Reamers enlarge, smooth, or contour an existing hole in a workpiece for a precise fit when installing fasteners or other parts in metalworking tasks. Hand reamers are manually operated with a tap wrench, adjustable wrench, or vise. Chucking reamers (also known as machine reamers) are operated with a drill press, lathe, screw machine, or similar machining tool. Bridge reamers are designed for use on structural materials such as iron or steel and are ideal for applications that don't require high levels of precision. Adjustable reamers have nuts and blades that can be adjusted to allow the tool to ream holes of different sizes. Expansion reamers have an adjustment screw that expands the size of the cutting head so it can be reground to its original size when worn.