Missing Bridge infill with no Top shell layers

Bambu Lab A Series
1

When I remove the top layer shells in my model the Bambu studio doesn’t slice the needed infill bridge and as a result, the “cross” on top is not printable:
(Strength → Advanced → Minimum sparse infill threshold → 50mm2)

image

In Prusa slicer, it is sliced correctly. Print settings → Infill → Advanced → Solid infill threshold area → 50mm2

image

Any idea? I’ve tried everything :man_facepalming:

Thank you for any suggestions! :green_heart:

The model: Lightweight modular tile grid for board games - Carcassonne, Karak, others by vajojajo - MakerWorld

2

In the Prusa slicer these infill bridges are triggered by:
Print settings → Infill → Advanced → Solid infill threshold area → 50mm2

Is BS setting Strength → Advanced → Minimum sparse infill threshold equivalent to that? Because it doesn’t work :frowning:

3

@kerosin, I played around with this and came up with a pretty close solution:

  1. Change wall generator from classic to arachne.
  2. Adjust your inner wall setting to half your nozzle width.
  3. Adjust the outer wall line width to nozzle width (I used .4). Don’t assume .42 or whatever your default is will be close enough.
    Here are my results:
    IMG_3690
    IMG_36901858×1422 757 KB

    IMG_3691
    IMG_36912256×2678 2.13 MB

    IMG_3692
    IMG_36922332×2452 1.88 MB
4

Thank you for the reply!

Unfortunately even with your suggested settings it doesn’t work:
image
image

Expected (screenshot from Prusa slicer):

image
image1044×700 70.1 KB

5

If you’re referring to the blue layer under the cross then it appears that in your BS version, the cross is not floating above the bed as in prusa.

6

Actually it is :slight_smile:

image

7

I know this is an old post, but I seem to be experience a similar issue. I do not think I have experienced this issue before.

I was working on a project and had a print fail. When I took a closer look, it was because the walls at a color change were floating. With no bridging over the sparse infill to support them. I am going to have to resort to turning on interface shells and waste the time and filament. But so far that is the only way that I can seem to get it to work.

I have replicated the scenario with simplified geometry within Bambu Studio. I cannot upload the file or images as a new user.

There are a couple of open issues on the Github that seem to be the same issue as this.

8

You have to complete the short tutorial in the forum and confirm the rules, then you can upload photos. You should have received a note about this somewhere. :+1:

Then you’ll get a badge like that too.

Screenshot 2026-01-22 030910
Screenshot 2026-01-22 0309101455×527 31.8 KB

9

According to Bambu engineer, you have to set the top layers more than your color penetration layers.

10

I have tested out all the possible combinations of setting higher and lower for Top shell layers, Top paint penetration layers, Bottom shell layers and Bottom paint penetration layers.

None of these settings have made a difference. I should note that in my situation, there are two separate parts with different colors. This is not painting a singular part different colors.

The model test I ran is attached to the Github issue that you created.

11

Finally able to get the ability to post an attachment.

Again this represents the situation on my project. The actual project is a lot more complex smaller color parts. But ultimately the same idea. Different color parts sitting on top of and beside the base color.

Bridging_test.3mf (28.8 KB)

image
image1687×1398 148 KB