Spi 21-992-3 Test Indicator Ball Contact Point

Product Description

The SPI 21-992-3 is a stainless steel ball contact point designed for use with dial test indicators. It replaces or supplements the standard stylus tip, providing a spherical contact surface that improves accuracy on curved, contoured, or hard-to-reach surfaces. The ball diameter measures 0.078 inches (2.00 mm) and the overall contact point length is 0.61 inches (15.50 mm). Machinists, quality control technicians, and toolroom professionals install this contact point when inspecting bores, slots, or irregular part geometries where a standard pointed tip would deflect or produce inconsistent readings.

This contact point is intended for precision measurement applications in machine shops, manufacturing facilities, and inspection departments. It is specifically listed for use with the SPI Integral Series of test indicators. Typical applications include runout checks, surface parallelism verification, and feature-to-feature measurement on machined components. The stainless steel construction resists corrosion and maintains dimensional stability under normal shop conditions.

Key Features

• Ball diameter of 0.078 inches (2.00 mm) for precise contact on curved and contoured surfaces
• Contact point length of 0.61 inches (15.50 mm) for reach into recessed features
• Stainless steel construction for corrosion resistance and long service life
• Tip diameter of 0.078 inches (2.00 mm) consistent with ball diameter for uniform contact geometry
• Sold as a single replacement point for direct swap installation

Compatibility

Designed for use with the SPI Integral Series of test indicators. Verify thread size and stem fitment against your specific indicator model before installation.

Installation Notes

Contact point replacement is typically performed by a machinist or metrology technician using hand tools. Remove the indicator from service before swapping the contact point to avoid damaging the indicator spindle or altering calibration. After installation, verify indicator calibration against a known reference standard before returning the instrument to production use. Do not overtighten the contact point stem, as excessive force can damage the indicator spindle threads.