Spi 21-378-5 Dial Test Indicator 0.03 in Horizontal

Product Description

The SPI 21-378-5 is a horizontal-style dial test indicator designed for precise surface and feature measurement in machine shop, metrology, and quality control environments. It measures up to 0.03 inches of travel with a graduation of 0.0005 inches, giving technicians and machinists resolution suitable for tight-tolerance inspection work. The fully jeweled movement reduces friction for repeatable, accurate readings, and the satin chrome finish resists corrosion in shop environments. The 1.25-inch white dial face provides clear contrast for reading, and the 0-15-0 bidirectional scale allows deflection measurement in either direction from zero. Licensed metrology professionals and precision machinists are the primary users.

This indicator is suited for use on surface plates, height gages, and machine tool setups where a low-profile horizontal indicator is required. The dovetail mount and included 5/32-inch and 3/8-inch dovetail extensions provide universal positioning capability, making it adaptable to a wide range of fixture and arm configurations. The kit ships complete with two contact points, a universal clamp, a height gage bar, and a fitted case for storage and transport. NIST-traceable calibration is included, which satisfies most quality system and inspection record requirements.

Key Features

• Fully jeweled movement for low-friction, repeatable measurement
• 0.0005 inch graduation with 0.03 inch total range per revolution
• 0-15-0 bidirectional dial scale reads deflection in both directions
• Dovetail mount with universal positioning capability
• Satin chrome finish for corrosion resistance in shop use
• NIST-traceable short-form certificate of calibration included
• Complete kit includes contact points, extensions, clamp, height gage bar, and fitted case

Compatibility

Designed for use with standard 5/32-inch and 3/8-inch dovetail indicator holders, arms, and height gage attachments common in precision measurement and machine shop applications.

Installation Notes

Mount the indicator using the included dovetail extensions and universal clamp, ensuring the spindle axis is aligned with the direction of measurement for accurate readings. Avoid side-loading the contact point, as lateral force can affect accuracy and jeweled bearing life. The contact point should be pre-loaded lightly against the workpiece before zeroing the dial. Handle the fitted case and calibration certificate carefully, as NIST traceability documentation may be required for inspection records.