How to Build a PVC Geodesic Dome

Intro: How to Build a PVC Geodesic Dome

Who wants to camp in a boring tent when there are so many other options? A Geodesic dome makes a nice hut-like structure that, when covered, is a great shelter for camping (or partying).

STEP 1: Tools and Materials

This dome can be built with three tools- PVC pipe cutters, a bandsaw, and a drill press. A handheld drill could be used, it will just take a lot more time.

Make sure you use ratcheting pipe cutters- there's a few hundred cuts to do.

Materials List:

For the hubs
30'         1" Schedule 40 PVC pipe (There will be waste)
130       1' Schedule 40 couplings
26          1/4" x 2" hex head bolts
26          1/4" hex nuts
52          1/4" washers

For the struts
35          Long struts   (53 5/16" for an 8' high dome)
30          Short struts   (46 7/16" for an 8' high dome)

If you want to make a dome of a different radius or do the calculation yourself, here's the formula (all units need to be in inches). Six inches need to be subtracted from each strut to compensate for the length of the hubs.

For the long struts:
strut length = (dome radius x .61803) - 6

For the short struts
strut length = (dome radius x .54653) - 6

Pipe choice:
I used Class 200 pipe (thin wall) for the struts. The dome is light, cheaper, packs into a couple of duffel bags for transportation, and is plenty strong to hold up tarps, lights, and a flagpole. If you feel this is not strong enough, you can use Schedule 40. It will just be a lot heavier.


Total cost
The final cost of the dome, including the tarps used to cover it, ended up around $200. If you shop around for the couplings online, you can save almost $100 from the average home improvement store price. I got all 130 connectors for $53, and the company that I bought them from, http://www.pvcfittingsdirect.com/, offers free shipping on orders over $50.

STEP 2: Making Hubs

The hubs are the most difficult, time consuming, and critical part of the dome. The hub design consists of PVC tabs, bolted together to make a strong and flexible connector between the struts.

The use of schedule 40 pipe is important. Class 200 cannot handle the stress of holding the dome together without breaking. Schedule 40 is flexible enough to allow the dome to be built without bending precise angles, but strong enough to keep from breaking.

You need to make:
10      4-way hubs
6        5-way hubs
10      6-way hubs

You will need:
130    4" pieces of 1" schedule 40 PVC
130    couplings
26      1/4" x 2" hex-head bolts
26      1/4 hex nuts
52      1/4 washers

STEP 3: Mass Production

Because of the number of pieces involved in the hubs, it is important to be able to mass produce large quantities of identical pieces. 

The easiest way to do this is with the assembly line method and using jigs to eliminate time consuming measurement.

I made my jigs out of plywood, cut to fit over the PVC to show where to cut without marking. This let me cut all of the hub pieces to length very quickly, and mark the notches without having to think. 

As well as cutting, drilling is assisted greatly by a jig. When making the jig, it helps a lot if you come up with a way to make the jig hold the workpiece to avoid error. I settled for an overhang along the back and a steady hand, but I'm sure that there is a better way.

By only doing one type of operation at a time, there is much less set up time and the entire process gets done faster.

STEP 4: Cutting the Notches

This is by far the most time consuming and difficult part of making the hubs.

The notch needs to be cut down the middle of the pipe, to a depth of 2.5 inches. The marking jigs make this a little faster, but expect to spend at least a couple hours cutting.

Dust collection is very important. PVC powder is not very good for your lungs, and there is quite a lot of it. This is one time where a good dust mask or respirator can make this a lot more pleasant. My shop has a dust collection system, so I used that. A shop vac would also work very well.

The blade that you use is also important. I had bad luck using some larger blades, so I used a 1/4" blade with fine teeth. The coarser toothed blades tended to cut too fast and chip the pipe.

STEP 5: Flattening the Tabs and Drilling the Holes

I flattened all of the tabs in a vise to make drilling and hub assembly easier. You don't have to do this, but it is worth the effort and makes the hub pieces fit together. 

Drill the hub pieces about 1/2" in from the end of the tab. This gives it enough strength while still making the hubs fit together right. Use a 5/8" bit to let the 1/4" bolts fit without any effort.

STEP 6: Assembling the Hubs

Put the hubs together by threading a 1/4" bolt through the holes. I used 2.5 inch bolts because it left me with enough thread to attach other things, like the dome covering, or later, lighting on the inside. 

If you don't want to have holes in your covering, make sure the bolts face inwards. I decided to make all of the bolts on the bottom hubs face outwards to attach to grommets on the covering, but it's up to you.

After the hubs are bolted together, attach couplings to all of the tabs.

STEP 7: Putting the Frame Together

The most rewarding part of building this dome is watching the frame together. At this time, you will have probably spent many hours in the shop cutting hundreds of pieces of pipe- now it's time to turn that pipe into a dome.

You will need:
3-4      Friends (the more people, the easier this step is)
10       4-way hubs
6         5-way hubs
10       6 way hubs
35       Long struts
30       Short struts
1         Large open space

There are many ways to begin putting the dome together. The first thing you need is a diagram of assembly. The best one that I've found is at http://www.desertdomes.com (Direct link: http://www.desertdomes.com/graphics/dome/2vdiagram.gif)

Even with the diagram, this step is still tricky. I like to build it from the top down, having a few people lift it up for each level. If you are alone, building it up from the bottom may work, but you will need a ladder. I found that it takes at least three people to set up the dome efficiently.

STEP 8: Covering the Dome

I chose to cover the dome with a few tarps. This worked well enough to block out the wind and look good, but it would never stand up to rain. Eventually, I will build a rainproof cover, but for now, this dome is only good for dry weather.

The tarps finally fit together with a lot of folding, rolling, and duct tape. We also took off a single strut to make a door. 

STEP 9: Party!

Turn that dome into a crazy party. You deserve it after all that work.

Comments

[Animaldelux]

im looking for 2v connectors like this. but in the website thingverse they dont provide all the elements....and i cant seem to find this Exact format which is the 1 i really need

[Animaldelux]

bravo ! im still curious about the connectors ...and i cant seem to find the info . plase let me know. take care

[ilpug]

You could do this much simpler if instead of building hubs you just heat formed all the ends of the pipes flat and drilled a hole.

[jst1man69]

I get what your idea is. Basically you flatten the ends to bolt them together. This is a really good idea and should hold up nearly as good as a hub. Using a triangle or hex won't make much of a difference as it will still be the same or nearly the same strength. You can always reinforce then after the build with slightly larger PVC pipes if you want a more durable structure. It all depends on if your climbing, camping, or growing.

Also note: I've learned that hot sand or hot water in PVC pipes allows you to shape them almost however you want. Remember PVC is toxic if burned. Hot water or sand is best.

[jdimare]

could you elaborate on this process further?

[ilpug]

Take your pipe and heat the end above a flame or a heat gun, Do it outside for good ventilation. Right when the pipe starts to turn color, remove it from the heat and squish the end in a clamp or a vise for like 15 seconds, then dip it in cold water. That crimps it flat. Then, drill a hole through the flattened end. Now, instead of making brackets, all you need to do is line up the holes in the flattened ends of each set of five pipes and stick a bolt through it and tighten. Much faster and simpler, not to mention cheaper and easier to store, because there are no hubs whatsoever.

[betty71bg]

Hot water instead of heat gun or flame, put only the ends in, flatten in the vise, no need to cool after and stress the material.

[fuzzyjez]

Did you do this because it's exactly what iI was thinking and I'm "about to start"....

[ilpug]

I haven't actualy done this project but I've heat formed a lot of PVC and I know this would work.

[alanna_burnett89]

This looks awesome! What would I need to do to frame out more of a door shape rather than stepping through a triangle?

[SandraA92]

For the people asking if you can build this alone... Short answer is... probably. I built one with a little help from my 7 year old, but I almost gave up because it was extremely difficult. Would not attempt again without a second adult.

[mrscannone4]

I haven't read all the comments, but I wonder if one person could put this together upside down, rolling it around on its side like a big upturned bowl, and then flip it over. That's how I built my portable shed by myself (it also called for three people)....

[solitary man]

If I may ask a question or two, in retrospect did you like how the hubs performed? Also, have you had any experience with it during winter time? Did you test the dome to see how well it would hold up well under a snow load?

[solitary man]

This is an excellent Instructable. Thank you!

[Malkaris]

you list 30' of pvc but that's just for the hubs.

I'm calculating at least 270 feet for the struts.

[hardhatpsp]

30x 10' pvc pipes would be the right way to read it. At 300' that would be why he says there will be waste.

[KristiM12]

I see the dome is 8' high but how wide is it?

[TechDante]

16' as the radius id 8'

[Sonostarhubs]

Another way to simplify this is to buy the hubs. That way you can make even more complex 4v and 5v geodesic models. We sell hubs at www.sonostarhub.com

[LocalH7]

yeah...for a freakin small fortune...lol