Geodesic Question

[rexhex]

Hello Everyone!

Im planing on building a dome for my first burn. I talked to someone today who has build over 300 in 12 years, but he gave me some advise I would of liked not to of heard. He says I should not go with 3/4' conduit but rather 1". The price difference for these two domes is incredible. It basically doubles, and Im a college student...

So the question is. Has anyone built a 3v 5/9 dome with 3/4" conduit? How did that work out? Is it sturdy enough? and how big was your diameter? Im thinking about going 22' diameter.

All advice is greatly appreciated on any aspect on building this, as well as covering it for the weather of the playa. Its a big investment for me and I dont want to end up there with an inefficient dome, what a waste that would be.

Thank you!

[BBadger]

That "I'm a college student" line made me chuckle. It's not like you need to make the dome in the first place.

Anyway, a lot of people use 3/4" conduit. You just have to make sure it can bear whatever forces will be applied to it. You should probably consult the other geodesic dome threads on this board too, such as this.

[mudpuppy000]

I've never built one, but there's probably a reason why your friend suggested that size. It would suck to go cheap on it and have it wrecked/mangled after the first big storm.

If cost is an issue, you can always go smaller in diameter too.

[trilobyte]

I agree with your friend, I'd go with 1 inch EMT at minimum. If you're going to claim the college student poverty thing, be smart and skip the dome. It's your first year, you'll likely already be facing a ton of expenses/costs and logistical hurdles.

[rexhex]

You guys are funny about me mentioning I'm a college student. I guess it's not that relevant but it does make it more difficult to afford everything when your going to school full time. Thankfully it's a Jc so does not cost that much.

I'm hearing 3/4" works and that 1" is the best way to go. it would be great to hear why 3/4" does not work with some people.

Someone said not to make it and just experience it for the first year. I have more plans for it than burning man but thank you for the advice. It might end up just costing too much to get done this year, but I plan on working on it with hopes to finish it on time. I would like to experience the desert for a week with a comfy space out of the sun. I camped in the desert before for long periods of time but this place sounds like a solid home base is a nessesity.

Thank you all for the fast responses

[rexhex]

And thank you for the link BBadger, I'm running to class but will check it later.

[MrBeardy]

I built a 3/4 inch conduit dome, and it is really all you need, especially if cash is an issue. The only downside is if you climb on it you have to stay on the joins when climbing it, or it will bend. if you go the 3/4 route, or even with the 1 inch, I'd strongly recommend having a few replacement pieces in case something fails. I've hung a couple hammocks and a trampoline inside of mine with no issues (knock on wood). Have fun, they are a blast to build and your friends will certainly be stoked to have it out there!

[rexhex]

That's good to hear Mr. Beardy! Thanks!

[Rice]

There are many factors as to why you would want to go with the thicker conduit. For instance, what do you intend to cover it with? Are people going to climb on it? Do you intend to hand stuff in it that will have the added weight of a person or 5? Weather conditions: If there are 70 Mile per Hour plus winds, how will it fare?

It is better to over-engineer something to accommodate the extreme possibilities, than to under-engineer and have it fail... (The playa is extremely unpredictable!!)

Make sure that you anchor the crap outa it, whatever thickness you do decide to use. Maybe google "eplaya geodome anchoring" or something like that to ensure you can plan for what you really need.

[BBadger]

You guys are funny about me mentioning I'm a college student. I guess it's not that relevant but it does make it more difficult to afford everything when your going to school full time. Thankfully it's a Jc so does not cost that much.

Well is it really relevant for you to mention it either? That's what made me chuckle. It's fine and well to seek out cost-effective solutions; however, citing a financial situation in the context of an unnecessary expense -- even ignoring that it's for something like Burning Man -- comes across as kind of ridiculous. Anyway, I'm not going to pursue that subject any longer.

Something to remember with your dome (or anything that matter) is that unless you're planning on the object being destroyed/discarded, it'll cost you more to buy/build something cheap and have it break, only to replace it with the version you should have bought/built in the end. If it's too expensive to buy the version you should buy now, save your money until you can.

[GreyCoyote]

Your friend has it right. 3/4 inch is marginal in a 22 foot 3V 5/8 dome. Consider going to more struts, or a larger strut diameter if you can. Or fall back to a 3/8 3V (ugh).

You can work the load figures for yourself, but anything over a 4 foot long strut is going to start inelastic deformation at about 55 mph on a windward surface perpendicular to the wind. In a dome that would be your bottom layer of triangles, and deformation here will have catastrophic effects on the integrity of the rest of the structure. Winds on the playa seldom exceed 50 mph as a constant, but there have been gusts recorded well over 70 mph. So it matters. Your proposed dome design would be considered marginal in a hard blow. But many people have done it successfully. I prefer not to camp near those people.

You can somewhat compensate for this structural shortcoming by orienting the dome properly against the wind and providing an anchor at each bottom vertex, but in a real blow its going to get dicey. And the game is absolutely over if the door comes off on a windward side, the dome pressures-up, and it starts to float. Then its gone. Or it will shed the cover rather dramatically. Either way, it wont be pretty.

If you go with 3/4 inch, make sure you can quickly get the skin off the dome. Take the lee side down first, using ropes to pull it backwards over the dome. Then just bungie it to the base of the windward side until things calm down. If you do it the other way, the dome will try to lift and fly, or bend into an interesting shape. Leeward to windward results in good control and few surprises albeit at the expense of some muscle aches. And as the wind dies you can use the falling breeze to help pitch the skin back over the dome.

FWIW, a well built dome will be largely immune to anything the playa can throw at it. Monkey huts, hexayurts, tents, and even RVs will be long gone before a well engineered dome gives up.

[rexhex]

Thank you Rice, BBadger, and Greycoyte for giving me all this advice. Really it is good stuff. Greycoyote your last paragraph is what makes me want to build one. Mr. Fuller was very smart and I love his designs. I am very excited to replicate something he has invented. BBadger, It may be for "something like BM", but its something that I would like to make happen. With that said anything is possible and I plan on making it to the best of my ability. I have learned from this forum post its best to make it with the proper materials. That i shouldnt cut a few hundred $ because its not going to be worth it when it all comes down to it. I will find a way to make it all work out and i will see you all on the playa but until then, eplaya it is.

thank you all again for your advice, I really do appreciate it.

-Rex

[MrBeardy]

Also dont forget to wrap every bolted area with fabric or something soft, otherwise your cover will snag and likely rip on on of them in high winds if it isn't made of something super strong. i used a sail as my cover, so this was essential. Some sail tape or something similar might be handy to have too for any small tears that develop through the week.

[DoctorIknow]

Your friend has it right. 3/4 inch is marginal in a 22 foot 3V 5/8 dome. Consider going to more struts, or a larger strut diameter if you can.

GreyCoyote seems to know his stuff, and if I'd done research, I never would have made a 4 frequency 25 foot dome out of 1/2" EMT, but it has been thru four burns without a problem (except when someone put their foot in the middle of a strut.)

Maybe I've been lucky as the covering is shade material (a combination of snow camo and aluminet) so forces on the structure must be less than what GreyCoyote has figured.

I do stake it down with 18" candy cane rebar in about six places.

I enjoyed pounding down both ends of 250 struts with a 3lb hand sized sledge, but if you are in college, you should know EVERYTHING about making a dome takes a LOT of time. And if you have to hunt down a tool to cut the pipe, hydraulic press for the ends, and find a drill press, and a way to grind down razor sharp refuse at the ends, and then the complete time suck of making or getting a cover....well, like others have said, for your first year, maybe no.

I would suggest you fabricate a nice shade structure for your tent. Even that will take more hours than you can imagine...

[Stickygreen]

I own a 32' 4V dome that's made from 3/4" conduit, and I regret not making it with 1" The bars tend to bend ever so slightly, and if there is any kind of unforeseen force, like some random raver climbing on it it can have destructive effects. Just last year at our Summer Regional event, the dome got wrecked, by climbers. 60 struts were bent. Thats alot of work to replace those..

Go with 1" you will have a very well built structure that will last you a long time.

[Martiansky]

I built a 16', 2V out of 3/4" conduit dome for my burgin year in '05.(the only year ive gotten to go so far)
I used the dome calculator on desertdomes.com
Each stick(40 if my memory serves correctly) of conduit needed to be cut only once, so there was no waste.
I used a billboard vinyl for the covering(got it for free). I cut it and sewed it to fit.
I do wish I had made it a 5/8 instead of 4/8, but it works just fine as it is.
Its plenty big for a couple people and gear.
My dome isnt made to climb on, its a shelter only.
I did hang a hammock from 2 low vertices and it held just fine.
I also used rebar bent into candycanes to stake down the frame in several spots.
The biggest cost was the conduit. Right now I think 3/4" is running around $3 each.

If I were to build a larger dome(I wish) I would definately go with 1".

[GreyCoyote]

This is a stale thread now, but whatever. Someone may find this useful in the future.

Today I had an occasion to do the math for a 30 foot diameter dome being loaded at various wind speeds. I know the O/P was talking about a 22 foot diameter dome, but the table below will give you some feel for the loads. Scale up or down as necessary for your particular dome.

When you look at the chart below, remember that playa winds can blow 40-50 mph sustained, and that gusts into the 70+ mph zone are routine.
---------------------------------------
Parameters:
30 foot diameter dome @ 15 feet high
Wind is parallel to ground. Laminar flow assumed.
Drag coefficient : 0.8
Cross sectional area : 423 sq ft

10 mph = 86 lbs
20 mph = 345 lbs
30 mph = 780 lbs
40 mph = 1383 lbs
50 mph = 2160 lbs
60 mph = 3110 lbs
70 mph = 4234 lbs
80 mph = 5529 lbs
90 mph = 6999 lbs
---------------------------------------

Before you decide which conduit diameter is appropriate for your dome, try to imagine hanging a full-sized car from it. This is the kind of load you will be looking at as the wind hits 70 mph.

I would also remind builders that dome failures are rarely of the "creeping" variety. Failures tend to be immediate, and catastrophic where the structure implodes or violently deforms when the failure point is reached. There is a lot of energy concentrated in a dome during a high wind, and this energy does not behave in a predictable manner once failure begins. You don't want to be in it, or near it, or down-wind from it, when it fails.

[theCryptofishist]

This is a stale thread now, but whatever.

A week just represents a quiet time to assimilate and build on the ideas in a thread. Especially a meaty one. This thread is nowhere near stale.

[EspressoDude]

DO NOT treat wind loads lightly..Give them a lot of respect. A few years back we watched wind come up and start to move a dome that was at about 7:30 and Esplanade. The only way to keep it from flying was to crush it with one of the high lift front end loaders..

[GreyCoyote]

DO NOT treat wind loads lightly..Give them a lot of respect. A few years back we watched wind come up and start to move a dome that was at about 7:30 and Esplanade. The only way to keep it from flying was to crush it with one of the high lift front end loaders..

2009 perhaps? IIRC, this was a 30 foot dome, essentially unanchored, that tried to float and skitter during setup (EA time?). If so, I remember that one. It was a bit of a rash action on the part of the lift operator, but that was still a lot better than having a dome go through BM like a frisbee.

The lesson here is "Stake 'em". Or at least make the covers so they can be dumped VERY quickly and with minimal effort. Better to chase a harmless cover a few dozen yards than deal with a wandering dome.

[AbundantChoice]

Better to chase a harmless cover a few dozen yards than deal with a wandering dome.

Oh man, imagine a tattered "wandering dome" MV that looks like it's rolling across the deep playa...

[BurnerBunny]

after a lot of desire to build a dome myself and then tons of research, the price and difficulty of making a dome lead me to choose to make a hexayurt.

How many people are you building this dome for? There are many hexayurt options that are super cheap and could meet your needs with less hassle than a dome.

[what time]

Sup everyone!

This year we want to recreate our Indian chill using Geodome as a base, so I’ve got some questions to anyone with dome installation practice:
I want me to have all the new knowledge, and all that I want to get away from Geodom. I want it to be possible, to be comfortable, and all options are thought out how to make it enjoyable to use.

* What the best color of outside cover? White? Mirrored? How hot will be inside in different cases?
* How many AC/person?
* How many fans/person?

*How many pcs Centrifugal Big fan
If I put Solar Centrifugal Fan size 350x360x285
And I think about
Fan work with cold water 340 W (new more for fun)
Can you tell me who have practice, what more better for geodome?
I want to attach a photo below as I would like to use a fan

We are trying to decide between full and not-full cover, want to do full one so much..

Geodome diameter 20m (~66ft)

And one more thing: 3500kg container with all the stuff including the dome will be shipped from India by air/by the sea - , could it be any kind of problems with the dome on customs?

[Ratty]

Customs can be a problem. Last year one of the art installations didn't clear customs. You can't predict what they will hold.

[some seeing eye]

Sup everyone!

This year we want to recreate our Indian chill using Geodome as a base, so I’ve got some questions to anyone with dome installation practice:
I want me to have all the new knowledge, and all that I want to get away from Geodom. I want it to be possible, to be comfortable, and all options are thought out how to make it enjoyable to use.

* What the best color of outside cover? White? Mirrored? How hot will be inside in different cases?
* How many AC/person?
* How many fans/person?

*How many pcs Centrifugal Big fan
If I put Solar Centrifugal Fan size 350x360x285
And I think about
Fan work with cold water 340 W (new more for fun)
Can you tell me who have practice, what more better for geodome?
I want to attach a photo below as I would like to use a fan

We are trying to decide between full and not-full cover, want to do full one so much..

Geodome diameter 20m (~66ft)

And one more thing: 3500kg container with all the stuff including the dome will be shipped from India by air/by the sea - , could it be any kind of problems with the dome on customs?

Our camp built a 65' 5/8 one in 2004. We used a crane to erect it and to put the cover on. If you put a vent on the top and have several panels out at the base it just becomes a shade structure, no cooling necessary. It is very important to have many exits on all the sides of a large dome for people to exit safely in an emergency.

We had a vinyl cover made in China, I don't know the source. The other approach is to use "boat wrap" or "construction wrap" which you shrink on with a very wide blowtorch while maneuvering yourself on a "cherry picker" lift. That is a single use, you would have to cut it off and take it to the refuse dump about 100 miles away. The best cover is Dacron or other sail cloth. Some years you will see Dacron covers that have been ink jet printed before they were sewn.

There is only one active commercial manufacturer of domes I'm aware of and they are based in Ashland, Oregon. They do a structural analysis on their domes, which the Burning Man organizers could demand to see. If you really want to actively cool a dome that big, that commercial dome maker would be experts.

[what time]

Customs can be a problem. Last year one of the art installations didn't clear customs. You can't predict what they will hold.

Thank you, we will try

[LowePro]

You can save money and materials with a 2v dome. (Longer but fewer poles.)
We use a 2v at about 30ft diam. The bonus is that the 10ft long poles from the store don't need to be cut down at all. You only have to cut the shorter struts.
The bummer is you need a larger vehicle to haul the longer poles.