Spi 21-229-0 Radius Contact Point 4-48 Dial Indicator

Product Description

The SPI 21-229-0 is a radius-style contact point designed for use with dial indicators in precision measurement applications. Machined from black oxide steel, this contact point threads into AGD Group 1 dial indicators via a 4-48 thread and provides a 3/8-inch contact length with a 3/16-inch diameter tip. The radius profile delivers consistent, repeatable surface contact on curved, flat, or irregular workpiece surfaces. Machinists, quality control technicians, and metrology professionals install this type of accessory when replacing worn contact points or when converting a standard indicator to a radius-tip configuration for specific gauging tasks.

This contact point suits precision measurement setups in machine shops, manufacturing floors, and inspection environments. It is compatible with dial indicators conforming to AGD Group 1 specifications, which is the standard sizing group covering most common shop-grade and inspection-grade dial indicators. The 4-48 thread is the industry-standard thread for this indicator class, making field swaps straightforward without additional adapters.

Key Features

• Radius contact point style for consistent surface contact on curved and flat workpieces
• Black oxide steel construction for corrosion resistance and durability
• 4-48 thread size matches AGD Group 1 dial indicator standards
• 3/8-inch contact length provides adequate reach for recessed measurement surfaces
• 3/16-inch tip diameter suits general-purpose indicator gauging tasks

Compatibility

Designed for use with dial indicators conforming to the AGD Group 1 industry designation using a standard 4-48 contact point thread.

Installation Notes

Installation requires no special tools beyond a small wrench or fingers to thread the contact point into the indicator stem. Remove the existing contact point by unthreading counterclockwise before installing the replacement. Avoid overtightening, which can damage the indicator stem threads or alter the gauge's zero calibration. Re-zero the indicator after any contact point change before taking measurements.