Carving The Sunburst
By: Frederick Wilbur
From: book: Carving Classical Styles In Wood
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Like the fan, the sunburst consists of flutes, or peaks and valleys, or entirely of reeds. The difference is that the sunburst is round or elliptical. The design can be incised into the surface of the material or carved separately and let into a recess. To draw the circular version, the circle is simply divided into an equal number of degrees; the widths of the divisions of the perimeter (their chords) are equal as well. As with fans, it is difficult to maintain the regularity of the elements as they diminish in width, so a central disk is commonly used.
The ellipse is a little tricky because it is made up of two different arcs, which vary depending upon the measurements of the major (longer) and minor (shorter) axes. One method of drawing an ellipse when one knows the minor axis dimension is to use two equilateral triangles (Fig 4.24a). Draw a straight line to represent the minor axis (the vertical line in Fig 4.24a). Set your compass to this known dimension and, placing the fixed leg on the line at A, draw a semicircle. Replace the fixed leg at the point where this arc intersects the vertical line (point B), and again draw a semicircle, creating the vesica piscis shape ADBC. Connect the four points ABCD to create two equilateral triangles, with a common base on the minor axis. Bisect the altitudes of these two triangles to give the points E and F. Use these two points as centers for the ends of the ellipse, adjusting the compass until the arc is tangential to the larger arcs of the vesica piscis. (These end arcs do not extend to the apexes of the triangles.)
Fig 4.24 Drawing the ellipse:
(a) the use of equilateral triangles when the required width is known
(b) The use of three circles when the required length is known
This article is excerpted from Carving Classical Styles In Wood by Frederick Wilbur.
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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.
Retaining
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
the
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
be
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.
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To mark out
the flutes or reeds, it is not sufficient simply to pick a measurement
and step off the increments around the perimeter, or to
give each division the same number of degrees. This will look uneven,
because the ends of the flute or reed are cut off nearly perpendicularly
at the axes, but obliquely between the axes. Also, the flutes or reeds
near the major axis will appear narrower than those near the minor axis
(in spite of the fact that the center disk is also an ellipse). Personal
preference may require that the major and minor axes be the centerline
of reeds or flutes (as opposed to valleys, which would be an easier layout).
Instead of bogging down in mathematical calculations, lightly sketching
the increments of one quadrant will help you to determine how many
increments fit well into the space. Some adjustment should be made so that
all elements appear to be the same width at the perimeter. Sometimes, of
course, the increments are so small that these issues are hardly troubling.
When transferring the design to the blank, I usually draw the ellipse
directly onto the material. It is hard to trace an ellipse through
carbon paper accurately.
Plastic templates for this purpose can be purchased, but the largest are
only 3—4in (75—100mm) in length.
The small sunburst being carved in Fig 4.25 illustrates the method of using
a routed recess to secure the blank. It also shows how the surface is sloped
in
toward the center disk, the same as for a fan. For larger applied sunbursts,
the waste from bandsawing the blank can be used to hold the work. This piece
can be snugged up to the blank and nailed to a scrap backing board in order
to hold the blank while carving. The holding pieces may need to be made thinner
than the blank in order to give access to the edges of the carving.
Fig
4.27 Detail of double sunburst
This article is excerpted from Carving Classical Styles In Wood by Frederick Wilbur.
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