Everyone loves domes- ESPECIALLY kids! The devil in their construction however relates to visualising their assembly (often not easy - even for adults!),organising cost effective materials and securing the struts!
Here's a simple 1V version that uses bamboo slid into black garden irrigation hose offcuts. These are (single) gutter bolted at the hose overlaps -the structure is both rigid & quickly dismantled for storage. All 24 struts are of identical length & thickness.
Step 1: Big Kids - Smaller Kids!
Never mind BIG kids- this Instructable is intended to stimulate youngsters! Aside from supervision, adults are only really needed to hold struts at the highest point (& to ensure concept lollies are NOT over indulged in!)
Step 2: Dome Features
Geodesic domes are a 20th century idea,being essentially the brainchild of American Buckminster Fuller, who enormously popularised their "do more with less" nature in the late 1940s. Refer "Bucky's" ideas => www.nices.com/RBFwords/ Numerous DIY dome designs have evolved,with their modern use at "Burning Man" gatherings particularly iconic (see => www.desertdomes.com/index.html ).
* Compared with rectangular buildings a key dome feature relates to their numerous triangles,which resist stress and greatly strengthen the overall structure, yet make it lightweight. Many dome designs however are intricate & may use struts of varying lengths. A few wonky struts or weakened joints can jeopardize the entire structure,much as happens with a cracked egg shell!
* Recall that a 2D circle contains the most area for the enclosing perimeter? A 3D dome,being near spherical, has the property of enclosing the most internal volume for the external surface area. Aside from reduced cladding costs, this feature is particularly valuable when thermal losses/gains need considering.
* Dome wind resistance is far superior to regular buildings - a particularly valuable atrribute for exposed positions (dome tents, hill top radar stations etc). See =>www.ecocamp.travel/Domes
* Snow loading & shedding abilities are greatly enhanced. The classic South Pole dome lasted ~40 years, and although it's base became well buried the "roof" remained clear. See =>.http://graphics8.nytimes.com/images/2009/11/10/science/10dome-span/articleLarge.jpg
* Rain accumulates at the dome base,requiring low level guttering which -although easy to clean!- may be unsightly.
* Human feelings of embracing security,along with novelty and expansiveness,often arise. "Roof" windows give privacy and may bring in valuable daylight & offer entrancing views of trees,birds,hills,clouds, sunsets,stars & the moon.
Although ideal for exhibition halls or short term events, dome homes however may have issues accomodating normal furniture & appliances, efficiently using small building sites (circles don't nest together well!), accessing utilities, providing regular windows & doors, circulating air or internally partitioning for privacy. As one user concluded "they're smart but not wise..."
Refer further dome insights => http://en.wikipedia.org/wiki/Geodesic_dome
Step 3: Traditional Kids Domes
This rolled news paper dome looks appealing (& suits older kids "technology challenges"), but it's assembly would be well beyond the pictured user... Construction would probably take adults many hours in fact, & it'd not lend itself to dismantling.
Step 4: Simplest Dome
The basic 1V icosahedron dome appeals for it's simplicity & unformity. The main materials needed are-
* 24 equal length struts (we've used 750mm long bamboo struts, but ~1m gives better headroom?)
* 11 securing points (irrigation hose offcuts,joined in "star" clusters with a single bolt,are used here)
Credit to https://www.jovoto.com/projects/300house/ideas/12565 for this lucid graphic !
Step 5: Visualising the Design
To aid in planning (& of course to foster kids attention) you can't beat toothpicks & winegums to make dome models. These suit more ambitious designs as well
Step 6: Lolly Model to Full Scale
The approach used here involves short lengths (each ~150mm) of thin walled 1/2" black garden irrigation hose to socket the bamboo struts. Such cheap hose is often discarded after garden jobs, but any small holes are of no issue for this dome application.
Note- the hose is normally very cheap, but irrigation fittings themselves can be quite costly. Unless you have an ambitious application in mind avoid hence using such "X", "T" & joiners.
When neatness,versatility and strength are important using such fittings can be justified however -refer my 433 MHz tape measure antenna Instructable =>www.instructables.com/id/433-MHz-tape-measure-antenna-suits-UHF-transmitte/
Step 7: Bamboo Strut Selection
Bamboo freely abounds in many parts of the world, & it can also be purchased cheaply at garden centres. Select diameters around 11mm that will neatly slide into the black hose "stars" of course- perhaps take along a hose offcut for trials. Note: Although it can be fattened up with masking tape, try to avoid any bamboo that is too thin as it may slip out or break.
Cat "Molly" shown on strut quality control duties.
Step 8: "Star" Joints
Unlike normal reinforced garden hose, this thin walled low pressure type is flexible & readily flattened. A centred drilled hole allows a single bolt (30mm x ¼ inch suggested) to secure strut overlaps into the 4 or 5 armed "stars". These nicely hold & strengthen the dome struts, and the structure looks clean and attractive. The following steps show the "star" making technique-
Step 9: Hose Cutting
The irrigation hose cuts readily, but it's best that an adult does/supervises this step! You'll need enough hose offcuts (with each about 150mm long) to make 5 x "4 stars" and 6 x "5 stars". All up hence 20 +30 = 50 hose offcuts will be needed - best make a few extra of course! As 50 x 150mm =7500 thus 7½ metres of hose are required for each dome- it doesn't need to be a continuous length of course.
In NZ this hose is usually sold in 20m rolls, so if you make ech hose offcut a shorter 130mm, then enough offcuts for 3 domes can be made + a few spare! . (130mm x 50 offcuts x 3 domes = 19500mm = 19½.metres, with. 500mm left over = enough for ~ 3 extras)
Step 10: Hot Air Gun Tab Creation
Use a hot air gun to heat the hose end, then flatten it (under a piece of wood etc) to create a tab. Adults should control the heat gun!
Step 11: Tab Drilling
When cool drill a somewhat oversized centre hole in each flattened end that'll readily accept a securing bolt. Adult supervision required!
Step 12: Securing Bolts- Rationale
Low profile pan/mushroom head bolts are best- avoid excessive bolt lengths that protrude inside the "star" as dome occupants may knock their heads on them.
Although tools are a magnet for budding engineers,many young kids become frustrated with screwdrivers & nuts and bolts. The dome design lends itself to assembly/dissassembly at these securing "stars", but this way is a tad fiddly & NOT intuitive. Bolts & nuts may become lost as well...
I've hence taken the approach of leaving the "stars" assembled (in 4 & 5 clusters), both for quicker erection/dismantling AND as intuitive "this looks to go there" visual aids.
* The downside of this is that undersized bamboo struts may annoyingly slip free unless taped thicker.
* An admirable upside is that longer struts (24) can be organised at any stage to simply slip into sockets to make a larger dome! It's hard to argue with that sort of flexibility!
Step 13: Taping Loose Struts
Bamboo struts that are somewhat too thin (& thus annoyingly prone to slipping out of the hose socket) can be fattened up with cheap masking tape. The idea is that struts essentially should stay friction "socketed", yet be still easy enough for kids to insert or remove. As the tape is within the black hose it'll not eventually be visible & should also be weather immune.
ALERT: Ensure the bamboo struts are not taped TOO tight of course, as otherwise they may be very hard to remove, only to suddenly pop out & injure someone nearby.
Step 14: Screws ?
For extended outdoor erection (perhaps as a film covered greenhouse etc), struts that tend to slip out of the hose socket can perhaps be secured with short self tapping screws. However such screws may soon get lost (or-OUCH- trodden on),& fiddly realignment will be needed if the dome is dismantled. It's probably best hence to get slightly thicker bamboo struts-or use tape!
Step 15: Assembly!
Assembly best starts at the base by laying out the five 4 armed "stars". These smart Kiwi kids immediately sensed the next 5 arm "star" stage without any adult intervention! OK -(& even if NZ didn't quite win the 2013 Americas Cup - sniff )- they continue a Kiwi tradition of capable technical excellence, but I was highly impressed.
Step 16: The Bedtime Team at Work
Yes-kids love building- their younger brother has now joined the fun! I'd thought that this bamboo dome concept would better suit ~8-10 year olds, but these 3 siblings (the eldest only ~6) put it together in a FLASH!
Step 17: Cling Film Covering?
Household cling film makes a suitable transparent cladding -repairs & vents are easily made of course too. Wider commercial grade rolls are available at food wholesalers- several layers could even be applied to thicken up the walls. Use a hot air gun to shrink the film tighter.
Such a structure can get very warm inside (perhaps TOO warm for kids), but it'd suit "lift off" cloche/greenhouse winter-spring garden duties, although securing/weighting would probably be needed to avoid wind damage & dome take off...
Step 18: RAPID Dismantling
Here's a partially dismantled dome. it took the 3 kids shown in the previous pictures under a minute to bring it down to this stage! Indoor bedtime called -their mum is now considering sewing up an old sheet cover for a summer evening sleepout. Stay tuned!
Step 19: Smaller Cat Nap/dog Box Version
Although this smaller ~400mm strut length version was intended for a small dog kennel, cat "Molly" promptly decided it suited her needs. Guess she'll merit her own, with maybe ~300mm length struts?
Step 20: Larger Versions?
Larger versions are certainly feasible, but the thin bamboo probably limits these to 1200mm (~4 feet) struts. Many garden centres sell packs of just such lengths (~US$5 for 20 canes), but assembly may need older taller kids and adult help.
The BoM (Bill of Materials) for the framework shown here is only ~US$10.
The improved door way access, greater headroom (~1700mm) and floor space (~2metres across) suits covering such larger domes for kids dens or sleep outs, and even possibly seasonal garden green/shade houses. Taller adults ( I'm 187cm) could be catered for with a low footing wall that'd elevate the dome up off the ground somewhat. This would improve drainage & also allow wind proofing if the lowest struts were secured to bricks or timber etc.
* Suitably sized galvanised mesh netting could be used as a screen to protect ripening crops from birds or poultry -or even pesky butterflies! (Pollinating bees,being used to tight hive spaces, could still get thru' bird netting mesh OK.)
N.B. Domes intended for longer term use (or likely kids hi jinks) should of course have heavier duty timber or metal struts that are firmly secured. These bamboo & hose offcut creations are really intended to stimulate youthful imaginations!
Liger Leadership Academy made it!