Spi 10-743-3 Mechanical Hole Micrometer 2.4-2.8 Inch

Product Description

The SPI 10-743-3 is a mechanical hole micrometer designed for precise internal bore measurement across a range of 2.4 to 2.8 inches. It delivers an accuracy of 0.00025 inches with a graduation of 0.0002 inches, making it a reliable tool for close-tolerance inspection work in machine shops, maintenance facilities, and precision manufacturing environments. The three-point contact design with solid carbide measuring anvils provides consistent, repeatable readings. A ratchet stop thimble controls measuring force for uniform contact pressure. This instrument is used by machinists, quality control technicians, and maintenance professionals who require accurate bore measurement without a digital readout.

The 10-743-3 is suited for internal diameter measurement of bores, cylinders, and housings in the 2.4 to 2.8 inch range. The self-aligning and self-centering contact point geometry allows the user to locate true bore diameter without manual adjustment for alignment. With a gage depth of 3.54 inches and a maximum extension rod length of 6 inches, it accommodates a range of bore depths typical in industrial and maintenance applications. It is appropriate for shop-floor use as well as inspection bench work where mechanical readout is preferred over digital instruments.

Key Features

• Measurement range of 2.4 to 2.8 inches with 0.0002 inch graduation
• Accuracy of 0.00025 inches for close-tolerance bore inspection
• Solid carbide measuring anvils for extended wear resistance
• Three-point contact design that is self-aligning and self-centering
• Ratchet stop thimble for consistent, controlled measuring force
• Gage depth of 3.54 inches and maximum extension rod length of 6 inches

Compatibility

Designed as a mechanical hole micrometer for internal bore measurement applications requiring a 2.4 to 2.8 inch measuring range. The 2.8 inch setting ring diameter is consistent with the instrument range.

Installation Notes

This instrument is used by machinists and quality control technicians and does not require permanent installation. Before use, verify the micrometer is set to zero using the appropriate setting ring or master. Keep carbide anvils clean and free of debris prior to measurement. Store in the provided case when not in use to protect the measuring surfaces and maintain calibration integrity.