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
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TYPES OF CALIPERS Direct reading calipersDial caliper: Simplest form of mechanical caliper Displays a reading directlyElectronic digital caliper: Gives more accurate reading than simple calipers Automatically switchable from english to the matric system
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…………
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” Adjusting nut Anvil Screw threads C frame
MICROMETER(CONTD….) 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.
READING THE MICROMETER•The "1" line on the sleeve isvisible, representing .100“•There are 3 additional linesvisible, each representing .025".025".•The calculation would be 3 x.025" = .075"Line "3" on the thimble coincideswith the reading line on thesleeve,each line representing .001"The calculation would be 3 x .001"= .003“ The micrometer reading is"