Spi 21-128-4 Ball Contact Point Carbide 0.039 in

Product Description

The SPI 21-128-4 is a carbide ball contact point designed for use with Tesa test indicators. It provides a precise, wear-resistant contact surface for accurate measurement work in machinist, quality control, and metrology applications. The ball tip measures 0.039 inches in diameter, and the overall contact point length is 1.437 inches. The carbide construction resists wear during repeated use on hard surfaces, maintaining measurement integrity over time. This contact point is a standard replacement or spare component for technicians and machinists who rely on Tesa indicators for surface runout, bore alignment, and similar precision measurement tasks.

This contact point suits residential shop, manufacturing floor, and quality lab environments where Tesa test indicators are in service. It is appropriate for any application requiring a small-diameter ball tip contact, including checking shaft runout, bore concentricity, and part alignment. Machinists, toolroom technicians, and quality control inspectors are the primary users. The compact ball tip geometry allows access to tight spaces and angled surfaces where flat or pointed contacts are not suitable.

Key Features

• Carbide ball tip for extended wear life on hard workpiece surfaces
• Ball diameter of 0.039 inches for precise, low-contact-force measurement
• Contact point length of 1.437 inches for standard reach applications
• Compatible with Tesa test indicators as a direct-fit replacement
• Sold individually, suitable for single-unit replacement

Compatibility

Designed for use with Tesa test indicators as stated by the manufacturer.

Installation Notes

Installation is performed by machinists or metrology technicians. Before replacing the contact point, remove the indicator from service and secure it in a stable holding fixture to avoid damage. Use the appropriate wrench or driver to avoid stripping the contact point thread. Handle the carbide tip carefully, as carbide is hard but brittle and can chip if dropped on a hard surface.