To accurately measure the diameter of a hole approximately 1/4 inch in diameter, the mechanic would use a

To accurately measure the diameter of a hole approximately 1/4 inch in diameter, the mechanic would use a

• A. Vernier calipers
• B. Small hole gauge and micrometer reading of the ball end
• C. Depth micrometer
• D. Tape measure

Answer: (B)

Internal hole measurement is best done by using a small hole gauge to size the hole, then reading that size with a micrometer on the gauge’s ball end. The ball end makes contact evenly around the hole’s circumference, giving a true diameter. This combination lets you obtain a precise measurement for a relatively small hole like a quarter inch. Other tools aren’t as suitable: a tape measure is far too imprecise, a depth micrometer only measures depth, and vernier calipers struggle to grab accurate, repeatable internal diameters in small holes. Using the small hole gauge with a micrometer readout provides the accuracy needed for engine work.

Internal hole measurement is best done by using a small hole gauge to size the hole, then reading that size with a micrometer on the gauge’s ball end. The ball end makes contact evenly around the hole’s circumference, giving a true diameter. This combination lets you obtain a precise measurement for a relatively small hole like a quarter inch. Other tools aren’t as suitable: a tape measure is far too imprecise, a depth micrometer only measures depth, and vernier calipers struggle to grab accurate, repeatable internal diameters in small holes. Using the small hole gauge with a micrometer readout provides the accuracy needed for engine work.