Last position before M400 U1 on BLA1 with no AMS is wrong/? #2178

New Issue

MrUnknownDE · 2026-04-06T01:09:46+02:00

MrUnknownDE commented

2026-04-06 01:09:46 +02:00

Originally created by @lucasavendano on 9/15/2025

Is there an existing issue for this problem?

I have searched the existing issues

OrcaSlicer Version

2.3.1 Alpha 2.3.1 Beta

Operating System (OS)

Windows

OS Version

11

Additional system information

No response

Printer

Bambu Lab A1

How to reproduce

No AMS, just external spool
Replace change filament Gcode with M400 U1
Use a tower
Slice an object with at least 2 colors/filaments
Print
On a M400 U1 execution observe where it raises the toolhead and where it starts again on resume printing

Actual results

On a filament change the toolhead raises just on the last position before the call for filament change and not over the position of the tower. In my case it stops on the last point of the object, execute the action and when resume it goes to this position, stain the object with new color and then it goes to the tower...

Expected results

On a filament change the toolhead travels to the tower position and then execute the M400 U1 so when resume printing it goes again to that position and restart from there.

Project file & Debug log uploads

Cubo.zip

log.zip

Checklist of files to include

Log file
Project file

Anything else?

The Gcode viewer shows a some sorter of "correct" travel path:

and this would be nice to happen but in practice the toolhead returns to the last point and then it goes to tower position.

May it be a matter of how M400 U1 works, in that case i think the last position to allow "filament change gcode" should be at the start of the tower.

*Originally created by @lucasavendano on 9/15/2025* ### Is there an existing issue for this problem? - [x] I have searched the existing issues ### OrcaSlicer Version 2.3.1 Alpha 2.3.1 Beta ### Operating System (OS) Windows ### OS Version 11 ### Additional system information _No response_ ### Printer Bambu Lab A1 ### How to reproduce 1. No AMS, just external spool 2. Replace change filament Gcode with M400 U1 3. Use a tower 4. Slice an object with at least 2 colors/filaments 5. Print 6. On a M400 U1 execution observe where it raises the toolhead and where it starts again on resume printing ### Actual results On a filament change the toolhead raises just on the last position before the call for filament change and not over the position of the tower. In my case it stops on the last point of the object, execute the action and when resume it goes to this position, stain the object with new color and then it goes to the tower... ### Expected results On a filament change the toolhead travels to the tower position and then execute the M400 U1 so when resume printing it goes again to that position and restart from there. ### Project file & Debug log uploads [Cubo.zip](https://github.com/user-attachments/files/22350091/Cubo.zip) [log.zip](https://github.com/user-attachments/files/22350098/log.zip) ### Checklist of files to include - [x] Log file - [x] Project file ### Anything else? The Gcode viewer shows a some sorter of "correct" travel path: <img width="786" height="608" alt="Image" src="https://github.com/user-attachments/assets/7b918406-6eda-44b0-980d-a31022a1c7f5" /> and this would be nice to happen but in practice the toolhead returns to the last point and then it goes to tower position. <img width="806" height="650" alt="Image" src="https://github.com/user-attachments/assets/69b590d9-9596-4be2-a11c-d2a61e4bbb9e" /> May it be a matter of how M400 U1 works, in that case i think the last position to allow "filament change gcode" should be at the start of the tower.

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Reference: github/OrcaSlicer#2178