PETG | 8-12 mm³/s | 18-25 mm³/s |
| ABS | 10-15 mm³/s | 20-30 mm³/s |
| ASA | 10-15 mm³/s | 20-30 mm³/s |
| TPU | 3-6 mm³/s | 5-10 mm³/s |
| Nylon | 8-12 mm³/s | 15-22 mm³/s |
Hotend Flow Capabilities
| Hotend Type | Typical Max Flow |
|---|---|
| Standard V6/Creality | 10-15 mm³/s |
| E3D Revo | 12-18 mm³/s |
| Bambu Lab | 28-32 mm³/s |
| Rapido HF | 35-50 mm³/s |
| Phaetus Dragon HF | 30-45 mm³/s |
| CHT Nozzle (any) | +50-100% increase |
How to Find Your Limit
- Use OrcaSlicer's Calibration > Max Flowrate test
- Print the calibration pattern
- Listen for extruder clicking/skipping
- Look for signs of under-extrusion
- The highest speed without issues is your max volumetric speed
Practical Example
Layer Height: 0.2mm
Line Width: 0.4mm
Max Print Speed = 15 / (0.2 × 0.4) = 187.5 mm/s
Layer Height: 0.3mm
Line Width: 0.5mm
Max Print Speed = 15 / (0.3 × 0.5) = 100 mm/sThis is why thicker layers print slower - you hit the volumetric limit sooner.