Intro: Build a Geodesic Dome Fruit Cage With Hubs
A few years ago we built a geodesic dome using old chestnut fence pales, eyelets, string, copious amounts of glue and a big jig. It was great fun but really complicated and time consuming.
So we set out to see if we could make it easier to make a geodesic dome; a sort of side project for our 3d printer. Lots of prototype connectors, a bit of crowd-funding and almost four years later the hubs geodesic dome kit finally exists.
There are lots of things you could make; a moonbase for the kids, a dome home for your dog, a nature hide, festival tent, planetarium, observatory? And we thought Instructables could be a great place to break down the process of making domes for different purposes.
This is the first one, a simple fruit cage. When we get around to others we aim to post them here.
And if you create something cool with hubs, we'd love to see it too.
Chris and Mike.
Step 1: What You Need
To make a 4.8m dome using hubs.
Please note to make it easier for people to get all the components, we've put together a kit of parts.
This can be bought here: Up to 4.8m (16ft) Walk In Vegetable / Fruit Cage Dome Kit
Or you can source everything listed below locally; plus you'll need a hub kit, available here: DIY Garden Dome Kit
For the sticks that create the dome:
- We used 5ft broom handles which were 27mm in diameter.
You’ll need enough to cut:
- 30 x Short sticks measuring 1005mm
- 35 x Long sticks measuring 1148mm
It's worth getting enough for some spares.
If you're in the UK and like the look of the broom handles we've used, we offer packs of 70 here.
Other parts for the fruit cage:
- 75mm x 47mm x 2.4m long treated wood for the base blocks
- Stretchy fruit cage netting – 6m wide x 10m long should do it
- Pegs x 30
- Paint, varnish or oil (1 litre tin)
- hubs geodesic dome kit
- Hand saw
- Power drill (speeds things up!)
- Pozidriv (PZ2) bit or screwdriver
- 2-3mm drill bit (if using hard wood)
- Pen or pencil
Where to get the parts?
You should be able to get most components and tools at a local DIY centre like B&Q (in the UK).
Other sizes or sticks?
If you want to use other wood, look for wooden poles between 20-32mm in diameter or battens with a max width of 32mm (you can go wider but this is a good rule of thumb). You can read more in our guide here.
If you want to make different sized dome, simply use the calculator to find the 2 lengths needed.
Step 2: The Kit in a Bit More Detail
The kit comes in a box and includes all the parts you need to make a 2v geodesic dome, apart from the sticks. You can choose the wood you'd like to use and by changing the lengths of the sticks (there are two lengths) you can change the size of the dome.
You can read a bit more about the kit on our website here.
What does 2v mean?
It refers to the frequency of sub-division of the base triangle in the simplest sort of spherical structure – the icosahedron. Higher frequencies (eg 3v, 4v, etc) have more triangles, more parts and become more spherical in form.
A 2v is a nice place to start as it's not too complicated!
There's a good visual explanation here.
Step 3: Cut the Rounded Ends Off the Broom Handles
You can't really attach the ball connectors to the round ends and they're difficult to measure from. So cut them off before you start and use this clean end to measure from.
When you cut to length in the next step, cut off the other end and that will remove any rounded ends at the other end – if that makes sense!
Cutting against a square block of wood is a simple way to get a nice square cut.
Step 4: Measure and Cut Your Sticks
Don't sweat the millimetres too much, hubs allow for a bit of inaccuracy.
If you have a chop saw, bundle the sticks together, create a jig/stop for the correct lengths and cut quite a few in one go to speed up the process.
Step 5: Smooth Off the Ends of Your Sticks
Cutting the sticks often leaves flaky bits around the edges. This just neatens the ends of the sticks to give a nicer finish and it'll make painting the ends a little easier too.
Step 6: Cut Your Base Blocks
It is best to use a wood that's treated for the outdoors for the base blocks as they will be sitting on the ground.
Step 7: Protect Your Sticks and Base Blocks
If the wood hasn't been treated you'll need to treat it to protect it against the elements, there are quite a few options, from oils and varnishes to coloured stains. There'll be something to suit your tastes.
You can get pre-treated wood, so look out for that if you don't want to have to paint, oil or varnish your wood.
Some woods are naturally rot-resistant, eg. chestnut. So that could be something to consider too – for a more rustic look (chestnut pales are often used in fencing here in the UK for that reason).
Step 8: Screw on the Ball Connectors
The main thing to check here is that your torque setting on your power drill isn't too strong. If it is it could strip the thread in the wood or even crush the ball connector. Do a test on one stick or a spare bit of wood – the ball connector should be firmly attached and you shouldn't be able to move it by hand.
If it’s a soft or green wood you can probably screw straight in. Do a test on one stick and see how it goes. We were able to screw straight in with the broom handles we've used here.
If your wood is hard, you should pre-drill a 2-3mm diameter pilot hole to a depth of about 35mm to avoid splitting.
Step 9: Build the Dome!
You snap in from the centre in stages and the dome grows up out of the ground. It should take less than 30 minutes first time out. Once you know what you’re doing you can build it in under 10 minutes.
If you want to see the build instructions in more detail you can download them here.
To reposition your dome once it's built – two people can drag it, four can lift it.
Look for flat ground to make any levelling of the dome a bit easier when you get your base in place.
Think about where you want your entrance to be (you go in under one of the triangles in the bottom ring. The 6-way hubs are a bit higher, so base your decision/orientation on the position of one of those.
Step 10: Correct Hub Alignment As Necessary
Once the dome is in position, correct any hubs that are out of alignment. Some will be fine, some might need a little adjustment. The last picture shows the guidance on how to adjust the hub alignment.
Hubs have a preference for the right position, see if you can feel them snap into place as you correct their position.
Step 11: Attach the Base Blocks
The base blocks lift the bottom row of sticks off the ground which helps to protect them from the damp. Screw the hubs onto the base blocks using wood screws from the kit.
Each hub comes with a washer, hub screw and wing nut to clamp it up and fix its position (See more in Step 14).
They aren't needed for the hubs in the base when this approach is used, but we suggest keeping the washer in-between the hub and wood to keep the ball connectors securely in the hubs, though screwing the hubs straight onto the wood will work ok too.
There are other base approaches outlined on pages 13-15 in the instructions, you can view/download them here.
You can embed a M6 threaded insert in the base block then use the hub screw included in the kit for a neater finish as the head of the screw fits neatly in the hub.
Step 12: Cover the Dome With the Netting
The netting needs to be the stretchy/diamond type shown in the last picture. This sits neatly on the dome and you can stretch and pull it in different directions to get a nice finish.
Step 13: Pin the Netting Down
You can use whatever pegs you have access to, roll up the excess and pin it down evenly around the base.
We haven't tried this but someone suggested cable-tying the netting to the bottom ring of sticks, so that could be something to try out too.
Step 14: Clamp Up the Hubs
Clamping up the hubs up secures the ball connectors in the hubs and prevents rotation, fixing their position.
Step 15: Create a Quick Entrance
There are some other ideas for entrances on page 23 of our instructions, again downloadable here.
Step 16: Fruit Cage Dome – Ready for Planting!
We hope that's been useful and perhaps given you some ideas for how you could approach your own dome-based fruit cage (or something else!).
If you have a go we'd love to see the results.
As we use the fruit cage we hope to update this instructable with any other ideas or learnings from the process.
Chris and Mike
hubs are simple to snap together joints that make durable geodesic domes fun, easy and quick to build. We're hoping to add instructables for different uses as and when we get around to them!
Step 17: Planted!
Here are some pictures of the fruit cage planted up, inside it's divided into a central section surrounded by outer sections. The hubs can act as quite nice locaters for bamboo canes and sweet peas seem to quite like growing up the sides of the dome.