5/16" x 18 Left Hand BSW HSS Tap Set

About this item:

• 5/16" x 18 Left Hand BSW HSS Tap Set
• HSS BSW LEFT HAND Hand and Machine Tap Set.
• 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.
• 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.