Which measuring instrument is best for measuring the inside diameter of holes?

Which measuring instrument is best for measuring the inside diameter of holes?

• A. Outside micrometer
• B. Vernier caliper
• C. Depth micrometer
• D. Telescoping gauge

Answer: (D)

Measuring inside diameters needs a tool that can be placed inside the bore and span the hole from wall to wall. A telescoping gauge does exactly that: you insert it into the hole, expand the segments until they lightly touch the bore walls, and lock the gauge in place. When you remove it, you measure the gauge’s span with a micrometer or caliper to read the internal diameter. This method works across a range of hole sizes and depths, including hard-to-reach or tight bores, where direct inside measurements with other tools are impractical or less accurate. The other instruments are for outside dimensions, depth, or offer less precise or direct inside measurements, so the telescoping gauge is the best option for this task.

Measuring inside diameters needs a tool that can be placed inside the bore and span the hole from wall to wall. A telescoping gauge does exactly that: you insert it into the hole, expand the segments until they lightly touch the bore walls, and lock the gauge in place. When you remove it, you measure the gauge’s span with a micrometer or caliper to read the internal diameter. This method works across a range of hole sizes and depths, including hard-to-reach or tight bores, where direct inside measurements with other tools are impractical or less accurate. The other instruments are for outside dimensions, depth, or offer less precise or direct inside measurements, so the telescoping gauge is the best option for this task.