Help with Mesh Boolean Union

I’m hoping someone can help me with this. I am creating a match plate pattern for sand casting. It will be 3D printed then assembled to form a pattern for the pour. I am down to the last steps and am having trouble creating the final mesh. I am trying to use the Mesh Boolean Union Command to combine the tools with the rest of the match plate. The command worked fine when combining the extruded surface to my runner and I adjusted the intersecting curves for the gates to get them to boolean also. A couple of the tools worked, but the rest do nothing.
The tools came to me as an STL, created in Solidworks I believe, so it was imported as a mesh. The rest of the pattern was formed in Rhino and converted to a mesh after the boolean. In order to avoid running a MeshToNURBS command, I made the rest of my file a mesh to join to the existing mesh tools. This is where I am stuck.
I have run a MeshIntersect command, which gives me closed curves where they need to be, so I’m not sure what the problem is.
I have attached some images, if someone feels they can assist I will attach the file.

Hi Kristen - there is not much we can do without the Rhino file.


Okay, here you go!
MeshBooleanUnion.3dm (5.5 MB)

Hm. the blue meshes need a bit of clean up - there are some nakeds (ShowEdges > Naked) which can be tuned up with MatchMeshEdge, which itself leaves a mesh with some flag-raising short edges… (Running Check after each repair to see what to do next) CollapseMeshFacesByEdgeLength, at .0001 sorts that out, then RebuildMeshNormals fixes the result that has a couple of face normals incorrect (Check again) nd the BU works, here… Here’s a clean blue thing.

MeshBooleanUnion_BlueThing.3dm (877.8 KB)


Thank you so much!! And thank you for the commands, that will definitely help me in the future when bringing in files created in other programs. So much appreciated :slight_smile:

Question. When I run the check command it says it’s a good mesh, but then this message below. I ran a RebuildMeshNormals command, and nothing. Next steps?

"Mesh has 4 faces where the face normal differs substantially from the vertex normals.
Although this does not necessarily mean that the mesh is bad,
these normals can cause problems if the ultimate goal is for rendering or boolean purposes.
Mesh has 4 pairs of faces that intersect each other. Although this does not
necessarily mean that the mesh is bad, it can cause problems if you’re doing mesh boolean operations with it."MeshBooleanUnion_2.3dm (2.9 MB)