METRIC COARSEAngle of thread is 60 degrees. The crest is flat and the thread has clearance at the root allowing external thread and internal thread to engage well. Larger root radius and lower thread height enable easy screw thread processing and increase thread screw strength. The major diameter of external thread and pitch are specified by a simple numerical value (most commonly measured in millimetres). TAPER TAPS have a lead of eight threads and are used as a starting tap in difficult or high precision holes. Manufactured from HSS this general purpose tap is designed for use in medium tensile materials and is for hand or general machine use. INTERMEDIATE TAPS have a lead of four threads and are used in most general purpose applications to cut a thread true to a pre-drilled pilot hole. BOTTOMING TAPS have a lead of two threads and are used to ensure minimum thread run-out when tapping to the bottom of a blind hole. Bottoming Taps are typically preceded by the use of a Taper or Intermediate Tap.
