Spi 20-643-3 Contact Point Extension 2 Inches 4-48 Thread

Product Description

The SPI 20-643-3 is a 2-inch drop indicator contact point extension designed to extend the reach of a dial indicator contact point in precision measurement applications. Machined from steel, this extension features a 4-48 thread for secure, vibration-resistant attachment. It provides an additional 2 inches of reach, enabling techs and machinists to access recessed bores, deep surfaces, and hard-to-reach measurement zones without repositioning the indicator base. The compact 1-inch profile in height and width keeps it easy to handle during setup. It is a simple, durable accessory that improves measurement versatility on the bench or on the machine.

This extension is suited for use in machine shops, manufacturing facilities, and precision maintenance environments. It is installed by machinists, tool and die technicians, and precision measurement professionals working with dial indicators that accept standard 4-48 threaded contact points. Typical applications include runout measurement, surface flatness checks, and bore alignment verification where standard contact point length is insufficient to reach the target surface.

Key Features

• 2-inch length adds significant reach to standard dial indicator contact points
• 4-48 thread matches standard contact point threading on most dial indicators
• Steel construction for durability and dimensional stability under repeated use
• Compact 1-inch height and width for ease of handling in tight setups
• Lightweight at 0.15 pounds, adding minimal mass to the indicator stem

Compatibility

Designed for use with any test indicator or dial indicator equipped with a standard 4-48 threaded contact point stem.

Installation Notes

Installation is performed by hand-threading the extension onto the existing contact point stem of the dial indicator. Ensure the indicator is removed from active use and secured before swapping contact point accessories. Avoid over-tightening, which can damage the 4-48 threads on either the extension or the indicator stem. Verify total stylus length does not exceed the indicator manufacturer's recommended extension range, as excessive length can introduce measurement error.