Spi 21-531-9 Vertical Dial Test Indicator Nist Calibrated

Product Description

The SPI 21-531-9 is a vertical dial test indicator designed for precision dimensional measurement in machining, inspection, and quality control applications. It covers a measurement range of 0 to 0.06 inches with a dial graduation of 0.0005 inches and a stated accuracy of 0.0012 inches. The jeweled movement reduces friction and wear for consistent, repeatable readings over extended use. A revolution counter and rotating dial allow the technician to track multiple passes without losing position. A short-form certificate of calibration with NIST traceability is included, making this indicator ready for use in documented quality processes without additional calibration steps.

This indicator is suited for surface plate work, lathe and mill setup, fixture alignment, and incoming inspection tasks in both production and job-shop environments. The dovetail mount is a standard attachment style compatible with common indicator holders and magnetic-base arms used in machine shop and inspection room setups. The 0-15-0 balanced dial reading simplifies bidirectional measurement. The contact point has a swivel range of 210 degrees, allowing the tip to be positioned in tight clearances or at angles not accessible to a standard plunger-style indicator.

Key Features

• 0 to 0.06 inch measurement range with 0.0005 inch graduations for fine-resolution readings
• Jeweled bearing movement for reduced friction and extended service life
• 0-15-0 balanced dial with automatic reversal for bidirectional measurement
• 210-degree contact point swivel angle for access in confined or angled setups
• Rotating dial and revolution counter for multi-pass tracking
• NIST-traceable short-form calibration certificate included

Compatibility

Designed for use with standard dovetail-style indicator holders, magnetic bases, and articulating arms commonly found in machine shop and inspection room setups.

Installation Notes

This indicator is typically mounted and adjusted by machinists, toolmakers, or quality control technicians. Secure the dovetail shank firmly in the holder before zeroing the dial to prevent drift during measurement. Avoid side-loading the contact point beyond its rated swivel range, as this can affect accuracy and damage the jeweled movement. Handle the instrument carefully and store it protected from impact when not in use.