Protractors and Angle Gages Information
How to Select Protractors and Angle Gages
Protractors and angle gages measure the angle between two surfaces of a part or assembly.
Types of Protractors and Angle Gages
A wide variety of protractors and angle gages are available that vary in construction and application.
- Angle squares consist of a square with angular graduations along the longest face or hypotenuse.
- Rule depths or angle gages are a combination rule with an attachment for indicating the depth orientation of the hole with respect to the top surface.
- Combination squares measure length, center, angular, or squareness determination, and have transfer or marking capabilities. These multiple tasks are possible because these sets have a series of optional heads (square, center, or protractor).
- Fixed angle gages have a series of fixed angles for comparative assessment of the angle between two surfaces.
- Protractor heads are an attachment or an optional part of a combination square set. The protractor head slides onto the steel rule and provides a tool for angular measurement or transfer. Rectangular or semicircular head protractors have long, thin, unruled blades and heads with direct reading angular graduations.
- Sine bars, blocks, tables, or plates are used for precision angular measurement and are used in machine shops, tool rooms, or inspection labs. Trigonometric calculations are used to determine the angles.
- Universal bevels, sliding bevels, combination bevels, or T-bevels are used to transfer or duplicate angle measurements. Usually, bevels do not have any graduations. Universal or bevel protractors have a base arm and blade with a wide angular range. Bevel protractors have a graduated, angular, direct reading, or Vernier scale located on a large disc.
Important Selection Properties
When selecting protractors and angle gages, the user must consider the application for which the tool is being used. Angular range, angular resolution, and material type are all important specifications to consider. Special features can also be incorporated in some protractors and angle gages to provide suitability and convenience for specific applications.