The
bevel protractor is used to establish and test angles to very close tolerances.
It reads to 5 minutes and can be used completely through 360o.
The
bevel protractor consists of a beam, graduated dial and blade which is
connected to swivel plate (with Vernier scale) by thumb nut and clamp.
The
beam sometimes used as Reference to the base or surface.
Before
we take angle measurement, the Protractor & the vernier has to be set to
Zero position
The
blade is adjusted (or) set over the component whose angle is to be measured.
As
the blade angle changes, Vernier scale also rotates with respect to blade angle.
Main Scale remains constant as it has joint with beam or reference.
*For Example
Zero
on the vernier scale has moved 28 whole degrees to the right of the 0 on the
main scale and the 3th line on the vernier scale coincides with a line upon the
main scale as indicated. Multiplying 3 by 5, the product, 15, is the
number of minutes to be added to the whole number of degrees, thus indicating a
setting of 28 degrees and 15 minutes.