Significant Possibility to Reduce AMS Waste? #883

New Issue

MrUnknownDE · 2026-04-05T16:33:43+02:00

MrUnknownDE commented

2026-04-05 16:33:43 +02:00

Originally created by @killerline10168 on 2/4/2026

Is there an existing issue for this feature request?

I have searched the existing issues

When OrcaSlicer performs a filament change for AMS / multi-material prints, the current workflow is:

Finish printing with the active filament
Retract 18 mm (by default) and cut filament.
Switch filament and fully purge the remaining filament in the hotend
Purge again to ensure clean color/material
Resume printing

This approach works, but it generates substantial and often unnecessary purge waste. Much of the filament inside the melt zone is still usable, yet it is discarded even though it could be consumed safely during printing.

Which printers will be beneficial to this feature?

All

Describe the solution you'd like

Introduce an intelligent filament-change strategy that uses the remaining filament in the hotend instead of purging it entirely. Instead of purging first, the slicer could:

Cut the current filament earlier.
Switch filament sooner
Allow the new filament to push the remaining filament from the previous spool
Print the final segments meant for the old filament using the leftover material in the hotend.

Once the remaining filament is nearly consumed, the printer would then purge only the small “mixed melt zone” where old and new filaments meet.

The slicer would:

Estimate the remaining filament volume in the melt zone + nozzle (adjustable per printer, of course).
Allocate that volume to upcoming print moves and how much of it can be used on the print before the next filament change.
Trigger a purge only when the new filament approaches the nozzle tip and a clean transition is required

This replaces the current strategy of purging nearly the entire hotend volume every swap, significantly reducing waste.

A conservative safety margin could be applied. For example, if the estimated usable volume is 50 mm³, only 30 mm³ would be allowed for printing.

Why this is feasible

OrcaSlicer already tracks extrusion lengths and material flow
The amount of filament inside the hotend and melt zone is finite and relatively predictable.
“Long retraction when cut” already demonstrates that OrcaSlicer models post-cut filament state, even though only a portion is retracted
Similar concepts are already used in purge tower sizing and purge minimization strategies
Since hotends differ in internal volume, a user-defined “purge volume” constant would be required. Existing melt-zone volume calibration prints could be added to OrcaSlicer’s calibration suite

Describe alternatives you've considered

No response

Additional context

I will also publish this on Bambu Labs forums, as it seems highly relevant to their printers!

*Originally created by @killerline10168 on 2/4/2026* ### Is there an existing issue for this feature request? - [x] I have searched the existing issues ### Is your feature request related to a problem? When OrcaSlicer performs a filament change for AMS / multi-material prints, the current workflow is: 1. Finish printing with the active filament 2. Retract 18 mm (by default) and cut filament. 3. Switch filament and fully purge the remaining filament in the hotend 4. Purge again to ensure clean color/material 5. Resume printing This approach works, but it generates substantial and often unnecessary purge waste. Much of the filament inside the melt zone is still usable, yet it is discarded even though it could be consumed safely during printing. ### Which printers will be beneficial to this feature? All ### Describe the solution you'd like Introduce an intelligent filament-change strategy that uses the remaining filament in the hotend instead of purging it entirely. Instead of purging first, the slicer could: 1. Cut the current filament earlier. 2. Switch filament sooner 3. Allow the new filament to push the remaining filament from the previous spool 4. Print the final segments meant for the old filament using the leftover material in the hotend. Once the remaining filament is nearly consumed, the printer would then purge only the small “mixed melt zone” where old and new filaments meet. The slicer would: - Estimate the remaining filament volume in the melt zone + nozzle (adjustable per printer, of course). - Allocate that volume to upcoming print moves and how much of it can be used on the print before the next filament change. - Trigger a purge only when the new filament approaches the nozzle tip and a clean transition is required This replaces the current strategy of purging nearly the entire hotend volume every swap, significantly reducing waste. A conservative safety margin could be applied. For example, if the estimated usable volume is 50 mm³, only 30 mm³ would be allowed for printing. ### **Why this is feasible** - OrcaSlicer already tracks extrusion lengths and material flow - The amount of filament inside the hotend and melt zone is finite and relatively predictable. - “Long retraction when cut” already demonstrates that OrcaSlicer models post-cut filament state, even though only a portion is retracted - Similar concepts are already used in purge tower sizing and purge minimization strategies - Since hotends differ in internal volume, a user-defined “purge volume” constant would be required. Existing melt-zone volume calibration prints could be added to OrcaSlicer’s calibration suite ### Describe alternatives you've considered _No response_ ### Additional context I will also publish this on Bambu Labs forums, as it seems highly relevant to their printers!

MrUnknownDE closed this issue

2026-04-05 16:33:43 +02:00

Sign in to join this conversation.

No Label enhancement enhancement enhancement enhancement enhancement enhancement enhancement enhancement enhancement enhancement enhancement enhancement enhancement enhancement enhancement enhancement enhancement enhancement enhancement enhancement enhancement enhancement enhancement enhancement enhancement enhancement enhancement enhancement enhancement enhancement enhancement enhancement enhancement enhancement enhancement enhancement enhancement enhancement enhancement enhancement enhancement enhancement enhancement enhancement enhancement enhancement enhancement enhancement enhancement enhancement enhancement enhancement enhancement enhancement enhancement enhancement enhancement enhancement enhancement enhancement enhancement enhancement enhancement enhancement enhancement enhancement enhancement enhancement enhancement enhancement enhancement enhancement enhancement enhancement enhancement enhancement enhancement enhancement enhancement enhancement enhancement enhancement enhancement enhancement enhancement enhancement enhancement enhancement enhancement enhancement enhancement enhancement enhancement enhancement enhancement enhancement enhancement enhancement enhancement enhancement enhancement enhancement enhancement enhancement enhancement enhancement enhancement enhancement enhancement

1 Participants

Notifications

Due Date

No due date set.

Dependencies

No dependencies set.

Reference: github/OrcaSlicer#883