Starrett 50974 Micrometer Calibration Standard 75mm

Product Description

The STARRETT 50974 is a spherical end micrometer calibration standard designed to verify and maintain the accuracy of outside micrometers in precision measurement environments. The 75mm length makes it suited for checking micrometer settings in the mid-range of common outside micrometer spans. It ships with a heat insulating handle, which allows the user to hold the standard during calibration without transferring body heat to the gauge bar — a critical detail because thermal expansion in metal standards can introduce measurement error. Calibration standards like this one are standard toolroom and quality-control equipment wherever tight dimensional tolerances are maintained.

This calibration standard is used in toolrooms, machine shops, quality labs, and inspection departments that require traceable micrometer verification. It is appropriate for use with outside micrometers when checking or setting instrument zero. The included heat insulating handle is especially useful in production environments where the standard is handled frequently. Technicians, metrologists, and precision machinists are the primary installers and users of this type of gauge reference standard.

Key Features

• 75mm nominal length provides a mid-range reference for outside micrometer calibration
• Spherical ends ensure repeatable point contact and consistent seating against micrometer anvils
• Includes heat insulating handle to minimize thermal transfer during use
• Compact and lightweight at 0.5 pounds for easy bench and field use

Compatibility

Designed for use with outside micrometers requiring a 75mm calibration reference standard. Consult instrument documentation to confirm the appropriate gauge bar length for the micrometer range being verified.

Installation Notes

This is a precision reference standard, not a mechanical component requiring installation. Store the standard in its case when not in use to protect the gauging surfaces from contamination and damage. Always allow the standard to thermally stabilize to room temperature before use, and handle it by the insulating handle rather than the gauge bar to prevent measurement error from thermal expansion. Periodic recertification of the standard to a traceable reference is recommended to maintain calibration integrity.