Spi 21-994-9 Test Indicator Ball Contact Point

Product Description

The SPI 21-994-9 is a ball-style contact point designed for use with test indicators in precision measurement applications. The contact tip features a 0.039-inch (1.00 mm) ball diameter and a contact point length of 0.59 inches (approximately 16.30 mm). Constructed from stainless steel, the tip resists corrosion and wear under repeated contact cycles. This contact point threads onto compatible test indicator spindles and is the correct choice when measuring curved surfaces, grooves, or bores where a ball tip provides more accurate and repeatable contact than a flat or conical tip. Machinists, quality control technicians, and toolroom professionals install this type of accessory as part of routine indicator setup.

The 21-994-9 is suited for use in machine shops, toolrooms, and quality inspection environments where SPI test indicators are in service. It is appropriate for both bench-mounted and surface-plate inspection work, as well as for in-machine measurements on mills and lathes. The small ball diameter allows contact in tight features and on small-radius curved surfaces. This contact point is a direct replacement or spare for setups that require a standard 1.00 mm ball tip.

Key Features

• Ball diameter of 0.039 inches (1.00 mm) for contact on small curved and recessed surfaces
• Contact point length of 0.59 inches (16.30 mm) for reach into confined measurement areas
• Stainless steel construction for corrosion resistance and long service life
• Compatible with SPI Integral Series test indicators
• Sold individually — package quantity of 1

Compatibility

Designed for use with SPI Integral Series test indicators.

Installation Notes

Contact points are installed by threading them onto the indicator spindle — ensure the indicator is removed from any active measuring setup before changing tips. Use the appropriate small wrench or the tool supplied with the indicator to avoid overtightening, which can damage the spindle threads. Handle the ball tip carefully to avoid nicks or surface damage that would affect measurement accuracy.