I’m having a recurring issue with Bambu Studio on Mac (latest version) when importing STL files exported from ArchiCAD.
My setup:
Printer: Bambu Lab A1
Nozzle: 0.4mm
Filament: PLA Matte
Mac (latest Bambu Studio)
Exporting architectural models from ArchiCAD at 1:300 scale
The problem:
When I import the same STL file multiple times, sometimes parts of the model are missing in the preview and some walls have holes. If I reimport the exact same file without changing anything, the missing parts sometimes come back. The geometry is correct in ArchiCAD — all walls are properly joined.
I also sometimes get filament not sticking to walls during the actual print.
Has anyone experienced this? Is this a known Mac bug with the slicer? Would switching to 3MF export help?
Thank you for the suggestion. Arachne was already set. I tested it and the missing parts are still random — sometimes a wall disappears, sometimes it comes back in the same file without changing anything. The wall thickness is the same everywhere in my model, so it’s not a thickness variation issue. The hole/missing part changes location each time I slice, which is what makes it strange. I also have a stringing issue — filament threads hanging inside the window and door openings after printing like the pictures I sent. I will export a 3MF from Bambu Studio and share it.
That sounds like rounding errors in the software to me. If you lie and say you have a .2mm nozzle, are the walls more stable? The only time I have experienced something like you are describing, is where my part walls are not too much thicker than the extrusion width. (Firewall here at work doesn’t let me access your 3mf file) [your model brings up the thought It’s not an FLW house if the roof doesn’t leak…]
I took a look at the 3mf. The fundamental problem is this: You’re thinking like an architect, not a 3D printer.
I imagine you either want to show the house to a client or use it for a demonstration, so the exterior needs to look good above all else.
What I mean is that you’re making it unnecessarily complicated for the 3D printer by printing every single detail inside, including the interior walls. This isn’t necessary to make the object look nice from the outside.
If you were to fill that space inside the house, at least in the middle, that would take care of a few problems right off the bat. From what I’ve read, you’ve already tried this to some extent? Be more consistent: Create a model based on the architectural concept and a model for presentation (3D printing).
Simply transferring an architect’s CAD file to a 3D printer is rarely a good idea. Think like a 3D printer, not like an architect.
Now, on to the second problem: your object is not manifold. This means that it is not closed. It has tiny gaps that you often can’t see, which means something went wrong during the export process. Bambu Studio also shows you this, although it’s a little hidden.
Then the 3D printer doesn’t know what to do, causing random errors during slicing. This isn’t actually a bug; your 3D object is simply defective - it’s not manifold.
Now you have three options: Either check your CAD program to see why it’s generating errors during export.
The second option is to let Bambu try to fix it - not ideal, because Bambu isn’t exactly an expert in that area. Click: Fix model
Yes, even if I’m lying, it still deletes parts of the wall. And the walls are all the same size; they’re two or even three times bigger than what the printer can print.
Thank you for the advice. I understand what you mean but I don’t need a realistic model. I just want the basic structure — exterior walls, floors and roof. The windows and doors are just holes in the walls, no frames or details. No furniture, no interior details. The interior walls need to stay because without them the floors and roof have nothing to support them during printing. So the model is already as simple as possible, the walls are just not printing consistently.
I already tried the repair tool inside Bambu Studio but it adds random geometry in mid-air which fills in the openings that should be empty. So the repair tool makes it worse, not better.
I know my comment was long, but read through what I wrote again: You should replace the interior walls with, for example, a solid block. That will support the roof and solve many of the problems.
Also, your 3D model is completely broken.
As I said, the root of the problem is your CAD program, which is producing faulty models.
But don’t worry. New filament is frequently quite moist. It has been travelling the 7 seas in bags that slow, but do not stop, moisture uptake. A good run in the drier (you can also use the printers heat bed for this) will improve this. Filament Drying Recommendations | Bambu Lab Wiki
It should also help with what looks like oozing (green)? Difficult to interpretate from this angle.
A more serious issue is the drooping during bridging (red). Printing this model without supports is asking too much of the printer. Default support settings are reasonable nowadays but it’ll be a pain to get out. But it has been a long time since I tried (unsuccesfully) to get decent support bases anchored on the model as well. That may be a tricky exercise as usual support interfaces could help, but they come with their own challenges too.
There’s also something going on in the corners. Filament drying can help somewhat (if it is flow dynamics related), but you’ll really need to do a print with dry filament to see if you may need to lower speeds.
Do the windows need to be open? Could they be recesses in the walls just for conceptual visualization? I’m doing things like that for quick stand-in model railroad structures (1:160 is almost twice as big as your scale though…) Or are you also looking at interior sight-lines?
Yes the windows need to be open because the model is used to see the interior — we look through the windows to check sight lines and how the spaces feel from outside. Just recesses wouldn’t work for that purpose. But I like your approach for model railroad structures, at 1:160 you already have very thin walls to deal with!
Thank you for the detailed analysis! I didn’t know wet filament could cause stringing, I will dry it before the next print.
Regarding the supports, yes I tried them but tree supports were impossible to remove from such a small detailed model. Do you have a recommendation for support settings that would be easier to remove at 1:300 scale?
For the bridging and corners, I will try again after drying the filament first to see what’s actually a filament moisture issue versus a settings issue. No point changing too many things at once.
I just ran it through Blender to analyze it, and the object really is completely broken. There are over 600 unconnected points - no wonder Bambu Studio has no idea what to do with it.
Until you fix that, you’re going to have a really big problem. To get this out of the way right away: Even Blender has been unsuccessful in fixing it - that’s how broken it is. A printer only understands mainfold objects, which yours isn’t - it’s like speaking the wrong language.
Thank you for checking in Blender! 600 unconnected points explains everything. So the problem is definitely coming from ArchiCAD during export. Do you have any advice on how to fix this? Should I try to clean it up directly in Blender, or is the only real solution to fix the geometry in ArchiCAD before exporting? I am open to learning Blender if that’s what it takes to get a clean printable file.
Does ArchiCAD have a STEP file export option? That will be closer to the native geometry definition than a faceted STL. In SolidWorks I haven’t touched STL output since I learned about STEP/STP files…
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