1.5.3 Micrometer Screw Gauge

Label of the Parts

Range and Accuracy

  1. The range of a micrometer is 0-25mm.
  2. The accuracy of a micrometer is up to 0.01mm.

How to Use a Micrometer?

  1. Turn the thimble until the object is gripped gently between the anvil and spindle. 
  2. Turn the ratchet knob until a "click" sound is heard. This is to prevent exerting too much pressure on the object measured. 
  3. Take the reading.

How to Read the Reading?

Reading = Reading of main scale + Reading of thimble scale.

Reading of main scale = 0 - 25 mm
Reading of thimble scale = 0 - 0.49mm

Example


(This image is licensed under GDFL. The source file can be obtained from wikipedia.org.)

Reading of main scale = 5.5mm
Reading of thimble scale = 0.28mm

Actual Reading = 5.5mm + 0.28mm = 5.78mm

Precaution Steps

  1. The spindle and anvil are cleaned with a tissue or cloth, so that any dirt present will not be measured. 
  2. The thimble must be tightened until the first click is heard. 
  3. The zero error is recorded.