Planar Operation with bull nose cutter violates boundary and cuts into a wall.
Solution
In NX, the Planar Mill module was built such that the system will compensate for the bull nose radius and key off the boundary plane. When the boundary plane is lower than the cut area, NX will try to compensate for the nose radius and put the flat of the endmill on the boundary. Hence, that will seem like the NX path is violating the boundary. However, we have that behavior because NX is assuming the boundary plane is the top of the block and is trying to compensate for the radius of the bull nose cutter and clear all material at the top of the block.To avoid this situation, the user should always put the boundary plane at the top of the block rather than the bottom of the pocket.
Notes