Spi 20-978-3 Ball Needle Contact Point Dial Indicators

Product Description

The SPI 20-978-3 is a ball needle contact point designed for use with dial indicators in precision measurement applications. Manufactured from chrome alloy steel, this contact point features a 3/16 inch ball diameter and a contact point length of 0.75 inches. The tip threads into AGD Group 1 dial indicators using a 4-48 thread specification. Metrology technicians, machinists, and quality control professionals install this type of contact point when setting up dial indicators for bore gauging, surface runout checks, and other inspection tasks that require a rounded contact profile.

This contact point suits light-duty precision measurement work in machine shops, manufacturing facilities, and tool rooms. It is intended for use with dial indicators that accept 4-48 threaded contact points conforming to AGD Group 1 standards. The ball needle style is chosen when a small, spherical contact surface is needed to minimize contact area on curved or irregular workpiece surfaces.

Key Features

• Chrome alloy steel construction for durability and wear resistance
• Ball needle style provides a small spherical contact area for curved surfaces
• 3/16 inch ball diameter for precise point contact
• 0.75 inch contact point length fits standard AGD Group 1 indicator stems
• 4-48 threaded shank for secure attachment to compatible dial indicators

Compatibility

Designed as a replacement or spare contact point for dial indicators accepting 4-48 threaded tips conforming to AGD Group 1 specifications.

Installation Notes

This contact point is installed by hand or with light tool assistance by machinists or metrology technicians. Thread the contact point carefully into the dial indicator spindle to avoid cross-threading the fine 4-48 thread. Do not overtighten, as excess torque can damage the indicator spindle or contact point threads. Verify indicator zero and calibration after any contact point change.