Tools & Gear Taps & Dies Chrome Alloy Taps

4228-1/4I 1/4" x 20 BSW Intermediate Chrome Tap Chrome Alloy BSW Intermediate Hand Tap. 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). 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.