Tools & Gear Taps & Dies HSS Hand and Machine Taps

BABRITISH ASSOCIATION In 1884 the British Association for the Advancement of Science adopted a thread form and series - primarily for use in precision equipment. It was inspired by one used in the Swiss watch and clock industry - and was formerly sometimes called the Swiss Small Screw Thread System; but is now just referred to as the BA series. Like the Whitworth thread - it has a rounded root and crest - but the included angle is 47.5°. Despite the date of origin and the British sponsorship - the BA is a metric series. Not only is it based on the metre - but the thread frequency is specified in terms of round numbers in the pitch sequence - with threads per metre allowed to fall where it may. 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. Manufactured from HSS this general purpose tap is designed for use in medium tensile materials and is for hand or general machine use.