Starrett 53072 Small Hole Gage 0.3 to 0.4 Inch

Product Description

The STARRETT 53072 is a small hole gage designed to measure internal diameters in the 0.3 to 0.4 inch range. It uses a full ball contact style, which provides consistent, reliable contact with the bore wall for accurate transfer measurements. The gage measures 3-3/8 inches in overall length, giving the technician a comfortable grip during use. Machinists, maintenance technicians, and precision tradespeople use this tool when a bore gauge or dial indicator cannot access a tight space. It is used in conjunction with a micrometer to take a final reading after the gage is set to the bore.

This small hole gage is suited for measuring bores, holes, and slots in close-tolerance work across machine shops, maintenance facilities, and manufacturing environments. The 0.3 to 0.4 inch range targets small-diameter features such as valve guides, bushing bores, and similar tight-clearance work where direct micrometer access is not practical. The full ball style is appropriate for through-holes as well as blind holes where the contact geometry needs to seat cleanly against the bore surface.

Key Features

• Full ball contact style for consistent seating in round bores and blind holes
• Measurement range of 0.3 to 0.4 inch for small-diameter applications
• 3-3/8 inch overall length for controlled handling in confined spaces
• Transfer-style measurement pairs with a micrometer for final dimensional reading
• Compact form factor suited to valve guides, bushings, and similar small-bore work

Compatibility

Designed as a standard small hole gage for use in any application requiring internal diameter measurement in the 0.3 to 0.4 inch range, used in combination with an outside micrometer to obtain a final reading.

Installation Notes

This is a hand-held precision measuring tool, not an installed component. No power source, fasteners, or special tooling are required for use. Handle with care to avoid dropping or impacting the ball end, as deformation will affect measurement accuracy. Store in a protective case or roll when not in use to prevent damage to the contact surfaces.