The Mitutoyo 526-103 Dial Bore Gauge for Extra Small Holes has a measurement range of 0.3 to 0.4" and is accurate to + or - 0.00016". It uses a split ball design to measure the inside diameter of holes and identify out-of-roundness problems with stainless steel contact points for high wear resistance. The gauge stem diameter is 0.375" and the probe depth is 2.2". This gauge is for use with Mitutoyo dial indicators (sold separately).

Bore gauges measure holes, or bores, in a workpiece. They can measure the interior diameter of a hole at any depth, while internal micrometers can only measure to the depth of their teeth. Bore gauges are typically calibrated with a setting ring and come in two types: simple and direct-measuring. Simple bore gauges are used with a caliper to transfer the hole measurement, while the more complex gauges take the measurement directly, and display it through a vernier, dial, or digital display. Bore gauges have a two- or three-point contact, indicating how many points on the gauge head touch the inside of the bore. Two-point contacts are better at measuring ovality, while three-point contacts are used to measure lobing or triangular form error. Pistol-grip bore gauges are used for fast, single-handed operation with repeatable results from one operator to another. Bore gauges can also be used in special applications, such as measuring threads, spline pitch diameters, and deep bores.

Mitutoyo manufactures precision measuring tools, metrology equipment, and related systems. The company, founded in Tokyo in 1934, formed Mitutoyo America Corporation in 1963 with headquarters in Aurora, IL.

What's in the Box?

• Mitutoyo bore gauge 526-103
• (6) anvils
• 2.2" needle