Spi 21-999-8 Test Indicator Ball Contact Point

Product Description

The SPI 21-999-8 is a ball-style contact point designed for use with dial test indicators in precision measurement applications. The stainless steel ball tip measures 0.118 inches (3.00 mm) in diameter, and the overall contact point length is 0.66 inches (16.80 mm). This replacement contact point threads into the indicator stylus stem and provides a stable, low-friction contact surface for measuring runout, surface variation, and bore alignment. It is a standard consumable component for metrology tools used by machinists, calibration technicians, and precision measurement professionals in shop and lab environments.

This contact point is designed for use with the SPI Integral Series of dial test indicators. It suits applications requiring a small-diameter ball tip for accessing tight bores, slots, or contoured surfaces where a flat or chisel-style contact point would not seat properly. Typical uses include machine tool setup, workpiece inspection, and fixture verification on manual or CNC equipment.

Key Features

• Ball diameter of 0.118 inches (3.00 mm) for access to small or contoured contact surfaces
• Contact point length of 0.66 inches (16.80 mm) for standard reach applications
• Stainless steel construction for corrosion resistance and wear durability
• Designed as a direct-fit replacement for SPI Integral Series test indicators
• Sold individually for single-point replacement without excess inventory

Compatibility

Designed for use with the SPI Integral Series dial test indicators.

Installation Notes

Contact point replacement is performed by a machinist or calibration technician and requires no special tooling beyond a small wrench or fingers to thread the contact point into the indicator stylus stem. Power-down and lockout procedures do not apply to manual measurement instruments, but the indicator should be zeroed and verified against a known reference surface after any contact point change. Avoid overtightening the contact point, as the stylus stem threads are fine and can be damaged by excessive torque.