Since the spaces, both on the main scale and the Vernier scale, are numbered both to the right and to the left from zero, any angle can be measured. To measure an angle of over 90°, subtract the number of degrees as indicated on the dial from 180°, as the dial is graduated from opposite zero marks to 90° each way. To measure an angle between the beam and the blade of 90° or less, the reading may be obtained directly from the graduation number on the dial indicated by the mark on the swivel plate. When the edges of the beam and blade are parallel, a small mark on the swivel plate coincides with the zero lines on the graduated dial. The bevel protractor consists of a beam, a graduated dial, and a blade that is connected to a swivel plate (with Vernier scale) by a thumb nut and clamp. It reads to 5 arcminutes (5′ or 1/12°) and can measure angles from 0° to 360°.
The bevel protractor is used to establish and test angles to very close tolerances. Universal bevel protractors are also used by toolmakers as they measure angles by mechanical contact they are classed as mechanical protractors.
It has wide application in architectural and mechanical drawing, although its use is decreasing with the availability of modern drawing software or CAD. Sometimes Vernier scales are attached to give more precise readings. What is Bevel Protractor?Ī bevel protractor is a graduated circular protractor with one pivoted arm used for measuring or marking off angles. One common use is in geometry lessons in schools. They are used for a variety of mechanical and engineering-related applications. Some precision protractors further divide degrees into arcminutes. Most protractors are divided into 180 equal parts. Radian-scale protractors measure angles in radians. Most protractors measure angles in degrees (°).
More advanced protractors, such as the bevel protractor, have one or two swinging arms, which can be used to help measure the angle.
A protractor is a measuring instrument, typically made of transparent plastic or glass, for measuring angles.