A rotary bell cup for atomizing particulate material such as paint includes a generally conical overflow surface having a generally constant flow angle defining a radially inward central axial opening and a radially outward atomizing edge with a bevel. A central flat portion is disposed between the conical overflow surface and the radially inward central axial opening. A deflector having a deflection surface of generally rotational symmetry is disposed in front of the central opening having a rear flat surface generally parallel to the central portion and a rear conical surface generally parallel to the conical overflow surface.