inspection and testing the calipers

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

FOR MORE HELP CONTACT ME

Muhammad Umair Bukhari

Engr.umair.bukhari@gmail.com

www.bzuiam.webs.com

03136050151

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