Spi 10-751-6 Mechanical Hole Micrometer 4 to 5 Inch

Product Description

The SPI 10-751-6 is a mechanical hole micrometer designed for precision internal bore measurement across a 4 to 5 inch range. It delivers a graduation of 0.0002 inches and an accuracy of 0.0004 inches, making it well-suited for tight-tolerance inspection work. The ratchet stop thimble provides consistent measuring force, reducing operator-induced variation during repeated measurements. Solid carbide measuring anvils resist wear and maintain accuracy over extended service life. This instrument is used by machinists, tool and die makers, quality control inspectors, and metrology technicians in precision manufacturing and industrial environments.

The SPI 10-751-6 is applied in settings where accurate internal diameter verification is required, including engine rebuilding shops, aerospace component inspection, hydraulic cylinder measurement, and general precision machining. The three-point contact design is self-aligning and self-centering within the bore, which simplifies technique and improves repeatability. It covers bores from 4 inches through 5 inches, a range commonly encountered in large-bore industrial and heavy-equipment applications.

Key Features

• Measurement range of 4 to 5 inches with 0.0002-inch graduation
• Accuracy rated at 0.0004 inches for tight-tolerance inspection
• Ratchet stop thimble ensures consistent measuring force
• Solid carbide measuring anvils for extended wear resistance
• Three-point contact design is self-aligning and self-centering in the bore
• Gage depth of 5.51 inches accommodates deep bore access

Compatibility

Designed as an OEM-style precision measurement tool for internal bore inspection in applications requiring coverage of the 4 to 5 inch diameter range.

Installation Notes

Installation and use should be performed by qualified machinists or metrology technicians familiar with precision bore measurement procedures. Zero the instrument against a calibrated setting ring before use, and verify calibration at the start of each measurement session. Keep the instrument clean and store it in its protective case to maintain accuracy. Do not force the anvils into a bore — allow the ratchet stop mechanism to apply measuring force.