Spi 21-237-3 Radius Button Contact Point Dial Indicator

Product Description

The SPI 21-237-3 is a radius button contact point designed for use with dial indicators in precision measurement applications. Machined from black oxide steel, this contact point features a 4-48 thread size and a 3/4-inch diameter button face. The contact point length is 0.25 inches, conforming to AGD Group 1 industry standards. It is the type of replacement or supplemental contact point that metrology technicians, machinists, and quality control inspectors reach for when switching measurement setups or replacing worn contact surfaces on their dial indicators.

This contact point is suited for shop floor, tool room, and inspection room environments where dial indicators are used for surface measurement, runout checks, bore gauging, and fixture setups. The radius button profile distributes contact load evenly across curved or flat workpiece surfaces, reducing the risk of surface marking and improving measurement consistency across repeated readings. Its compact size and standard thread make it a practical addition to any precision measurement kit.

Key Features

• Radius button contact style for consistent contact on flat and curved surfaces
• Black oxide steel construction for durability and corrosion resistance
• 4-48 thread size compatible with AGD Group 1 dial indicators
• 3/4-inch diameter button face for broad contact coverage
• 0.25-inch contact point length for standard reach applications
• Meets AGD Group 1 industry designation standards

Compatibility

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

Installation Notes

Contact point replacement is typically performed by machinists or metrology technicians. Before swapping contact points, remove the dial indicator from the fixture and ensure it is not under spring tension from the measuring spindle. Thread the contact point in by hand until snug, then tighten carefully to avoid cross-threading the fine 4-48 threads. Overtightening can damage the spindle threads and affect indicator accuracy.