1/4" x 20 Left Hand UNC HSS Tap Set

About this item:

• 1/4" x 20 Left Hand UNC HSS Tap Set
• HSS UNC LEFT HAND Hand and Machine Tap Set.
• Unified National Coarse thread form was introduced in 1948 as an attempt to standardise thread forms in the USA, Canada and the UK.
• The thread profile of UNC is the same as for metric threads and is described in the JIS B0206 standard.
• The thread is described by its major diameter and the number of threads per inch of length (TPI).
• This thread series is commonly used in the mass production of bolts, screws and nuts.
• It is used for threading into lower tensile strength materials (bronze, brass, aluminium and plastics) to obtain the best resistance to stripping of the internal thread.
• It is also used on quick assembly or disassembly or if corrosion or slight damage is possible.
• 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.
• 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.
• Taper Taps have a lead of eight threads and are used as a starting tap in difficult or high precision holes.
• Manufactured from HSS this general purpose tap is designed for use in medium tensile materials and is for hand or general machine use.