Starrett 50990 Micrometer Calibration Standard 275mm

Product Description

The STARRETT 50990 is a spherical end micrometer calibration standard designed to verify and maintain the accuracy of outside micrometers in precision measurement applications. Measuring 275mm in length (approximately 10.83 inches), this calibration bar features spherical contact ends that provide repeatable, point-to-point reference measurements. It includes a heat insulating handle, which prevents thermal expansion errors caused by hand heat transfer during use. This standard is an essential bench tool for metrology technicians, quality control inspectors, and precision machinists who rely on certified micrometer accuracy.

This calibration standard is suited for use in machine shops, tool rooms, quality labs, and manufacturing environments where micrometer calibration and verification are part of routine inspection protocols. It is used with outside micrometers to check for zero error, anvil wear, and measurement drift. The heat insulating handle makes it practical for extended calibration sessions without introducing measurement error from body heat.

Key Features

• Spherical ends provide precise, repeatable contact points for micrometer calibration
• 275mm (approximately 10.83 inches) reference length covers a wide calibration range
• Includes heat insulating handle to prevent thermal expansion from hand contact
• Designed for use with outside micrometers in verification and accuracy checks
• Compact and lightweight at 0.5 pounds for easy bench or field use

Compatibility

Designed as an OEM-style calibration reference for use with outside micrometers requiring a 275mm span verification standard.

Installation Notes

Calibration standards are handled and stored by metrology technicians or quality control personnel, not installed in the traditional sense. Always handle the standard by the heat insulating handle to avoid thermal growth that can affect measurement accuracy. Store in the provided case or a clean, dry location away from temperature extremes. Follow your facility calibration procedures and applicable metrology standards when using this bar to verify micrometer accuracy.