Starrett 53073 Small Hole Gage 0.4 to 0.5 Inch Full Ball

Product Description

The STARRETT 53073 is a small hole gage designed for accurate inside-diameter measurement in tight spaces. With a measurement range of 0.4 to 0.5 inches and a full ball contact style, it transfers bore dimensions directly to an outside micrometer for a precise reading. Overall length is 3.5 inches, making it easy to maneuver in shallow or restricted bores. Machinists, tool-and-die workers, and precision mechanics rely on this type of gage when calipers cannot reach or when bore finish demands a non-marring full ball contact surface.

The 53073 is suited for inspecting small bores, holes, and internal grooves in production and maintenance environments. It works in any application where a technician needs to transfer an inside measurement to a micrometer — including engine rebuilding, hydraulic component service, pump bore inspection, and precision machining setups. The full ball style distributes contact evenly across the bore wall, reducing the risk of measurement error from tool tilt.

Key Features

• Measurement range: 0.4 to 0.5 inches
• Full ball contact style for even bore-wall contact and consistent readings
• 3.5 inch overall length for access in shallow bores
• Transfers inside dimensions to an outside micrometer for a precise reading
• Compact and lightweight at 0.016 pounds for one-handed use

Compatibility

Designed as a standard small hole gage for use with any outside micrometer covering the 0.4 to 0.5 inch range in precision machining, maintenance, and inspection applications.

Installation Notes

Small hole gages require no installation. Insert the ball end into the bore, expand the gage until light drag is felt against the bore wall, then lock the knurl and withdraw carefully. Transfer the set dimension to a calibrated outside micrometer immediately. Avoid over-expanding the gage inside the bore, as this can spring the ball and introduce measurement error.