I recently started learning Rhino 7 and have been modelling a parts library. I had success in creating mostly closed polysurfaces, however I cannot see why these two parts aren’t closed. There don’t seem to be any open surfaces on the parts anywhere from what I can tell, is there something I am missing? Thanks so much for your help!
Open Polysurfaces.3dm (1.7 MB)
Hi Thomas - run ShowEdges and look for NonManifold edges - you have a few here - that is where there are more than two faces joined along an edge - i.e. you have some ‘internal’ faces that need to be removed.
-Pascal
Thanks so much Pascal! I ran the ShowEdges command and then exploded the part and was able to fix the non-manifold edges. Unfortunately, when I tried to BooleanUnion everything together again I seem to have created naked edges everywhere is there a reason this is happening?
Naked Edges.3dm (945.7 KB)
Hi Thomas -
The BooleanUnion command is not the command to use to join adjacent surfaces. Use the Join command in this case. You could preselect all geometry and then use Join but, especially when learning, I’d recommend to run Join and pick surface-by-surface. That will take way longer but will show you possible issues. In this case, you’ll notice that there are a few surfaces that are hard to locate when picking one-by-one. There are at least 5 surfaces that have edges that are 0.003 units apart and your document tolerance is set at 0.001.
For things to work as expected, ensure that the smallest features are one magnitude bigger than the document tolerance. Boolean operations include trimming surfaces to each other. When dimensions are as close to the tolerance as they are in your object, things will definitely fail. Joining works but it’s still not recommended to have such small features.
The images that Nacho posted show an area where 3 small surfaces are located. I’m pretty sure that the design intent does not include this narrow shoulder and it would be better to remodel the entire center cylinder surfaces and replace those with a single cylindrical surface.
The other area with small features is indicated in this image:
I’d extend the larger vertical surfaces from the bottom of the structure to meet the horizontal hook.
Attached is a file with your surfaces joined into a closed polysurface and a remodeled version.
Black Shoulder Button Part-2versions.3dm (4.7 MB)
-wim
Hi Thomas -
Better to use ExtractSrf on the internal faces highlighted by non-manifold edges, and delete them.
Also, what Wim said.
-Pascal
