# Geometric Shapes #1: Geodesic Domes

 Blog entry by rance posted 08-13-2011 06:55 PM 11409 reads 1 time favorited 24 comments
 no previous part Part 1 of Geometric Shapes series Part 2: Truncated Icosahedron (without the math) »

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. :D

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

-- Backer boards, stop blocks, build oversized, and never buy a hand plane--