Starrett 53085 Small Hole Gage 0.3 to 0.4 Inch

Product Description

The STARRETT 53085 is a small hole gage designed to measure bore diameters, holes, slots, and grooves in the 0.3 to 0.4 inch range. It uses a half ball contact style that expands to fit the interior of a bore, allowing the technician to transfer the measurement to a micrometer for a precise reading. Overall length is 3.375 inches, making it easy to control in tight quarters. Machinists, tool and die makers, and maintenance technicians use this style of gage when inside micrometers or bore gages are too large for the application.

This gage is suited for measuring small bores in machined components, castings, housings, and valve bodies encountered in HVAC, plumbing, and industrial maintenance work. The compact size and half ball tip allow accurate transfer measurements in locations where access is restricted. At 0.016 pounds, it is light enough to carry in a tech pouch without adding meaningful weight to a tool kit.

Key Features

• Measurement range of 0.3 to 0.4 inch for small bore applications
• Half ball contact style for accurate seating in bores, holes, and slots
• 3.375 inch overall length for use in confined spaces
• Transfer-style measurement pairs with an outside micrometer for final reading
• Lightweight at 0.016 pounds for everyday carry

Compatibility

Designed as a standard small hole gage for use wherever transfer-style bore measurement is required in the 0.3 to 0.4 inch range.

Installation Notes

Small hole gages are hand tools requiring no power source or installation. Expand the half ball contact to light contact with the bore wall, then transfer the set dimension to an outside micrometer to obtain the measurement. Do not over-expand the gage inside the bore, as this can distort the contact and introduce measurement error. Handle with care to preserve calibration accuracy.