A magnetic system comprising: a machine including a base that is configured to perform an operational cycle; at least one magnetic coupling device (10; 450; 1000; 1100; 1200) operatively coupled to the machine at a first end of the machine opposite the base, wherein each magnetic coupling device of the at least one magnetic coupling device comprises: a housing including a switchable magnetic flux source supported by the housing; a plurality of workpiece engagement surfaces (44; 454) supported by the housing and magnetically coupled to the switchable magnetic flux source, the plurality of workpiece engagement surfaces adapted to contact a ferromagnetic workpiece (17; 27; 1202), a first workpiece engagement surface of the plurality of workpiece engagement surfaces corresponding to a north pole of the magnetic coupling device and a second workpiece engagement surface of the plurality of workpiece engagement surfaces corresponding to a south pole of the magnetic coupling device; and at least one magnetic field sensor supported by the housing, wherein a magnetic field sensor of the at least one magnetic field sensor is positioned to monitor a first magnetic flux associated with the first workpiece engagement surface or a second magnetic flux associated with the second workpiece engagement surface; and a logic control circuit operatively coupled to the magnetic field sensor and the machine, the logic control circuit configured to perform a calibration sequence for the at least one magnetic coupling device using an output from the magnetic field sensor during the operational cycle, characterised in that the logic control circuit is configured to determine if a ferromagnetic workpiece is coupled to the at least one magnetic coupling device and if the ferromagnetic workpiece is present the calibration sequence is performed when the at least one magnetic coupling device is coupled to a ferromagnetic workpiece and otherwise the calibration sequence may be performed when the at least one magnetic coupling device is not coupled to the ferromagnetic workpiece. a machine including a base that is configured to perform an operational cycle; at least one magnetic coupling device (10; 450; 1000; 1100; 1200) operatively coupled to the machine at a first end of the machine opposite the base, wherein each magnetic coupling device of the at least one magnetic coupling device comprises: a housing including a switchable magnetic flux source supported by the housing; a plurality of workpiece engagement surfaces (44; 454) supported by the housing and magnetically coupled to the switchable magnetic flux source, the plurality of workpiece engagement surfaces adapted to contact a ferromagnetic workpiece (17; 27; 1202), a first workpiece engagement surface of the plurality of workpiece engagement surfaces corresponding to a north pole of the magnetic coupling device and a second workpiece engagement surface of the plurality of workpiece engagement surfaces corresponding to a south pole of the magnetic coupling device; and at least one magnetic field sensor supported by the housing, wherein a magnetic field sensor of the at least one magnetic field sensor is positioned to monitor a first magnetic flux associated with the first workpiece engagement surface or a second magnetic flux associated with the second workpiece engagement surface; and a housing including a switchable magnetic flux source supported by the housing; a plurality of workpiece engagement surfaces (44; 454) supported by the housing and magnetically coupled to the switchable magnetic flux source, the plurality of workpiece engagement surfaces adapted to contact a ferromagnetic workpiece (17; 27; 1202), a first workpiece engagement surface of the plurality of workpiece engagement surfaces corresponding to a north pole of the magnetic coupling device and a second workpiece engagement surface of the plurality of workpiece engagement surfaces corresponding to a south pole of the magnetic coupling device; and at least one magnetic field sensor supported by the housing, wherein a magnetic field sensor of the at least one magnetic field sensor is positioned to monitor a first magnetic flux associated with the first workpiece engagement surface or a second magnetic flux associated with the second workpiece engagement surface; and a logic control circuit operatively coupled to the magnetic field sensor and the machine, the logic control circuit configured to perform a calibration sequence for the at least one magnetic coupling device using an output from the magnetic field sensor during the operational cycle, characterised in that the logic control circuit is configured to determine if a ferromagnetic workpiece is coupled to the at least one magnetic coupling device and if the ferromagnetic workpiece is present the calibration sequence is performed when the at least one magnetic coupling device is coupled to a ferromagnetic workpiece and otherwise the calibration sequence may be performed when the at least one magnetic coupling device is not coupled to the ferromagnetic workpiece.