To split non-manifold edges

Resolve the ambiguity between more than two triangles sharing the same edge

Non-manifold edges, or more precisely non-two-manifold edges can confuse toolpath generation. An example of a non-two-manifold edge is two cubes of equal size sitting on a flat surface and touching only along one of their edges each. To resolve the ambiguity, one common edge is halved, creating new triangles.

Note: Before or after splitting, this is and remains technically a self-intersection, and Netfabb does report such edges as self-intersections. Actually removing such n-manifoldness for any n>2, or whether to remove it at all, depends strongly on n, whether it is even, and also the edge's orientation with respect to toolpath generation, primarily whether it is parallel to the XY plane in particular, and should be dealt with individually; manually, if necessary.

Functions to split non-manifold edges are in two places: in the mesh export dialog and in repair. In repair, the function exists as a menu command as well as a repair script action. Only the latter two are addressed here.

Menu command

1. In repair, select the part.
2. From the menu, choose Repair > Split non-manifold edges.
3. Optional: In the dialog, make adjustments regarding the tolerance. The command requires a tolerance due to the finite precision of computing. Typically, you can leave this unchanged, deriving the tolerance from the size of the part.
4. Click OK.

Script action

1. Enter repair with any part.
2. Create a new script.
3. Add the script action Split non-manifold edges.
4. Optional: save the script.
5. Run the script on the part to be fixed.