Building a "play dome"

[ellorbito]

Hi there Burners! Anybody have any ideas as to what frequency dome, and or thickness of tubing i need to construct a dome, that is strong enough to screw around on? I need to build a play dome for my camp and don't want it to collapse when the going get fun. (not as massive as Death Guild's T-dome)
Thanks.
Kisses and stuff.

[bm_cricket]

Hi there Burners! Anybody have any ideas as to what frequency dome, and or thickness of tubing i need to construct a dome, that is strong enough to screw around on? I need to build a play dome for my camp and don't want it to collapse when the going get fun. (not as massive as Death Guild's T-dome)
Thanks.
Kisses and stuff.

I built one last summer. It's interesting, sturdy. You can climb on it but it's not a jungle gym.

If you want to build a jungle gym then make it 4 times stronger than you think it needs to be and be sure to cover all the bolts with something really padded. I used 3/4" EMT. It's strong but it bends... If I had used 2inch EMT I'd feel a lot better about climbing on it. If I had gone into it to make a jungle gym I would not have used EMT at all, there are better, more sound, far more expensive items. Also, if you really want it to be structurally sound you need to get the sizes of each strut really accurate. The closer to a perfect dome it is the better it will hold itself together. Make sure that each strut is exactly the length it is "supposed" to be. For a big shade structure you may accept half an inch of slop? More? For something you want to build strong you want it to be exactly the right size.

I built mine for a camp sleep structure for 6 people. It worked well. I don't recommend it to anyone else. Will it be used exclusively for climbing all around on or are there any other uses? What general size are you looking for?

Short struts=strong structures!

[Bob]

Death Guild's dome is from Pacific Domes, look at their FAQ -- 3/4" EMT for standard domes, 1" for heavy-duty, 1-1/2" for extreme.

http://www.pacificdomes.com/

[bm_cricket]

Death Guild's dome is from Pacific Domes, look at their FAQ -- 3/4" EMT for standard domes, 1" for heavy-duty, 1-1/2" for extreme.

http://www.pacificdomes.com/

I stand corrected. All I know is that my 3/4" stuff is sturdy but I doubt it would be good for a climbing structure. None of my struts are over 40" which is probably why I feel okay about climbing on it at all...

[robotland]

My first big dome was the "default 2V", made from 3/4" EMT at the largest size easily cut from 10' tube lenghts with minimal waste...(about 18' diameter, give or take- Go to Tara's Desert Domes site for the strut calculator.)
Over the years I've experimented with various decks, platforms, suspended contraptions...I've even stacked two smaller domes on top of it, with plenty of load tolerance to spare! The critical element is to ONLY load the vertices (connection points) and NOT the middles of the struts- They will NOT tolerate the weight of a person without bending! One way around this problem is to "splint" any struts that need to take load by fastening a 2x4" to it with two-hole pipe straps, (at least three per strut) thus adding the flexible strength of the wood to the metal strut. I built a deck this way, splinting the struts of the entire top pentagon of the dome and then screwing down reinforced plywood triangles.
Another climbability solution is to scout the flea markets or scrapyards for old aluminum ladders and mod them to fit the curve of the dome by cutting and bolting back together at an angle. Fasten to the dome with more pipe straps!
Best advice- Build a dome and then try some load experiments!
Also try substituting eyebolts for regular bolts- You can then hang weight from your vertices with carabiners! GREAT way to suspend a hammock, or even a deck!
Also also- Cover some of the triangles of your dome with plywood and add indoor climbing handholds. Available in kits from big box home improvement stores, or at inflated prices from sporting goods stores and places like REI. (Or make your own!)

[trystanthegypsy]

Another climbability solution is to scout the flea markets or scrapyards for old aluminum ladders and mod them to fit the curve of the dome by cutting and bolting back together at an angle. Fasten to the dome with more pipe straps!
Best advice- Build a dome and then try some load experiments!
Also try substituting eyebolts for regular bolts- You can then hang weight from your vertices with carabiners! GREAT way to suspend a hammock, or even a deck!
Also also- Cover some of the triangles of your dome with plywood and add indoor climbing handholds. Available in kits from big box home improvement stores, or at inflated prices from sporting goods stores and places like REI. (Or make your own!)

The eyebolts are BRILLIANT! thank you for the fabulous idea! currently I just wrap webbing/straps around my vertices and clip to that, but this is effing brilliant.

*also I would like to defend the climbing industry by saying there actually is way more quality and design in most "official" climbing holds than the playground ones... but for this application it's mostly irrelevant..*

[illy dilly]

The over all design of Geo domes is extremely sturdy. The triangle design allows weight from any point to be spread down ward, while the members above provide tensile strength because their connected to the other side of the dome. (Similar to how on small spoke bike tires your axle isn't sitting on the spokes, but hanging from the spokes above). The strongest part of the dome is at the very top center, because all the weight is being distributed out and down, similar to a fly buttresses or the dome of the Hagia Sophia. The dome is one of the strongest designs around. And the 'A' frame-ish design created by the triangles is another very strong strucutre.
My concern would be that the bolts might be two small and the weight applied to the top of the dome might sheer a bolt near the bottom, were things are more vertical. I'd say spend the extra bit of money for larger bolts. My last thought is that keeping the EMT lengths shorter will make them less likely to bend. I can imagine the individual EMT rungs bending before the structure it self is compromised or deforms.
But these are all just my theories I've never seen a Geo Dome in a load test.

[Bob]

A 60-ft dia. covered dome w/ 3/4" EMT eggshelled in a storm back in 2000 -- ie, a huge concave dimple. I understand Pacific Domes upped most such domes since then to 1" tubing, and the Death Guild still probably has to fix dozens of bent struts every year.



Here you go, try aluminum.

Hey, it's for sale.

[capjbadger]

3/4" EMT will take a lot of weight, but like robot said, only at the junctions.



I built a 1 freq dome (made of 2x4s) on top of that with a base the same size as the top pentagon. The base dome is a 2 freq dome of "optimal" size for 10' sticks of EMT.

If you want to be able to climb closer to the middle of a strut, 1" EMT *minimum*.

-Badger

[robotland]

If you know WHICH struts might get climbed on, you can use heavier EMT for THOSE and default to 3/4" on the others*. Identify the beefier ones with paint, maybe. But you'll have to trust others to identify your system....
I've also tried sticking scrap rebar INSIDE of the struts before flattening the ends...moisture condenses in there, rusting the rebar which then pees rusty water on you when you move the struts around. *nasty*



*Until you get over 20' diameter, freq 2...then you might want to bump to 1" overall.

[robotland]

The eyebolts are BRILLIANT! thank you for the fabulous idea! currently I just wrap webbing/straps around my vertices and clip to that, but this is effing brilliant.

*also I would like to defend the climbing industry by saying there actually is way more quality and design in most "official" climbing holds than the playground ones... but for this application it's mostly irrelevant..*[/quote]

Nothing against the climbing industry...I'm just cheap.

I neglected to mention- Don't buy eyebolts that are too long, or you'll have to contend with them sticking out and ripping your dome cover. Wiffle balls are good covers for pokey ends!
If you're assembling your dome singlehandedly, those eyebolts can be handy for temporarily connecting those stubborn six-way junctions.

[falk]

I can tell you that 3/4 definitely will not NOT cut it. Anybody climbing on the dome will have to be very careful to only put their weight at the vertices. Stand in the middle of a strut and you'll bend it for sure.

1" *might* do for a climbing structure, provided the struts aren't too long.

[theCryptofishist]

Remember, only a grasshopper builds a "play dome." Ants build "work domes." Small children build "play do'."