Spi 21-379-3 Horizontal Dial Test Indicator 0.0005 in

Product Description

The SPI 21-379-3 is a horizontal dial test indicator designed for high-precision surface, runout, and alignment measurements in machining, inspection, and metrology applications. It covers a measurement range of 0 to 0.03 inches with a graduation of 0.0005 inches and an accuracy of 0.0005 inches, making it suited for close-tolerance work. The dial reads 0-100-0 on a 1.25-inch black dial with a satin chrome finish. A fully jeweled movement reduces friction and wear, extending service life in repeated-use inspection environments. A NIST traceability certificate is included, supporting quality-system and calibration documentation requirements. Machinists, toolmakers, and quality technicians are the primary users.

This indicator is used in machine shops, tool rooms, and inspection departments for tasks such as part centering, surface plate work, height gage setups, and runout checks on lathes and mills. The horizontal style allows the contact point to approach the workpiece from the side, which is useful when vertical clearance is limited. The universal positioning capability and dovetail mount system support a wide range of fixture and arm setups. Two contact points are included along with dovetail extensions in 5/32-inch and 3/8-inch sizes, a height gage bar, a universal clamp, and a fitted case, making the kit ready for immediate deployment.

Key Features

• Measurement range of 0 to 0.03 inches with 0.0005-inch graduation for fine-tolerance inspection
• Fully jeweled movement for low friction, consistent readings, and extended service life
• Dovetail mount with universal clamp and dovetail extensions for flexible positioning
• 1.25-inch black dial with 0-100-0 reading and satin chrome body finish
• NIST traceability certificate included for calibration and quality-system compliance
• Kit includes two contact points, height gage bar, extensions, universal clamp, and fitted case

Compatibility

Designed for use with standard dovetail-style indicator holders, arms, and height gage attachments common in machine shop and inspection setups. Compatible with 5/32-inch and 3/8-inch dovetail extension systems as included in the kit.

Installation Notes

Mount the indicator using the dovetail clamp on a rigid arm or height gage bar, ensuring the contact point is perpendicular to the measurement surface for accurate readings. Power down or lock out any rotating equipment before positioning the indicator on a spindle or chuck for runout checks. Do not overtighten the dovetail clamp, as excessive clamping force can distort the body and affect calibration. Recalibrate or verify against a known reference after any impact or drop event.