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Dodecahedrons

Don C Davis

Don C Davis

Joined
Feb 15, 2018
Messages
256
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Location
Canton, GA
I am wanting to build some dodechedrons that are hollow and stuff could be stored in them--I was thinking the length of the pentagon sides to be around 4-5 inches. I would love it if someone could tell me what angles to cut on the pentagons themselves and the angles for the edges to glue the completed pentagons together.

Any advice, direction is appreciated.
 
I did see one where some one turned a sphere from the soccer ball pattern, 12 pentagons and 20 hexagons. Turned with plywood, which made for a very interesting circular pattern in each facet. A dodecahedron can also be made using rhomboids. I made custom footbags, known more commonly by the registered trade mark name of Hack Sack. I have seen them from one piece to 320 pieces... I would guess you need o consider inside thickness as well. Maybe make 2 halves and then glue them together after turning the insides...

robo hippy
 
Don C Davis said:
I am wanting to build some dodechedrons that are hollow and stuff could be stored in them--I was thinking the length of the pentagon sides to be around 4-5 inches. I would love it if someone could tell me what angles to cut on the pentagons themselves and the angles for the edges to glue the completed pentagons together.

Any advice, direction is appreciated.
Click to expand...


The corner angles of each of the 12 pentagons are 72 degrees. I haven't done the calculation myself, but Wikipedia gives the dihedral angle (the angle between two pentagons) as 116.56505°. Assuming you want all edges cut the same, the cutting angle will be half that or about 58.3°.
 
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Don,

Check out the book, Woodturning Wizardry, by David Springett. He has a lot of those kinds of calculations there.

The other person to contact is Jean-Claude Charpignon. He showed me a spreadsheet that makes those calculations.

Good luck,
Rich
 
Gary Beasley said:
I see. I think he decided on the name because the first glueup made five sided assemblys then built the ball from that. A tactic to avoid the need for thicker material.
Click to expand...


Yep, if he had glued them flat instead of domed he would have gotten a dodecahedron.
 
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Gary Beasley said:
I see. I think he decided on the name because the first glueup made five sided assemblys then built the ball from that. A tactic to avoid the need for thicker material.
Click to expand...

By the way, there was a thread last November about using laminar rings to achieve the same result.
 
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