Mesh Boolean Problems

I am trying to enlarge holes in two places in an STL mesh. I created a cylinder and used MeshBooleanDifference to subtract the cylinder from one end of the object. That worked. When I try to do the exact same thing at the other location, it doesn’t work.

MeshBooleanDifference selecting the mesh as the first object and the cylinder as the second object results in deleting the cylinder. When I select the cylinder as the first object and the mesh as the second object, the difference works correctly, returning a cylindrical mesh with a notch cut out of it.

MeshBooleanSplit selecting the mesh as the first object and the cylinder as the cutting object does nothing. I’ve also tried using an open surface lofted between two circles as the cutting object and it also does nothing.

MeshTrim using the cylinder as the cutting object will slice out the desired portion of the original mesh. However, it leaves an opening in the mesh instead of closing up the volume. I’ve been unable to join a mesh bridging the opening so as to form a closed volume.

What do I need to do to subtract this cylinder from the mesh and leave a closed mesh suitable for 3D printing?

MainGearModAxle.3dm (3.5 MB)

Well, that was a BAD post. I got the trim to work, though.MainGearModAxleck.3dm (594.8 KB)

What did you do to fix the problem?

Actually, now that I look at the file you posted, I don’t think the problem is fixed. If you look down the axis of the cylinder, you will see the mesh still has the original sized hole.

This issue has been overcome by events. The file I posted was actually version 2 of the mesh, having had the holes previously enlarged to an intermediate size. I went back to the original version and I was able to cut out the larger holes with no problem. So there is something wrong with the particular mesh I posted.

It is now of academic interest to know what was wrong and what to do to fix it, but the problem itself is no longer holding me up.