Protractors and angle gages measure the angle between two surfaces of a part or assembly.  Fixed angle gages, universal protractors, combination sets, protractor heads, sine bars, and "T" bevels are used for angular measurement.  Protractors and angle gages fall under the category of measuring tools.  Measuring tools are instruments and fixed gages that provide comparative and quantitative measurements of a product or component's dimensional, form and orientation attributes such as length, thickness, level, plumbness and squareness.  Measuring or shop tools include rules, linear scales, protractors and angle gages, level and inclinometers, squares and fixed gages.  Measuring tools are used in construction and building (contractors), drafting and drawing (designers), machine shops and tool rooms (machinists), field work (surveyors) and offices.

Types of protractors and angle gages available include angle square, rule depth or angle gage, combination set or square, fixed angle gage, protractor head, rectangular or semicircular head protractor, sine bar or block or plate, universal or sliding bevel, and universal or bevel protractor.  An angle square consists of a square with angular graduations along the longest face or hypotenuse.  A rule depth or angle gage is 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 capability.  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 a 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.  Protractors and angle gages can be level sensing or inclinometers.  Mechanical or electronic tools that indicate or measure the inclination of a surface relative to the earth's surface usually in reference to horizontal (level), vertical (plumb) or both axis.

Protractors and angle gages measure the angle between two surfaces of a part or assembly.  Fixed angle gages, universal protractors, combination sets, protractor heads, sine bars, and "T" bevels are used for angular measurement.  Protractors and angle gages fall under the category of measuring tools.  Measuring tools are instruments and fixed gages that provide comparative and quantitative measurements of a product or component's dimensional, form and orientation attributes such as length, thickness, level, plumbness and squareness.  Measuring or shop tools include rules, linear scales, protractors and angle gages, level and inclinometers, squares and fixed gages.  Measuring tools are used in construction and building (contractors), drafting and drawing (designers), machine shops and tool rooms (machinists), field work (surveyors) and offices.

Types of protractors and angle gages available include angle square, rule depth or angle gage, combination set or square, fixed angle gage, protractor head, rectangular or semicircular head protractor, sine bar or block or plate, universal or sliding bevel, and universal or bevel protractor.  An angle square consists of a square with angular graduations along the longest face or hypotenuse.  A rule depth or angle gage is 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 capability.  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 a 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.  Protractors and angle gages can be level sensing or inclinometers.  Mechanical or electronic tools that indicate or measure the inclination of a surface relative to the earth's surface usually in reference to horizontal (level), vertical (plumb) or both axis.

Important specifications to consider when searching for protractors and angle gages include angular range and angular resolution.  There are many choices for scales or displays on protractors and angle gages.  These include none or non-graduated, audible indicator or buzzer, column or bar graph, dial, digital display, direct reading scale, remote display, and Vernier scale.  Features for protractors and angle gages include machine or instrument mounted, certificate of calibration, locking feature, marking capability, and linear ruled protractor.  Common materials of construction for protractors and angle gages include aluminum, brass or bronze, cast metal or iron, plastic, fiberglass, glass, granite, stainless steel, steel, and wood.