Module-7 Universal Bevel Protractor Review Questions Solved

1. Name the parts of a universal bevel protractor and state the purpose of each.

The dial/Main scale: The main scale is graduated into four 90-degree components. The main scale is numbered to read from 0 to 90 degrees and then back from 90 degrees to 0 The vernier scale: The vernier scale of the bevel protractor allows the tool to divide each degree into smaller increments. The vernier scale is divided into 24 spaces, 12 spaces on either side of the zero. Blade: Touch the surface to be measured with the combination of Base. Clamp: To tightened the dial with vernier scale. Acute angle attachment If an angle is less than 90 degrees, it is known as an acute angle. This attachment is used to measure acute angle.

2. Describe the principle of the vernier protractor. This type of protractor can be accurately read to 5 minutes or 1/12° (Fig. 1).Any size angle can be measured. It should be remembered that the vernier reading must be read in the same direction from zero as the protractors, either right or left.

3. Sketch a vernier protractor reading of:

a. 34°20'

b. 17°45' Sine Bar.

4. Describe the construction and principle of a sine bar. The sine bar is a precision instrument for measuring angles and locating work at a desired angle to some other surface or line. The bar is made of hardened steel with two cylinders of equal diameter attached near the ends. The center distance between these cylinders is usually 5″, 10″ or 20″.