Spi 10-746-6 Mechanical Hole Micrometer 4 Inches

Product Description

The SPI 10-746-6 is a mechanical hole micrometer designed for precise internal bore measurement. It features a ratchet stop thimble that delivers consistent measuring pressure, reducing operator-induced error. With a maximum measurement range of 4 inches and an accuracy of 0.00025 inches, this tool is built for dimensional inspection work where tight tolerances matter. The measuring anvils are solid carbide for wear resistance and long service life. It is a three-point contact instrument, which provides self-aligning and self-centering behavior inside the bore, making it well suited for production inspection environments and tool rooms.

This micrometer is used in precision machining shops, maintenance facilities, and quality control departments where internal diameter measurements must meet close tolerances. It is appropriate for measuring bored holes, cylinder bores, bearing housings, and similar features in both production and maintenance contexts. Licensed machinists, metrologists, and skilled trade technicians handling precision measurement work are the typical users of this instrument.

Key Features

• 4 inches maximum measurement range with 0.0002 inches graduation
• Accuracy of 0.00025 inches for tight-tolerance inspection work
• Ratchet stop thimble ensures consistent, repeatable measuring force
• Solid carbide measuring anvils resist wear for extended service life
• Three-point contact design is self-aligning and self-centering in the bore
• Maximum extension rod length of 6 inches for deeper bore access

Compatibility

Designed as a direct-use mechanical hole micrometer for internal bore measurement applications requiring a 4 inches maximum range. No specific OEM replacement compatibility is stated for this instrument.

Installation Notes

Hole micrometers are calibrated instruments and should be handled and stored with care to protect the measuring surfaces. Before use, verify the instrument against a known setting ring or calibration standard appropriate to the measurement range. Do not overtighten the thimble beyond the ratchet stop engagement, as this can affect reading accuracy and damage the anvils. Cleaning the measuring faces before each use removes debris that could affect measurement results.