A reamer is a specialized tool used in machining to enlarge or finish holes in various materials, such as metal or wood. It has a cylindrical shape with cutting edges that help create a smooth and precise hole. Reamers are often used after drilling to achieve a specific diameter or to improve the surface finish of the hole. There are different types of reamers, including hand reamers and machine reamers, each designed for specific applications. Hand reamers are operated manually, while machine reamers are used with machines like lathes or milling machines. Using a reamer ensures that holes meet exact specifications, which is crucial in many engineering and construction projects.