What is Radius Gauge?
Dec 13, 2025
Deepak Choudhary
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During the early period, there were no standard units for measuring thickness, which led to the invention of gauges.
The word gauge is derived from the French word “jauge”, which means the result of a measurement.
Gauges are commonly used to measure the thickness, size, or capacity of an object.
Similarly, radius gauges are instruments used to measure the radius of an object. The radius gauge is often associated with another gauge known as the fillet gauge, where a fillet in mechanics refers to the rounding of a part’s design.
A radius gauge is primarily used to measure internal radii, whereas external radii are measured using a fillet gauge.
The construction of a radius gauge consists of two gauge sets containing multiple steel strips or blades, which are screwed together in a single holder. The screw used to secure the blades is known as the lock screw.
Radius measurements are generally in metric units, measured in millimetres (mm).
The gauge is typically made entirely of stainless steel. In some cases, a satin chrome finish is added to improve corrosion resistance and prevent rust.
The blades are manufactured in both concave and convex shapes. These blades can be swung out from the holder when measurements are required. The measurement markings are engraved on the upper surface of each individual blade.
Types of Radius Gauge
Three standard sets of radius gauges are commonly manufactured:
Set 1: Measures radii from 0.6 to 0.8 mm
Set 2: Measures radii from 1 to 7 mm
Set 3: Measures radii from 3 to 8.25 mm
To measure a radius, the workpiece is taken and the blades are inserted one by one until a blade fits perfectly with the radius of the object.
Specifications of Radius Gauge
A radius gauge is lightweight and compact in design. With advancements in technology, more precise and advanced instruments have been developed, such as the digital radius gauge. Digital radius gauges provide higher accuracy and precision. They are user-friendly, portable, and allow fast measurements due to their digital display.
Construction of Digital Radius Gauge
The construction of a digital radius gauge is entirely different from that of a conventional radius gauge. It consists of a digital display screen for reading values, a measuring head, and a set of brackets or jaws of various sizes, typically ranging from 5 to 100 mm.
The digital display, measuring head, and jaws are integrated to perform measurements effectively. It is important to note that simple radius gauges are generally used for measuring small radii, while digital radius gauges are preferred for measuring larger radii with higher accuracy.
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