Another method can be used when the desired length of the major axis is known (Fig 4.24b). Draw a straight line and mark on it the overall length CD. Bisect this line and raise a perpendicular as before, then bisect the two segments so as to divide the overall length of the major axis into four parts. At the three internal points draw
three overlapping circles: the circumference of the middle circle cuts the perpendicular at A and B, and passes through the centers of the outer two circles; the outer circles pass through the end points of the axis. With center A, draw a large arc which meets the two outer circles at a tangent; repeat on the other side of the figure, with center B. The straight line drawn from A, through the center of the outer circle, indicates where the circle and the large arc merge.
One may have to suit the shape of the ellipse to the available space. This
is easily done by simply changing the relationship of major to minor axis.
the length of the minor axis, the ellipse can be made rounder by placing the
centers for the end arcs (points E and F) closer to the intersection of the
axes. Of course, the closer they are to the intersection, the closer to a circle
figure becomes. On the other hand, as one moves the centers towards the apex
of the vesica piscis, the smaller the arcs (circles), and the more pointed
the figure becomes. The same applies when the length of the major axis is known:
as the centers of the end arcs move toward the axis intersection they become
larger (the radius becoming longer) and overlap. As the centers move outward
and become smaller, the ellipse becomes narrower. Adjustments will have to
made to the centers on the minor axis to complete the figure.
Fig 4.25 A small sunburst being carved in a routed recess. The center disk is
being rounded over
Fig 4.26 The parting tool being used to define the valleys between the reeds of a double sunburst
This article is excerpted from Carving Classical Styles In Wood by Frederick Wilbur.