Two unbalances can have the same size, but their angular position is offset by precisely 180° to each other. This unbalance distribution cannot be detected by swinging, because the rotor does not take up a unique position at rest.

Question: Does the rotor being dynamically balanced need to be supported on  the balancing machine in the same way as when it is assembled.


A real rotor does not only have a single unbalance, theoretically it has an infinite number arbitrarily distributed along the axis of rotation.