Reamer
A reamer is a particular kind of cutting tool that is used for widening or finishing drilled holes. Designed to leave the sides of a hole smooth, a precision reamer has a high degree of accuracy. Reamers are made with a set of parallel and straight or helical cutting edges all along the side of the cylinder-shaped body. When helical, the spiral down the reamer can follow either a clockwise or counter clockwise design. The odd number of flutes that can be found on a reamer make these tools best measured using a v-anvil micrometer.