Screw tap for production of female thread inside cylindrical bore has three tap wheels with bearing stubs running in tool head and circumferential ridges of increasing diameter towards tool shank

摘要

The tap has a shank carrying a head with bearing grooves which hold the three tap wheels (4-6) at a slight angle so that the circumferential ridges screw themselves into the bore, rolling the threads to shape as they do so. The three tap wheels have ridges (F1.4-5.4; F1.5-4.5; F1.6-4.6) which successively increase in diameter to form the threads in easy stages.