ANGULAR MEASURING INSTRUMENTS
Vernier Bevel Protractor
•The bevel protractor is a type of protractor t h a t is circular and ha s a pivoted
arm used for measuring and marking of angles.
•The basic protractor is most commonly used in school geometry classes for
measuring angles up to 180 degrees.
•The bevel protractor is used when measuring angles up to 360 degrees.
•Bevel protractor ha s a full circular scale t h a t is made up of 360 degrees.
•A bevel protractor ha s also a vernier scale. One vernier is equal to 1/12 of a degree,
which provides a more accurate measurement .
•The vernier scale is divided into 24 increments, with 12 spaces on either side of the
- Used for laying out, checking, and setting up work.
- Beam and blade form a right angle.
- Good quality squares are hardened.
Using Solid Steel Squares.
• Remove all burrs from work surface. Wipe clean.
• Wipe square clean.
• Face source of light.
• Hold work with one hand . Grasp square with other.
• Place inside of square against finished surface,Lower blade to surface of work.
• All light should be excluded.
• Checking inside and outside squareness.
• Drawing lines parallel to edges of work piece.
• Measuring depth.
• Finding centers of round work pieces.
• Checking 450 angles.
A sine bar is used in conjunction with slip gauge blocks for precise angular
measurement. A sine bar is used either to measure an angle very accurately or face
locate any work to a given angle. Sine bars are made from a high chromium
corrosion resistant steel, and is hardened, precision ground, and stabilized.
Two cylinders of equal diameter are placed at the ends of the bar. The axes of these
two cylinders are mutually parallel to each other, and are also parallel to, and at
equal distance from, the upper surface of the sine bar. Accuracy up to 0.01mm/m of
length of the sine bar can be obtained.