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− | {{Geomag-construction|PageTitle=Annular Dodecahedron |
+ | {{Geomag-construction|PageTitle=Annular Dodecahedron|Filename=Geomag Annular Dodecahedron (side 3).jpg|Caption=Side 3 version|Type=[[:Category:Dodecahedron]]|Triangles=|Rods=1350|Balls=700|Author=--[[User:Karl Horton|Karl Horton]] 11:34, 29 October 2007 (UTC)}} |
A Geomag classic: pentagonal torii stitched together into a dodecahedron. |
A Geomag classic: pentagonal torii stitched together into a dodecahedron. |
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+ | === Steric Interference === |
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+ | |||
+ | There is a technical problem with this construction: all of the rods along the red edges of the outer dodecahedron are too crowded: they cannot all remain with full contact on the 1/2" spheres. Nontheless, after the model is complete there is no tendency for the joints to slip. |
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=== Counting === |
=== Counting === |
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Each module has 40 balls: 25 center, 10 edge and 5 vertex. So there are 12*25 + 30*10 + 20*5 = 700 balls. |
Each module has 40 balls: 25 center, 10 edge and 5 vertex. So there are 12*25 + 30*10 + 20*5 = 700 balls. |
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+ | The model weighs 27lb (12.4kg) but can, with care, be moved. |
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+ | Rod to Ball ratio: 2:1 |
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+ | |||
== Building Instructions == |
== Building Instructions == |
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# Rest the linked modules on the hinge, and erect scaffolding poles to support the modules at the right angle. |
# Rest the linked modules on the hinge, and erect scaffolding poles to support the modules at the right angle. |
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# Now, resist the temptation to proceed onwards with modules. Instead, learn how to build the diamond-shaped tube ''in-place'' on the model. Use a contrasting color for the true edges of the dodecahedron to keep yourself orientated. |
# Now, resist the temptation to proceed onwards with modules. Instead, learn how to build the diamond-shaped tube ''in-place'' on the model. Use a contrasting color for the true edges of the dodecahedron to keep yourself orientated. |
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+ | # It helps to use pentagonal panels to stabilise the build. |
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# Let the structure grow at first like a bowl, then like a dome. Keep the build balanced and keep evolving the model with an eye to the symmetry. |
# Let the structure grow at first like a bowl, then like a dome. Keep the build balanced and keep evolving the model with an eye to the symmetry. |
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+ | == More Pictures == |
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+ | |||
+ | <gallery> |
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+ | Image:2007-07-20 IMG6865.jpg|Gallery1 |
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+ | Image:2007-07-20 IMG6874.jpg|Gallery2 |
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+ | Image:2007-07-20 IMG6867.jpg|Closeup |
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+ | Image:2007-07-20 IMG6876.jpg|Steric Interference |
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+ | Image:2007-07-25 IMG6966.jpg|Module Reference1 |
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+ | Image:Pentagonal torus.jpg|Module reference2 |
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+ | </gallery> |
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{{clr}} |
{{clr}} |
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== Related Links == |
== Related Links == |
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− | * [http://www.flickr.com/photos/karlhorton/sets/72157600964329389/ Flickr Photoset] |
+ | * [http://www.flickr.com/photos/karlhorton/sets/72157600964329389/ Karl Horton's Flickr Photoset] |
+ | * [http://www.flickr.com/photos/geomag_model_team/857724516/ Similar model from Geomag SA] |
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[[Category:Polyhedron]] |
[[Category:Polyhedron]] |
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[[Category:Dodecahedron]] |
[[Category:Dodecahedron]] |
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+ | [[Category:Platonic Solid]] |
Latest revision as of 07:57, 10 January 2009
Annular Dodecahedron | |
Side 3 version | |
Type | Category:Dodecahedron |
Rods | 1350 × |
Spheres | 700 × |
Author | --Karl Horton 11:34, 29 October 2007 (UTC) |
A Geomag classic: pentagonal torii stitched together into a dodecahedron.
Steric Interference[]
There is a technical problem with this construction: all of the rods along the red edges of the outer dodecahedron are too crowded: they cannot all remain with full contact on the 1/2" spheres. Nontheless, after the model is complete there is no tendency for the joints to slip.
Counting[]
Each module has 105 center rods, and 15 edge rods. So, there are 12*105 + 30*3 = 1350 rods in total.
Each module has 40 balls: 25 center, 10 edge and 5 vertex. So there are 12*25 + 30*10 + 20*5 = 700 balls.
The model weighs 27lb (12.4kg) but can, with care, be moved.
Rod to Ball ratio: 2:1
Building Instructions[]
- Build a Pentagonal Torus module: it is helpful to build an extra module out of a different color and leave it nearby, because its really easy to get lost whilst building.
- Build another torus
- Strip the edge of one torus to join the two together
- Rest the linked modules on the hinge, and erect scaffolding poles to support the modules at the right angle.
- Now, resist the temptation to proceed onwards with modules. Instead, learn how to build the diamond-shaped tube in-place on the model. Use a contrasting color for the true edges of the dodecahedron to keep yourself orientated.
- It helps to use pentagonal panels to stabilise the build.
- Let the structure grow at first like a bowl, then like a dome. Keep the build balanced and keep evolving the model with an eye to the symmetry.
More Pictures[]