Drill America Adjustable hand reamer with High-speed steel tools are good for most general purpose applications, offering a combination of hardness and toughness for wear resistance. Black oxide treatment adds lubricity and creates small pockets on the surface of the tool that act to hold coolant near the cutting edge. Round shank with square end. Straight flute tools allow chips to collect in the flutes as they cut and are well suited for most applications in shallow cuts. Right-hand cut tools have a cutting action that engages when they are run in a clockwise direction. Reamers expand by loosening one adjusting nut and tighting the other. Each reamer expands to the next size.