Spi 10-731-8 Mechanical Hole Micrometer 1 Inch Range

Product Description

The SPI 10-731-8 is a mechanical hole micrometer designed for precision inside-diameter measurement up to 1 inch. It uses a three-contact-point design with solid carbide measuring anvils that self-align and self-center in the bore, eliminating operator positioning error. Graduation is 0.0002 inches with an accuracy of 0.0002 inches. The ratchet stop thimble delivers consistent, repeatable measuring force. This tool is suited for machinists, toolroom technicians, and quality-control inspectors working to close tolerances on bored or reamed features.

The 10-731-8 is used in precision machining and inspection environments where accurate bore measurement is required. The 3.15-inch gage depth allows measurement in moderately deep bores, and the design accommodates extension rods up to 6 inches when measuring deeper features. It is appropriate for inspection of cylinder bores, bushings, bearings, and similar precision-bored components in both job shop and production settings.

Key Features

• Three-point contact design with self-aligning and self-centering anvils
• Solid carbide measuring faces for wear resistance and long service life
• Ratchet stop thimble for consistent measuring force and repeatable readings
• Graduation of 0.0002 inches with 0.0002-inch accuracy
• Gage depth of 3.15 inches; maximum extension rod length of 6 inches
• Maximum measurement capacity of 1 inch

Compatibility

Designed as a standalone precision measuring instrument for inside-diameter inspection up to 1 inch. A 1-inch setting ring is specified for calibration setup. No extension rods or additional setting rings are included.

Installation Notes

Hole micrometers are calibrated using a setting ring matched to the nominal bore diameter before use. Calibration and measurement should be performed in a temperature-controlled environment to minimize thermal expansion error. No power tools or fasteners are required; handle the instrument carefully to avoid dropping, which can damage the carbide anvils or alter calibration. Store in the supplied case when not in use to protect the measuring surfaces.