A method of assembling an electric motor, the method comprising: inserting a first end and a first centering ring of a rotor assembly into a longitudinal bore of a stator core through a second end of the longitudinal bore, wherein the rotor assembly includes a rotor, the first end extends longitudinally from the rotor, a second end extends longitudinally from the rotor, the first centering ring is arranged on the first end, and a second centering ring is arranged on the second end the first centering ring having an outer diameter smaller than the inner diameter of the longitudinal bore and larger than an outer diameter (d) of the rotor of the rotor assembly to prevent contact between the rotor and an internal surface of the longitudinal bore; the second centering ring having an outer diameter smaller than the inner diameter of the longitudinal bore and larger than the outer diameter (d) of the rotor; characterised by placing the rotor in a first position by axially translating the rotor assembly in a first direction through the longitudinal bore such that the first centering ring is positioned adjacent a first end of, and within, the longitudinal bore and rotatably supporting the first end of the rotor assembly with a first support member configured to support the first end of the rotor assembly; axially translating the rotor assembly in the first direction to place the rotor assembly in a second position in which the first centering ring is outside the longitudinal bore and the second centering ring is within the longitudinal bore adjacent the second end thereof, whereby the first support member and the second centering ring cooperate to prevent contact between the rotor and the internal surface of the longitudinal bore; rotatably supporting the second end of the rotor assembly with a second support member configured to support the second end of the rotor assembly when the motor has been assembled; and axially translating the rotor assembly in a second direction, opposite the first direction, to place the rotor assembly in a third position in which both the first centering ring and the second centering ring are outside the longitudinal bore. inserting a first end and a first centering ring of a rotor assembly into a longitudinal bore of a stator core through a second end of the longitudinal bore, wherein the rotor assembly includes a rotor, the first end extends longitudinally from the rotor, a second end extends longitudinally from the rotor, the first centering ring is arranged on the first end, and a second centering ring is arranged on the second end the first centering ring having an outer diameter smaller than the inner diameter of the longitudinal bore and larger than an outer diameter (d) of the rotor of the rotor assembly to prevent contact between the rotor and an internal surface of the longitudinal bore; the second centering ring having an outer diameter smaller than the inner diameter of the longitudinal bore and larger than the outer diameter (d) of the rotor; characterised by placing the rotor in a first position by axially translating the rotor assembly in a first direction through the longitudinal bore such that the first centering ring is positioned adjacent a first end of, and within, the longitudinal bore and rotatably supporting the first end of the rotor assembly with a first support member configured to support the first end of the rotor assembly; axially translating the rotor assembly in the first direction to place the rotor assembly in a second position in which the first centering ring is outside the longitudinal bore and the second centering ring is within the longitudinal bore adjacent the second end thereof, whereby the first support member and the second centering ring cooperate to prevent contact between the rotor and the internal surface of the longitudinal bore; rotatably supporting the second end of the rotor assembly with a second support member configured to support the second end of the rotor assembly when the motor has been assembled; and axially translating the rotor assembly in a second direction, opposite the first direction, to place the rotor assembly in a third position in which both the first centering ring and the second centering ring are outside the longitudinal bore.