No top/bottom layers for internal multi material interfaces

Bambu Lab Software Bambu Studio
1

I am doing prints that combine flexible TPU and rigid PLA using the dual extruder of the H2D.

Expected behaviour: top and bottom walls for both materials on the internal interface
Observed behaviour: inconsistent top/bottom walls on the internal interface
The PLA (orange) has neither top nor bottom and the TPU (white) only has them sometimes

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I think if you are printing with similar materials like multi color PLA this makes sense as the parts will bond and it will structurally intact. But for materials that don’t stick there should really be top and bottom walls on both materials to ensure that they are strong.

2

That isn’t an option available.

Have you explored the beam interlocking features?

3

Yes, I also have not found a way to do it besides adding a small air gap to force it to generate top and bottom. But I think it should be a feature.

I have not tried beam interlocking since the geometry already locks the parts together. Beam interlocking just increases the print time by a lot and also the wasted material because it add interlocking layers below and above the interface. I did attempt using just beam interlocking with no internal geometry but that was not strong enough.

My current workaround is to use 100% infill on the TPU part so at least that is strong.

4

Edit your post categories (use the pencil near the title, change the second category to one with “request” in it.

The staff do not go through the forum for new feature ideas. Occasionally, they will look for feature request ones. Until you do the above, this is not one.

1 Like
5

It says I have to add a feature request tag. How do I do that?

6

As I stated a moment ago.

Here it is with a step by step and pictures using one of my posts to illustrate the point.

7

I don’t have the field for optional tags and it doesn’t let me save in the request category without any tags

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8

I am encountering this same issue trying to design a custom support interface as a separate body. My assumption was that the slicer would slice the separate bodies separately, but it considers them one item and does not slice properly

1 Like
9

I am seeing the same issue. I have a multi-part model and I am using separate parts as an interface layer. The slicer just sees the part as all one big part so it does not add a top and bottom layer to the individual parts.

I believe this is a slicer error and should be fixed.

10

I can replicate the same thing except I am using PLA Matte and PLA Support material. The slicer just ignores that I have multiple parts does not make the top and bottom shell layers for the two different parts.

11

Is there any official response on when they will fix this problem? I am a new user (got H2D) and cannot use custom supports as I did on my old Ultimaker printer. I would also like to see materials grouped by assigned colors in CAD and exported as STEP files (STEP supports color), not only by solids as now. That feature (grouping by color) would simplify setup when I have many small support elements, as I now have to assign materials to each solid one by one.

12

Exactly the same thing here. It is not much use to model in-place removable supports for horizontal bearing bores and such when the supports result in elimination of the actual surfaces I want to support..

This happens even when I leave a gap of half a layer height between the part and the support. Back to normal supports (for me, the cleanest to remove) plus some handwork to refine the surfaces…

But it would be nice for Bambu to rectify this issue!

13

+1, I am having the same issue. I am trying to print a PLA part on top of a PETG support body, but there’s no top surface on the PETG body and no bottom surface on the PLA one. If I set the PETG body to 100% infill, the PLA part still does not generate a ‘floor’. The only time they behave is if both are set to 100% solid, which is not feasible for this part. I am going to try an air gap, but previous posts seem to indicate I may still have problems.

I was considering buying an X2D to be able to more easily print parts with custom modeled PETG support bodies, but if the slicer can’t even handle it, what would be the point?

14

I tried a bunch of air gap sizes, and it appears the slicer requires an air gap equal to one full layer height. I confirmed this at 0.2 mm and 0.14 mm layer heights. This is a pretty hefty gap, and I fear it will cause the surface of the part to look bad which was the whole point of using a PETG support with zero gap.

I also tried a height range modifier at the range where the two materials meet, setting the sparse infill % to 100. While this does create a ‘floor’ and ‘ceiling’ on the two bodies, it does not generate bridging in the layers leading up to those solid layers - so the printer tries to lay solid layers down on top of sparse infill at full speed. This pretty much ruins the print while making a ton of noise and quite a mess.

15

I am just living with it at this point. My part is a proof-of-concept front bezel for a new piece of equipment, that would be injection-molded in production. The fiddly convoluted air vents are fine, it’s the relatively broad,flat face around the power switch and nameplate that have the little canyons. I’m almost ready to go to the hobby shop and buy some Tamiya plastic model putty and fill and touchup-paint the things… Almost…

16

I have the same problem. If you google it you find many similar threads.

One workaround (see another solution under edit, further down) i’ve found is to add extra parts in the model to act as modifiers to force 100% infill. The 100% infill will then act as top/bottom shell layers.

Pretty sure there will be differences, and you now also have to set the top/bottom surface thickness in your cad model, rather than in bambu studio.

Cad file: Thin layer of PLA between the two PETG-bodies:

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Will result in the bug (top and bottom shell is missing):

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Add modifiers to cad model (yellow):

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Set 100% infill for yellow modifiers. Set 100% infill for middle PLA part. I just realised one big modifier part would have been enough in this case. Anyway, result is that the 100% infill act as top/bottom surfaces:

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I dont like this solution but what to do.

Edit:

After some experimenting, I found that if the middle layer is divided into lines, it triggers the top/bottom shell surfaces to be generated again. Not sure why or how much of the middle part needs to removed, but thought it was interesting:

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top and bottom surfaces now generates again, and correctly follows the top shell layers/top shell thickness settings:

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I had the problem where the lines were to thin and bambu studio would ignore them. Smallest lines that worked (as in pictures above) were 0.02mm height (since that is my layer height setting in bambu studio), and 0.06mm wide (i dont know why, but 0.04mm wouldnt generate properly sometimes).

Maybe there are better ways to do this. Maybe just cutting away some holes in the middle parts also works? I might try it later, we’ll see.

Tip for onshape users:

If you use onshape, when you extrude the middle lines, it will create multiple parts. Do that, then use the tool “composite part” with the option “close” checked, to make the line parts into 1 single composite part. When you then export your files to STL (not STEP), you have to export the composite part separat by itself (so that it exports as 1 single part). Then drag all 3 parts together into bambu studio. Bambu studio askes if the import should be one single object with multiple parts, click yes.