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Have a pile of 2x4's, and a while before you use them?
Well, if you don't cut them, or use fasteners or glue, they will still be usable in a new project after trying these projects.
The dome was more than 30 feet across. Note that the dome is NOT a geodesic dome, it is actually a lofted tiling. (Which is why it is so flat.)
The bridge supported two adults of my weight, and that of several children, at the same time.
If I were to do this for something permanent, I'd want to bolt the pieces in place at the places that they cross.
Well, if you don't cut them, or use fasteners or glue, they will still be usable in a new project after trying these projects.
The dome was more than 30 feet across. Note that the dome is NOT a geodesic dome, it is actually a lofted tiling. (Which is why it is so flat.)
The bridge supported two adults of my weight, and that of several children, at the same time.
If I were to do this for something permanent, I'd want to bolt the pieces in place at the places that they cross.
One could inverse the junctions to make a bowl shape, but there is not (to the best of my knowledge) any way to do the vertical sides needed to join the dome and the bowel without needing something more than gravity to hold it together.
But, now that you mention it, a "flying saucer" shape would be possible, but I've not done an engineering analysis of it. The lower section would have twice the strain, and therefore would hit the size limits much earlier, but I don't know the limits would be. (Nor can I see an immediate way around some assembly issues.)
The current dome by adding cells to the edges of an original cell. So it was always a dome during construction, and I had freedom to put the legs anywhere. I can't, right off, see what the partly constructed version of the saucer would look like. [I think I'd have to prop parts up during construction to make it work right.]
If I had to mate it to a lower half I'd have less freedom of where to put each leg, and I have my doubts of whether or not I could be accurate enough to pull it off.
But those all had at least somewhat elastic materials. I'll have to think about how it would work with something as non-flexible as 2"x4"'s.
http://en.wikipedia.org/wiki/Stick_bomb
Can you make 2x4 bomb?
i seen a full sides one at his exhibit, maybe your his reincarnation
Do you have a pointer you could share to where this was found?
And no, I'm definitely not his reincarnation.
Here is the PBS program documenting the design from a 900 year old painting.
http://www.pbs.org/wgbh/nova/lostempires/china/builds.html
I recommend the link. And it also shows how they put a deck on it, which is something I'd not tried.
Note that because 2x4's are proportionately skinnier than the logs that are used in the Nova program that the link points to, my bridge that holds our weight is a lot flatter than what they constructed. (Although the first picture below has an arch closer to what they used... but if weight is applied it drops down to the same as the other)
The same basic bridge design exists in 2000 year old bridges in China also.
Here is a picture of starting another bridge we did that afternoon.
It may make it clearer how it works.
What they get my cutting it is that they can have much steeper ends.)
It is clearly the same arch.
I've seen this as a 1000's of year old Chinese or Japanese bridge also,
but I've not been able to find it on the net. (But
http://www.pbs.org/wgbh/nova/lostempires/china/builds.html
Was this just an exercise in making something without fasteners, or do you have a use for this kind of lofted tiling?
I have used the square cell version of the dome for a grape trellis, but not for anything else practical.
Here is a photo of the square celled dome.
Note that all the supporting legs are on a rectangle... So if you build a raised rectangular frame over a picnic area, and build the dome on that, you can cover it nicely. (I never actually bolted the one I used... and after a year the grape vine itself started to hold it steady.
The important thing to notice here is that, unlike the hex dome, none of the 2x4s are anywhere near their engineering limits.
Therefore this design is a MUCH better choice than the hex dome if you plan to put weight on it. (Such as I did when using essentially the same design for a grape trellis)
*BUT*
But you'd want a lot more overlap on the joints if you were to have people under it.
And I've not undertaken an engineering analysis of the weight of the water pooled in the middle of each cell... How tight you you put it on would make a difference.
But any tiling with equal length edges, and edges meeting at intersections of three or more edges, with no angle greater then about 60 degrees, can be turned into one of these domes. The four sided cell dome below shows how to join four edges at a junction. I assume that how to join more is reasonably obvious. But joining more than about 6 at a junction poses practical issues.
Note that these don't have to be what are called "regular tilings". Turning children with stir sticks to the task of design usually gets me some nice irregular tilings.
Certainly makes for a bit of fun, I'll have to have a fiddle next time I get my hands on some.
The sticks are fussier because they don't have as much friction (compaired to weight) as 2x4s, which will mostly just stay where they are put.
I've started eight year old kids with sticks in the house, and then a few hours later they've been able to build the same structures, full sized, outside.
Just remember that stir sticks bend better than 2x4's, so limit yourself to structures that don't involve bending.
But, if you just get into making small structures WITH bending, but without fasteners or glue, there is a lot you can do also.
What features are you having trouble seeing? Are you talking bridge or dome?