Rhino 7 booleandifference and booleanunion

I’m having a bug where my booleanunion will actually do a booleanDifference. and my booleanDifference is making a booleanUnion! Confusing.

Hi @sonderskovmathias - Can you please post the 3DM file?

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please check the normal directions of your objects.

They were solids - arent the normals always pointing outwards?

In theory yes. But depending on the details of how the surfaces were creaed and modified surface normals are sometimes flipped.

Sometimes you think they are… but they are not. All it takes is one tiny naked edge to have an open object - even though it looks “solid”. The normals could then face inwards and Boolean operations will go backwards or fail. Select the object and check in Properties - it will tell you. Also make sure the objects are valid (_Check).