DESCRIZIONE
An apparatus for cutting a wellbore includes a motor with a stator and a rotor. The rotor includes an output shaft connected to a cutting structure to drive the cutting structure in use. The stator and rotor are spaced radially outwardly of the axis of the rotor such that at least one of the stator and the rotor has an access bore that extends through the motor to a position adjacent the cutting structure and through which a further object can pass without obstruction from the stator and rotor. The further object includes a further cutting structure. The motor workings are radially outward of the output shaft and the further cutting structure so as not to obstruct passage of the further cutting structure toward the cutting structure, such that the motor workings do not require drilling or removal to allow the further cutting structure access to the cutting structure.