Introduction: Tensegrity Playset
It is best described as floating compression. there is Great amount of model building knowledge available HERE!!!
There are 2 basic elements to the construct, compressed members and tensioned members.
I wanted to experiment with with several forms so I chose to print the compressed members from ABS plastic.
The tensioned members are rubber bands for simplicity and quick construction due the flexibility and friction of the material. There is one side effect that is undesirable, the structures are easily deformed with mild force, they are however a great starting point to work out the mechanical properties and dimensions of the members.
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Step 1: The Compressed Members
I started by creating a simple rod of 10cm length. I chose a hexagon shape for ease of printing.
I selected the top plane and drew a 10mm hexagon.
This hexagon was then extruded from midpoint to a total length of 10cm.
Both ends were were finished with a 2mm chamfer.
A grove was created in one end that is 5mm deep with chamfered edges.
This grove was then mirrored to the other end.
The resulting model was then saved as .STL and arranged for printing.
I used a sparse infill to print these rods.
On some structures the short rods are difficult to work with so I have also included files with deeper groves and 15cm length.
Step 2: Tensegrity Prisms
I started with the 3 strut variety before moving upward. An excellent resource for the forms is found here...
Begin by holding 3 rods as shown. This will create 3 sides
Each side needs to be connected with 1 elastic band.
The assembled construct will be out of shape and gradually adjusting the bands will bring it into shape.
Step 3: Almost Icosahedron...
This construct has the basic shape of an Icosahedron but it has a ratio 0f 2 not the golden ratio.
Nonetheless it is an interesting shape to build..
Begin by placing a rubber band on each rod as shown.
Assemble the rods to make a "T" shape as shown. The linking end needs to be held in place with a tightly wrapped rubber band.
Use a third rod to make another "T" then a third connection will create an unusual triangle as shown.
3 more rods need to be attached at he mid point of each long rod on the triangle as shown. These too need to be held in place with tightly wrapped rubber bands as shown.
In a clockwise movement, connect one point of the triangle shape to the mid point of the long rod. these connections will need to be held in place with wrapped rubber bands.
This step will begin to create tension and the construct will begin to fold in on itself.
Finally in a counterclockwise motion connect the last rod tip to the last side. These do not need the rubber band.
Once assembled the tip bands can be removed.
The last step is to adjust the bands to make the opposing rods parallel to one another.
Second Prize in the
Rubber Band Speed Challenge