Spi 21-238-1 Radius Button Contact Point Dial Indicator

Product Description

The SPI 21-238-1 is a radius button contact point designed as a replacement or spare tip for dial indicators used in precision measurement applications. Machined from black oxide steel, this contact point features a 4-48 thread size and a 13/64-inch diameter button face. The contact point length is 0.157 inches. It meets AGD Group 1 industry standards, making it a recognized specification for interchangeable dial indicator accessories. Metrology technicians, machinists, and quality control professionals install this type of contact point when a rounded button profile is needed for surface contact on workpieces.

This contact point is suited for use in machine shops, inspection rooms, and production floor measurement setups. It is appropriate for any dial indicator requiring a 4-48 threaded contact point with a radius button style tip. The rounded button contact geometry is commonly chosen for measurements on curved or irregular surfaces where a standard pointed tip would rock or give inconsistent readings.

Key Features

• Radius button contact style for consistent contact on curved and flat surfaces
• Black oxide steel construction for durability and corrosion resistance
• 4-48 thread size meets AGD Group 1 industry designation
• Contact point length of 0.157 inches for precise reach
• 13/64-inch diameter button face for stable surface contact
• Direct replacement for AGD Group 1 compatible dial indicators

Compatibility

Designed for use with dial indicators accepting a 4-48 threaded contact point and conforming to AGD Group 1 specifications.

Installation Notes

Contact point installation and replacement is performed by machinists or metrology technicians using standard small wrenches or contact point tools. Ensure the dial indicator spindle is retracted and the instrument is secure before threading in the new contact point. Do not overtighten, as the 4-48 thread is fine-pitched and the spindle tip can be damaged by excessive torque. Verify indicator zeroing and function after contact point replacement before returning the instrument to service.