Spiderwebs, triangulation when combining solids for 3d printing

I’m working at an architecture firm preparing a building for 3D printing. I’ve taken the sketchup model (that I didn’t create) and have been combining walls, balconies, windows etc from groups and components into larger, more complex solids. Mainly using the Solid Tools>Union tool and fixing problems identified in Solid Inspector. Over time some actions cause a lot of lines to appear across faces that should be flat. For the most part I can clean them up, hiding them with the soften tool if I can’t delete them, but my boss is convinced I’m doing something wrong since this is happening despite the fact that he can’t say what it is, and isn’t interested in my very brief explanation. :confused:

I’m assuming this is due to some inherent inaccuracy within Sketchup, which makes it think that a flat plane might not be flat and then connects lines across all corners in order to keep the face complete. It’s definitely predictable when taking a complex building model that might have slight gaps or angles between geometry that looks parallel.

Since I’m not going to be rebuilding this file just so I can 3d print it, I’m not worried about it, but can anyone let me know more specifically why this is happening? Just curious, thanks!

It’s possible you are inducing some small displacement of points within the model and SketchUp is triangulating to keep faces. An extension like CleanUp3 could remove any coplanar edges. If your boss doesn’t like the triangulaton, don’t let him see the .stl files you are exporting for 3D printing. By their very nature they are entirely triangulated.


Thought I had diligently tried to hide all of them in one piece he looked at but there was one left that he immediately pounced on lol.

I’ll give Cleanup a shot, but yeah as long as it looks fine on the surface and it can actually work in the printer I’m not worried.


As an aside, is what you are doing necessary? If all the parts of the model are solids, many slicer applications can do the combining automatically.

The model is bigger than what can be printed, so I’m making things solid so that I can divide them into printable parts and have more control over it. I’m working closely with the printing shop but I’m not the one sending the files through the slicer software.