Micrometer

• lFunction

lMicrometer allows the measurement of the size of the body i.e. thickness, depth, inner/outer diameter.

• lFeatures

lTwo jaws (one fixed, one movable)
lSpring loaded twisting handle
lEasy to use and more précised
lCan measure up to .001cm

Structure of the Micrometer

 

• lJaws

l2 jaws (one fixed, one movable)

• lCircular Scale

lMovable jaw is attached to a screw, scale on this screw is called Circular scale.

lEither 50 or 100 divisions

• lLinear Scale

lHorizontal Scale

• lFrame

lThe C-shaped body that holds the anvil and sleeve in constant relation to each other.

• lAnvil

lThe jaw which remains stationary.

• lSpindle

lThe jaw which moves towards the anvil.

• lLock Nut

lA lever, one can tighten to hold the spindle stationary.

• lSleeve

lThe stationary round part with the linear scale on it. (Main Scale)

• lThimble

lThimble rotates around the sleeve.

• lRatchet Stop

lDevice on end of handle that limits applied pressure by slipping at a calibrated torque.

Pitch of Micrometer
 

l

When the head of the micrometer rotate through one rotation, called pitch of the micrometer.

lThe screw moves forward or backward 0.5mm on the linear scale.

lPitch of Micrometer = distance on linear scale in one rotation

Pitch of Micrometer = 1/2 = 0.5mm 

 

Least Count

• lLeast Count = Pitch of the Micrometer / Total number of circular scale division

• lLeast Count = 0.5 / 50 = 0.01mm           = 0.001cm