Cylinder Bore Gauge Instructions

Brad Chacos

While the most common use for cylinder bore gauges is to check the size of an engine cylinder, home-remodeling enthusiasts can also use these gauges to quickly get an extremely accurate measurement for holes or bores in any material with depth.

A locked micrometer can be used in place of a calibration ring.

Bore gauges come in a wide variety of different makes and models. Telescopic bore gauges use compressing heads to make measurements, while small-hole bore gauges use an expanding head to fit the hole's diameter. Dial bore gauges function like telescopic gauges, but they have an attached dial indicator. Modern cylinder bore gauges employ electronic screens that instantly display measurement results.

  1. Select an anvil slightly larger than the diameter of the hole being measured. Screw it into the measuring stud. The finished anvil-and-stud configuration should be just long enough to fit snugly inside the hole diameter.

  2. Power-on the electric bore gauge.

  3. Select a master ring of the same approximate size as the hole being measured. Input the ring's size value in the bore gauge, using instructions provided with the tool. If there are no master rings available, you can use a micrometer that is locked to a set value.

  4. Slide the bore gauge's anvil and stud into the calibration ring or locked micrometer.

  5. Calibrate the bore gauge against the calibration ring or micrometer by pressing a "Zero," "Min" or "Cal" button, depending on the model being used. You may have to perform a simple calibration function.

  6. The distance across the calibration ring or micrometer faces should flash on the electric display when calibration is complete.

  7. If you get an inaccurate reading the first time, repeat the calibration step.

  8. Insert the bore gauge into the hole being measured.

  9. Press the same button you used earlier to initiate calibration.

  10. Rock the bore gauge up and down gently in the hole. The diameter of the hole will display on the electric screen.