Reamer

A reamer is a rotary cutting tool used to enlarge and finish holes to precise dimensions. After drilling, reaming produces a bore with tight tolerances and a smooth surface finish. While most commonly associated with metalworking, reaming is also applied in plastics, woodworking, and other materials using specialized tools. The process improves hole roundness and alignment in assemblies.

Common types include hand reamers, machine reamers, and adjustable reamers. Hand reamers are turned by hand, often with a T-handle; machine reamers are used in lathes or milling machines and provide higher accuracy. Flute geometry varies: straight-fluted reamers cut with even teeth; spiral- or helical-fluted reamers evacuate chips more effectively; expansion or adjustable reamers allow final size to be varied within a narrow range.

Reamers are made from high-speed steel (HSS), carbon steel, or carbide-tipped steel, and may be coated to reduce wear. They require cutting fluid or light oil during use to minimize friction and heat. A drilled or punched hole should be slightly undersize for the final dimension, and the reaming operation is performed with a light, consistent feed and proper alignment to avoid tapering or exit burrs. In quality work, reamed holes meet tight diameter tolerances and smoothness requirements.

Care and maintenance: reamers should be kept sharp, cleaned after use, and stored in protective sleeves to prevent damage. They are sensitive to bending and can chip if forced or misaligned. Reaming tools may be resharpened or replaced depending on wear and manufacturer guidance.