Before the first world war,the need for interchangeability of product components was felt. To ensure interchangeability limit gauges – plain and threaded were required to be developed. The first thread was developed accidentally by Sir Joseph Whitworth. As the story goes, he was filing a log of wood, when his hand slipped resulting in the creation of an angular groove in the wood.
This set him thinking and he invented first thread form (55°), which was named as Whitworth thread. He was the pioneer who standardized screw threads, which are named after him.
Components using various types of threads have been developed, for various end uses. Presently Metric (60°), Unified (60°), Whitworth (55°), BA (47.5°), BS cycle (60°) , ACME (29°), trapezoidal(30°), Standard Buttress (7°/ 45°), NPT/NPTF (60°), BSP, BSPT (55°) are popularly used. Accordingly, gauges to check these thread types have been developed.