Spi 20-979-1 Ball Needle Contact Point 4-48 Thread

Product Description

The SPI 20-979-1 is a ball needle contact point designed for use with dial indicators in precision measurement applications. Machined from chrome alloy steel, this contact point features a 0.75-inch length and a 0.2188-inch ball diameter, with a 4-48 thread size that conforms to AGD Group 1 industry standards. It is a direct-fit replacement tip for dial indicator spindles requiring a fine-thread, ball-style stylus. Metrology technicians, machinists, and quality control professionals use this type of contact point when measuring bores, grooves, or recessed surfaces where a standard flat contact cannot reach.

This contact point is suited for bench and floor-level inspection setups in machine shops, manufacturing environments, and tool rooms. It threads onto the spindle of AGD Group 1 dial indicators and is appropriate for both surface plate inspection and fixture-mounted indicator configurations. Its ball needle profile makes it well suited for applications requiring contact in confined or curved geometry locations.

Key Features

• Ball needle style tip for access to recessed and curved measurement surfaces
• Chrome alloy steel construction for wear resistance and consistent contact
• 0.75-inch contact point length provides reach for confined measurement locations
• 0.2188-inch ball diameter for precise point contact
• 4-48 threaded shank conforms to AGD Group 1 standards

Compatibility

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

Installation Notes

Installation is performed by hand-threading the contact point onto the dial indicator spindle until snug — do not overtighten, as the fine 4-48 thread is easily damaged. Verify the indicator reads zero correctly after swapping contact points, and re-establish your datum before taking measurements. No special tools are required, though needle-nose pliers with jaw protection can assist if the tip is stubborn.