Rotary cutting tool of cylindrical or conical shape, used for enlarging and finishing to accurate dimensions holes that have been drilled, bored, or cored.
A reamer cannot be used to start a hole. All reamers have lengthwise flutes or grooves; either the sides of the tool or the tip may be used for cutting. Reamers are made from high-carbon steel , high-speed steel , or cemented carbides .