Geo Shapes

 

How to draw a star, pentagon, hexagon, octagon and equilateral triangle.


Many times when drawing a plan for a project it is necessary to create a geometric shape. This page covers the four most common, a star, pentagon, hexigon, octagon and triangle. The angles to set a miter saw are also included with each figure.

 

Angles On Your Saw

The scales on your table saw and miter saw can be a bit confusing, this is because they tell you how far from square or 90 degrees the cut is from the edge of the board against the fence, not the actual angle you are cutting. The zero mark tells you that there will be no variation, the cut will be square. At 5 degrees the cut will be 5 degrees off square, the actual angle measured with a protractor will be 95 or 85 depending which side is measured.

To calculate the angle to set your saw for a multi-sided item divide 180 by the number of sides and set your scale to that value.

To Draw a Star

star layout

Draw a circle with a compass that the required star will fit into, then draw perpendicular diameters, mark midpoint F.

Set compass to CF and with point at F mark off G.

Set compass length CG and starting at C strike four arcs around circumference.

Connect every second point.

To Draw a Pentagon

To draw a pentagon follow above but connect every point around circumference of circle.

 pentagon

Set miter saw at 36 degrees

To Draw a Hexagon

hexagon

Set compass to radius of circle AB

Strike five arcs around cirfumference starting at A, connect arcs.

Each side of a hexagon is equal to the radius of the circle it fits into.

Set miter saw at 30 degrees.

To Draw an Octagon

octagon

Draw a square equal to the distance across the flats of required octagon.

Draw lines from corner to corner to determine center of square.

Set compass distance from corner to midpoint, draw arcs to intersect adjecent sides.

Repeat on all corners,

Connect arcs across corners.

Set miter saw for 22.5 degrees.

Equalateral Triangle

triangle

Set compass to length of one side, AB.

Draw arcs from A and B to intercect at C

Connect AC and BC.

Set miter saw at 30 degrees.

* 30 degree butt joint suggested because 60 degree miter is past the limit of the scale and is a difficult cut to make.