The Micrometer - 7: Holding
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WARNING: Machine tools present a safety hazard. Improper operation can result in severe injury. These topics are for non-laboratory study only and are not to be used in conjunction with the operation of any tool or machine described herein. Never use a machine tool without the supervision of a qualified instructor.
The proper way to hold the micrometer when taking a measurement is:
  • Hold the workpiece in the left-hand and the micrometer in the right hand.
  • The frame of the micrometer should be placed in the palm of the hand.
  • The index finger and thumb grips the knurled surface of the thimble
  • The ring finger is inside the frame holding it against the palm or heel of the hand
  • The little finger is curled back behind the frame.

The work is placed in position on the anvil and the thimble is rotated until it clamps slightly between anvil and spindle adjusting the part to assure alignment.

For micrometers not having a friction thimble or rachet, a learned feel must be used to ensure consistent, accurate measurement. The index finger and thumb rotate the thimble until it clamps slightly, the fingers must then slip so no additional clamping will occur.
As you can see, larger micrometers are more difficult to hold and require some rather creative approaches.
Many will ask, "why should I learn to use manual micrometers when everyone now has digital micrometers?".

I don't have a good answer for that. Perhaps you should skip the topic that teaches how to read the old style of micrometers. But the graphics above demonstrate that there are hundreds of shops with an inspection crib that contains thousand of dollars of the old style micrometers in ranges from 1 inch to 80 inches (particularly shops who employ large vertical lathes). I am sure that shop will not throw away that investment and replace them all with digital just because they can. R.S.
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label: micrometer, history, anvil, thimble, spindle, frame, barrel, ratchet, adjustment, holding, handling, reading, vernier