Rotary cutting tool

A rotary cutting tool having a longitudinal axis of rotation and comprising:

• a conduit, for passage of fluid, formed in the cutting tool and extending generally axially,
• an insert pocket opening out to a peripheral surface of the cutting tool via an aperture, the insert pocket communicating with the conduit, and
• a cutting insert slidably retained in the insert pocket, the cutting insert being slidable from a retracted position to an extended position in which at least a portion of the cutting insert protrudes from the aperture beyond the peripheral surface of the cutting tool;
• wherein:
• a back surface of the cutting insert is in communication with the conduit such that a fluid present in the conduit is capable of urging the cutting insert from the retracted position to the extended position, without the assistance of a spring.

A method of drilling a hole in a workpiece comprising:

• providing a drill having longitudinal axis of rotation and comprising:
• a conduit, for passage of fluid, formed in the drill, the conduit extending generally axially,
• an insert pocket opening out to a peripheral surface of the drill via an aperture, the insert pocket communicating with the conduit, and
• a cutting insert slidably retained in the insert pocket, the cutting insert being slidable from a retracted position to an extended position in which at least a portion of the cutting insert protrudes from the aperture beyond the peripheral surface of the cutting tool;
• wherein:
• a back surface of the cutting insert is in communication with the conduit such that a fluid present in the conduit is capable of urging the cutting insert from the retracted position to the extended position, without the assistance of a spring;
• and
• forming a hole in the workpiece with the drill while passing fluid through said conduit such that said fluid applies pressure to the back surface of the cutting insert and causes the cutting insert to slide towards the extended position.