I’ve searched the interwebs at large, and combed the forums, but can’t find a solution to this issue - and I’m pretty sure it’s going to be solved with a setting that I can’t find, buried somewhere in the Bambu Studio interface…
Printer - X1C with AMS
Slicer - Bambu Studio v2.0.3.54
I have an STL (proprietary, so cannot upload it here), which is essentially a hollow box with a shallow groove running around the top edge (I’ve sliced it to make the groove more obvious in the image below):
I have another STL which is the negative of this groove, which I’m able to successfully add as a separate part, placed in the correct position, and set it to Support PLA (with the intent of popping it out when the model is printed):
The problem I have is that when it prints in this configuration, although the side walls of the groove remain intact, the top and bottom layers of the groove are missing (as shown in the sliced image below, taken 1 layer up from after the groove ends). Note the back wall of the groove is in place, but the infill transitions directly from one filament type to the other, without any top / bottom layers where the filament changes and the groove ends:
What I’m looking for is some way of forcing the parts to print all their walls / layers, so that I can just print this insert part out of support material, and then pop it out after printing, leaving a fully-formed groove behind. I’ve tried printing with automatic & manual supports enabled, but printing this part out of support seems to be far simpler & more efficient…
Oh, and yes - the main STL definitely includes a top layer to this groove
You’ve posed a fascinating challenge — and thank you for taking the time to post clear, annotated screenshots along with your lucid explanation.
I respect that the STL is private, but it would help to isolate the problematic section using the cut tool. This would not only make it easier to debug but also allow for faster, more efficient test prints using less filament and time. Once the subsection is isolated and reliably reproduces the issue, you might be able to share just that portion for direct inspection.
In lieu of access to the full part — and to avoid excessive back-and-forth — it would be helpful if you could upload a smaller example that still demonstrates the phenomenon. Here’s what I’m looking at: I’ve noticed that slicers can behave differently when handling transitions between subcomponents in a model. For example, a model derived from a STEP file with distinct design elements (like yours) may be interpreted by the slicer as separate objects, whereas the same geometry exported as an STL lacks that object-level granularity.
Here’s an illustration. I created a simple cube in CAD with a rectangular notch similar to what you described. I exported the model twice: once as a STEP file and once as an STL.
You can see in the screenshots below that test slots.stl has hidden associated objects that don’t appear in the preview, while in test slots.step, those objects are fully visible:
A “blink” comparison might make it more obvious that there are invisible structures in the STL model — they just aren’t visible in the left-hand pane.:
The key observation is what happens when slicing — we get the same type of artifact that I believe you’re encountering with your STEP file:
If you still have access to the original CAD file and can export a STEP version, try increasing the number of wall loops. This seems to resolve the issue by reinforcing those weak boundaries. Here’s the progression:
Thanks for your in-depth analysis and review - I see and understand what you are explaining. Alas, I don’t have access to the original CAD, however I have tried increasing the number of wall loops on the model in Bambu Studio.
Increasing to 8 will get me out of trouble & give complete coverage at the points where needed, at an appreciable increase in filament (50% again of the model’s original estimate). This will also fundamentally change other aspects of the print, which make it an unsuitable workaround.
Any additional help you (and others) may be able to provide with the sample 3MF in-hand would be greatly appreciated
For anyone else with this issue I have found an alternative method that may work for you.
I was able to make it work by using Normal Supports on Snug mode, and selecting my support material as the support base and interface. disable “On build plate only” and paint on the underside of the upper surface where you want the supports.
Hey everyone, I had this same issue with a manual support I designed in F360.
I think I’ve found a proper solution, but it looks like the magic setting is in OrcaSlicer only.
Multimaterial > Advanced > Interface shells
Force the generation of solid shells between adjacent materials/volumes. Useful for multi-extruder prints with translucent materials or manual soluble support material.
This fixed my issue.
Not sure if it helps since it’s a different slicer. I couldn’t get my part to slice properly in BS, so I had to resort to Orca anyway.
