Unable to define which filaments print first, for each layer

[mattie47]

Describe the bug

BambuStudio does not seem to follow a consistent process for deciding which filament color prints first on each layer.

I've read on bambu forums to solve this by:

• Ordering Filament in the slicer to the priority of filament color

This however does not consistently work, and I can find myself slicing the same STL with differing results

I have also tried other settings with no luck:

• Slicing/combining multiple objects
• Changing filament order in the slicer, and also "default Color"
• Changing "Order of inner wall, outer wall, infill" etc
• Tried the two latest versions of Bambu Slicer

Nothing seems to impact how the slicer decides which filament color is first.

As a user, I NEED the ability to do this, to ensure the first layer on the print bed has one filament color, before another.

Use case
In my case, white needs to go down before black, to ensure text on the object I'm printing comes out consistently. If the black goes first, then the white text becomes unreadable.

3mf File for This Bug
I've attached in a zip file:

• A sample STL which can be imported into Bambu.
• 3MF file

Case V0.3.7-bottom-test.zip

To Reproduce

I have tried many things to "workaround" but consistently get black generated first.

Please see attached 3MF, as well as the below video

Video details:

• Open Bambu 1.6.0.65 (note that I'd downgraded from 1.6.2.4 which is where I was also encountering this problem)
• Drag in the STL
• Assign default color of STL as black
• Fill in text with white
• Slice file
• observe issue, despite filament order having white, then red, then black, then support W

I then show the same STL with same steps open in Orca Slicer, and show white is printed before black.

2023-05-17.15-46-13.1.mp4

Expected behavior
G-Code generated is prioritized in order of Colors defined in Filament Ordering within the slicer. I.e. White, then Red, Then Black.

Alternatively, a feature which makes this ability more obvious for user control.

Screenshots
If applicable, add screenshots to help explain your problem.

Good:
The following is from Orca Slicer:

Bad:
White is generated Last:

2023-05-17.16-29-25.mp4

Desktop (please complete the following information):

• OS: Windows 10
• Version: Attempted Bambu 1.6.2.4, and then Bambu 1.6.0.65

Thanks

[mattie47]

TL;DR - I think I've solved the issue with my specific file, however still being able to more explicitly set the first print colour would be useful

With "dots" or things painted a certain colour which are "too small", the slicer seems to decide to print the stuff around it first.
See the below video demoing this, as well as a "workaround" for the STL to use 0.6 circle as a replacement:

2023-05-18.18-02-16-new.mp4

Perhaps this is due to nozzle size and print size and first layer line width default of 0.5 for a 0.4 nozzle?

Analysis - Below is just some notes, but not of complete relevance

I think I've figured out what's different between Bambu and the print I have with Orca slicer.

In Bambu I have:

;===== prepare print temperature and material ==========
M104 S[nozzle_temperature_initial_layer] ;set extruder temp
G91
G0 Z10 F1200
G90
G28 X
M975 S1 ; turn on 
G1 X60 F12000
G1 Y245
G1 Y265 F3000
M620 M
M620 S[initial_no_support_extruder]A   ; switch material if AMS exist
    M109 S[nozzle_temperature_initial_layer]
    G1 X120 F12000

    G1 X20 Y50 F12000
    G1 Y-3
    T[initial_no_support_extruder]
    G1 X54 F12000
    G1 Y265
    M400
M621 S[initial_no_support_extruder]A
M620.1 E F{filament_max_volumetric_speed[initial_no_support_extruder]/2.4053*60} T{nozzle_temperature_range_high[initial_no_support_extruder]}

In Orca I have:

;===== prepare print temperature and material ==========
M104 S[nozzle_temperature_initial_layer] ;set extruder temp
G91
G0 Z10 F1200
G90
G28 X
M975 S1 ; turn on 
G1 X60 F12000
G1 Y245
G1 Y265 F3000
M620 M
M620 S[initial_tool]A   ; switch material if AMS exist
    M109 S[nozzle_temperature_initial_layer]
    G1 X120 F12000

    G1 X20 Y50 F12000
    G1 Y-3
    T[initial_tool]
    G1 X54 F12000
    G1 Y265
    M400
M621 S[initial_tool]A

The key difference I see is around M620, and M621

From looking at the raw Gcode, I see the following each AMS colour change:

M620 S0A - I assume AMS 1 slot 1
M620 S1A - I assume AMS 1 slot 2
M620 S2A - I assume AMS 1 slot 3
M620 S3A - I assume AMS 1 slot 4

I've tried changing the gcode to the following:

;===== prepare print temperature and material ==========
M104 S[nozzle_temperature_initial_layer] ;set extruder temp
G91
G0 Z10 F1200
G90
G28 X
M975 S1 ; turn on 
G1 X60 F12000
G1 Y245
G1 Y265 F3000
M620 M
M620 S[initial_tool]A   ; switch material if AMS exist
    M109 S[nozzle_temperature_initial_layer]
    G1 X120 F12000

    G1 X20 Y50 F12000
    G1 Y-3
    T[initial_tool]
    G1 X54 F12000
    G1 Y265
    M400
M621 S[initial_tool]A
M620.1 E F{filament_max_volumetric_speed[initial_tool]/2.4053*60} T{nozzle_temperature_range_high[initial_tool]}

I tried editing this, but still didn't seem to make a change. I couldn't find anything on those two variables to know which is "better" practice to have.

[Photogad]

I will +1 this. It would be nice to pick which filament prints first for multicolor prints, this would help solve some printing problems when the printer decide to print certain small details first and they can become detached from the bed.

[lockeandev]

This feature is desperately needed.

[coryisakson]

+1, I am printing a lot of things with white and other colors on the first layer. I have found that when other colors go first they often leave artifacts in the white layer. When I can get the white to print first I have consistently good outcome.

[mattie47]

One thing for consideration around potential improvements:

• It may be desirable to only specify print color order for the first layer.

What I'm printing is a black box/case with white logo/text on first layer, and then white text/labels on different layers outside of the box

If white is prioritized in the print order, it will use white infill on subsequent layers. It seems this is impacting the overall finish of the outside black case. Perhaps this could be tuned with the "right settings" but my prints were definitely better on the outside of the box when black was also being used as in-fill.

Right now I'm looking at slicing two files, and then merging the gcode to get around the first layer color challenges.

[coryisakson]

I recommend creating 2 STL files and then importing as a single object. You can then set the colors of each object. Still can't decide what color prints first, but it gives you excellent control over individual colors of the model.

…

On Wed, May 24, 2023, 19:51 Matt ***@***.***> wrote: One thing for consideration around potential improvements: - It may be desirable to only specify print color order for the first layer. What I'm printing is a black box/case with white logo/text on first layer, and then white text/labels on different layers outside of the box If white is prioritized in the print order, it will use white infill on subsequent layers. It seems this is impacting the overall finish of the outside black case. Perhaps this could be tuned with the "right settings" but my prints were definitely better on the outside of the box when black was also being used as in-fill. Right now I'm looking at slicing two files, and then merging the gcode to get around the first layer color challenges. — Reply to this email directly, view it on GitHub <#1816 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AACKFQ2ZHYZGIYLNAMHR4GLXH23LFANCNFSM6AAAAAAYEQN57I> . You are receiving this because you commented.Message ID: ***@***.***>

[Mrblazed]

Please allow us to choose the first layer color order.

[zhimin-zeng-bambulab]

Currently, our first layer is printed according to the minimum area of each color, in descending order of size, which can ensure the highest printing success rate.

If it is for a higher printing success rate, the current first layer printing order is the best. If it is to remove artifacts, it can be achieved by setting a larger flushing volume. We are also evaluating whether it is necessary to allow to modify the first layer order.

[Mrblazed]

Currently, our first layer is printed according to the minimum area of each color, in descending order of size, which can ensure the highest printing success rate.

If it is for a higher printing success rate, the current first layer printing order is the best. If it is to remove artifacts, it can be achieved by setting a larger flushing volume. We are also evaluating whether it is necessary to allow to modify the first layer order.

Thank you. In certain circumstances, such as lettering, being able to control the first layer color order can be the sole difference between a high quality print and a low quality print. I appreciate your consideration.