The most popular landing page on Domerama is by far the one for geodesic connector hubs. This is very understandable. But many who wish to build a geodesic dome home or any similar structure seem to believe that one can avoid using connector hubs simply by cutting the correct angles at the tip of each strut.
That thinking is suicidal, especially if you plan to build a dome home. If you build a very small, simple dome such as a 2v or 3v, cutting the angles with a saw is a good exercise, but not the most efficient way to build your geodesic dome.
Domerama has published the compound angles for 4v timber domes, but it was mainly to demonstrate how complex it was. The equipment, precision and skills required are out of almost everyone’s reach. It’s similar to trying to make a soufflé, except that it’s expensive to start a geodesic home until you get it right.
Cut angles for a 3v dome without connector hubs: you will need to make compound cuts (tilt and angle the blade)
Two alternatives to purchasing connector hubs
OPTION 1: If you want to avoid using geodesic hubs for your timber dome, the first alternative is the following: make a regular metal conduit dome with mechanical tubing with a thick wall, then screw plywood panels onto the metal frame.
OPTION 2: use round pipe with metal straps attaching all struts together: this method has worked very well in the past for domes as large as 60 feet (18m) in diameter. You will require to cut each strut end at an angle, but these are simple to do. The image below is a fancier connector that required machine work. Though it is more sturdy, it is also more expensive to make. Using heavy gauge metal strapping is a simpler way to attach to the pipe.
It does not pay to cut corners (or cut compound angles)
The best alternative, though the more expensive one is to purchase a set of hubs. If this is the obvious solution, why do we need to mention it? Because most people try to avoid the expense, plain and simple. Good quality geodesic connector hubs can cost between $100-$125 each, so for a typical geodesic timber dome the cost for a set would be:
For a 2v: 26 hubs required = $2,600 -$3250 per set
For a 3v: 61 hubs required = $6,100 -$7625 per set
For a 4v: 91 hubs required = $9,100 -$11375 per set
For a 5v: 126 hubs required = $12,600 -$15750 per set
For a 6v: 196 hubs required = $19,600 -$24500 per set
Keeping the cost in perspective
Geodesic connector hubs such as the one in the image below become more cost effective as your dome becomes larger because many are engineered for large loads, and larger homes require more reinforcement. With connector hubs, you can often use the same version for a dome ranging from 30 to 60 feet (9m-18m). In the end, if you want to build a solid, reliable geodesic structure, you need proven materials. Another benefit is that most hubs are made to be used with 2″ X 6″ timber planks.
You can cut every single angle on every single strut, but this takes a lot of time, a lot of effort, and a significant amount of skill. Just because the struts all come together nicely is no indication that a hub-less connection is structurally sound or strong enough. It is almost certain that you will need to reinforce the vertex with an additional set of reinforcing timber pieces around every single hub.
See our list of geodesic connector hubs on Domerama here
