Make your own 3v geodesic dome hubs

Geo-dome home

Navigation

Geo-dome masterclass

whatch dome building videos on youtube

start here

Geo-dome shop

dome kits

Dome plans

Build your own dome

The Geo-dome porfolio

Geo-dome forum


Make your own 3v geodesic dome hubs Trying to track down hubs for building a dome can be difficult and often expensive so why not make your own? Use these drawings to build hubs for a 3v geodesic dome. Because hub angles don’t change, these drawings will work for practically any size dome just adjust the strut lengths to build a bigger or smaller dome. OK lets get started: To build a 3v geodesic dome you’re going to need a total of 46 hubs in six different configurations (it’s actually only three but you need to cut some in half to make the base hubs) take a look at the drawings below. Here’s the exact breakdown of hubs: Six red hubs (all 10 degree) Five green hubs (all 12 degree) Twenty RGB hubs (mixed angles) Five green hubs cut in half Five RGB hubs halved (left handed) Five RGB hubs cut in half (right handed) What are the angles? Below is a diagram that shows the angles, they’re colour coded to match the Dome calculator colour code so you can see exactly were each hub goes. Angles have been rounded to the nearest whole degree; this hub design is very forgiving so a degree or so out shouldn’t be a problem. Use the diagrams below to workout were each hub goes, when you build your dome it’s a good idea to colour code your hubs and struts as it will make it much easier to put together. A couple of last things I haven’t taken into account are that the base of a 3v dome is not quite flat, you can make some of the struts slightly longer to achieve this and the hubs should still work and you may need to make different hubs around doorways but you could just build them in after.

[ comments 76 ]

posted by colin	29/05/2007 21:34:11

Hi Paul 20 degrees for the red hub? Looks like a typo to me ..10 deg :)

posted by Greame	31/05/2007 04:03:56

Hi Should it be six red hubs at (10 degree) Great article

posted by Admin	11/06/2007 01:14:52

Thanks for letting me know about the 10 degree angle error, I've fixed that now. Colin sent this drawing showing all the angles (makes things a bit clearer I think. Cheers .

posted by Carlton	21/07/2007 02:31:49

What material are these hubs made from?

posted by Colin	21/07/2007 12:39:50

Hi Carlton, It`s a typical design used for house sized domes. The material needs to be geared to the size of timber used for the struts and the dome itself but it`s usually steel. Many hobbiests would struggle to fabricate these hubs accurately without the proper skills and tools. For small scale domes there are far easier ways of making the hubs.. a short section of tubing drilled accordingly for example.

posted by miiblz	10/08/2007 21:27:03

hey has anybody tried to make a hub by drilling holes in a tube that has a cap and then threading a large bolt in the cap..humm

posted by miiblz	10/08/2007 21:29:00

hey has anybody tried to make a hub by drilling holes in a tube that has a cap and then threading a large bolt in the cap to the right angle ..humm it could even have caps on both sides

posted by Colin	25/08/2007 12:02:23

Hi Miiblz A tube with caps could be useful, not quite sure what the angled bolt in the cap is for though ;) The struts would presumably be attached to the side of the tube. Tubular hubs are the easiest to make in terms of time and effort.. cut the tube off, drill the holes Et voila, job done :)

posted by Oleson Lyng	03/10/2007 06:01:42

What does the 6 off, 5 off and 20 off refer to in your drawing?

posted by Oleson Lyng	03/10/2007 06:06:28

How about laying 2 2x6's on top of each other and cutting out a regular hexagon and then strapping metal over the top and bottom of the strut and hub with screws. (for a 45 foot dome where the frame is only temporary until concrete and wired together panels are in place and concreted.

posted by Colin	04/10/2007 19:34:14

Hi Oleson 6 off, 5 off etc refers to the required number of hubs of each type. A hexagon would work for a non flat base 3v dome but not for a flat based one. By the time you`ve cut the strapping and wound in hundreds of screws it would be a lot faster and easier (cheaper?)to use tubular hubs and struts with a coachscrew (or wood/metal dowels)each end. Pvc tube (sch.80) would be sturdy enough for a big domes temporary framework (or a permanent small dome). Aluminium or steel tube hubs would be better for a long term hub.

posted by Bill Bennett, Greece	08/10/2007 05:34:36

Hello to the group but mainly to Colin (who seems to be the 'leader') I am hoping to build a dome on Mt. Olympus, Greece, next year. BUT!! I have no plans and I need an ISO certificate.(The biggest con since Irak). Any ideas anyone?

posted by Colin	09/10/2007 14:38:00

Hi Bill Not sure about the leader bit, i`m just a regular visitor and tend to post more than most :) It`s years since i was in greece last but they used to have some very novel building methods over there. "Plastering" internal walls with marmaral (sp?) was a real eye-opener, they fling it at the wall from 6ft away, smooth it out roughly and then come back 2 days later to "sand" it down with polystyrene floats hehe, when i was there the favourite word for most tradesman was "avriol" (sp?)meaning "tomorrow" so don`t expect anything to get done too fast lol Anyway, back to your dome,is it for a home? I`ve no experience of ISO certificates but a well designed dome would be stronger than most buildings over there. You shouldn`t need the 30ft deep pit for the concrete foundations normally used for earthquake protection either.

posted by Bill	12/10/2007 02:37:40

Hi Collin. You are correct, 'Avrio' is tomorrow in Greek. I don't know what 'marmaral' is. you may mean 'marmaroskoni'. That is marble dust, used in plastering, that leaves a very smooth and hard finish. My dome will indeed be a home of 12 meters diameter (40 ft)Of hub and strut construction, using 2 x 6 struts. I intend to build it myself. I will need a pit of about 20 ft deep, as I have 3000 m2 of grape vines near a small village called Rapsani. Look in Google. I will try to put a seller under my seller for wine and tsioro. (deadly stuff) A quake of 4 or 5 Richter would just wobble a dome, but it may cloud my wine.

posted by colin	12/10/2007 05:54:54

Hi Bill It`s been a few years, the old memory fades a bit.Marmaroskoni doesn`t ring a bell but it could well be that, i do remember it was mixed with "asphestae" which was like very very wet cream cheese in a sealed poly sack hehe..greeks have all the good stuff. A 20ft pit doesn`t sound too bad, the ones i saw were immense.. certainly wouldn`t want to fall into one on a dark night :) Your vineyard sounds like a marvellous place to live and a perfect backdrop for a dome. Do you plan on a 3v 5/8 or something else perhaps? A 40ft 5/8 would be around 23.5ft high, so plenty of height for an upper floor A hub and strut is fairly easy to fabricate but harder to cover and seal..depending on how you plan to cover it. A panel dome is the alternative but uses more material and needs to be very accurately cut so it all fits together perfectly. I guess you`ll need to plan very carefully for ventilation and insulation to keep the dome cool with the temps you get over there. The location and number of windows will have a bearing on that too. The cellar sounds like a nice cool place to be in the summer.. cloudy wine wouldn`t be a good thing though, so hopefully you won`t get too many earthquakes ;)

posted by David	27/01/2008 13:04:30

Looking at the flat angles, for the blue, red, blue, green ie 56 56 and 62 degrees, it seems to me it should add up to 180 degrees..right?

posted by Admin	28/01/2008 02:18:58

Good point David but no it doesn't add up to 180 degrees because a 3v dome doesn't have a flat base - a 7 meter dome would have the green base hubs about 2"-3" off the ground (it's such a small amount that it doesn't show up on the 3v drawings on the site)

posted by Colin	28/01/2008 02:56:21

The flat based 3v doesn`t add up to exactly 180 degrees either :)

posted by Colin	28/01/2008 03:34:01

Here`s part of the bottom ring of a flat base 3v 5/8 which illustrates why hubs don`t necessarily add up to the expected 180 deg. Notice how the struts are tilted in relation to the ground yet the ring itself is flat. In fact, some of the 4 way hubs add up to more than 180 deg :) The strut end angles make a difference to the expected hub angles as together they form a compound angle.

posted by David	02/02/2008 12:23:27

thanks collin for your above response. Since I wish my dome to be flat on the bottom to match the all green hubs, I dont see why I could not make the blue green connectors that are are on the bottom slightly different angle to match the all green angles so that it would lay flat. Keeping the upper red, blue, 56 degree at the proper angle. At least this works out in my mind, am I correct.

posted by Colin	03/02/2008 04:16:16

Hi David The angles for a flat base are somewhat different.The other thing is you can`t use only 3 strut lengths from the calculator and alter the hubs to get the base flat. You`d need 5 different strut lengths to alter the bottom row of triangles. It can also be done with just 4 but then the entire strut layout is different :)

posted by Rich	07/02/2008 12:34:36

To Bill in Greece, do they use expanded polyurethane in Greece. I live in Spain & we're planning on building the frame for the dome from galvanised steel tubing covering it with cheap shade cloth & mesh, then spraying it with "espuma" (expanded polyurethane). We may then render on top of this or just paint it

posted by David	03/03/2008 14:37:12

Colin Have two questions here. One if the base of the dome is not flat how does one effectively fasten to a riser wall. Second instead of brackets for the hubs as you describe above, what is your opinion on using two say 3/8 hanger bolts in end of struts fasten to a round hub with the holes drilled at property angles. Strength?

posted by Colin	05/03/2008 08:00:57

Hi David, Ideally modifying the base so it is flat will make it easier, kinda depends on the size of the dome though (small domes don`t create much of a lift compared to larger sizes) The easiest way to connect to the riser is to make some angled wedges to alter the included angle and then bolt right through the base strut,wedge and top plate of the riser. Some commercial dome companies use full length wedges but you can use 2 or 3 short ones per strut instead. Regarding the hub question, it will work with 2 bolts per strut end but you`ll have to cut the struts differently to get the correct dihedral angles.. a flat plate hub doesn`t bend too well :) Alternatively, a steel or aluminium plate hub formed into a shallow dish will give you the angles. Either way you will need to fill in the gap left by the struts at the centre of the hub plate. I`ve found that whichever method you use to build a dome..there will always be some hurdle to overcome :)

posted by colin	05/03/2008 08:22:16

Not a great pic but it shows where the short wedges are located. The riser wall uprights also have an angled top to meet the hub at the correct angle..these are taking the majority of the dome weight.

posted by furtherbuilder	06/04/2008 23:49:11

I would like to know the over size of the hub if it is A big concern,this is for anyone to answer thank you

posted by Brian	07/04/2008 19:55:13

Is there anyone that pre fabs these hubs other than naturalspace domes naturalspacesdomes.com/super_lok.htm they have a nice system but expensive

posted by colin	10/04/2008 11:10:37

Hi Brian The natural spaces hub design is protected by patent so its unlikely anyone else is producing them commercially. If you have the means you can make a set for your own personal use.

posted by Eyal	03/05/2008 21:51:33

It dosent work. sorry i try... :-(

posted by Colin	05/05/2008 04:53:23

Hi Eyal Nice artwork :) Your rendering appears to show a 90 degree axial angle, which will result in a flat hexagon. You will either have to incorporate the 10 or 12 degree axial angle into the hub "arms" as per the hub graphics, or alternatively, into the actual strut ends in the case of a tubular hub :)

posted by Jordan	24/10/2008 00:49:18

Hi all, I am building 3v 4/9 (3/8) dome, 28' (8.53m) diameter and have only just realized that the base does not lie flat on the ground...! The strut lengths, as per the dome calculator (thank you so much by the way!) are: A - 9.76' (2.97m) B - 11.30' (3.44m) C - 11.55' (3.52m) I am wondering if anyone can tell me (or give me a clue how to calculate) exactly how much certain hubs would need to be raised off the ground if all struts are kept to the calculated lengths (as they are already cut...!). I am thinking that the hub that connects 4 C struts needs to be raised, but I'm not sure about the others. Do the hubs on either side of the pentagon both sit on the ground, or is one raised? Any help would be most apreciated as I am hoping to have it up before the snow flies... Peace!

posted by Jordan	24/10/2008 07:30:51

Hi all, I am building 3v 4/9 (3/8) dome, 28' (8.53m) diameter and have only just realized that the base does not lie flat on the ground...! The strut lengths, as per the dome calculator (thank you so much by the way!) are: A - 9.76' (2.97m) B - 11.30' (3.44m) C - 11.55' (3.52m) I am wondering if anyone can tell me exactly how much certain hubs would need to be raised off the ground if all struts are kept to the calculated lengths (as they are already cut...!). I am thinking that the hub that connects 4 C struts needs to be raised, but I'm not sure about the others. Do the hubs on either side of the pentagon both sit on the ground, or is one raised? Any help would be most apreciated as I am hoping to have it up before the snow flies... Peace!

posted by Jacques louis Vidal	27/12/2008 22:18:23

hello, I am a sculptor in the yale university graduate art program, and while im surrounded by good mathmaticians at the school no one has been able to help me with a problem im having...I building a 3v geodesic sphere 28 inches in diameter out of hardwood triangles, I am not making struts so a hub connector is not what i need, what I am trying to figure out, and am unable to is what the bevel angles on the three different sides of my triangles should be as I construct this thing, I thought they were all 6, but Ive been running into some problems, any info is helpful thanks

posted by simon	28/12/2008 17:25:24

Hi Jacques On the red edges the bevel is 7.2, on the green edges it's 6.8, on the blue edge of the red-red-blue triangles it's 4.1 and on the blue edge of the green-green-blue triangles it's 7.2 - I think, perhaps someone else will confirm. Simon

posted by Admin	30/12/2008 16:37:25

Yes Simon, I think that's right. I get 4.8 on one and I have rounded for ease as it's not possible to cut 0.2 degrees on most saws. Heres a diagram...

posted by Max	18/01/2009 16:30:33

Hello, I am hoping to build a ten meter diameter 4V 3/8ths dome. I couldnt find any answers to the few questions i have on any dome calculator site, so I hope you can help me. 1- The diagrams only show 4/8 domes and i can't quite figure out what determines a 3/8 from a 4/8, and so, I can't figure out how many hubs i would need. 2- All 4V calculators I've found work on a 4/8 basis but are there any that work on a 3/8 basis? if not, is there a way of figuring out the diameter of a 4/8 dome, considering it's 3/8 level needs to be 10 meters wide? 3- The hubs needed are of three sorts : -four way hubs (for the bottom) -five way hubs -six way hubs For the 3V dome, I understand the 6 way hubs are to be divided into two categories : those with all angles equal, and those mixing 10 degree and 12 degree angles because of the length of the struts attached to them. On the 4V dome, there are 6 different strut lengths, which means, I should have more than 2 six way hub categories (right?). If so, could anyone tell me what those angles might be? Your help would be much appreciated, thanks a lot -Max-

posted by Simon	21/01/2009 01:34:25

Hi Max. I'm not sure what a 3/8 4v would be. Do you mean it's like a hemisphere with the bottom row of triangles missing? I'd call that a 5/12 - because the dome has 5 rings of triangles of a total of 12 for the whole sphere. A 5/12 4v icosahedral dome with a diameter of 10.47m has a base diameter of about 10m - remember that a 5/12 4v doesn't have a flat base, so unless you adjust the base struts to make it so it's base doesn't exactly have a circular profile. It stands 3.92m high resting on the pent rims. These are the strut lengths:total struts: 190 strut parts: 6 part number: 4, number off: 30, length: 1.325 part number: 0, number off: 50, length: 1.541 part number: 1, number off: 30, length: 1.545 part number: 5, number off: 20, length: 1.563 part number: 2, number off: 40, length: 1.637 part number: 3, number off: 20, length: 1.700 There are four kinds of hex bubs, one kind of pent hub and four kinds of quad hubs, 71 hubs in total, though I don't know the angles so hopefully someone else can help you out there, but I'll see if I can't work it out. Simon

posted by Keith	26/01/2009 22:18:41

Thank you to Admin and especially to you Colin. Your knowledge is greatly helpful. I'm looking at building a little cabin on 30 acres I own in the Ozark mountains of Missouri (USA). I'm looking at a 24' (8.5 m) 5/8 diameter dome. Use it as a weekend get-aways.

posted by Max	31/01/2009 21:31:06

Thanks a lot Simon, it helps a lot... Now that i have strut lengths I'll calculate the different angles myself :) Now all i need is to get these hubs made hehe.. tanks again -Max-

posted by Doug	04/02/2009 21:04:48

Could you tell me how a doorway would be installed?? Thanks

posted by Emu	09/02/2009 23:53:08

HI everyone, I´m planning a 2V wooden sphere as a treehouse and got stuck with the face angles of the plywood panels I want to use. Can anyone help? And are there any door suggestions for a 2V sphere having the floor level one level below the middle line?? Thanks! emu

posted by jacques vidal	13/02/2009 20:45:27

hey simon, your answers were very helpful, and i am underway in constructing my miniature sphere, i will upload photos once done, thanks again

posted by MIKE	31/05/2009 19:13:36

Why not just take 2 circles of sheet metal, cut a line to center radius, then overlap and rivet at necessary angle. Then sandwich wood ends between these two. Drywall screws go through 30g steel, and it should hold up strong. right?

posted by Alex ROMANIA	14/06/2009 22:13:02

I have a geodesic dom structure whith Natural spaces habs .Because the price and taxes for europa make the structure to expensive write now i want to made it my self and the model is similar with this but more simple.I whant to made the hab and slives whithout angles in the same plan and the angles i used it when i make the holes in to the wood beam (the section of beam is 5*20 cm)

posted by Alex Romania	14/06/2009 22:24:49

the metode whith 2circles of sheet metal is made it in my country for a metalic dom 12m diameter and work good.the structures in uncovered and have 15year minimum

posted by George Frazier	16/07/2009 22:33:56

Wonderful work on this site! We have been working with hub design systems for cold formed steel for a few years. It is not cheap, but cost effective if a person need something for the long haul. Feedback is welcome, ozarkdome.com

posted by Lindburg	23/08/2009 16:49:06

After taking all in to account I assume if one builds a half dome, the base of that dome would be flat to connect to risers?

posted by simon	25/08/2009 11:59:47

Hi Lindburg Simple answer is yes, the base of a half dome is flat, but not every design can form a half dome. For example, even-frequency icosa domes can, but odd-frequencies can't. So the popular 3v icosa dome doesn't have a perfectly flat base, but the simpler 2v icosa dome does.

posted by David	05/09/2009 14:06:30

In designing a flat base dome to avoid uneven risers, why not just use octahedral. It does not matter what frequency you use, a half dome would be flat. At least my calculations show that. Or is my math wrong

posted by David	05/09/2009 14:10:22

I would also like to ask. When building solid triangles and beviling the sides, my math goes out 5 places. I assume one could remove the minutes and seconds go with whole degrees with out much problem. Using solid triangles does not allow for small adjusting such as using hubs hubs. Your opinion on this would be greatly appreciated

posted by Pieter	06/09/2009 13:13:48

David, I believe an octahedral based dome would slice in half with a flat base. The problem is, in order to achieve a rounder dome you have to increase the number of divisions - so you would have to go V4 or higher to achieve something that looked as round as a V3 Isos. dome. This increases the complexity of the design (more struts of differing lengths etc). Alternatively - from a book I read, apparently any even numbered division frequency on an Isos. based design should result in a great circle (i.e. a flat base) along the equator, but my maths is not good enough to confirm this.

posted by simon	06/09/2009 20:27:13

Hi David, you're right, vertex-up octa-domes all have flat bases, but the dodecahedral dome's advantages are that it has the fewest number of strut parts and the smallest range of strut lengths and this makes it structurally efficient so you use less material building it, and some people just think the shape is the most beautiful. Those advantages can make it worth living with the disadvantages.

posted by SkyKing	21/01/2010 21:06:58

If we make the vertical 'C' struts longer on the Base Hex wouldn't we need to change the 62 deg to 68 deg on the multi angle 4-way hubs? This gives 180 deg total and should allow the center of the Hex on the base to sit flat, modifying strut lengths to compensate of course.

posted by SkyKing	22/01/2010 21:07:20

I see David has already asked about base hubs equaling 180 deg for a flat base. Since there seems to be interest in a 3/8 on flat base, can someone come up with the altered strut lengths for the hexagon top half sitting on a flat base? I'm creating a 29' diameter dome as a garden habitat. Thanks, great info here.

posted by glandslow	17/08/2010 01:36:55

it's mad isn't it...these structures are so intuitivily beautiful yet so finnicky to make...all these little angles..no wonder people built (almost) rectilinear structures....

posted by Anne	01/10/2010 12:36:53

Hi Has anyone had experience with flat-plate connectors? These could have fillets attached to pick up the angles of the struts. I am designing a 'curved' photovoltaic screen of flat panels using square plastic conduiting for the struts so that we can lead the cabling through it, and the conventional connectors would inhibit this and make maintenance a hassle.

posted by Steve	02/11/2010 20:22:50

I am building a 16 ft. diameter 3v 5/8, or should it be 4/9 geodesic dome. I saw the materials on making one's own hubs and am doing that, though I am using steel pipe as the center and welding conduit at the various angles to that, then will insert smaller conduit into these hubs. I am unclear on the number of hubs needed for the 5/8 or 4/9 dome, which I want for the extra height. Can you let me know how many of each type I need? This site has been most helpful already. Thank you so much. Stephen Feher

posted by Samdhe	07/03/2011 22:13:50

I have inherited a fiberglass Radome, I think 40 ft Dia. Does anyone have any ideal of how to assemble it? Where do I get some plans?

posted by Keith	11/03/2011 22:42:25

Sorry Samdhe I haven't heard of that dome. Try to assemble a few sections together, to the best of your ability and see what happens. Are all the sections the same size? If they are then perhaps it would be to difficult however, if they are different sizes, I would recomment going to desertdomes.com and check out their calculator and see if the sizes fit.

posted by simon	13/03/2011 00:04:03

Are the panels triangular Samdhe, or some other shape. Most likely it's based on a dodecahedron so if you can put the pentagons together you should be able to work out how everything else fits together from there.

posted by Gerry1	17/03/2011 22:10:02

Stanford University's collection of R.B. Fuller's Papers in California, USA has many documents on Radomes, mostly from the 1950s. But you may have to go there in person or else make special arrangements to get copies of the technical material. I don't know about their access procedures.

posted by r08	06/05/2011 22:14:06

I just started taking a look at these and wondered if it's possible to cut these hubs on a CNC machine out of 3/4 ply? I'll upload an image to show what i'm talking about.

posted by John	09/07/2011 18:33:48

An easier hub uses the strap pipe design. You cut the axial angles at the end of your struts then cut a piece of heavy steel 3 inch pipe to the length of the cut. Then run a Simpson 24 inch strap through the pipe and nail half to each side of the strut. Very simple and inexpensive.

posted by Pomponderoo	12/07/2011 03:41:02

The amount of knowledge contained on this site is invaluable! So many questions I had coming into my dome project habe all basicaly been answered already. Thanks Everyone for being so open and helpful!

posted by fred temple	04/12/2011 00:22:52

I would like to build a big geo dome. I have trid Star Plates with some succes, but would like to use your method.

posted by Mario	07/01/2012 05:40:57

please can you suggest how i can connect T section aluminium lengths together, and are there any links showing how to double glaze the dome...which is 6 metres in diametre. thank you..:)

posted by Aric	10/01/2012 02:57:10

What will happen If I build a dome using only 1 of the hubs?

posted by David LeVine	23/06/2012 19:12:09

A question was raised, and I now either missed a comment or have a weird idea. How about a Reprap or Mendel 3-D printed version of the hubs? If done for something strong but light (soda straws, for example), sample hubs could be fabricated for little cost and, after the first one of each was successfully printed, could easily (but not quickly) be replicated. Comments? And, no, I don't have a 3D printer to make them on, but the hackerspace to which I belong may be getting one.

posted by iain	05/09/2012 15:46:24

fantastic article that i keep coming back to and will evetually build 1, i don't suppose someone has done something similar for a 4v version (the hub design details) the struts on my planned 12 m dome are getting a bit long

posted by Jack	06/09/2012 05:49:05

Hi everyone, I am planning to build a fifteen meter diameter 4v dome to use as a greenhouse. Am I right in thinking I need 8 different hub configurations? 4 six way, 4 four way and 1 five way, can anyone help me out with the angles on the hubs? Thanks guys!

Comments Have been disabled
comments will be accessed through the forum in the new site design (coming soon)

7866

Copyright © 2007- 2014 geo-dome.co.uk. All Rights Reserved.