What procedure would you use to measure a hole about 1/4 inch in diameter?

What procedure would you use to measure a hole about 1/4 inch in diameter?

• A. Cable and ruler
• B. Small hole gauge and micrometer reading of the ball end
• C. Depth gauge and micrometer
• D. Ruler and micrometer

Answer: (B)

To measure a small hole accurately you need a tool that fits inside the bore and a way to read its exact size. A small hole gauge does the fitting work: you insert it and expand it until it just binds in the hole. Once the gauge is set to the hole’s size, you read that size with a micrometer by measuring the gauge’s ball end. The ball end provides a precise contact point for reading the bore dimension, so the resulting number reflects the true diameter of the hole. Ruler-based methods or a combination of ruler with micrometer aren’t precise enough for a quarter-inch bore, and a depth gauge is meant for measuring depth, not diameter. Using a micrometer alone can’t access the interior of the hole to read its size directly, which is why the hole gauge plus micrometer reading is the right approach.

To measure a small hole accurately you need a tool that fits inside the bore and a way to read its exact size. A small hole gauge does the fitting work: you insert it and expand it until it just binds in the hole. Once the gauge is set to the hole’s size, you read that size with a micrometer by measuring the gauge’s ball end. The ball end provides a precise contact point for reading the bore dimension, so the resulting number reflects the true diameter of the hole.

Ruler-based methods or a combination of ruler with micrometer aren’t precise enough for a quarter-inch bore, and a depth gauge is meant for measuring depth, not diameter. Using a micrometer alone can’t access the interior of the hole to read its size directly, which is why the hole gauge plus micrometer reading is the right approach.