A reamer is a cutting tool used to enlarge or finish to size a hole that has already been drilled. Reamers have cutting edges along their length and rotate to smooth out rough edges and bring the hole to precise size. They are used in metalworking, woodworking, and machining operations to improve the accuracy of existing holes. Reamers are the most accurate hole-making tools and can meet the high H6/H7 tolerances.