3. Lay out and Cut out the Cooker Reflector
To cut the EB Hypar 42 cooker reflector from a single piece of material, you will need a piece of material that is 4 feet wide by about 5 feet long. If you are using a smaller piece of material, we recommend making any necessary splices along the fold between petals.
Figure 4 shows the layout for the 16 sided EB 42 cooker reflector. The green lines in Figure 4 show the edges of the 48 inch wide material from which the cooker reflector is to be cut out. You will be cutting red lines and folding solid blue lines. The layout may look complicated but is not too hard to construct if you proceed step by step. The recommended steps for creating a layout similar to that shown in Figure 4 are:
1. Locate a center point that is 29.5 inches from both the left end and the top of the material. Clearly mark the location of this center point because you will be using it in later steps.
2. Draw a circular arc using the center point established in step 1 with a 29.42 inch (about 29 7/16 inch) radius. It is important that this radius be as accurate as possible. The arc should go from the bottom edge of the material all the way around and back to the bottom edge. It is not essential but we found it useful to draw two additional arcs using the same center point with 22.27 inch (about 22 ¼ inch) and 7.72 inch (about 7.75 inch radii. (Note: We found that, unless you have special tools, probably the best way to draw large circles is to use a long thin wood, metal, or plastic stick (A yardstick works well if you have one that you are willing to drill holes in). Drive a small nail through the stick near one end. Carefully measure the desired radius from the center of the nail and drill a small hole just large enough to fit the pen or pencil you plan to use do draw the circle. Drive the nail into the material at the center point, insert a pen through the hole that you drilled and draw the circle as you swing the stick around the nail.)
3. Starting at the lower left corner of the largest arc, use your full size pattern to mark the ends and center of each of the sixteen 8.2 inch chords around the arc. The sixteenth chord should end short of the point where the right hand end of the arc intersects the edge of the material. Use a straightedge to draw solid lines from the edge of each chord to the center of the arc. Also draw dashed lines from the center of each chord to the center of the arc.
4. Use a straightedge to draw solid lines from the end of each chord to the center of the arc. Also, draw dashed lines from the center of each chord to the center of the arc.
5. Use your full size pattern to draw the outline of each of the 16 petals. When positioning the pattern, the corners should just touch the larger circular arc and the point of the tab on the small end of the pattern should be on the dashed line you drew in step 4. Draw the lines that cross each petal between the trapezoidal portion and the curved portion, and the lines between the curved portion and the pointed tab.
6. Assuming that your layout looks similar to Figure 4, you can now cut out the reflector. How you cut the material depends upon the material you are using. If the material is Chloroplast® or cardboard, it can be cut with a utility knife.
a. Cut around the outside of the reflector. You can make this cut either along the outside circular arc or along the chords. We prefer to cut along the circular arc.
b. Before cutting the curved section of each petal, we recommend punching or drilling a small hole at the junction between the trapezoid portion and the curved portion of each petal. If you drew the second smaller circular arc in step 2, the junction where the hole is to be punched is where the circular arc intersects the edge of the petal. These holes positively locate the point where each cut ends. Note: The smaller circular arc is not shown in Figure 4
c. Cut along the curved sides and pointed tab of each petal. Also, cut around the large tab at the edge of the reflector
d. With the cutout complete, score and bend the material at all of the edges that will be folds when the cooker reflector is assembled (the solid blue lines in
Figure 4). We do this by placing a straightedge along the edge, scoring the edge with a relatively blunt instrument such as a screwdriver, and then bending the edge while holding the straightedge in place to help force the bend to be at the proper place. This step insures that the bends will be at the proper place when the cooker is assembled.