Category: Mechanical Measurement

Combination set is a measuring tool which is frequently used in fitting and machine shop. It consists of a square head, centre-head, bevel protector, sprit level, and graduated steel rule. Therefore, it is known as combination set as shown in Figure 18.22. The square head having two edges at 90° and 45° with steel rule can slide…

A sine bar is a tool used to measure angles of a block. It consists of a hardened steel body with two precision ground cylinders fixed at the ends. The distance between the centres of the cylinders is precisely controlled, and the top of the bar is parallel to a line through the centres of…

Slip gauges are classified into various types according to their use as follows: (a) Grade 2, (b) Grade 1, (c) Grade 0, (d) Grade 00, and (e) Calibration grade.

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…