Operating system: Mac OS X 10.14.6
Graphics card: irrelevant
2.80 and 2.81 development build 2019-08-26. Also reproducible in 2.79.
Short description of error
Boolean operations will sometimes produce non-manifold errors like missing faces, even if all meshes involved are manifold and share no common vertices, faces, nor edges.
Exact steps for others to reproduce the error
- Open the attached .blend file and execute all boolean operators on both the Clapper Slate-black and Clapper Slate-white meshes.
- For both these ‘finalized’ meshes, go into edit mode, switch to Vertex Select, deselect any selected points, and test for non-manifoldness (Select, Select All By Trait, Non Manifold).
- Expected result: there are no non-manifold errors.
- Actual result: in Clapper Slate-black, the ‘D’ in ‘DIRECTOR’ is missing its bottom faces. In Clapper Slate-white, the ‘P’ in ‘PRODUCTION’ is missing its top faces.
All meshes used in these boolean modifiers are manifold and have neither duplicate points or edges, nor degenerate geometry. There are no shared points, edges, or faces. These operations should just work.