Abstract: What is disclosed is an apparatus for measuring the relative magnetic field strength of magnetic workpieces such as miniature permanent magnet rotors which, for example, are included in miniature watch motors. The apparatus includes a nonmagnetic shaft member, one end of which is attached to a motor and the other end being positioned in a bearing. The shaft has a reduced portion thereof extending beyond the bearing and located between the poles of an electromagnet which acts as a miniature alternator. Located in the end of the shaft opposite the motor, are inserts for receiving the magnetic workpiece which may be a basic rotor or a rotor/axle assembly. The shaft is rotated at a speed which produces an alternating magnetic field in the electromagnetic pole pieces thus generating an alternating current voltage. This voltage is measured on a digital volt meter or the like with maximum and minimal levels established by calibrating with good and average rotors.

Abstract: There is disclosed an electromechanical system for measuring the concentricity of small disk magnets with respect to their axle pivots. The apparatus includes a fixture to accurately position a rotor assembly with respect to the active member of a variable reluctance transducer and a work piece for rotating the axle member while displacement measurements are being displayed on a suitable meter. The work piece for driving the rotor is designed so that no damaging forces are transmitted to the radial magnet material.