Tool Talk - Taps and Chamfers

Tool Talk - Taps and Chamfers - July 2019TOOLTALK Taps and Chamfers JULY 2019 Taps are used to make threads in existing or pre-drilled holes. The chamfer of a tap is the tapering of threads to distribute the cutting forces over several teeth. Different chamfer types are required or best suited for different types of holes such as through-holes, deep, and blind holes. Types of Taps Hand/Straight Flute – Popular in hand use, general machine tapping or CNC tapping. Appropriate for tapping the vast majority of materials in through or blind hole conditions. Spiral Point (Gun) – Reduces loading and clogging in flutes by “shooting” chips ahead of the cutting action. Spiral Flute – Draw chips out of a tapped hole where chip management is an issue. Thread Forming – Form threads rather than cut threads, eliminating the problems with chip evacuation and management. Pipe – General purpose pipe taps are used for threading both ferrous and non-ferrous materials that will be used to transport liquids or gas. Acme – Produce transversing motions on machine tools and are typically used to manufacture valves, jacks and other mechanisms. Pulley – Have longer length shanks to tap pulley hubs and set screw holes. Screw Thread Insert (STI) – For use in tapping holes according to screw thread standards. Types of Chamfers Taper (7-10 Threads) – Also known as a started tap, a taper tap has the longest standard chamfer and requires less tapping torque. Plug (3-5 Threads) – The most common and most efficient chamfer for use by hand or machine in through or blind holes. Modified Bottoming (2-2.5 Threads) – Allows for threading close to the bottom holes. Due to slightly longer chamfer and more working teeth, this chamfer is more efficient than a bottoming chamfer. Bottoming (1-2 Threads) – Used for threading blind holes to the bottom of the work-piece Taper Tap Chamfer = 7 to 10 Threads Plug Tap Chamfer = 3 to 5 Threads Modi ed Bottoming Tap Chamfer = 2 to 2-1/2 Threads Bottoming Tap Chamfer = 1 to 2 Threads Applications Taper taps are best used on through-hole application or in starting new threads entirely. Plug taps are the most common and versatile chamfer types for most applications. Bottoming taps are best used in shallow holes because it allows threads to be cut closest to the bottom of the hole. Looking for Metalworking Tools? Contact Fastenal at 844.365.8665 or cuttingtoolsupport@fastenal.com Go to www.fastenal.com/metalworking for previous Tool Talks FMPM-8838 JP 6/19