Micrometer screw gauge, ITI fitter, std 8 t0 12

Micrometer (Screw Gauge) 

Screw gauge or micrometer screw gauge is a measuring instrument used for precision measurement.  

Micrometr : Frame

Frame : Made up of Dropped Forged steel or Malleable Steel. All other parts joint with frame. 

Micrometer (Screw Gauge)  : Anvil

Anvil : Most important parts of Micrometer, which is made up of Alloy steel, hardening, tempering and finishing is done very accurately. 

Micrometer (Screw Gauge) : Spindle

Spindle : Is made up of Nickel Chrome metal, which is also hardened, Grind and accurately made. Which is move to and fro as we rotate thimble. The maximum displacement of spindle is 25 mm.

Micrometer (Screw Gauge) : Measuring Faces

Measuring Faces : Both the end of Anvil and Spindle, Measuring face is fixed, which is made from Alloy steel, as well as hardened, grind and accurately finished. 

Micrometer (Screw Gauge) : Barrel or Sleeve

Barrel or Sleeve : The Barrel or sleeve is connects the frame to the cylindrical tube. It is a non-movable part of the screw gauge and has a scale inscribed over it which is the main scale of the device. Moreover, it also carries the most important part of the micrometer- the screw. 

Micrometer (Screw Gauge) : Thimble

Thimble: The thimble or head is the end of the cylindrical tube and is turned to move and adjust the spindle. The thimble carries the Micrometer or secondary scale. 

Micrometer ( Screw Gauge) : Ratchet

Ratchet : There is one more part called the ratchet which is provided at the end of the tube. The ratchet is kind of limiting device which applies a pressure by slipping at a predetermined torque and thus prevents the spindle from moving further. 

Micrometer (Screw Gauge) : Lock nut

Lock Nut : screw gauges also consist of locking devices which holds the scales at a particular position for prevent any kind of error while taking readings.

Before you use any micrometer you should know the Least count .

Pitch = distance travelled by thimble on linear scale in one rotation.