Which measuring instrument uses a sleeve and a thimble for precise dimensions?

Which measuring instrument uses a sleeve and a thimble for precise dimensions?

• A. Vernier caliper
• B. Micrometer
• C. Ruler
• D. Tape measure

Answer: (B)

Precise small-dimension measurements rely on a micrometer, which uses a sleeve and a thimble to achieve fine resolution. The sleeve holds a fixed linear scale, while the thimble rotates to move the spindle in tiny, controlled amounts. To read the measurement, you note the value on the sleeve for the larger portion and the value on the thimble for the finer portion, then combine them for the final reading. This setup provides very high precision—often to 0.01 mm or 0.001 inch—making it ideal for small parts where tight tolerances matter. A vernier caliper uses a main scale and a sliding vernier scale rather than a thimble, so it offers good but not this level of precision. A ruler gives only basic markings, and a tape measure is designed for longer, flexible measurements and lacks the micrometer’s mechanism.

Precise small-dimension measurements rely on a micrometer, which uses a sleeve and a thimble to achieve fine resolution. The sleeve holds a fixed linear scale, while the thimble rotates to move the spindle in tiny, controlled amounts. To read the measurement, you note the value on the sleeve for the larger portion and the value on the thimble for the finer portion, then combine them for the final reading. This setup provides very high precision—often to 0.01 mm or 0.001 inch—making it ideal for small parts where tight tolerances matter.

A vernier caliper uses a main scale and a sliding vernier scale rather than a thimble, so it offers good but not this level of precision. A ruler gives only basic markings, and a tape measure is designed for longer, flexible measurements and lacks the micrometer’s mechanism.