Spi 20-637-5 Drop Indicator Contact Point Extension

Product Description

The SPI 20-637-5 is a 0.5-inch drop indicator contact point extension designed to increase the reach of dial indicator contact points. It threads directly onto compatible dial and test indicators using a standard 4-48 thread, providing added depth access for measurements in recessed bores, grooves, and hard-to-reach surfaces. Made from steel, this extension offers the rigidity and wear resistance required for repeatable precision measurement work. It is a single-piece accessory used by machinists, metrologists, and quality control technicians in shop and inspection environments.

This contact point extension suits applications where the standard stylus length on a dial or test indicator is insufficient to reach the measurement surface. Common uses include bore gauging, part runout checks, surface plate layout, and machine tool setup. The 4-48 threaded connection is an industry-standard thread size for dial indicator accessories, making it compatible with a wide range of test and dial indicator bodies used in general machining and inspection work.

Key Features

• Steel construction provides rigidity and resistance to wear during repeated contact
• 4-48 thread is the industry-standard connection for dial and test indicator contact points
• 0.5-inch extension length adds reach for measurements in recessed or deep features
• Compact single-piece design with no moving parts to affect measurement accuracy
• Sold individually for targeted replacement or single-application use

Compatibility

Designed for use with any dial or test indicator that accepts 4-48 threaded contact point accessories. Specific model compatibility depends on the indicator brand and thread specification — verify the thread standard on your indicator before installation.

Installation Notes

Installation is performed by hand-threading the extension into the indicator contact point port until snug. Avoid overtightening, as the 4-48 thread is fine-pitched and can be damaged by excessive torque. Ensure the indicator is removed from active measurement setup before swapping contact point extensions to avoid zero-shift errors. No special tools are required for installation.