Expandable multi-flute reamer with tapered pin

An expandable reamer includes a shank portion, a cutting portion extending from the shank portion, and a tapered pin capable of being at least partially received in the cutting portion. The cutting portion includes a plurality of blades separated by flutes, and a tapered inner surface with threads. The tapered pin includes a tapered outer surface with threads and causes expansion or contraction of the cutting portion when the tapered pin is screwed or unscrewed into the cutting portion. In one embodiment, a coolant channel extends from a coolant cavity through a wall of the cutting portion to provide fluid to the blades during machining of through-holes. In another embodiment, the tapered pin includes a coolant passage in fluid communication with the coolant cavity to provide fluid to the blades during machining of blind holes.