Starrett 67678 Inside Micrometer 4 Inch Range

Product Description

The STARRETT 67678 is a mechanical inside micrometer designed for precise internal bore and hole measurements in demanding shop and field environments. It covers a measurement range up to 4 inches with a graduation of 0.0003 inches and an accuracy of 0.0002 inches, making it suitable for work where tight tolerances matter. The micrometer uses a ratchet stop thimble for consistent, repeatable gaging pressure and features three self-centering contacts with solid carbide measuring faces for durability and wear resistance. This tool is used by machinists, toolmakers, metrology technicians, and precision trades professionals.

The 67678 is appropriate for measuring internal diameters in bores, cylinders, housings, and similar features in manufacturing, maintenance, and inspection applications. The three-contact design with self-centering contacts ensures true readings without operator-induced tilt error. The maximum extension rod length of 6 inches provides reach flexibility for deeper bores. A setting ring with a 3.25-inch diameter is included for calibration. The tool ships complete with a case, contacts, instructions, setting ring, and wrenches, making it ready for immediate use in a shop or field setting.

Key Features

• Measurement range up to 4 inches with 0.0003-inch graduation and 0.0002-inch accuracy
• Ratchet stop thimble provides consistent gaging pressure for repeatable readings
• Three self-centering contacts eliminate tilt error for true internal measurements
• Solid carbide measuring faces resist wear in high-use environments
• Maximum extension rod length of 6 inches accommodates deeper bore reach
• Includes case, contacts, setting ring, wrenches, and instructions for complete out-of-box readiness

Compatibility

Designed for use as a standalone inside micrometer in bore and internal diameter measurement applications. Compatible with standard extension rod accessories up to 6 inches maximum length.

Installation Notes

This instrument is used by machinists, toolmakers, and precision measurement technicians. Before use, zero and calibrate the micrometer against the included setting ring following the manufacturer instructions. Ensure the workpiece and micrometer are at thermal equilibrium before taking measurements to avoid thermal expansion errors. Handle measuring faces with care and store in the provided case to protect carbide contacts from damage.