One complete revolution of the micrometer thimble moves the measurement along the barrel by how many inches?

One complete revolution of the micrometer thimble moves the measurement along the barrel by how many inches?

• A. 0.010 inch
• B. 0.025 inch
• C. 0.050 inch
• D. 0.100 inch

Answer: (B)

A micrometer measures by turning a precision screw. The distance the spindle moves with one full turn is determined by the screw’s pitch. Standard outside micrometers use a screw with 40 threads per inch, so one revolution advances the spindle by 1/40 inch, which equals 0.025 inches. That fixed advance is what the sleeve and thimble scales rely on to build up the measurement. So, a full turn of the thimble moves the reading along the barrel by 0.025 inch.

A micrometer measures by turning a precision screw. The distance the spindle moves with one full turn is determined by the screw’s pitch. Standard outside micrometers use a screw with 40 threads per inch, so one revolution advances the spindle by 1/40 inch, which equals 0.025 inches. That fixed advance is what the sleeve and thimble scales rely on to build up the measurement. So, a full turn of the thimble moves the reading along the barrel by 0.025 inch.