robotland wrote:Hey, Bruce!
So: what flavor of deck wouldja like? My assumption would be a wooden one
Thanks for this amazingly fast and detailed reply, robotland! It's such a pleasure to be talking with someone who is as interested in this stuff as I am. Over the last couple of years I have had what was to me a new idea only to see that other folks had already done it... which is both encouraging and discouraging. I guess with the available materials and analytical tools out there we'd come up with the same results... in fact I was going to do something similar to what you did last year, complete with nested geodesic objects, net suspension, and deck!
Your description is amazingly clear and followable especially since you have no pictures! Very well written, and thank you again.
I also agree that a wood deck is the way to go, and my thinking on this so far has paralelled yours in many aspects: wood deck, top pentagon, wooden strut reinforcement, nesting another geodesic object to create stability and avoid buckling (less chance of this with a 2v dome, but mine is 3v).
My plans were also a little different in a couple of ways, but they mostly used all of the principles you seem to have already tried out...
Instead of creating a flat surface where there is only the pseudo rounded top of the dome I was thinking of building an inverted dome that intersected with the topmost pentagon-forming vertices of the first dome. Like what you described with your topmost sphere. The bottom of this inverted dome (call it a bowl) would be below the top of the base dome, and I was thinking of putting something like a long bolt or piece of 2x4 between the vertices at the top of the dome and the bottom of the bowl to make sure neither buckled.
I was going to use conduit clamps or something similar to attach 2x4's to the 5 struts that radiate out from the top vertex of the dome-- it's the best solution I could come up with, and I'm glad to see that you used it effectively. I was going to make my deck non flat, with the 5 triangles of the pentagon lying along the top of my 3v dome, which is not unreasonably sloped but enough so that I thought it would make folks a little more cautious, which would be good, I think. The rising edges of the bowl would provide a railing, though I didn't really want to close it off over the top and I suspected that I might have to have bracing that ran from the top edges of the bowl back to the dome top vertex. Your experience also suggests that this is necessary... thanks for sharing! Maybe I should just make the bowl a geodesic sphere that intersects with the dome, like you did!
I was also a little stumped about how to get the five 2x4's that lie over the top 5 struts of the dome to have flattened surfaces for board attachment (in much the manner you suggest). I was thinking I could cut the 2x4s with a good table saw, but talking to a friend who works with wood more than me suggested this might be difficult. I wonder if I can leave the 2x4's flat on top and just attach the floor boards with brackets underneath????
If you would like to send images to me directly (posting on the eplaya is a little bit of a pain) you can send to bscanlon AT sonic DOT net
There is a really excellent book that explains the mathematical geometry of geodesic domes and more importantly gives you the tools to create non spherical derived geodesic shapes. It takes a little patience to get through but it's pretty rewarding. It was out of print for 30 years and very difficult to find, but is back in print now. Geodesic Math and How to Use It, by Hugh Kenner. Amazon has it...
Thanks again,
Bruce
