# Geometric Shapes



## rance (Sep 30, 2009)

*Geodesic Domes*

In some discussions both online and back channel(PM), Moment brought up the question of the angles used in building a Geodesic dome from watching this video. With a little research I found that someone had published the lengths and angles for pipes, if you were building a structure you might cover with a parachute. What Moment asked about was as if you were building it from solid wood(or framed) panels. Specifically, the angles between the panels.

Background: From his post and some research, I learned of the different levels(or frequencies) of the domes. Namely, 2v, 3v, 4v… I won't go into detail here since it is easilly found on the internet by googling Dome calculations. Just to say we are looking at a 3v model: 









Panels: Another thing I found out is that even if you use all triangle panels, not all triangles are the same size. This too can be found from searching the internet. Maybe the guy in the video ignored this rule. I don't know because I couldn't hear all of the audio. I could be wrong in my deduction here.

Size: From looking at the models and with more research, I have also deduced that the overall size of a dome(or sphere) does not in any way affect the angle relationship between the panels as long as you stay within the same Level(3v in our case). It only affects the size of the panels.

Angles: I do like math, and I'm sure there is a simple equation to figure this out, but I'm not familiar with the formulas needed to calculate such angles. And having failed at being able to find this answer on the internet, I resort to the brute force method. I do, however, have SketchUp at my beck and call as an aid. I will post my progress as it happens. And I'm not promising this at any lightening speed either. At first I thought this might be easy. I have failed twice in my attempts to figure this out using SU alone.

Guessing & "I think": On this page , about 2/3 of the way down, Jacques asks this same question with guessing answers. If someone says "I think…", then to me, that is not an answer in the case of building a G. Dome. I prefer to have more accurate answers. Oh, and let me do the rounding myself. 

I welcome anyone to interrupt the previously scheduled program to save me some grief, set me straight, or to help me along. The 3v model may be exactly the same as a Soccer Ball, which Sam Shakouri has built many times. Sam, feel free to shut me up and put me out of my misery. 

Thanks in advance for any and all input to this puzzling question.


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## ptweedy (Feb 9, 2009)

rance said:


> *Geodesic Domes*
> 
> In some discussions both online and back channel(PM), Moment brought up the question of the angles used in building a Geodesic dome from watching this video. With a little research I found that someone had published the lengths and angles for pipes, if you were building a structure you might cover with a parachute. What Moment asked about was as if you were building it from solid wood(or framed) panels. Specifically, the angles between the panels.
> 
> ...


try goggling buckminister fuller for domes and calculations. he invented the thing


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## rance (Sep 30, 2009)

rance said:


> *Geodesic Domes*
> 
> In some discussions both online and back channel(PM), Moment brought up the question of the angles used in building a Geodesic dome from watching this video. With a little research I found that someone had published the lengths and angles for pipes, if you were building a structure you might cover with a parachute. What Moment asked about was as if you were building it from solid wood(or framed) panels. Specifically, the angles between the panels.
> 
> ...


Yeah, I should have done that first. I did find This site 'claims' to have the Dome Math(4.2 about 1/4 down the page). However, I can't get past the physiwidgamafloogle to understand what they are telling me. They even have an alternate creator of the thing.

"Spherical Trigonometry", "Chord Factors", "How to tesselate a sphere"? I didn't even know these domes had testicles. I'm not sure I want to even build one now. I can see it now. For its annual checkup, the doctor comes out, he says "OK, now make it cough", and I tap on the roof of the dome real hard.


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## JoeLyddon (Apr 22, 2007)

rance said:


> *Geodesic Domes*
> 
> In some discussions both online and back channel(PM), Moment brought up the question of the angles used in building a Geodesic dome from watching this video. With a little research I found that someone had published the lengths and angles for pipes, if you were building a structure you might cover with a parachute. What Moment asked about was as if you were building it from solid wood(or framed) panels. Specifically, the angles between the panels.
> 
> ...


Rand, you're SO FUNNY!!

It's been a LONG time since I've had to turn my head and cough! LOL

I don't know much about them domes either…

At first glance, I thought "Oh, just a bunch of equilateral triangles… aka 60,60,60.
You know what a 45,45,90 and a 30,60,90 are YES?
It looks like these start out at 60,60,60 and are merely put together!
But, without making slight changes (as it appears) you could not get it to go in curve for a circle…
Their edges would have to be cut a certain angles to make them fit nice and flush with each other.
The more I think about it, just trying to follow a set of plans would be a nightmare… having to Number every triangle and sides too!

The more I think about it, it boggles my mind… I guess I'm too old for that kind of stuff now…
I think I could've handled OK when I was younger.

Good luck, Rand…

Now, turn head, cough, laugh, and do something you can easily handle! LOL


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## rance (Sep 30, 2009)

rance said:


> *Geodesic Domes*
> 
> In some discussions both online and back channel(PM), Moment brought up the question of the angles used in building a Geodesic dome from watching this video. With a little research I found that someone had published the lengths and angles for pipes, if you were building a structure you might cover with a parachute. What Moment asked about was as if you were building it from solid wood(or framed) panels. Specifically, the angles between the panels.
> 
> ...


More simple than mere math. Just go to Google 3D Warehouse. They have the models. EVERYTHING is on the INTERNET. It is simply a matter of measuring the angles between the faces on that completed SU model. Arrrrrgh.

From one of the links above:
>"On the red edges the bevel is 7.2, on the green edges it's 6.8, on the blue edge of the red-red-blue triangles it's 4.1 and on the blue edge of the green-green-blue triangles it's 7.2 - I think, perhaps someone else will confirm."

Well, when I measured the first one, I got 7.2°. The same as what was posted. I'm gonna assume(I know) the rest are correct. Of course I need to figure out the relationship of Red/Green/Blue edges to A/B/C on the drawing, but I think I can handle that.

I still want to figure out how to do it in SU. It'll be an interesting exercise to compare the two. My contention is that it can be done with a means that does NOT require an inborn knowledge of physiwidgamafloogle mathematics.

Thank you, all 104 of you for bearing with me through this exercise. No eta on my SU solution.


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## JoeLyddon (Apr 22, 2007)

rance said:


> *Geodesic Domes*
> 
> In some discussions both online and back channel(PM), Moment brought up the question of the angles used in building a Geodesic dome from watching this video. With a little research I found that someone had published the lengths and angles for pipes, if you were building a structure you might cover with a parachute. What Moment asked about was as if you were building it from solid wood(or framed) panels. Specifically, the angles between the panels.
> 
> ...


Rance… sorry, I called you Rand by mistake…

OK, are you going to make one to live in?
... Doll house?

What?


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## rance (Sep 30, 2009)

rance said:


> *Geodesic Domes*
> 
> In some discussions both online and back channel(PM), Moment brought up the question of the angles used in building a Geodesic dome from watching this video. With a little research I found that someone had published the lengths and angles for pipes, if you were building a structure you might cover with a parachute. What Moment asked about was as if you were building it from solid wood(or framed) panels. Specifically, the angles between the panels.
> 
> ...


No problem Joe.  I knew what you meant. There's really only 3 kinds of triangles made up from 4 different edge bevels. Kinda interesting actually. Now when it comes to assembling them, that might complicate things.

I think I want to eventually take this to the table saw. Maybe a box of some kind.


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## JoeLyddon (Apr 22, 2007)

rance said:


> *Geodesic Domes*
> 
> In some discussions both online and back channel(PM), Moment brought up the question of the angles used in building a Geodesic dome from watching this video. With a little research I found that someone had published the lengths and angles for pipes, if you were building a structure you might cover with a parachute. What Moment asked about was as if you were building it from solid wood(or framed) panels. Specifically, the angles between the panels.
> 
> ...


I see a lot of hole drilling for Nuts & Bolts… One DP setup… 1,000's of holes!

I can't see nailing them together… Nuts & Bolts would be easier… a ton of expense!! Weight too!

So, you just make so many of three dif. triangles… I picture a half-lap joint at each angled point… Glue & pin-nail the individual triangle points.

One heck of a lot of angle cutting…

... then, bolt them together?

I picture triangles using about 36" long pieces…

2×4x10 ??

Sounds like a lot of work! ...but it might be a little FUN to do…

Maybe a small Greenhouse for starters… to get the procedure & jigs squared away… LOL

I just thought of the foundation! That would be a paid to layout… Cut a few 2×4's with the proper angle on them and start laying them on the ground (flat level ground), pound stakes, start digging the trench… or just make it as part of a slab… different ways to do that I guess…

I also see Brace pieces to be used as you go from level to level up the curve… either that or using LONG ladders… or a combination…

So, what you gonna do? LOL


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## S4S (Jan 22, 2011)

rance said:


> *Geodesic Domes*
> 
> In some discussions both online and back channel(PM), Moment brought up the question of the angles used in building a Geodesic dome from watching this video. With a little research I found that someone had published the lengths and angles for pipes, if you were building a structure you might cover with a parachute. What Moment asked about was as if you were building it from solid wood(or framed) panels. Specifically, the angles between the panels.
> 
> ...


Thanks* rance *, Let me know your progress on the SU , that should be interesting . I guess its time to make a small model and see how that goes . Although obtaining accurate results when comparing the Diff.
of 5 degrees and 7 degress on small pieces is problematical for me . How accurate is your TS ? lol .
*Proxxon* needs to come out with a tilting blade . : )


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## rance (Sep 30, 2009)

rance said:


> *Geodesic Domes*
> 
> In some discussions both online and back channel(PM), Moment brought up the question of the angles used in building a Geodesic dome from watching this video. With a little research I found that someone had published the lengths and angles for pipes, if you were building a structure you might cover with a parachute. What Moment asked about was as if you were building it from solid wood(or framed) panels. Specifically, the angles between the panels.
> 
> ...


Moment, You could make a tilting sled to accomplish almost the same thing. 'Will do' on the progress.

Joe, I'd use screws, not bolts. Much faster and less labor intensive. No holes to drill.

>"One heck of a lot of angle cutting…" 
Have you ever built a house? The G. Dome method seems about par to me.

I like your idea about half lapping the corners. Actually, you gave me another idea. Build ALL the triangles with rectangular lumber, then once built, I could cut the bevels.

Also understand that the bottowm row that rests on the foundation is not naturally a flat line. Provisions have to be made for that.


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## JoeLyddon (Apr 22, 2007)

rance said:


> *Geodesic Domes*
> 
> In some discussions both online and back channel(PM), Moment brought up the question of the angles used in building a Geodesic dome from watching this video. With a little research I found that someone had published the lengths and angles for pipes, if you were building a structure you might cover with a parachute. What Moment asked about was as if you were building it from solid wood(or framed) panels. Specifically, the angles between the panels.
> 
> ...


rance,

*"the bottom row that rests on the foundation is not naturally a flat line."*

I do not understand how that can be… each triangle has straight sides… straight sides on a foundation equals one straight side or flat side. (if the the proper angle is cut, of course). LOL

They are at a compound angle… Vertically inward… Horizontally inward… but seems like they should still be in a flat line… NO? By how much? Maybe they have to be Set with mortar like concrete blocks on the bottom edge?

OK, use SPAX screws instead of bolts… They're good at drilling their own holes… I use'em from McFeeley's… Love'em…


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## rance (Sep 30, 2009)

rance said:


> *Geodesic Domes*
> 
> In some discussions both online and back channel(PM), Moment brought up the question of the angles used in building a Geodesic dome from watching this video. With a little research I found that someone had published the lengths and angles for pipes, if you were building a structure you might cover with a parachute. What Moment asked about was as if you were building it from solid wood(or framed) panels. Specifically, the angles between the panels.
> 
> ...


Joe, look carefully at the picture above. You can see that there is a slight zig zag. It CAN be flat, but it takes more work on that bottom row.


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## JoeLyddon (Apr 22, 2007)

rance said:


> *Geodesic Domes*
> 
> In some discussions both online and back channel(PM), Moment brought up the question of the angles used in building a Geodesic dome from watching this video. With a little research I found that someone had published the lengths and angles for pipes, if you were building a structure you might cover with a parachute. What Moment asked about was as if you were building it from solid wood(or framed) panels. Specifically, the angles between the panels.
> 
> ...


Yes, it looks like ALL of the lines are zig-zagging all over the place!

Weird…

Also looks like it might be easy to put groups of hexagons together then, arrange them around the bottom row, filling-in with single triangles between them…
Then, go on to the next row with another set of Hexagons & triangles…

Very interesting…


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## rance (Sep 30, 2009)

rance said:


> *Geodesic Domes*
> 
> In some discussions both online and back channel(PM), Moment brought up the question of the angles used in building a Geodesic dome from watching this video. With a little research I found that someone had published the lengths and angles for pipes, if you were building a structure you might cover with a parachute. What Moment asked about was as if you were building it from solid wood(or framed) panels. Specifically, the angles between the panels.
> 
> ...


Joe, there's a little bit of discussion of this problem at the following page:
http://www.geo-dome.co.uk/article.asp?uname=stressdome
Just past half way down the page. They try to fudge it out by distorting the dome, but I'd rather build special shims for that bottom row. That's the right way to do it IMO.


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## JoeLyddon (Apr 22, 2007)

rance said:


> *Geodesic Domes*
> 
> In some discussions both online and back channel(PM), Moment brought up the question of the angles used in building a Geodesic dome from watching this video. With a little research I found that someone had published the lengths and angles for pipes, if you were building a structure you might cover with a parachute. What Moment asked about was as if you were building it from solid wood(or framed) panels. Specifically, the angles between the panels.
> 
> ...


Yeah… that's probably the best way to do it… Seems Mickey Mouse though…


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## Domerama (Feb 11, 2012)

rance said:


> *Geodesic Domes*
> 
> In some discussions both online and back channel(PM), Moment brought up the question of the angles used in building a Geodesic dome from watching this video. With a little research I found that someone had published the lengths and angles for pipes, if you were building a structure you might cover with a parachute. What Moment asked about was as if you were building it from solid wood(or framed) panels. Specifically, the angles between the panels.
> 
> ...


Here something I put together as a 3V flat base calculator:

http://www.domerama.com/calculators/3v-geodesic-dome-calculator/3v-38-flat-base-krushke-calculator/

To get a flat base, use the Kruschke method. A regular 3V uses 3 lengths. Kruschke method uses 4 lengths.


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## rance (Sep 30, 2009)

rance said:


> *Geodesic Domes*
> 
> In some discussions both online and back channel(PM), Moment brought up the question of the angles used in building a Geodesic dome from watching this video. With a little research I found that someone had published the lengths and angles for pipes, if you were building a structure you might cover with a parachute. What Moment asked about was as if you were building it from solid wood(or framed) panels. Specifically, the angles between the panels.
> 
> ...


Looks like some good reading Mr. Domerama. Thanks.


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## TexCoats (May 15, 2009)

rance said:


> *Geodesic Domes*
> 
> In some discussions both online and back channel(PM), Moment brought up the question of the angles used in building a Geodesic dome from watching this video. With a little research I found that someone had published the lengths and angles for pipes, if you were building a structure you might cover with a parachute. What Moment asked about was as if you were building it from solid wood(or framed) panels. Specifically, the angles between the panels.
> 
> ...


For a practical DIY dome, East TN Domes has a booklet (and one on A-Frames) that are pretty cheap to build wood domes of 2×4 or 2×6 and plywood. The math in it is minimal but with a little effort it would be easy to upgrade the dome to other sizes. The one the booklet is about is a 20' dia, 5/8 or 1/2 with rizer dome. The one with straight riser would be good, but I like the 5/8 dome looks better.

This guy does domes for a living, but not a huge concern. The booklet is pretty good IMHO.


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## TexCoats (May 15, 2009)

rance said:


> *Geodesic Domes*
> 
> In some discussions both online and back channel(PM), Moment brought up the question of the angles used in building a Geodesic dome from watching this video. With a little research I found that someone had published the lengths and angles for pipes, if you were building a structure you might cover with a parachute. What Moment asked about was as if you were building it from solid wood(or framed) panels. Specifically, the angles between the panels.
> 
> ...


Oops, the "East TN Domes" is now "South East Domes"

They make plans and sell dome kits of lots of sizes. They have fixed up their web site since I was there last some time ago.


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## rance (Sep 30, 2009)

rance said:


> *Geodesic Domes*
> 
> In some discussions both online and back channel(PM), Moment brought up the question of the angles used in building a Geodesic dome from watching this video. With a little research I found that someone had published the lengths and angles for pipes, if you were building a structure you might cover with a parachute. What Moment asked about was as if you were building it from solid wood(or framed) panels. Specifically, the angles between the panels.
> 
> ...


Tex, I would love to help someone build a Dome home just for the experience. Thanks for the link.


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## TexCoats (May 15, 2009)

rance said:


> *Geodesic Domes*
> 
> In some discussions both online and back channel(PM), Moment brought up the question of the angles used in building a Geodesic dome from watching this video. With a little research I found that someone had published the lengths and angles for pipes, if you were building a structure you might cover with a parachute. What Moment asked about was as if you were building it from solid wood(or framed) panels. Specifically, the angles between the panels.
> 
> ...


Glad you like it. ... A friend of mine an I got into a project to make a concrete dome (20' dia) from concrete. We got one of the two sizes of panels made. (No re-bar, but using lots of chemicals and plastic fibers for reinforcing … basically a high-tech concrete mix.) We stopped due to my friends divorce and heart attack. We still need to make the second steel mold. We can easily produce one panel of each size a day, and each requires 1.5 cu ft of concrete and slightly less for the second panel/triangle. It takes 105 of the larger triangles and 75 of the smaller ones if I remember right. (for comparison, 1.5 cu ft of concrete is roughly one bag of sack-crete)

Oh well, it was a fun hobby for a while. But with both of us being 'older', it probably won't get completed. To bad.

Yes, I used the booklet from South East Domes to design the panels and molds.

Enjoy. ... If you want to build a dome with comparative ease, I suggest their pamphlet.

If you want to learn to build great domes and want to take a 'buss-mans holiday' go look on www.monollithic.com and look into their workshops. I know they do them in Italy, TX (a hour or so south of Dallas in I45), but may do them elsewhere too. Also get their $25 book on 'Dome Living'. It explains their building system (not Geodesic by any means) but also shows how/why their domes are so VERY energy efficient. And lots of pretty pix of their domes.

Anyway, I will keep 'talking' if I don't shut up.


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## rance (Sep 30, 2009)

rance said:


> *Geodesic Domes*
> 
> In some discussions both online and back channel(PM), Moment brought up the question of the angles used in building a Geodesic dome from watching this video. With a little research I found that someone had published the lengths and angles for pipes, if you were building a structure you might cover with a parachute. What Moment asked about was as if you were building it from solid wood(or framed) panels. Specifically, the angles between the panels.
> 
> ...


One bag of sack-crete don't seem like much for a triangle. Must be smaller than I imagined. Sounds like you had the system down pat.


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## TexCoats (May 15, 2009)

rance said:


> *Geodesic Domes*
> 
> In some discussions both online and back channel(PM), Moment brought up the question of the angles used in building a Geodesic dome from watching this video. With a little research I found that someone had published the lengths and angles for pipes, if you were building a structure you might cover with a parachute. What Moment asked about was as if you were building it from solid wood(or framed) panels. Specifically, the angles between the panels.
> 
> ...


The panel is roughly 1" to 1.125" thick, and the rest goes into what looks like 2×4 (but in a trapazoidal end shape).

Each side has 2 bolts in each side, and a 1" hole in the center of each side.

Counting it up, it is about 1.5 cu ft

feel free to ask if there are more questions


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## JoeLyddon (Apr 22, 2007)

rance said:


> *Geodesic Domes*
> 
> In some discussions both online and back channel(PM), Moment brought up the question of the angles used in building a Geodesic dome from watching this video. With a little research I found that someone had published the lengths and angles for pipes, if you were building a structure you might cover with a parachute. What Moment asked about was as if you were building it from solid wood(or framed) panels. Specifically, the angles between the panels.
> 
> ...


I find this whole subject very interesting… 
I just wish this day was about 30 years ago when I would be better suited to really DO something with it…!!
... getting old is the pitts! LOL

COOL stuff…

Looks like some companies are really DOING something about it!

I think it would be fun to maybe build something about the size of a small shed… something that could easily fit in a normal back yard… Like a small greenhouse…

Thank you…


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## TexCoats (May 15, 2009)

rance said:


> *Geodesic Domes*
> 
> In some discussions both online and back channel(PM), Moment brought up the question of the angles used in building a Geodesic dome from watching this video. With a little research I found that someone had published the lengths and angles for pipes, if you were building a structure you might cover with a parachute. What Moment asked about was as if you were building it from solid wood(or framed) panels. Specifically, the angles between the panels.
> 
> ...


I really suggest getting the booklet I mentioned and I think I (or you) could build the 20' wood dome.

I live where my wife works and her employer provides housing. When she decides to retire, I want to build a retirement home (or actually have someone else build it) of a Monolithic.com concrete dome for a residence. Then either have them build a garage/workshop dome or build a wood geodesic using the plans for a workshop and/or garage.


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## rance (Sep 30, 2009)

*Truncated Icosahedron (without the math)*

*I am again intrigued by another …hedron shape.* Is it an Icoso…, a Dodeca…, or a Tetra…, they are all mumbo jumbo to me. I just want to make one, I don't want to learn the math. Maybe I should just go buy a Soccer ball and be done with it. Naaaaaaaaw. I want one made of wood.

*For the design*, my tool of choice is Google SketchUp…..... again. Maybe I cheated, well, I probably did. Sure I did. I went out to '3D Warehouse' and downloaded a soccer ball and proceeded to tear it apart. I removed all the smoothed surfaces and was left with just a few lines. I then rebuilt the surfaces enough to get the angle between the surfaces.

*The Truncated Icosahedron *is made up of 12 Pentagons and 20 Hexagons. The Pentagons are surrounded on ALL sides by a Hexagon. Thus, the angle of all sides is the same. The Hexagons, however, are surrounded by alternating Pentagons and Hexagons. This means that 3 of its edges are at one angle, and the other three are at another angle.

*The angles* between the Pentagon and Hexagon are(from my cheating) 37.4 degrees. For a segmentation(which is what this becomes), you take half off of each side. So the *Pentagon edges *are all cut at *18.7 degrees*. Likewise, *half of the Hexagon edges* are cut at that same *18.7 degrees*. *The other three edges* of the Hexagon are joined to other Hexagons but that angle is 41.8 degrees. Half for each one brings that to an angle of *20.9 degrees*.

Next was to *rebuild it from scratch*, and using those discovered angles, construct my own Soccer Ball. I set an abstract of having the edges at 2" long. With that, I built the two components I needed. 








The 'H' and 'P' notations were indicators to let me know what mating piece would be adjacent to that piece. H for Hexagon, and P for Pentagon(doooooh). With these two components, it was infinitely easier to build them using triangles. Eventually I'll eliminate those extra lines.

Next was to *bend them *at my previously discovered angles. Make more copies, then keep bending until I got all 32 pieces in place. 









*Well, it seems to work* with the angles I used. Next will be the manufacture of the actual pieces.

I searched for 'Icosahedron angles' on LJ and found Sam and Paul's works. I'll be using some of Paul's techniques for cutting the shapes on the TS. Sam and Paul have both been an inspiration to me with their work. I hope this work here somehow helps someone else in attaining their goals.

- - - - - - - - - -

Update:

And with some judicious rotating, I am able to place a Pentagon at the top(and bottom) and have a straight line in case I want to open it up like a clamshell.










It only takes cutting 5 of the Hexagons in half. Wow, that was easy. I like easy. And with it open…









Or an alternate separation(similar to Paul's):









.

.

.

[Note: For reference, Sam says "Hexagons have to be cut at 69.2 degrees and pentagons at 75.3 degrees.".]


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## PurpLev (May 30, 2008)

rance said:


> *Truncated Icosahedron (without the math)*
> 
> *I am again intrigued by another …hedron shape.* Is it an Icoso…, a Dodeca…, or a Tetra…, they are all mumbo jumbo to me. I just want to make one, I don't want to learn the math. Maybe I should just go buy a Soccer ball and be done with it. Naaaaaaaaw. I want one made of wood.
> 
> ...


just be careful playing with this soccer ball, I've heard of tree huggers, but not tree kickers - could be painful.


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## lanwater (May 14, 2010)

rance said:


> *Truncated Icosahedron (without the math)*
> 
> *I am again intrigued by another …hedron shape.* Is it an Icoso…, a Dodeca…, or a Tetra…, they are all mumbo jumbo to me. I just want to make one, I don't want to learn the math. Maybe I should just go buy a Soccer ball and be done with it. Naaaaaaaaw. I want one made of wood.
> 
> ...


This guy: http://www.answerbag.com/q_view/1920110
has similar finding.

His angles and yours are few minutes off. If he is right that could add up…

I think Sam has the answer.

I sure will be following.


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## rance (Sep 30, 2009)

rance said:


> *Truncated Icosahedron (without the math)*
> 
> *I am again intrigued by another …hedron shape.* Is it an Icoso…, a Dodeca…, or a Tetra…, they are all mumbo jumbo to me. I just want to make one, I don't want to learn the math. Maybe I should just go buy a Soccer ball and be done with it. Naaaaaaaaw. I want one made of wood.
> 
> ...


lanwater, I agree completely. Thanks for the link. If I'm off, then I'll know it when I am gluing 85 joints in one swale foop.  Hey, this is an experiment at this point. If it actually works, THEN I'll call it a project.


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## FatherHooligan (Mar 27, 2008)

rance said:


> *Truncated Icosahedron (without the math)*
> 
> *I am again intrigued by another …hedron shape.* Is it an Icoso…, a Dodeca…, or a Tetra…, they are all mumbo jumbo to me. I just want to make one, I don't want to learn the math. Maybe I should just go buy a Soccer ball and be done with it. Naaaaaaaaw. I want one made of wood.
> 
> ...


Intriguing…now my brain hurts. Thank you for a captivating post!


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## Michael1 (Feb 12, 2011)

rance said:


> *Truncated Icosahedron (without the math)*
> 
> *I am again intrigued by another …hedron shape.* Is it an Icoso…, a Dodeca…, or a Tetra…, they are all mumbo jumbo to me. I just want to make one, I don't want to learn the math. Maybe I should just go buy a Soccer ball and be done with it. Naaaaaaaaw. I want one made of wood.
> 
> ...


Very creative design. I am anxious to see how the project turns out. Thanks for posting.


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## SPalm (Oct 9, 2007)

rance said:


> *Truncated Icosahedron (without the math)*
> 
> *I am again intrigued by another …hedron shape.* Is it an Icoso…, a Dodeca…, or a Tetra…, they are all mumbo jumbo to me. I just want to make one, I don't want to learn the math. Maybe I should just go buy a Soccer ball and be done with it. Naaaaaaaaw. I want one made of wood.
> 
> ...


See, I was right. You are a techno weenie.
Nice study.
Bugger to build I would think.

Thanks,
Steve


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## rance (Sep 30, 2009)

rance said:


> *Truncated Icosahedron (without the math)*
> 
> *I am again intrigued by another …hedron shape.* Is it an Icoso…, a Dodeca…, or a Tetra…, they are all mumbo jumbo to me. I just want to make one, I don't want to learn the math. Maybe I should just go buy a Soccer ball and be done with it. Naaaaaaaaw. I want one made of wood.
> 
> ...


You're probably right Steve. 

I Googled more and found a real Scientific-Looking site(Coolmath.com) that states the mathematically-calculated angles. It looks like I'm just mere minutes away from my final answer. They publish the Dihedral angles as follows:


*138 degrees, 11 minutes *for the *hex-hex* angle
*142 degrees, 37 minutes *for the *hex-pent* angle

So what's a minute? A minute is 1/60 of a degree.

So… (for the *Hex - Hex*) 11 minutes = 11/60 of a degree, or 0.18333 degrees. And the dihedral is stated from a flat surface. So… 180 - 138.18333 = 41.81667. Divide that by 2 to get the miter angle and I get *20.908335 degrees*. I believe my *20.9 degrees* agrees with that.

Now… (for the *Hex - Pent*) 37 minutes = 37/60 of a degree, or 0.61667 degrees. And converting from the dihedral, 180 - 142.61667 = 37.38333. Divide that by 2 to get the miter angle and I get *18.691665 degrees*. I believe my *18.7 degrees *should be fine there too.

Of course this all assumes that 'Coolmath.com' knows what they are doing. I sure hope so. I trust their math more than my SketchUp.

I believe that *cutting the pieces* out will be simplified using Pauls method on the TS.

However, *the glue-up* could be a bear with 90 joints all at once. One way would be to use the Tape-Hinge method like what I use with mitered boxes. The tape gets it close(if not right on) and the clamps shmooze it into exact position. The key to this is the Net:








I got this one from Wikipedia. It is better than most as it centers it all around the base piece. Other 'Nets' can be found elsewhere and are typically used when making folded paper models.

Lastly, I'm sure a glue with *a looooong open time* would work best.


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## lanwater (May 14, 2010)

rance said:


> *Truncated Icosahedron (without the math)*
> 
> *I am again intrigued by another …hedron shape.* Is it an Icoso…, a Dodeca…, or a Tetra…, they are all mumbo jumbo to me. I just want to make one, I don't want to learn the math. Maybe I should just go buy a Soccer ball and be done with it. Naaaaaaaaw. I want one made of wood.
> 
> ...


Why do you have to glue all at once?
That may prove unmanageable

Can you just start with a pentagone and add all the surrouding hexagone? That might keep it tight.
Once that is done then add more to the first subassembly?

I was thinking CA glue for very fast drying time and the glue does not "creep". For clamping, small paper clips like those:

http://www.officedepot.com/a/products/909309/OIC-Mini-Binder-Clips-916-Wide/

Just ideas.


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## JoeLyddon (Apr 22, 2007)

rance said:


> *Truncated Icosahedron (without the math)*
> 
> *I am again intrigued by another …hedron shape.* Is it an Icoso…, a Dodeca…, or a Tetra…, they are all mumbo jumbo to me. I just want to make one, I don't want to learn the math. Maybe I should just go buy a Soccer ball and be done with it. Naaaaaaaaw. I want one made of wood.
> 
> ...


*Rance,*

You have done a wonderful job in studying, researching, & great use of SketchUp,

*to SIMPLIFY a complex (to me anyway) problem!*

.

*I LOVE your idea of using the Taping Method*, as used for gluing Miter joints, for gluing up your domes!
Hinge-type devices could be used for putting larger dome pieces together… (just thinking out loud)...

*You are doing some GREAT work here… Keep it up!*

You have peaked my interest again in this geometric subject!

*Thank you very much!*

*edit:*
After reviewing Part 1, I realize that *you SOLVED the slight ZIG ZAG (bottom) problem! YES?*
I knew there had to be a way to do it! I'm glad your brain was Up To the task… mine wasn't… LOL


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## rance (Sep 30, 2009)

rance said:


> *Truncated Icosahedron (without the math)*
> 
> *I am again intrigued by another …hedron shape.* Is it an Icoso…, a Dodeca…, or a Tetra…, they are all mumbo jumbo to me. I just want to make one, I don't want to learn the math. Maybe I should just go buy a Soccer ball and be done with it. Naaaaaaaaw. I want one made of wood.
> 
> ...


lanwater,

Yes, it could turn out to be unmanagable. This is one of those situations where any error in gluing one joint becomes accumulative to the next. Actually it almost compounds itself logarithmically. By building something like this all in one glue-up, any slight errors would be schmoozed out as it is pulled together.

This would be similar to gluing up an octagonal box, but with a 3rd dimension. The key to a straight Octagon is having the miters cut darned near perfect, and using a band clamp. Gluing up one joint at a time would be analogous to gluing one picture frame joint at a time. When you get to that last corner, any errors from the other 3 would be magnified at the last corner.

Of course, in building a separated lid, some of the edges would simply not be glued. This kind of a project SCREAMS for Planning. Something that gets left by the way side with many a project.

Hey, I'm talking out the side of my head here. Your suggestion could possibly work just fine. 

One more bizarre solution might be to drill a hole in one segment, apply all the (slow setting)glue, quickly wrap it all up, and apply a vacuum to it. A weightless chamber would come in handy for this method. It would be a hoot if it actually worked. I'd be afraid it'd suck all the glue out of the joints though.


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## JoeLyddon (Apr 22, 2007)

rance said:


> *Truncated Icosahedron (without the math)*
> 
> *I am again intrigued by another …hedron shape.* Is it an Icoso…, a Dodeca…, or a Tetra…, they are all mumbo jumbo to me. I just want to make one, I don't want to learn the math. Maybe I should just go buy a Soccer ball and be done with it. Naaaaaaaaw. I want one made of wood.
> 
> ...


If you did a Dry Glue-Up using Tape, you could hold off on the glue until you got it Right ahead of time…

Then, do another Dry fit up… to be sure…

Then, go for it with Glue!

Yes?


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## BertFlores58 (May 26, 2010)

rance said:


> *Truncated Icosahedron (without the math)*
> 
> *I am again intrigued by another …hedron shape.* Is it an Icoso…, a Dodeca…, or a Tetra…, they are all mumbo jumbo to me. I just want to make one, I don't want to learn the math. Maybe I should just go buy a Soccer ball and be done with it. Naaaaaaaaw. I want one made of wood.
> 
> ...


Someone made it already…. just recently posted on this project

Rance, Thanks for posting this technique… I like to make one of this too! I am planning to use 2 hollow circular jigs clamping the layers of the joint pieces per latitude. But it will be variable circle diameter with the right angle (you already mentioned it above) of radii. Hard to explain… hope I can make it.\


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## AlexeyKhasyanov (Jul 15, 2010)

rance said:


> *Truncated Icosahedron (without the math)*
> 
> *I am again intrigued by another …hedron shape.* Is it an Icoso…, a Dodeca…, or a Tetra…, they are all mumbo jumbo to me. I just want to make one, I don't want to learn the math. Maybe I should just go buy a Soccer ball and be done with it. Naaaaaaaaw. I want one made of wood.
> 
> ...


Hi, LJ's!

Here is info for You. In One place.


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## JoeLyddon (Apr 22, 2007)

rance said:


> *Truncated Icosahedron (without the math)*
> 
> *I am again intrigued by another …hedron shape.* Is it an Icoso…, a Dodeca…, or a Tetra…, they are all mumbo jumbo to me. I just want to make one, I don't want to learn the math. Maybe I should just go buy a Soccer ball and be done with it. Naaaaaaaaw. I want one made of wood.
> 
> ...


That site will put your brain out to lunch! LOL

Thank you.


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## waleedwaheed2013 (Mar 29, 2013)

rance said:


> *Truncated Icosahedron (without the math)*
> 
> *I am again intrigued by another …hedron shape.* Is it an Icoso…, a Dodeca…, or a Tetra…, they are all mumbo jumbo to me. I just want to make one, I don't want to learn the math. Maybe I should just go buy a Soccer ball and be done with it. Naaaaaaaaw. I want one made of wood.
> 
> ...


Hi dear , Thanks for your data , Can you tell me How to fixed them by glue.

Thanks
Waleed


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## Dark_Lightning (Nov 20, 2009)

rance said:


> *Truncated Icosahedron (without the math)*
> 
> *I am again intrigued by another …hedron shape.* Is it an Icoso…, a Dodeca…, or a Tetra…, they are all mumbo jumbo to me. I just want to make one, I don't want to learn the math. Maybe I should just go buy a Soccer ball and be done with it. Naaaaaaaaw. I want one made of wood.
> 
> ...


Nicely done!

I'd make jigs to get it into its final shape and then use CYA and let it wick in. Normal wood glue will just let things slip and slide, and you'd have a tough time getting it all together. I made a skeletal dodecahedron out of copper strips many years ago. Since I didn't have welding facilities at the time, I soldered it together. That made the patination process I used on it a little tough.

Even though I can do the math, the fixturing needed to make it a regular polyhedron is pretty tough.


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## waleedwaheed2013 (Mar 29, 2013)

rance said:


> *Truncated Icosahedron (without the math)*
> 
> *I am again intrigued by another …hedron shape.* Is it an Icoso…, a Dodeca…, or a Tetra…, they are all mumbo jumbo to me. I just want to make one, I don't want to learn the math. Maybe I should just go buy a Soccer ball and be done with it. Naaaaaaaaw. I want one made of wood.
> 
> ...


What is the finally of Soccer angels 20.9 and 18.7 or 20.733 and 18.334 .
Thanks


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## soccer2010 (Oct 1, 2011)

rance said:


> *Truncated Icosahedron (without the math)*
> 
> *I am again intrigued by another …hedron shape.* Is it an Icoso…, a Dodeca…, or a Tetra…, they are all mumbo jumbo to me. I just want to make one, I don't want to learn the math. Maybe I should just go buy a Soccer ball and be done with it. Naaaaaaaaw. I want one made of wood.
> 
> ...


I am going from memory on my calculations and I remember 20.905 but can't remember the other off-hand.


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## TonyTokyo (Jun 13, 2021)

rance said:


> *Truncated Icosahedron (without the math)*
> 
> *I am again intrigued by another …hedron shape.* Is it an Icoso…, a Dodeca…, or a Tetra…, they are all mumbo jumbo to me. I just want to make one, I don't want to learn the math. Maybe I should just go buy a Soccer ball and be done with it. Naaaaaaaaw. I want one made of wood.
> 
> ...


Hi Rance

Could ask for the sketchup file please? This is exactly what I have been scratching my head over for the last few weeks

Cheers 
Tony


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## TonyTokyo (Jun 13, 2021)

rance said:


> *Truncated Icosahedron (without the math)*
> 
> *I am again intrigued by another …hedron shape.* Is it an Icoso…, a Dodeca…, or a Tetra…, they are all mumbo jumbo to me. I just want to make one, I don't want to learn the math. Maybe I should just go buy a Soccer ball and be done with it. Naaaaaaaaw. I want one made of wood.
> 
> ...


I need to know what is the bevelled angle for the hexagons and Pentagon's please.


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