University of North Carolina Manual

Object : - Study of various measuring tools like dial gauge, micrometer, vernier caliper and telescopic gauges. Apparatus Required : - Vernier Callipers, Dial Gauge and Micrometer. Theory : - Measurement is an essential part of dev elopment of technology and as technology becomes more complex the techniques of measurement become more sophisticated. For every kind of quantity measured there mu st be unit to measure it. This will enable the quantity to be measured in nu mber of that unit. If we say that “A” is longer than “B” until and unless we answer how much, our statement is incomplete. We must be able to express this difference in quantitative terms i.e. in terms of numbers. Linear measurement applies to the measurement of lengths , d iameters, height nd thickness, covering both external and internal measurements. The instruments used for linear measurements can be classified 2 groups : - 1. Non precision instruments such as steel rule, caliper etc. 2. Precision instruments such as Vernier calipers, micrometers , slip gauges etc. Vernier alipers Vernier Calipers is a valuable measuring tool that enable us to increase our degree o f precision when measuring the size of objects. Howev er, learning to read callipers can be somewhat confusing, thus requiring a certain amount of practice. Vernier caliper is a measuring device used to me asure precise increments between two points. Vernier calipers can measure internal dimensions (using the uppermost jaws), external dimensions using the lower jaws, and dependin g on the manufacturer, depth measurements b y the use of a probe that is attached to the movable head and slides along the centre of the body. This probe is slender and can get into deep grooves that may prove difficult for other measuring tools. The vernier scales may include both metric and inch measurements on the upper and lower part of the scale. Vernier calipers commonly used in industry provide a precision to a hundredth of a millimetre (10 micrometres), or one thousandth of an inch. A rod extends from the rear of the caliper and can be used to measure the depth.

University of North Carolina Manual

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