Starrett 53074 Small Hole Gage Set 1/8 to 1/2 Inch 4-piece

Product Description

The STARRETT 53074 is a 4-piece small hole gage set designed to measure internal diameters and hole sizes ranging from 1/8 inch to 1/2 inch. Each gage in the set uses a full-ball contact style, which provides accurate, consistent readings across the measurement range. The gages feature sensitive adjustment mechanisms that allow for fine, controlled expansion inside bores, slots, and grooves. This set is well-suited for general-purpose metrology work in machine shops, maintenance environments, and fabrication settings. A licensed machinist, toolmaker, or maintenance technician typically uses these gages in conjunction with an outside micrometer to transfer and verify measurements.

This set is applicable across a range of trade and industrial environments where precise internal measurement of small bores is required. Typical use cases include checking valve guides, bushings, bearings, and similar small-bore components in HVAC equipment, pumps, motors, and general mechanical assemblies. The four gages cover a graduated range from 1/8 inch to 1/2 inch, providing the right contact size for different bore diameters within that span. Individual gage lengths are 2-7/8 inches, 3 inches, 3-3/8 inches, and 3-1/2 inches. The set ships in an included case for organized storage and transport.

Key Features

• Full-ball contact style for accurate internal diameter transfer measurements
• Sensitive adjustment mechanism for precise, controlled expansion in the bore
• 4-piece set covers 1/8 inch to 1/2 inch measurement range
• Individual gage lengths: 2-7/8 inches, 3 inches, 3-3/8 inches, and 3-1/2 inches
• Designed for general-purpose work with a well-balanced handle profile
• Includes a case for storage and protection

Compatibility

Designed as a general-purpose small hole gage set for use with any standard outside micrometer capable of reading in the 1/8 inch to 1/2 inch range. Part of the STARRETT S82 series.

Installation Notes

Small hole gages are hand tools that require no installation. Expand the ball end inside the bore until light drag is felt, then lock the adjustment and transfer the measurement to an outside micrometer. Avoid overtightening the knurled lock nut, as this can distort the ball and affect accuracy. Store gages in the supplied case when not in use to protect the contact surfaces.