In the example below is a 18 hours print job. Toolhead #3 & #4 are only being used in the first 4 hours, after that it is all toolhead #1. Why keep the inactive #3 & 4 warm the whole time instead of turn them off completely at 0c?
It’s been mentioned recently, a search should find it.
Check the discussion here — the G-code needs a few tweaks:
Snorca is “blind” to long time gaps. It processes prints layer‑by‑layer, not by looking ahead at the overall timeline.
When a toolhead finishes its task on a given layer, the slicer simply tells it to park and drop to a standby temperature. It doesn’t consider whether that tool will be needed again 10 minutes or 14 hours later.
So even if a tool is never used again after the first few layers, the slicer still treats it like any other pause — keeping it warm “just in case” it’s needed on the next layer. This is why idle nozzles stay around 70°C for the entire print, even when they’re no longer in use.
He’s talking about heads that are not used throughout the remainder of the print.
Hey, thanks for the notice.
I did a little search earlier about why inactive nozzles stay at a “standby” temperature (usually around 70°C to 170°C depending on the platform) instead of dropping to 0°C.
The multi-tool system keeps them warm due to three critical engineering reasons:
- Slicer “Blindness” to Big Picture Time Gaps.Slicers process 3D prints layer-by-layer rather than evaluating chronological time gaps.
- Thermal Expansion and Calibration ConsistencyToolheads rely on extreme structural precision. Letting a toolhead completely cool down to room temperature (0°C/off) causes the metal heater block, nozzle, and assembly to contract, such as Z-Height Variance.
- Preventing Filament Clogs and Softening (Glass Transition)Dropping a nozzle all the way down to room temperature with filament still loaded inside can introduce mechanics that jam the toolhead.
For this situation, the first one might be the most critical.
That’s how all FDM printers do when they are power off, leave filament inside of nozzle.
It sounds like slicer could be a bit smarter by evaluating chronological time gap, considering the slicer code was written before toolchanger printers.
I have had print job that left the nozzles that have done printing their part at full temperature for remaining of print job, but that’s vanilla Orca. I just turn them off by changing the temperature to zero, save a bit for electricity.