Iso-scallop trajectories, tool orientations and a tool swept volume for the 5-axis machining of an impeller have been developed in the paper. As the merits of ball end tools, the planning work has been done on the cutter location surface. Firstly, a boundary curve is selected as the master trajectory, and cutting intervals are calculated from the geodesic curvature on the blade surface to keep a constant scallop height. Secondly, tool orientation determinations are discussed to promise the trajectories interference-free. The determined tool orientations are starting from the trajectory point and pointing to a guide line located in the mid-plane between two neighbor blades. Finally, measurement results from a machining simulation and a produced tool swept volume are given to illustrate the feasibility and validity of the proposed method.