Compasses and Protractors

A compass (or pair of compasses):a technical drawing instrument that can be used for inscribing circles or arcs.

Compass

Yes, there is another form of a compass which used for navigational purposes

O An instrument with two arms, one sharp and one with a pencil that can be used to draw circles or arcs.

Circles can be made by fastening one leg of the compasses into the paper with the spike, putting the pencil on the paper, and moving the pencil around while keeping the hinge on the same angle.

The radius of the circle can be adjusted by changing the angle of the hinge.

Here is an example of a 30 degree angle:

Types and CostStudent Beam Compass$30-$40

Scribe Compass$15-$95

Loose Leg Wing $1 - $85 (dependent upon material)

Many Useso Draftingo Mathematicso Finding radiuso Duplicating

circleso Arcso Finding midpointo Segmenting

Safetyo These instruments were once a larger safety problem in

the class

o One end held the pen/pencil and the other was an

extremely sharp point

o Improvements have been made to decrease injuries and

increase safety

Definition of Protractor Protractor is a tool used to measure angles.

More about ProtractorSome of the protractors are half circle protractors to measure angles up to 180° and some of them are full circle protractors to measure angles up to 360°.

Protractor

Common Types Used

Types and CostPrintableFREE

Bevel Protractor $40.00 - $380.00

Plastic Protractors$1 - $85 Most Common

Paper

SAFETY

• Throwing• Sliding• Bending• Breaking

Diversity• Break angles

in groups• See handout