Geodesic domes made simple
buildwithhubs.co.uk
buildwithhubs.co.uk
If you have woodworking skills (and table-saw, chop-saw), it looks like a no-brainer. For better or worse, the guy goes on a long time about the template/jig he creates — its utility become obvious later when he begins to make the panels.
I've built on with hubs and it worked ok, we used thin plastic to cover it overlapping two panels on the horizontal seams but that is rather wasteful in material and allows less light in.
Right. The "natural materials" people ruined geodesic domes. Buckminster Fuller wanted the parts produced in factories, with tight tolerances, and assembled on site. Radar domes in northern Canada and Greenland were built that way in the 1950s, from aluminum and Fiberglas parts, and many are still holding up, abandoned and facing high winds and snow.
The hippie era wood framing with shingles approach works far worse. It's so bad that the author of "Domebook 1", etc. told people to give it up.
[1] https://www.radomes.org/museum/parsehtml.php?key=IceCap1Gree...
https://www.motherearthnews.com/sustainable-living/renewable...
That's the kind of engineering that should be applied to domes.
Edit: this idea could be easily executed with carbon tent poles and a nice waterproofed canvas tarp over the top. A portable, easy to build and durable DIY building more substantial than a nylon tent.
There’s some disadvantages though. A flexible structure is not always desirable. Bamboo (or an equivalent replacement) isn’t available everywhere. Also, flat-line domes are easier to cover with flat inflexible materials like wood panels. In short: if you have access to Home Depot and no access to bamboo, flats might be easier for you to build.
In on extreme, you can either aim panels for optimal daily production (minimizing panel count) and buy more batteries, or aim extra panels at the horizon so that you don't have to store as much electricity for peak times (minimizing battery count).
In practice, something in between the two extremes probably makes the most sense, though most installers err toward minimizing panel count these days.
"Household power usage peaks at dusk and dawn" is true for households on average, during average (normal) conditions. If your energy production is optimized for the average case, you'll face problems when your household schedule changes. Say you take a week of leave to do some home improvements, or everyone in your house is down with a flu, etc. - suddenly, your power usage might become flat, or have more and bigger peaks during the day. It's not a big deal if you're just selling to the grid, but if you're relying on your own solar power, it's now something to plan around - you lose lifestyle flexibility.
At larger scale, if everyone has their solar installation built based on this "working household" assumption the transition from fossil fuels towards renewables turns the "two peaks" phenomenon from something that sort of happened on its own, into something people are being forced to follow, because of energy availability. Optimizing solar panels for morning and evening load suddenly stops following a preexisting pattern, and becomes the cause of it.
For both of those reasons, it's best to overprovision panels or batteries (or both), or, where possible, install the kind that follows the Sun.
EDIT: They do appear to make "simplified" 3D models available for download from their hub-part-specs pdf. I suspect with a high layer height like 0.3mm you could print replacements. I understand why they don't advertise this though.
That being said the glass transition point of ABS plastic is 105'c, a little over boiling. I'm not worried about ABS from a thermoplastic perspective, although I am worried about long-term UV performance. I'd also be worried about thermal cycles and plants/mold as most 3D printed ABS will take on water.
I think you'd get a few years out of an ABS plastic component in these circumstances, more if you resin coat it or use acetone vapor smoothing, and start with a filament that has good UV resistance.
Either way I expect 3D printed components to be more expensive and otherwise worse than one manufactured by this company, but being able to repair stuff like this if you need to is important and it's not like you can just go to the hardware store and get a replacement one of these hubs.
By entry-level I mean able to be printed on the everymans Ender 3, <$300 printer with little expertise. There are of course dozens of exotic filaments you can print on a slightly more advanced machine and even that can be done for pretty cheap, <$500 perhaps if you have the expertise to upgrade an Ender and tune it properly.
The benefit injection molding has over printing in this case, is these parts might want to be redesigned to reduce sheering at the layer lines on the peg things.
I've had a greenhouse melt nursery pots left in it and they're made out of polypropylene, which has a glass temp 50C higher than ABS.
EDIT: the glass transition point of PP is -25C, vs ABS's 105c. I think you confused glass transition point with melting point, they're very different things. I think polypropylene will always be a bit soft, and will hold a shape that it's deformed into, it it hold that shape long enough.
I don't think it should be too surprising that 3D printing filaments can withstand similar characteristics to other outdoor plastics. One commonly used outdoor plastic is PVC which has a glass transition temp between PETG and ABS: PETG: 80c, PVC: 85c, ABS: 103c. If you left a PVC pipe in your greenhouse you wouldn't expect it to deform.
As for 3D printing, I guess ABS could work (PLA can melt or become soft in the sun), but I can't imagine a hobbist grade printer producing a part that is comparably strong. The option would still be nice, though. Maybe you just need a prop for the theater, where weather is a non-issue, and being able to replace parts quickly is more important than longevity.
https://www.youtube.com/watch?v=thOifuHs6eY
Hexagons, Pentagons, and Geodesic Domes
http://mathtourist.blogspot.com/2010/06/hexagons-pentagons-a...
Introduction to Hexagonal Geodesic Domes
https://www.strombergschickens.com/blog/starplate-building-s...
How much maintenance do you do on the wood in your current house?
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A slight tangent, but check out the demo carbon-fiber strut work here: https://dragonplate.com/carbon-fiber-truss
> The truss measures 8 feet long, 16 inches high with a depth of 12 inches. This is just one of many structures that could be easily built using our square tubes and gussets. Weighing in at just 14lbs., the truss is light enough for a six year old child to lift and carry!
They show that: a cute kid holding it up, no problem. Then they load it up.
> ...we loaded it with 35 80lb. bags of concrete mixture, totaling a whopping weight of 2800 lbs.! Again, we saw no signs of weakness or flexing. We would have put on more bags, but we just couldn't stack them any higher!
We could cover whole cities with domes...
the trillium domes that someone shared is definitely the 'nicest' version I've also seen loads of other 'hub' designs. personally I think zip tie domes are really interesting, seem the cheapest: https://www.ziptiedomes.com/geodesic-dome-hub-kits/index.htm
but seeing this just gave me an idea for a really simple hub design that would potentially be more sturdy than these single screw attached, plastic socket hubs.
what if the hub was simply a pentagonal puck of wood, and the spokes are attached with hinges? the complicated part of building domes is getting the angles right and using hinges mean you really only have to get the distribution of spokes around the hub right and the hinge will naturally fall into the correct angle? anyone got any land I can try to build this on?
No hubs, it's all 4x8 sheeting and long straight cuts. This one was taped together, but it could be plywood and screws as easily.
[0] https://colaborativa.eu/blog/2015/09/domenico-iterations/
For end-grain I find estimates of 75% stength on average expecting considerable variation joint-to-joint, assuming proper pilot holes have been drilled. If the hold scales with the diameter of the screw, then a larger screw might compensate.
The square of the wood's specific gravity might dominate differences:
https://www.engineeringtoolbox.com/wood-screws-allowable-wit...
Also, what is the pull-resistance on the snap joints themselves?
Indeed, their gallery shows a good fraction of examples doing so.
They feel nowhere near as big as their square footage listing. Our target square footage of 2500-3000 square feet required an equivalent of 4000 geodesic. The smallest one was 2700 and it felt downright tiny. Their round nature makes room partitioning awkward and unless you purposefully put ceilings on rooms at the top level, you’re going to have situations where the master bedroom opens up to the kitchen via the roof.
It had 4 pine trees fall on it during a “microburst”. It ended up deformed and some of the tubes bent but it held up pretty well considering the impact.
(Note that I'm not an architect, but neither was Buckminster Fuller).
Main difference is that on a flat surface the dome weight is distributed across the base "automatically". If you just "copy-paste the default flat-terrain dome" on a sloped terrain, the bottom vertices might end up supporting more weight than the top ones. This might be ok for small/temporary domes. For something bigger/more permanent, you might want to "cut the sphere" in such a way that the weight distribution is as uniform as possible.
Also keep in mind that even on a flat surface geodesic domes a foundation - for example so that they don't fly away when there's strong wind. This would go double in sloped terrain.