Spi 21-906-3 Mechanical Hole Micrometer 1.2-1.6 in

Product Description

The SPI 21-906-3 is a mechanical inside hole micrometer designed for precise bore and hole measurement in machining, manufacturing, and metrology applications. It covers a measurement range of 1.2000 to 1.6000 inches with a graduation of 0.0002 inches and an accuracy of 0.0002 inches. The ratchet stop thimble provides consistent measuring force to reduce operator error. Three self-centering carbide contact points ensure repeatable, accurate readings across the bore without requiring manual alignment. This instrument is suited for quality control technicians, machinists, and tool and die professionals working to tight tolerances.

The 21-906-3 is used in precision measurement of bores, holes, and cylinders in manufacturing and inspection environments. It is well-suited for both production floor use and tool room inspection tasks where inside diameter verification is required. The instrument includes one extension rod with a maximum extension rod length of 6.0000 inches and a gage depth of 3.8200 inches, allowing measurement access into deeper bores. A setting ring with a diameter of 1.6000 inches is included for calibration setup before use.

Key Features

• Measurement range of 1.2000 to 1.6000 inches with 0.0002 inch graduation
• Accuracy of 0.0002 inches (0.005 mm)
• Ratchet stop thimble for consistent, repeatable measuring force
• Three self-centering carbide contact points for accurate bore alignment
• Chrome finish for corrosion resistance and durability
• NIST traceability certification included for calibration compliance
• Includes one setting ring and one extension rod

Compatibility

Designed as a standard mechanical hole micrometer for inside diameter measurement in general machining and inspection applications within the 1.2000 to 1.6000 inch range.

Installation Notes

This instrument should be used and stored by qualified metrology or machining personnel following standard measurement practices. Before use, zero and verify the micrometer against the included NIST-traceable setting ring. Keep the carbide contact points clean and free of debris to maintain accuracy. Store in the provided case away from temperature extremes and direct contact with other metal tools to protect the measuring surfaces.