An R8 collet is a type of collet commonly used in milling machines, particularly those made by Bridgeport and other manufacturers of manual and CNC knee mills. R8 collets are designed to hold cutting tools (such as end mills, drills, and reamers) or workpieces securely in the spindle of the machine. The R8 collet features a 3.25-inch-per-foot  taper that matches the internal taper of an R8 spindle. Its slotted design allows it to compress slightly when tightened, ensuring a firm grip on the tool or workpiece. R8 collets are available in standard imperial sizes and  in metric sizes plus our new 25mm R8 Collet.