The basic uniform noncircular curves are the ellipse, the parabola, and the hyperbola. These curves are derived from conic sections as shown in figure 4-43. The circle itself (not shown, but a curve formed by a plane passed through a cone perpendicular to the vertical axis) is also derived from a conic section.

This section describes methods of constructing the ellipse only. Methods of constructing the hyperbola are given in Engineering Drawing by French and Vierck and in Standards.

Of the many different ways to construct an ellispe, the three most common are as follows: the pin-and-string method, the four-center method, and the concentric-circle method. The method you should use will depend on the size of the ellipse and where it is to be used.