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2004-03-16 04:59 pm![[personal profile]](https://www.dreamwidth.org/img/silk/identity/user.png){kind=small}
archershipsI'm contemplating building a geodesic dome gym out of 1" galvanized steel pipe (the kind used for plumbing). There are several sites on the web that describe building geodesic domes out of pipes ( many of the domes are used for Burning Man). Most of those domes are made using either 1" - 2" diameter galvanized electrical conduit or PVC. Although conduit can be quite strong (strong enough to support human weight), I don't think it would be strong enough to support jolting forces, particularly from large heavy weights. Therefore, I'd like to use steel pipe. However, the hubs used for conduit framed domes are formed by smashing the ends of the tube flat, and drilling a hole through it. I don't think that would be practical with 1" steel pipe (although I may be wrong). A fairly extensive search of the web doesn't reveal any sources of hubs appropriate for steel pipe geodesic domes -- anyone have any suggestions?
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Date: 2004-03-17 06:18 am (UTC)i think we're building a single, larger dome this year.
maybe consult
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Date: 2004-03-17 06:49 am (UTC)no subject
Date: 2004-03-17 03:32 pm (UTC)They're great! Amazing! Frustrating! Inflexible! Impractical!
A lovely idea /nobody uses anymore/!
;-p
truly ... fill your boots; you'll enjoy it as long as you don't have romantic expectations; all those cranky angles are /such/ a /total/ pain in the ass ...
HeyHo
:-)
What everyone else said
Date: 2004-03-17 04:13 pm (UTC)For corners, rather than trying to crush the ends of pipes, how about pentagonal plates cut from 1/4" steel? Find someone with a plasma cutter, if you drill the holes right you probably don't have to do any bending, just let the bolts take up the slack.
Or, if you're going for a permanent structure anyway, consider one of the concrete spray construction techniques for domes and get away from the corner issue altogether.
Re: What everyone else said
Date: 2004-03-18 06:25 am (UTC)What I'm contemplating will be a jungle gym/weight training arena. I'd like to suspend heavy weights (300 - 600 lbs) by ropes from the ceiling, which may, at times fall abruptly several feet. Although the joints of a conduit could almost certainly take it, the spans may not. I don't want to have to worry about where I attach the rope.
I think you're suggestion of using pentagonal plates is probably the most workable. I haven't heard of a plasma cutter before--thanks for the suggestion.
Re: What everyone else said
Date: 2004-03-18 05:40 pm (UTC)It's probably a slightly smarter breed of spectator, you don't survive long on heights at Burning Man unless you know not to jump on the middle of the bars (besides which, even if the hardcore punks think the Death Guilders are pansy-ass goths, they'll still kick your sorry drunk butt if you break their arena), and I don't know if this is 300-600 lb training weights, but it can certainly be 200 lbs * 2 (or more?) of extremely dynamic weight. See some of the battle pics from 1999 for a quick overview, and that was a 45' dome.
Re: What everyone else said
Date: 2004-03-18 08:23 pm (UTC)Yep, f=m*a
Date: 2004-03-19 05:01 pm (UTC)Something else to consider is how prone to cracking and brittleness the 1" steel pipe might be. That old conundrum of stronger but stiffer materials making the total construction weaker. Maybe building a single face/pentagon out of a couple of different materials, building a frame to hold it in place, and subjecting it to assorted stresses to see how the various materials work would be a good starting point. If you can drop a quarter ton onto a pyramid made from each of several different materials, that's probably worth any number of discussions and simulations.
As you design the dome, also remember that the higher order the dome the less margin for error you have in your joints, and the more prone your faces are to inversion if you have such error. I first ran into this in my first order (all lengths equal, 20 sided as a complete shape) domes where I splayed the legs to get a little more space and (I thought) make the whole shape more stable. One big gust and inverted side later I was revamping the thing.
Just thanks.
Date: 2004-03-17 06:06 pm (UTC)Re: Just thanks.
Date: 2004-03-18 06:22 am (UTC)no subject
Date: 2004-03-17 07:21 pm (UTC)I'm betting you could find quite a few different things either at your basic big box with a gardening center or at an architectural salvage yard.
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Date: 2004-03-18 06:19 am (UTC)no subject
Date: 2004-03-17 11:09 pm (UTC)You don't think? I think domes made out of "standard" materials are a lot stronger than you think. I've seen domes with 30 people climbing and jumping. Do you need it much stronger? Do you know anyone at thunder dome (death guild), the thunder dome dome is terribly strong, I would ask someone over there.
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Date: 2004-03-18 06:21 am (UTC)What I'm contemplating will be a jungle gym/weight training arena. I'd like to suspend heavy weights (300 - 600 lbs) by ropes from the ceiling, which may, at times fall abruptly several feet. Although the joints could almost certainly take it, the spans may not. I don't want to have to worry about where I attach the rope.
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Date: 2004-03-18 03:57 pm (UTC)I have some good friends who're working on next-gen dome designs, I'll fwd your question on to them. I'm actually trying to find and/or make a new joint design for a spline-based structure for this year.
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Date: 2004-03-18 08:24 pm (UTC)no subject
Date: 2004-03-19 03:21 am (UTC)