Filament › Cooling› Part cooling fanpre_start_fan_time
Pre-start fan time
How many seconds before an overhang the fan starts ramping up, because it takes time to reach its speed.
How it works
The fan blades don't speed up instantly. If the command arrives just as the overhang starts, the first millimeters get less air. With this value, the command comes early so the air is there when the nozzle arrives.
When to change it
- PLA: 0 s, as it comes in the A1 profile.
- The start of each overhang comes out worse than the rest: try 1–2 s.
Typical values
| Value | What for |
|---|---|
| 0 s | PLA Basicdefault |
| 1–2 s | Overhangs that start badly |
Watch out for
- Takes 0 to 5 s.
- Only used with “Force cooling for overhang and bridge” on.
Goes well with
What Bambu Studio saysits help card, quoted
What Bambu Studio says
Force fan start early(0-5 second) when encountering overhangs. This is because the fan needs time to physically increase its speed.
Bambu Studio tooltip for this setting · AGPL-3.0
Read more at the official source
In your profileBambu PLA Basic @BBL A1 · 0 s
In Bambu Studio, the profile Bambu PLA Basic @BBL A1 sets it to0 s
In other slicers
- Orca Slicer
- Fan speed-up timeBasic information › Cooling FanIn Orca it's a printer setting; with fan_speedup_overhangs it's limited to overhangs.
- PrusaSlicer
- No clear equivalent.
- Cura
- No clear equivalent.
Names taken from each program's code (Orca Slicer 2.4.2, PrusaSlicer 2.9.6, Cura 5.13.0). Credits