Using A1 printer. Thus far I have been saving my CAD files in .STEP format via Solidworks (AP203 to be specific). Maybe right or wrong but I was under the impression STEP might be better than .STL in certain circumstances. Today in Studio I ran into this ‘error 6106 non-manifold edge’. What is weird is when I previewed in Studio, the part was distorted. Went back & checked the native CAD file, looked normal, not corrupted. This time saved as an STL & no error message. Any idea whats going on?
CAD file section view red vs Studio image on slicer. Somehow it deleted a surface
STL image
You are correct that STEP files provide greater accuracy and fidelity than STL files. STLs are mesh files, whereas STEP files are mathematical vector files that describe lines, arcs, and circles. STEP files scale infinitely, whereas mesh files do not. This is why preserving your work in STEP ensures it scales correctly at any size.
However, when you import the file into the slicer, it translates it into a mesh, just as if you had originally imported an STL. So why not just export it as an STL? For the reasons mentioned above.
You received the non-manifold error because the slicer could not render the mesh. Apparently, when you exported it as an STL, the rendering software in CAD handled it better. A manifold mesh consists of a series of triangles whose points connect at the triangle vertices. The slicer expects a “watertight” container. If this does not happen correctly, you get a non-manifold error (meaning a hole in the container). You actually had the remedy on your screen—did you try clicking “Repair”? This should fix the holes in your mesh.
If you’re curious, next time right-click on your model and select “simplify” then click on Show wireframe. It will let you visualize the mesh.
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Thank you for this information. I am relatively new to 3DP. I did see the repair button but assumed something more fundamental must be wrong.
I was under the (probably false) assumption that if I saved as STEP from Cad, then Studio might convert it into a ‘better’ STL file upon from that vector format, as opposed to saving directly as STL from Cad. But maybe you are saying there is no such advantage? My Cad has default STL settings but I can override them to increase resolution/density. Before I got my A1, I was making files for a friend, providing him increasing levels of resolution without really knowing much of anything. Of course the files got larger but he said there was no discernable benefit. Maybe he had arrived at the limits of his printer or just a function of those parts. ie. if they are mostly flat surfaces, limited benefit.
I am just about to inserted my 0.2 nozzle for the first time tonight for some smaller more detailed cylindrical parts. Would you still advise to save as STL because that is kind of baked in the Bambu A1 workflow, or continue what I’m doing with STEP & just repair if there are issues?
Also - using this error number 6106 for example, does this correspond to a Bambu Studio level error code, or is it specific to the printer itself?
If you closely, the answer is actually in the entire sentence. I think you’re misreading it to say “Error code = 6106” when what it is actually say is that there are “6,106 non-manifold edges”. All that means is that when the slicer tried to compute the 3D model, 6,106 of the edges did not meet.
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How the mesh works in the slicer.
Here’s a little tidbit for future reference. One might feel that having a higher resolution file is always better and indeed, it’s always better to have more information than less because whether it’s an image or 3D model, it can always be rendered-down or simplified. However, “printing” at such a high resolution has no such advantage.
For example, if let’s say I am rendering a 200mm sphere in CAD. Upon export, it’s going to give me a lot of vertices if I my CAD allows me to select detail level(Not all CAD allows this). However, the triangles points in the real world might be let’s say less than 0.2mm on each edge. Well, you can quickly see that the resolution of the filament is lower than the resolution of the edge of the triangle so having that extra resolution won’t give you a higher quality print but it will make the slicer and the printer do a whole lot more work.
Try this in CAD and export these object.
- Create two solid sold spheres. One at 200mm and one at 50mm
- Export them as STEP file or STL, it doesn’t matter for this experiment.
- Load both onto the same plate and note the number of triangles in both.
- Next Scale the 200mm down to 50mm using the slicer’s scale tool. Note the number of vertices for both the 50 mm and what was once the 200mm not scaled down to 50mm.
This is how it looks.
Click on the photos to get the full resolution to see details.
This what the mesh looks like for each before we scale it.
Now Next Scale the 200mm sphere using the slicer’s scale too so that it is 50mm and the same size as the one drawn in CAD at 50mm. Note that the number of triangles for the 200mm sphere(now 50mm) remains the same.
Now that both spheres are 50mm, examine the mesh using the caliper tool.
200mm scaled to 50mm and down-rezed. Notice that the triangle edge is larger but definitely inside the tolerance of the layer height. In other words, if you print both of these at 0.28, you won’t see a difference.
Clearer picture of after we down-rez an object even further so that there are fewest number of vertices. Now you can see an actual difference in the slice. The one on the right has much fewer vertices and it shows when you slice it.
You can see that there is a limit to how low one can simplify the model to the point where it does start to make a difference in the output quality.
Here’s a link to where people use this feature to actually make something of a kind of art form using “low-poly”–short for low-polygon–models. Personally, I don’t understand the appeal but I guess that’s why they call it “a matter of taste”. 
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Aha! Very useful & clear information, Olias. Thank You! I’m going to pay more attention to this in the future.
I (re) stumbled on this link I read back when I was curious about STEP vs STL. This is probably the source of my impression (right or wrong) that Studio was indeed saving as STL as a final output, however before that, it was somehow ‘optimizing’ or at least able to utilize some of the features of STEP to make a ‘better’ STL. Maybe in conjunction with user adjustment settings? I didn’t get that far. Certainly an interesting subject.
The original STEP file is the vector model, when importing the STEP file, Bambu Studio converts models into triangular mesh automatically according to a tolerance that is small than the half of default arc fitting tolerance. That is, it is converted into a high-precision STL model in Bambu Studio.
Thanks for posting that. I just learned something.
This is one area I had not previously explored in STEP to ARC conversion inside the slicer and the link you just shared is one I had not previously seen, it’s only six months old and truth be told, it’s one of the only features in BS that is not in Orca and since I abandoned BS about a year ago, and so the new STEP file conversion tool never came up.
Bambu definitely has best in class Wiki, I can’t take that away from them. In this example, they do explain the STEP to STL conversion and you want to note this section where they do a pretty good job of explaining at a summary level of what is going on and what exactly is sacrificed upon conversion to a mesh.
If you follow one of the links to the section on Arc fitting-which prior to this post I had not looked at-they give you a really good tutorial that includes the graphic below that does a great job of explaining how the slicer takes a curve from and STL model and tries to fit it to an arc. Note that STEP files would just define it as an arc with a radius whereas STL has to turn it into a series of line segments.
Here’s the source of this photo Arc move | Bambu Lab Wiki
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