Bore Gauge Instructions

Bore gauges are used to measure the inner diameter of bores or holes. Most have to be used in conjunction with a micrometer or caliper and, if measurements are performed correctly, can be as accurate as the tool used to measure the gauge. Other models come equipped with a dial indicator to perform measurements themselves. What ever the type of bore gauge used, all use similar simple principles to obtain dimensional readings.

Things You'll Need

  • Telescopic bore gauge
  • Small hole bore gauge
  • Caliper or micrometer
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Instructions

  1. Telescopic Gauge

    • 1

      Twist the ratchet at the end of the gauge so that the telescopic rods forming the "T" are slightly larger than the opening of the hole being measured.

    • 2

      Place the edges of the "T" at the lip of the hole being measured, at a slight angle.

    • 3

      Slowly straighten the telescopic gauge until the base of the "T" is vertical, with the telescopic anvils touching opposite sides of the hole. Gently rock the gauge in the hole once the gauge is upright. The anvils will compress to match the size of the bore and lock into place.

    • 4

      Remove the telescopic bore gauge from the hole.

    • 5

      Measure the size of the gauge with a caliper or micrometer. This is the size of the bore or hole.

    Small Hole Gauges

    • 6

      Twist the knob at the base of the small hole bore gauge until the head is just smaller than the hole being measured.

    • 7

      Lower the small hole bore gauge into the bore.

    • 8

      Twist the gauge's knob until the anvil touches the side of the hole just enough to feel pressure. Gently rock the gauge inside the hole.

    • 9

      Remove the gauge from the hole.

    • 10

      Measure the size of the gauge with a caliper or micrometer. This is the size of the bore or hole.