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Bamboo |
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Construction of Bamboo Geodesic Domes
instructions
by R. Buckminster Fuller |
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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
Dome Assembly
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:
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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'.
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Cutting and Measuring the Members
There are only two different lengths of members
used in the erection
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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. |
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Cross
Assembly
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The
B cross consists of two B members whose lengths are: 1/2 BB plus 1/2 BR
plus 12" extra at each end |
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The
R cross consists of two R members whose lengths are: 1/2 BR plus 1/2 RR
plus 12" extra at each end |
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With 12" extra on the end of each stick, there'll be a
24"
overlap when the crosses are assembled.
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Cross Tying
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Place members at right angles to each other
and tie firmly, but not too tight. During assembly of the dome, the
crosses will twist into proper position as shown.
In all cases, when looking at a cross with the acute angles at the
sides and the obtuse angles at the top and bottom, the member
going from the upper right hand corner to the lower left hand
corner always passes over the other member. |
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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.
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Step A:
Tie together two B crosses as shown in in the diagram. Note that the end
measuring points have the same designation as the cross to which they
are connected.
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_-_R._Buckminster_Fuller.jpg) |
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_-_R._Buckminster_Fuller.jpg) |
Step B:
Add two more B crosses in the same manner as shown in step A.
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Step C:
Add fifth B cross between the untied legs. In order to insert this
cross, all crosses will be twisted so that a regular pentagon is formed |
_-_R._Buckminster_Fuller.jpg) |
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Stage 2 Assembly
The second stage consists of closing the five triangles around the
pentagon.
Use five R crosses.
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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. |
Prop It |
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Lift the assembled figure off the ground to facilitate the addition of
new crosses. Use five bi-ped props. Each prop consists of two bamboo
sticks about 7 feet long, tied together near the top with a cord about a
foot long. These props will then support the dome at equidistant points
from it's apex; first at the five vertices at the top of the pentagon,
later at five corresponding points on the top five hexagons. |
Stage 3
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For the third stage, use ten R crosses as shown
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Stage 4
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Stage 5
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The fifth stage uses ten B crosses to close ten triangles.
Six of the
crosses can be seen in the diagram above
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Stage 6
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The sixth stage uses ten B crosses and ten R crosses to complete
the
first horizontal band. We now have a 3/8 dome
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Stage 7,8 |
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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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