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THE CALIPERS
“Calipers are traditionally means of assessing dimensions”
•COMMONLY USED WITH STEEL RULES OR OTHER MEASUREMENT INCREMENTS
•Generally provide a dimensional accuracy of 1/64inch
TYPES OF CALIPERS
Direct reading calipers
Dial caliper: Simplest form of mechanical caliper Displays a reading directly
Electronic digital caliper: Gives more accurate reading than simple
calipers Automatically switchable from english to the
matric system
Dial caliper
Electronic Digital caliper
VERNIER CALIPER A measuring instrument consisting of an L-
shaped frame with a linear scale along its longer arm and an L-shaped sliding attachment with a vernier
used to read directly the dimension of an object represented by the separation between the inner or outer edges of the two shorter arms.
Accuracy up to 1/1000 inch or 0.05mm
They are manufactured for either internal or external measurements
PARTS OF A VERNIER CALIPER: Outside jaws: used to measure external
diameter or width of an object Inside jaws: used to measure internal
diameter of an object Main scale: scale marked every mm Main scale: scale marked in inches and
fractions Vernier gives interpolated measurements to
1/10 mm or better Vernier gives interpolated measurements in
fractions of an inch
PARTS OF VERNIER CALIPER:
Main scale:Each inch on the main scale is subdivided into
10 equal parts & each of these part is again subdivided into quarters…..
Thus each individual graduation on the main scale represents 1/40th of an inch………
Vernier scale: The vernier scale contains 25 subdivisions in
the same total length embraced by the 24 subdivisions on main scale…..thus each individual graduation on the vernier scae represents 1/1000th of an inch…………
READING THE VERNIER CALIPER
VERNIER DEPTH GAGES:
These are used to measure the depths of holes, recesses, slots, counterbores, and so forth
It is essentially a depth rule with vernier attachments and markings
The care should be taken during usage
MICROMETER SCREW GAUGE A device incorporating a calibrated screw
used widely for precise measurement of small distances
Can be used for inside & outside measurements
It is more versatile and accurate of the hand-held measuring device
Can give dimensions accurate upto 0.001 inch
MICROMETER(CONTD………)
The principal of the micrometer is: “A Screw turning in a Nut and end of the
screw advancing towards or receding from the opposite “Anvil “of “C” frame”
Screw threads
Adjusting nutAnvil
C frame
PARTS OF MICROMETER:
The length of the sleeve scale is divided into 10 equal parts of an inch….and each tenth part is again subdivided into 4 equal parts
The micrometer thimble has 25 graduations and each graduation is equal to the 1/1000th of an inch
Rotating the thimble for one line moves the spindle longitudinally 1/25 of .025" or .001" of an inch;Twenty five divisions indicate a complete revolution, .025 or 1/40 of an inch.
MICROMETER(CONTD….)
READING THE MICROMETER
• The "1" line on the sleeve is visible, representing .100“
• There are 3 additional lines visible, each representing .025" .025".
• The calculation would be 3 x .025" = .075"
Line "3" on the thimble coincides with the reading line on thesleeve, each line representing .001"
The calculation would be 3 x .001" = .003“
"
The micrometer reading is
