Spi 21-235-7 Radius Button Contact Point Dial Indicator

Product Description

The SPI 21-235-7 is a radius button contact point designed for use with dial indicators in precision measurement applications. Machined from black oxide steel, it features a 4-48 threaded shank and a 1/4 inch contact point length with a 3/8 inch diameter button face. The black oxide finish provides corrosion resistance and reduces light reflection during use. This contact point is a direct replacement or supplemental tip for AGD Group 1 dial indicators and is used by machinists, metrology technicians, tool-and-die professionals, and quality control inspectors who require reliable, repeatable contact geometry during inspection routines.

This contact point suits bench-top and in-process inspection work where a radius button profile is needed to contact curved, irregular, or hardened workpiece surfaces cleanly. It is appropriate for use in machine shops, inspection labs, and production floor quality stations. Compatible with standard AGD Group 1 dial indicators that accept a 4-48 threaded contact point, it is sold individually and can be swapped in as a replacement tip or carried as a spare for fieldwork.

Key Features

• Radius button contact profile for consistent contact on curved or irregular surfaces
• Black oxide steel construction for durability and corrosion resistance
• 4-48 thread size matches AGD Group 1 dial indicator standards
• 1/4 inch contact point length and 3/8 inch diameter button face
• Sold individually — suitable as a replacement or spare tip

Compatibility

Designed for use with AGD Group 1 dial indicators that accept a 4-48 threaded contact point.

Installation Notes

Installation is performed by hand-threading the contact point into the indicator spindle using the 4-48 thread. Avoid over-tightening, as the small thread size can be damaged with excessive torque. Ensure the indicator stem is clean and free of debris before threading in the new contact point. No special tools are required for standard tip replacement.