Dome build methods - flattened conduit

This is the first of a series of videos looking at dome building methods, what works what doesn't and some pro's and con's for each build method. Flattened conduit is a really simple, cheap way of building a reasonably strong dome framework but it's not easy to cover with anything other than canvas. The most common question I'm asked about this build method is how to calculate the bend angle on the end of each strut.
Here's the link to the dome bend angle calculation page:
geo-dome.co.uk/article.asp?una...
Dome calculation tools page:
geo-dome.co.uk/article.asp?una...

[@pandjnixon]

You could use a 3 ton hydraulic jack set up on a steel bench, with a simple RHS frame around it, temporarily welded to the bench, in combination with an alignment locating jig, that also keeps the 2nd end to be flattened in the same plane as the first flattened end. The jack will also be fitted with radiused flattening tooling, so that the point where the tube transitions from flat to round after flattening, it does so with a radius, rather than just a straight edge transition, to give it a more professional look. Also a 2nd radius (as you've nicely done), that's ground on the very end of the flattened tube, completes the finished look. Then another jig is made for nest-centering the tube ends in the drill-press, to auto align them for drilling the holes, with a locating pin for locating the first drilled hole, set at the correct centre distance from the 2nd hole about to be drilled.

[@astoops]

Thanks Paul. As usual, simple and to the point.

Thanks for the video. I'm interested in using this technique to make a form for a monolithic dome, then taking it apart from the inside. It is best to press the ends of the conduit in a ( shape. so they dont bend.

[@StructureS]

Hello, Sir, I want to build a 4v dome of 7.5m diameter. I actually don't know much about hubs for it. can u suggest me which hub I should use which is cost effective structurally good?

[@lucianofreitas2009]

At last, one with info about bend angles!!! Very, Very,Very thanxs for sharing!!!

[@Geo-Dome]

You are welcome!

[@halasimov1362]

Curious to the feasible or a dome where the struts are bent in the middle and using flate disks as hubs. Perhaps square tubing notched and welded to the sum of the two angles. Do you think this structure would be strong still?

[@gio.9129]

thanks for sharing, in the 3v dome, for each upright do I have to bend to a different degree?? because I have seen plates with 13° grading and they are the same for all uprights. thanks for any response

[@lonefoxbushcraft]

Paul could you make us the bars and ship them, I'm UK location Manchester, u sound like Newcastle cud drive ? Price including materials ? Danny

[@elfantasma...1886]

Thanks Paul..

[@samyoungblood3740]

How could you put Plexiglass in each triangle section? Thats what I want an can’t figure out how to do it this same way, add thick plexiglass and keep it from leaking.

[@samyoungblood3740]

Wonder if this design could be a frame an build something to attach over it? Added strength an stability.. hide the Ugly?

[@JaisimhaAllalghatta]

thanks for the video and the link too :-)

[@Geo-Dome]

No problem!

[@jorgeh.farfan7381]

Great!

[@user-fq6cj6pi8h]

How to sale for mater steel

[@THEWORDCHRISTIANMINISTRY]

How are you going to attach the poly sheeting over the outside of the dome? Thank you.

[@Geo-Dome]

This was made as a climbing frame for a dance production so no polythene required, I don't recommend building this way of you want a covered structure.

[@user-qf8gd9or4d]

ropes and grommets across look at the tents at the county fairs nearby you or at the weddings you go to look where the side walls are meeting above your head when they put it together inside the folds are rope loops permanently affixed in rows and the other side the grommets and they put rope through and then lace it through the next rope to secure and keep going to the end there is about 4 walls to the design you need for the domes and funny not one dome maker out there is doing it right because they have not been tent makers or installers who have to make them to be set up and torn down in a days time whereas we had to do so and you might wonder why the tent rentals do not use the domes because the weight of the metals is such it takes quite a lot of time and also it reduces the size of use such as a 20 foot has only about 15 across can be used and with dome they wont pay the kind of money to get ones as a easier way is sqaure tents in 20 feet that have full area and are simpler. Also the flimsy coverings the dome companies sell with zippers wont hold up I am afraid to say and the real cost of a pro tentmaker to make a good dome would be actually 30 000 with properly vinyl sewn and welded and rope gromets and permanent durable fabrics to stand up even in extreme conditions . Where as same style sqaure tent so easy to put up are between 5000 to 10000 the bigger wedding ones at 40 x 40 are 20 000 for only the two end pieces together to make a 40x40 and they go up easier than the time for a small dome that would cost more in time effort its why you dont see the tent rentals put up domes . The research scientist want them as they need weighted sturdy structure they can assemble by themselves in a jungle or such and they might lug them in and use them for a hut to blend in because they dont want to carry the steaks for a larger tent or its poles as many as they have 72 plus so they would rather strap togethr the smaller poles and haul them to remote areas. To make them the proper walls with specialty vinyl firerated and approved by building inspectors not these flimsy zips but the heavy vinyls sewing welding and rope grommets in the proper designs there are two good designs to do so but none have them ! Real tent people can figure out the geometry and where rope and grommets go I have but as I said it costs over 20 to 25000 to make fully and shipping is thousands so if they had this amount most would just buy the large 40x40 and get the bigger tents . The domes to explain can have 4 pieces and them seam them together in rope and grommet style . If you have not seen what that looks like wait for the county fair time and go a day early watch for the tent companies hired to install tents and see what it looks like on square ones then apply same if you can sew and install rope and grommets think in terms of 4 sides for such. Us strap and rathets to secure the frame to the ground also there are two ways to do doors out of it. Cant believe not one video of the proper way but then when I was working doing them I was too busy working to film anything either sad to say now thinking back on it i wish i had. What videos i had are gone now. Anyways it is rope grommets and I and others have already copyrighted the idea of how to build it just its too expensive for the amatures to build the heavy duty kind like i said it would in todays money cost over 25000 few companies do make the pieces and sidewalls and they are costly to order even one like I said the 40x40 pieces square are just 20,000 so this is why when you see the chinese say we can make you a tent 500$ these cheap flimsy things look at the amazon reports of how they fell apart broke tear and then wreck so if you have a one time thing yes the 500 to 5000 cost to rent a heavy duty ones is the same as buying but when people get the garden or garage covers and greenhouse things and then it falls apart due to weather they lose the money anyways whereas if they rent on an important day if they get sturdy they know it will not fall down. If you try to make your own you can sew ones with plastic vinyl a cheap cover then attach grommets and if you cant use a sail needle to sew the ropes on just use shoe laces if its a little tent cover they might not work on larger ones for full green house but for small you can or you can get polycarbine stuff and then put it together and get blocks of wood to screw nail to it and try that maybe ? That might make you a small green house eh? Is that what you are going for ? A green house or what is it that you are trying to make ? Is it full larger tent for a church camp? There are ones at 3000 to 5000 that are 20 x 30 might do for a small church camp things? the larger 40 x 40 tents that are 2000$ to rent they cost 40,000 for the two pieces together and that is why they are so costly per rentals but the smaller 20 x 30 there are tent companies USA that make them and they go up so quick two people can do it. Look online for those also many car dealers and other also sell their used tents when they look a bit raggedy but you can patch them so if you can find one on ebay they cant rent anymore and a tent co sells it as bridezill wont like it then maybe a church camper for kids to stay out of shade wont be as mindful of it duct tape it up and if a bride needed it they can rent tent linings to decorate cover it up anyways lol! I know the brides are the worst arent they fussing? LOL

[@lowboy003]

Nice instructional video. The strut angles need not be calculated, the calculated length of the struts are the controlling angle factor in each of the the dome hub groups as the dome comes together.

[@Geo-Dome]

Yes that's correct you only need the strut length and radius to work out the angles.

[@RollerPigg]

So for hubs, why not a small metal disk, bent into a slight dome/cone shape, with holes drilled appropriately? Such a thing couldn't be that difficult, and would be cheap.

[@engineeredlifeform]

I've been musing on something like this, and using a plasma cutter to cut a conical template, rolling it and welding a seam, then welding the pipe to it,....

[@dalemurray4083]

making a straight line across the pipe at the falttened end makes an easier bending point, in high winds the strut ends could flex and break more easily..

[@jasonkeuma1986]

In another video someone used a hydraulic press with plated that had a curve.

[@marxnutz]

4:14 Maybe take three double-length pieces of conduit, flatten each dead center, drill the single hole in the center of that. That way, you only stack three levels tall instead of six. What do you think?

[@TheRebelmanone]

I don't understand, because in order to build a dome you will need those points to have 6 framing pieces spanning to the other hubs, where those will need 6 framing pieces all joining and then spanning to the other hubs, of which will need 6 framing pieces all joining and spanning etc, etc...

[@TheRebelmanone]

Better to just use a coupling and weld it to a flat plate cut round(hexagon), weld 6 of them in the correct directions and angles on the round flat plate to make hubs, then the pipes don't need to be flattened and can all be aligned on the same plane in order to achieve a flush surface on the finished dome. Use the hubs in every center of every hexagon and pentagon(only need 5 couplings), and the dome will be professionally looking, more stable, and flush able to be paneled, and set with real glass if preferred over cheap plastic.

[@iamiwasthenaiiamnow6846]

@@TheRebelmanone Just use a flat,galvanized hexagon plate.

[@titusneguers8577]

very god

[@SimpleTek]

I love your videos, but I have to tell you, if you're going to build with metal you need a hydraulic press to squish the ends (I call it a squisher) - a 20 ton one on eBay is under $300 US, soooo much faster. a 12 ton one is only about $200. I can't imagine the time and effort you put in doing that with a hammer!

[@oldmanfromscenetwentyfour8164]

Time? It took less than 20 seconds to flatten each end piece, another 10 to drill a hole. Maybe he'll spend a minute and a half on each tube. Depending on how many he plans to use, it might take a total of 2 hours to get it all prepped. The spending isn't justified.

[@SimpleTek]

36 hits for one side - check out how fast I did this with a hydraulic press. . kzbin.info/www/bejne/qnK5kmiGiLZjhLc

[@SimpleTek]

$200 for a decent hydraulic press new on eBay.

[@oldmanfromscenetwentyfour8164]

Hammer $12

[@SimpleTek]

Good anvil $200 - you can buy junk but you need something with weight, real steel costs money.

[@kvidobenak]

OK, but just make a steel plate hub with 3-6 holes and the stacking issue is solved.

[@Geo-Dome]

Yes but you will need around 75 of them for a 3v dome and the hub can twist so you will also need two holes in each strut end. If the stacking doesn't bother you I don't think it is worth the extra cost/effort. Also you then have the same drawbacks as hub and strut construction: kzbin.info/www/bejne/qIrcqYl9nbBlnrs No system is perfect you just have to pick the compromises you want to live with.

[@stumpynicholls268]

Maybe if you covered one of those in shrink wrap and hat treated it you could use those as cheap alternatives to poly tunnels?

[@Geo-Dome]

I don't recommend covering this style because you can't cover them neatly, shrink wrap is a temporary cover (usually over boats etc) and will always have wrinkle/creases which spoils the look in my opinion, I don't think t is designed to last more than a year or two either.

[@user-ut9kh4hw2b]

I don’t like the over lap method. Nothing is even for sheeting.

[@rjaquaponics9266]

Now that was funny! Conduit... WAY TOO MUCH WORK!

[@zeed33r]

but it's cheap and nice, i'm building a house using it as a base, which i'm gonna cover with bricks and iron rods at the bottom and ferrocement at the top

[@dalecarpenter8828]

glad to see some one just pound them flat instead of using several hundred dollars worth of equipment and way to much time making the ends !

[@willlaflam]

Yeah no doing it by eye and hand isn’t going to work super good

[@etankohcz1842]

One "wack"= 19 actual wacks?? Aye,, Bloke !. . . grab yer 9 kg hammer instead!!