An ellipse, often called an oval, looks like a compressed circle. Although these geometric shapes are mathematically complex, drawing an ellipse precisely on a 4-by-8 piece of plywood is a fairly simple task. Anyone with the ability to read a ruler and add two numbers together can accomplish this by using a handmade adaptation of the Trammel of Archimedes, constructed from a thin strip of wood.

- Skill level:
- Moderately Easy

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### Things you need

- 4-by-8 plywood sheet
- Measuring tape
- Pencil
- T-square
- Strip of wood, 4.25-feet or longer

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## Instructions

- 1
Determine the major and minor axes of the ellipse. The minor axis is the height and the major axis is the width of the ellipse.

- 2
Draw the minor axis of the ellipse on the plywood. Lay the plywood flat. Find the horizontal centre of the board with measuring tape and mark with pencil. Align the cross of the T-square with a long edge of the plywood and the stem of the T-square with the centre mark. Draw a line along the edge of the T-square the length of the minor axis.

- 3
Draw the major axis of the ellipse on the plywood. Find the centre of the minor axis and mark. Align the cross of the T-square with a short edge of plywood and the stem of the T-square with the mark bisecting the minor axis. Draw a line along the stem of the T-square the length of the major axis. Switch the T-square to the other side if it is not long enough to complete the entire line.

- 4
Construct a simple elliptical trammel, or mechanism to precisely trace the path of an ellipse.(See Reference 3) Divide the major axis in half; make a note of the distance and label it "a." Divide the minor axis in half, make a note of the distance and label it "b." Mark the letter "A" near one end of a thin strip of wood longer than the minor axis of the ellipse. Measure the "b" length from the "A" on the wood strip and mark that point "B." Measure the "a" length from "A" and mark that point "O."

- 5
Trace out the ellipse using the trammel. Place the trammel just to the left of the minor axis of the ellipse. Line "B" up with the major axis and "A" up with the top point of the vertical axis. Move the trammel slightly to the left keeping "O" on the minor axis and "B" on the major axis. Make a mark on the plywood at "A," which traces the outer edge of the ellipse when "B" and "O" are aligned with the major and minor axes, respectively. Continue to move the trammel to the left and mark at "A" until the trammel aligns with the major axis to complete that quadrant of the ellipse Repeat with the other four quadrants, moving from the minor axis at centre out to the sides. Draw a line around the marks to complete drawing an ellipse on plywood.