Starrett 68021 Outside Micrometer 4 in 0.0001 Grad

Product Description

The STARRETT 68021 is a mechanical outside micrometer designed for high-precision linear measurement of external dimensions. It covers a 0 to 4 inch measurement range with a graduation of 0.0001 inches and an accuracy of 0.000050 inches, making it suitable for exacting inspection and machining verification work. The measuring faces are solid carbide for long-term wear resistance. A friction thimble provides consistent measuring force, and a ring-style lock nut secures the spindle position once a reading is set. Machinists, toolmakers, and precision measurement technicians are the primary users of this instrument.

The STARRETT 68021 is used in machine shops, manufacturing facilities, and tool rooms where close-tolerance part inspection is required. It handles flat-surface external measurements such as shaft diameters, stock thickness, and precision ground components. The flat anvil and 0.2500 inch anvil and spindle diameters suit a wide range of workpiece geometries. The satin chrome finish reduces glare under shop lighting. The micrometer ships with a lock nut and wrench for field adjustments.

Key Features

• 0 to 4 inch measurement range with 0.0001 inch graduation
• Accuracy to 0.000050 inches for tight-tolerance inspection
• Solid carbide measuring faces for extended service life
• Friction thimble ensures repeatable measuring force
• Ring-style lock nut with included wrench for spindle locking
• Satin chrome finish reduces glare in shop environments

Compatibility

Designed as a direct-use mechanical outside micrometer for general external measurement applications; no specific system or equipment compatibility is stated in the product data.

Installation Notes

Outside micrometers require periodic calibration verification against a known standard or gauge block set; confirm the instrument reads zero or the appropriate setting value before taking production measurements. Handle the measuring faces carefully to avoid nicking the solid carbide surfaces. Store the micrometer in its case with a small gap between the anvil and spindle to allow for thermal expansion. Calibration and adjustment should be performed by a qualified metrologist or toolroom technician following the manufacturer's procedure.