Author: Haroon Khalil

Slip gauges are used as measuring blocks. It is also called as precision gauge blocks. They are made of hardened alloy steel of rectangular cross-section. The surfaces of slip gauges are made to a high degree of accuracy. The distance between the two opposite faces indicates the size of the gauge. But all slip gauges…

The dial gauge or dial indicator consists of a small clock and a stylus probe as shown in Figure 18.18. Very small pressure on the stylus probe in upward direction results in rotation of pointer, i.e., the linear movement of stylus is converted into angular movement of pointer. Thus, this device is used to measure the…

The spindle of an ordinary metric micrometer has two threads per mm, and thus one complete revolution moves the spindle through a distance of 0.5 mm. The longitudinal line on the frame is graduated with 1 mm divisions and 0.5 mm subdivisions. The thimble has 50 graduations, each being 0.01 mm (one-hundredth of a mm).…

A micrometer is also known as a screw gauge: It consists of a calibrated screw and is used for precise measurement of small length. The first ever micrometric screw was invented by William Gascoigne in the 17th century, as an enhancement of the vernier; it was used in a telescope to measure angular distances between…

The following precautions must be taken in using the vernier calipers:

Vernier calipers are used for more accurate measurement than that of a slide caliper. It can measure internal and external dimensions; it can also be used as a depth gauge and height gauge. Vernier calipers are available with metric and imperial graduations. A sample of vernier caliper is shown in Figure 18.16 with name of different parts. Figure…

Uncertainty of measurement is the doubt that exists about the result of any measurement. You might think that well-made rulers, clocks, and thermometers should be trustworthy and give the right answers. But for every measurement even the most careful, there is always a margin of doubt. In everyday speech, this might be expressed as ‘give…

No measurement is exact. When a quantity is measured, the outcome depends on the measuring system, the measurement procedure, the skill of the operator, the environment, and other effects. Even if the quantity were to be measured several times, in the same way and in the same circumstances, a different measured value would in general…

Suppose the angle of twist on the shaft due to application of torque T is θ, which can be directly read by pointer and scale (Figure 18.15). The value of torque applied is directly related to angle of twist as Figure 18.15 Torque Measurement by Pointer and Scale where L is the length of the shaft; J is polar moment of inertia; and G is…