What measuring tool is used for measuring rounded or circular features?

The fillet-and-radius gage is specifically designed to measure rounded or circular features, making it the most suitable tool for this purpose. This type of gage has various notches and radii that correspond to specific sizes, allowing for direct comparison with the rounded features being measured. By using the gage, one can easily determine the radius of fillets, rounds, and similar features on a workpiece, ensuring accurate measurements for quality control in machining and fabrication.

While calipers and micrometers are versatile measuring tools, they are not specifically designed for measuring rounded features. Calipers can measure external and internal dimensions as well as depths, but they require careful placement to accurately assess curves or radii. Micrometers are primarily used for precise measurement of thickness or diameter, which may not adequately capture the specifications of a rounded feature without specialized attachments. Depth gages are intended for measuring the depth of holes or recesses and do not apply to assessing rounded shapes. Therefore, the fillet-and-radius gage is the optimal choice for accurately measuring rounded or circular features.