Mitutoyo 64AAA221 Thread Measuring Wire 20 Tpi 2.25 in

Product Description

The MITUTOYO 64AAA221 is a thread pitch diameter measuring wire used to determine the pitch diameter of threaded workpieces with precision metrology methods. Designed for 20 TPI threads, this wire has a pitch of 0.05 inches and a nominal best wire diameter of 0.0289 inches. The nominal constant is 0.0433 inches. Each wire measures 2.25 inches in length. The set includes 3 wires, providing the full complement required for the three-wire measurement method. Machinists, metrology technicians, and quality control professionals use these wires with a micrometer to achieve accurate pitch diameter readings on external threads.

These measuring wires are suited for use in machine shops, manufacturing inspection departments, and tool rooms where threaded fasteners and components must be verified to specification. The 20 TPI designation makes this set appropriate for unified national thread forms and other thread standards cut at that pitch. They are used alongside a bench micrometer or outside micrometer as part of a standard three-wire measurement setup. The wires are sized as best-wire diameter for 20 TPI, meaning they contact the thread flanks at the pitch line for the most accurate reading possible.

Key Features

• Designed for 20 TPI threads with a 0.05 inch pitch
• Nominal best wire diameter of 0.0289 inches for optimal flank contact at the pitch line
• Nominal constant of 0.0433 inches used in pitch diameter calculations
• Each wire is 2.25 inches long for easy handling during measurement
• Set of 3 wires supports the standard three-wire measurement method

Compatibility

Designed as a best-wire-diameter set for external threads at 20 TPI, suitable for use with standard bench and outside micrometers in three-wire pitch diameter measurement procedures.

Installation Notes

Thread measuring wires are installed by a machinist or metrology technician during inspection, not as a component in a mechanical system. Handle wires carefully to avoid nicks or bending that could affect measurement accuracy. Keep wires clean and free of oil or debris before use. Store in the supplied container when not in use to prevent damage.