Tools & Gear Taps & Dies Chrome Alloy Taps

4228-1TS 1" x 8 BSW Chrome Tap Set Chrome Alloy BSW Hand Tap Set. Used as thread chasers to clean an existing thread. They can also be used to create a new female thread in non-ferrous metals and plastics. Chrome alloy taps are not suitable for creating precision, safety or critical threads. British Standard Whitworth has a thread angle of 55 degrees as opposed to 60 degrees in Metric and Unified threads. This thread form was developed by Sir Joseph Whitworth in 1841. The thread form has rounded roots and crests and is specified in BS84:1956. The major diameter of external thread and pitch are specified by a simple numerical value (most commonly measured in millimetres). 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. Taper Taps have a lead of eight threads and are used as a starting tap in difficult or high precision holes. 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 are typically preceded by the use of a Taper or Intermediate Tap.