Spi 20-348-9 Cupped Ball Contact Point M2.5 Ruby

Product Description

The SPI 20-348-9 is a cupped ball contact point designed for use with dial indicators in precision measurement applications. The contact point is made from ruby, a material chosen for its hardness and wear resistance, which helps maintain accuracy over repeated measurements. It threads into the indicator spindle via an M2.5 thread and measures 4 mm in diameter with a contact point length of 7 mm (approximately 0.28 inches). The cupped ball profile centers the contact on curved or spherical workpiece surfaces, reducing lateral slip and improving repeatability. Metrology technicians, machinists, and quality control inspectors are the primary users of this accessory.

The 20-348-9 is suited for use in machine shops, manufacturing facilities, and inspection environments where dial indicators are used to check runout, surface variation, or part alignment. The ruby ball tip is well suited for contact with hardened steel, ceramic, and other abrasive surfaces where a steel contact point would wear prematurely. This contact point conforms to AGD Group 1 industry designation, making it compatible with standard AGD Group 1 dial indicators.

Key Features

• Ruby contact material provides high wear resistance on hardened and abrasive workpiece surfaces
• Cupped ball profile improves contact stability on curved or spherical surfaces
• M2.5 thread fits standard dial indicator spindle mounts
• AGD Group 1 industry designation for broad indicator compatibility
• 4 mm ball diameter and 7 mm contact point length suit general-purpose indicator use

Compatibility

Designed for use with dial indicators conforming to AGD Group 1 standards. Thread size is M2.5.

Installation Notes

Thread the contact point into the dial indicator spindle by hand first, then snug using the appropriate small wrench or pliers with jaw protection to avoid damaging the ruby tip. Do not overtighten, as excessive force can crack the ruby ball or strip the M2.5 thread. Before swapping contact points, ensure the indicator is removed from any active measuring fixture to prevent accidental spindle damage. Replace the contact point if the ruby ball shows visible chips or flat spots that affect measurement consistency.