A powered surgical handpiece includes a housing, an electric motor disposed in the housing, the motor including plural windings, and a rotor having a longitudinal axis and an even number of magnets. The rotor is disposed within the windings. The powered surgical handpiece further includes an output drive shaft connected to the motor rotor to be rotated by the motor rotor, the output drive shaft having an elongated bore dimensioned to receive the shaft of a cutting accessory. Furthermore, the powered surgical handpiece includes a coupling assembly with at least one locking element that extends into the bore of the output drive shaft, the at least one locking element releasably holding the cutting accessory shaft to the output drive shaft so that the cutting accessory shaft rotates in unison with the output drive shaft. The rotor is formed with an axially extending bore and the magnets are disposed in the rotor bore, wherein each said magnet has an outer surface located adjacent the bore-defining inner surface of said rotor, and two side surfaces that extend away from the outer surface and towards the longitudinal axis of said motor rotor so as to define a corner between the inner side surfaces that is located adjacent the longitudinal axis of the rotor and spaced inwardly from the magnet outer surface. The magnets are arranged so that a first pole of a said magnet is located at the outer surface of the magnet and the opposed second pole is located at the corner of the magnet and said magnets are disposed in the rotor bore so that arcuately adjacent magnets have corners with opposed magnetic polarities.
