How much does the micrometer thimble advance the spindle in one complete turn?

How much does the micrometer thimble advance the spindle in one complete turn?

• A. 0.025 in
• B. 0.1 in
• C. 0.005 in
• D. 0.001 in

Answer: (A)

The key idea is the screw pitch: how far the spindle moves for one full turn of the micrometer’s screw. In a standard imperial micrometer, the screw has 40 threads per inch, so one complete turn moves the spindle 1/40 inch. That equals 0.025 inches. So the spindle advances 0.025 inches with a full turn of the thimble. The other values would imply a different pitch or represent just the finer divisions used for reading, not the total travel per full turn.

The key idea is the screw pitch: how far the spindle moves for one full turn of the micrometer’s screw. In a standard imperial micrometer, the screw has 40 threads per inch, so one complete turn moves the spindle 1/40 inch. That equals 0.025 inches. So the spindle advances 0.025 inches with a full turn of the thimble. The other values would imply a different pitch or represent just the finer divisions used for reading, not the total travel per full turn.