A screen shot or two would help us help you as MANY things can cause booleans to fail.
Boolean operations may sometimes produce unexpected results if the original objects are not closed volumes, or if they contain nearly coincident vertices. Other conditions to note include:
- The region of intersection should not contain border edges. You can display border edges by selecting Display > Polygons > Border Edges.
- Avoid meshes that are non-manifold in nature. That is, an edge does not connect to more than two faces.
- The normals on the meshes must consistently point outwards on the volumes. You can view the normals on a mesh using Display > Polygons > Face Normals. You reverse face normals using Normals > Reverse. or turn of two-sided lighting.
- Before applying a boolean operation, fill any openings in the original objects (for example, use Mesh > Fill Hole)
- Ensure the meshes involved do not have very small faces and edges. Booleans operations do not work on meshes that have zero area (or very small) faces or zero length (or very short) edges. The boolean feature automatically checks for and removes very small faces and edges via the Use Thresholds option on the polyBoolOp node. This controls two threshold settings that determine whether small faces and edges are checked for and removed automatically during the boolean operation. The default setting is on.
The Vertex Distance Threshold checks for zero length edges (or very short edges). Any vertices closer than the value specified will automatically be merged into one vertex.
The Face Area Threshold checks for zero area faces (or very small faces). Any faces with an area smaller than the value specified will automatically be collapsed into one vertex.
Note The default threshold settings are a good starting point. If the boolean operation fails, you can experiment with the threshold settings to achieve best results. Increasing either the Vertex Distance Threshold or the Face Area Threshold on the polyBoolean node by too large a value will cause portions of the mesh to disappear.
- Maya runs out of memory when using the boolean operations Using booleans on large polygonal objects is a memory intensive operation. Maya can run out of memory if this operation is performed many times on large polygonal objects.
To reduce the possibility of running out of memory, keep the undo queue length small or flush the undo queue every now and then when performing boolean operations on large polygonal objects.
note the section in bold I see a lot.
"If I have seen further it is by standing on the shoulders of giants." Sir Isaac Newton, 1675