C. Micrometers
C. Micrometers
A micrometer is another tool for measuring distance. Micrometers are capable of measurements that are even more precise than vernier callipers. The micrometer shown below can measure to the nearest 0.01 mm. Some micrometers include a vernier scale and can measure to the nearest 0.001 mm!
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Micrometer
A device for measuring small objects precisely. |
On a micrometer, the thimble and the sleeve are connected by a screw. Each rotation of the thimble will move the spindle 0.5 mm relative to the anvil. To use the micrometer, place the object of interest against the anvil and turn the thimble until the spindle reaches the object. The ratchet knob can be used to turn the thimble, and the ratchet knob will slip once a certain pressure is reached. This allows you to apply the same pressure between the spindle and anvil for every measurement taken.
Once the anvil and spindle are pressed against the object, you can read the measurement. There are 50 increments listed on the thimble and each rotation of the thimble moves the spindle 0.5 mm, so each increment on the thimble represents 0.01 mm.
In the diagram below, you can see that the measurement will be slightly over 3 mm because the 3 mm tick is the last one showing. The 31 on the thimble aligns with the line on the sleeve, so the measurement is 0.31 mm past 3 mm. This means the measurement is 3 + 0.31 = 3.31 mm.
In the following diagram, the last value showing on the sleeve is 10.5 and the thimble reading is 18. This means the measurement is 10.5 + 0.18 = 10.68 mm.
