Parade Of Domes 2007/Whatcha Buildin'?

robotland · Post by **robotland** » Tue Jan 30, 2007 2:08 pm

Recent DOMES postings have awakened my curiosity regarding what's being built around town for '07....So? GIVE.

robotland · Post by **robotland** » Tue Jan 30, 2007 2:19 pm

Actually, I'LL start...Building a three-story structure, a rough replica of a Soyuz spacecraft at about 2/3 scale. It'll be the escape craft for the LabWerks station, part of Apokiliptika this year.
DOME TIPS '07, #1- I'm making custom internal hammocks for the structure, woven out of rope with mesh on top. Since they needed to be linked to the structure I installed threaded eyebolts at numerous vertices and the ends protrude outward, menacing the tarps. Solution? A trip to the dollar store yielded a bag of "practice golf balls", like teensy wiffleballs, that can be popped over the exposed ends after enlarging one of the holes. To prevent their escaping and subsequent MOOPage, simply run a zipstrip through other holes and around the vertex.

MikeVDS · Post by **MikeVDS** » Tue Jan 30, 2007 4:22 pm

We're doing a 40 foot dia. dome. Would like to do extra floor(s) but probably lack the man power to do that and everything else this year. We were thinking using cargo net for large portions of the extra floor. We already have a 20 footer.

Robotland, what are you using for the net? Are you making it yourself out of rope?

robotland · Post by **robotland** » Wed Jan 31, 2007 6:36 am

Yep. I started with 3/8" nylon rope and then covered it with a piece of "truck mesh" tarp and anchored the two together with lots and lots of zipstrips. I discovered that the best way to get exactly the right degree of "hang" (and for the tarp to play right) is to "compose" the net right out in the dome "in realtime". Ideally, while you're sitting in it so that you can see how the weight affects the layers. I picked up a book on knots that had a good section on making cargo nets, and used that as a guide. Think spiderweb-meets-cargo net. The finished "quintammock" isn't very large- It's for inside of a 6' diameter sphere- But I used 100 feet of rope pretty easily since it's knotted together so that there isn't a hole in it anywhere that's bigger than a CD case. No freakin' way anyone's falling through THAT sucker.
If you try this technique, don't forget to include your fasteners (carabiners or screw-links) into your calculations- Like macrame', you need to include the hanging rings! I also zipstripped the knots into place wherever possible, and made sure that the sharp cutoffs from the 'zips were all on the bottom.
A forty-footer would take major effort to weave a whole level for, but maybe you could enhance it with those flat plastic palates that groceries use for storing racks of baked goods...Rope 'em together, and then weave sections that reach out to the anchors!

thisisthatwhichis · Post by **thisisthatwhichis** » Wed Jan 31, 2007 6:53 am

We are thinking of 2 - 3/8 2v domes with 12.9 radius. What are your thoughts on strength (using 3/4 EMT)?

timburly · Post by **timburly** » Wed Jan 31, 2007 12:06 pm

Its our first attempt at a dome and the design is going to be a 4v 32 foot diameter floor. We're going to make this out of 3/4" EMT. I've managed to gather all the tools now just need to get the EMT and start cutting smashin and drillin. The neibors are going to think we're nuts when this thing gets test build on the lawn :)

MikeVDS · Post by **MikeVDS** » Wed Jan 31, 2007 4:51 pm

3/4 EMT can barely support my weight (230lbs) gently standing in the middle of a 4 foot length. We've had a few bend so far and all lengths are between 3 and 4 feet. 3/4 inch is not good for a jungle gym, but the structure strength of the dome is more than adequate. I probably wouldn't use more than 6 foot lengths with 3/4 EMT and if you go that far you have to be real careful about putting weight in the middle of the struts.

Post by **mdmf007** » Wed Jan 31, 2007 5:12 pm

Trying to build a small dome - there used to be a supplier of fittings for various frequency domes. These were just little brackets as big as a frisbee. They were intended to be used with bamboo of a uniform size.

I would love to build a bamboo dome, and found a cheap supplier, and was trying to find the brackets.

later all

MikeVDS · Post by **MikeVDS** » Wed Jan 31, 2007 6:27 pm

I may soon have access to 300 feet of 1/2" stainless steel pipe in 20' lengths. I'm trying to figure out something good to do with it if I get a hold of it. Any ideas? I could do a decent 2 frequency dome with it. A nice little chill spot, but since it's stainless I'd like to do more with it. Ideas?

BAS · Post by **BAS** » Wed Jan 31, 2007 7:03 pm

A jungle gym for adults? Painted in bright primary colors?
(Be certain to have some medics standing by, for those of us who get a little too far into trying to recapture our childhood!

)

B.

MikeVDS · Post by **MikeVDS** » Wed Jan 31, 2007 7:20 pm

Can't paint stainless. Might as well use normal pipe if you're going to paint it all up.

BAS · Post by **BAS** » Wed Jan 31, 2007 9:30 pm

Darn. Oh well-- I probably don't want to get airlifted out or anything, after falling off a jungle gym and breaking my neck (or something similar!), anyway....

B.

bobfj40 · Post by **bobfj40** » Thu Feb 01, 2007 8:33 pm

Well you can paint stainless as long as it is not to pollished. you are thinkng of the EMT that is covered in zink and you can still paint it but it does chip off. :)

Bob

MikeVDS · Post by **MikeVDS** » Thu Feb 01, 2007 10:43 pm

I was thinking that you can't paint it because it's a mortal sin to paint stainless, not that the paint won't stick. But painting EMT is a booger, but that dome of yours sure does look like a nice multi-colored jungle gym. I guess we can check that off the list, and still have some stainless to work with.

robotland · Post by **robotland** » Fri Feb 02, 2007 8:02 am

thisisthatwhichis wrote:We are thinking of 2 - 3/8 2v domes with 12.9 radius. What are your thoughts on strength (using 3/4 EMT)?

You'll have to settle for a "4/8" dome, I think, if you're going Frequency Two. Strengthwise, 3/4" will be FINE as long as the struts aren't over six feet and you place all loads at the vertices. It's been a while since I looked at the calcs, but it could bear consideration to make the domes a little smaller so that you won't waste short ends of each conduit. A 2V that's around 9' radius gives you optimal usage from sticks of 10' EMT- you need only about 35 sticks instead of one for each strut (65?) plus lotsa waste.
But you probably need to make bigger boobs than 18' diameter, given the expected popularity of your establishment. And a 9' rad is hard to get in and out of without either ducking a lot or opening up a few struts.

thisisthatwhichis · Post by **thisisthatwhichis** » Fri Feb 02, 2007 8:48 am

Yea, the more I consider it, 2V won't have the strength for that size. I'll need to work out some numbers for 3V. Stargeezer did some nice calcs on the BoobyBar thread.
Some of the waste I can use to strengthen cut outs in doorway openings. The rest, I'll have to come up with new projects for.....

PurpleKoosh · Post by **PurpleKoosh** » Fri Feb 02, 2007 12:47 pm

mdmf007 wrote:Trying to build a small dome - there used to be a supplier of fittings for various frequency domes. These were just little brackets as big as a frisbee. They were intended to be used with bamboo of a uniform size.

They're meant for 2Xn rather than for bamboo, but StarPlates sound remarkably like what you're describing. (One of these years I will have a vehicle of my own big enough to bring along the material to make one of these for my living space....)

robotland · Post by **robotland** » Sun Feb 04, 2007 9:29 am

I've seen those Starplates too- Thought they were designed for use with 2x4s. I've been trying to work out some hubs for conduit, like the ones made for playground domes in the Sixties, but in the end it comes down to having to make four, five or six mechanical connections at each vertex instead of just one.

DOME TIP #2
I've found that certain parts of my structures get used as steps, while others are left alone. As a results, some of the struts have gotten swaybacked and I've even had to replace one or two! Experimenting with ways to reinforce EMT from the inside AND outside, I have determined that sticking a length of rebar inside of a strut BEFORE squashing the ends will add considerable strength. Colorcoding them makes them easier to sort out from the strutpile, and gives a visual cue to potential climbers about which spots are safer to put weight on.
To add stability from the OUTSIDE, use two-hole conduit hangers to attach a length of 2x4. (Use at least three, fastened with drywall screws.) The flexibility of the wood strengthens the struts A LOT. This also gives you a place to fasten crossbeams for a deck, or to lay on a sheet of plywood. Remember that the clamped-on wood will rotate around the conduit!
Reinforcing the topmost five struts of a 2V dome with lumber, you can then fasten down crosspieces of 2x4 (with ends cut at 18 degrees) to make a deck capable of supporting numerous guests!

capjbadger · Post by **capjbadger** » Wed Feb 07, 2007 1:49 pm

Dome dreams are getting to the point where not even my nice 2 story dome (v1 stacked on a v2 (Starplate & Wood dome on a EMT dome)) is enough.

Ever wanted/needed to know what the wind loads are on your dome? Me too. Internet to the rescue! Found this great PDF all about it. The data for domes is page 7

http://www.aij.or.jp/jpn/symposium/2006 ... _main3.pdf