one cutting structure with the axis of the tool passing through that cutting structure this ensures that the cutting structure which spans the axis of the tool rotates independently of the tool to prevent the existence of a zero velocity point on the cutting face of the tool application_number US 42781699 A description as shown in fig1 a first embodiment of the tool 10 of the present invention includes a housing 12 a drill motor 14 and a cutting assembly 18 the housing 12 is connectable to the lower end of a drill string or coiled tubing ds the housing 12 is rotatable about its longitudinal axis 26 either by rotation of the drill string ds or by being driven by a separate drill motor not shown above the housing 12 on the drill string ds alternatively the housing 12 can be rotated by a secondary drive not shown off the drill motor 14 the drill motor 14 can be driven by drilling fluid or by compressed air or by any other suitable means the drill motor 14 can be mounted and centered if desired in the housing 12 by means of one or more mounts or centralizers 16 the cutting assembly 18 is mounted on the lower.