Starrett 53087 Small Hole Gage Set 4-piece Half Ball

Product Description

The STARRETT 53087 is a 4-piece small hole gage set designed to measure internal diameters, slots, and grooves in the 0.125 to 0.5 inch range. Each gage features a half-ball end that expands to contact the bore wall, allowing the technician to withdraw the gage and transfer the measurement to a micrometer or caliper for a precise reading. The set covers four sizes with handle lengths of 2-13/16 inches, 3-1/8 inches, 3-3/8 inches, and 3-1/2 inches. The sensitive adjustment mechanism provides fine control during sizing, making the gages suitable for general inspection and layout work in machine shops, maintenance, and trade environments.

Small hole gages from the STARRETT S83 series are used wherever a standard inside micrometer cannot reach a small bore. Typical applications include checking valve guides, bushings, drilled holes, keyways, and similar features on mechanical components. Machinists, tool-and-die workers, maintenance technicians, and trade professionals who perform precision layout or inspection use this style of gage. The set stores in an included protective case, keeping all four pieces organized and protected between uses.

Key Features

• Measurement range of 0.125 to 0.5 inches across the 4-gage set
• Half-ball end style allows contact in tight bores and slots
• Sensitive adjustment mechanism for accurate sizing
• Four handle lengths: 2-13/16, 3-1/8, 3-3/8, and 3-1/2 inches
• Well-balanced design reduces hand fatigue during repeated use
• Includes a protective storage case for all four gages

Compatibility

Designed as a general-purpose small hole gage set suitable for measuring internal diameters, slots, and grooves in metalworking, maintenance, and inspection applications where access is limited to small-bore measuring tools.

Installation Notes

Small hole gages are transfer-measurement tools and do not display a reading directly. After sizing the gage in the bore, withdraw it carefully without disturbing the setting and measure across the ball with an outside micrometer or caliper. Ensure the workpiece is secure and free of burrs before gauging to avoid damaging the ball end. No power source or lockout procedure is required for use of this tool.