Bore Gages

Bore gages are precision instruments designed to measure the internal diameter of holes, bores, cylinders, and other circular features. Unlike external measurement tools, bore gages use a contact-based method to assess diameter, roundness, and taper from inside the workpiece. They are indispensable in high-precision manufacturing where bore tolerances are measured in microns and direct comparison to a master ring gauge is required.

Common types include dial bore gages, digital bore gages, small bore gages, and telescoping gages. Digital models with USB or Digimatic output allow integration with SPC systems for real-time process monitoring. Extension rods extend the measurement reach into deep bores and long cylinders, making them versatile for engine blocks, hydraulic cylinders, and gearbox housings.

Typical Applications

Engine cylinder bore measurement and honing verification in automotive manufacturing
Inspection of hydraulic and pneumatic cylinder bores in industrial machinery
Verification of bearing housing and bore diameters in precision assembly
In-process and final inspection of machined bores to tight ISO tolerances
Roundness and taper assessment in metrology and calibration laboratories

Popular Brands

Mitutoyo offers one of the widest bore gage ranges available, including the 368-series dial bore gages and 209-series digital bore gages with Digimatic output. Starrett, Fowler, and Mahr also supply bore measurement solutions trusted in automotive, aerospace, and precision engineering industries.