@tig said:
You are running into the well documented 'tiny-geometry' limitations of SketchUp.
Sketchup regards points closer that 1/1000" apart as being coincident.
Thus tiny any such edges are not created and the faces they support are then missed.
The simple trick is to scale up the two parts x10 or x100 and then doing the subtraction.
When you have the desired form you can scale it down to the original size...
The tiny geometry can exist, but it can't be created directly.
Thanks a lot! This makes a lot of sense. Even with other models I have made, I have been pulling my hair it with tiny imperfections around curves that appeared somewhat randomly