The geodesic dome, as shown in the assembly diagrams, contains two different joints: a B joint which occurs at the vertices of all pentagons formed, and an R joint which occurs at all other points.
The spans from joint to joint are BB, BR, or RR. The arc factors of these lengths are:
BB=.26030616, BR=.31030984, RR=.32636688.
For these factors, the radius of the dome is 1.00. To construct a 22' dome (11' radius) the lengths of the arcs would be as follows: BB=2.86', BR=3.41', RR=3.59'.
Cutting and Measuring the Members
There are only two different lengths of members used in the erection.
For a 5/8 dome, 80 B members and 90 R members are required.
A line of color can be drawn around the bamboo members at each measuring point. Use blue for the B points and use red for the R points.
With 12" extra on the end of each stick, there'll be a 24" overlap when the crosses are assembled.
Stage 1 Assembly
The first stage in the assembly of the dome is the construction of the pentagons at the top of the dome. This process employs 5 B crosses.
Stage 2 Assembly
The second stage consists of closing the five triangles around the pentagon. Use five R crosses.
Again, the end measuring points always have the same designation as the cross to which they are connected.
At this point, the structure will tend to bow. Turn the figure so that it is concave downward.
For the third stage, use ten R crosses as shown.
The fourth stage uses 5 B crosses which close the five hexagons.
The fifth stage uses ten B crosses to close ten triangles. Six of the crosses can be seen in the diagram above.
The sixth stage uses ten B crosses and ten R crosses to complete the first horizontal band. We now have a 3/8 dome.
To complete the 5/8 dome requires two stages. The seventh stage uses ten R crosses and the eighth stage uses ten R crosses and ten B crosses. On the last twenty crosses, all members pointing towards the ground should be cut off 12" from the cross' central point.
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