If you dont like the way your connection looks or fits together this connector can be a nice compliment to the rigidity of your connection and structure. This is the Simpson Stronge-tie Gazebo connector GT6Z. Listed under Home Project connectors in the SIMPSON catalog. This are designed for 6-sided (hexagon) roof trusses. A case of 8 connectors cost under $50. These can be used on any size dome kit made of wood or light gauge steel.
Dome Kits no connector connection. I dont believe there is anything prettier made of wood than the spherical geodesic structure connected with the compound angles cut on the ends. This connection method shows all the geometric angles and done correctly is truly a piece of art. The steel hub connects sold by other dome kit manufactures cost over $50 each. The same time is taken to cut the proper compound angles as to cut and drill bolt holes for steel hub connectors at a savings of $5000.
This web page is created to share some generic connection systems for a 2x 2 wood 3 Frequency geodesic Green house or Gazebo under 16 in diameter. One of the advantages of using the 2x 2 lumber is the ability to cut the 54 and 60 degree angles with any type saw. All these compound angles were cut with a circular saw. If your connections are not as perfect as the pre-cut kits from Dome Kits your exterior plywood may not fit as accurately.
These reducer washers can be used in many combinations on the inside or out. You may feel you need the structural strength or in the case of the connection in the picture you may want to hide the poor workmanship you did trying to cut the compound angles. During construction Dome Kits has found that they are a real benefit keeping your struts in alignment. All hardware stores offer Simpson Strong -Tie galvanized engineered connectors, hangers, strapping and smaller electrical reducer washers.
All the wood geodesic dome kits manufactured by Dome Kits are cut with a radial arm saw. All the different angles are cut within one-tenth of one degree. You can not be this accurate with a 60 degree skill saw or modified miter saw. A bolt together steel hub system may move in and out fifteen degrees or more. If your geodesic structure gets to far out of round at the lower levels it can become difficult and even impossible to complete.
The pentagon connection angle cut is 54 degrees and 12 degrees. The hexagon angle cut is 60 degrees and 12 degrees. You will be cutting these angles off each side of the strut and both ends. REMEMBER! The A lettered strut is one directional. The one end is the pentagon and the other is a hexagon. Dome Kits will mark the A struts with an arrow (A
) so we know what end is the 54 degree pentagon and which end will be a 60 degree hexagon cut.
In Dome Kits 3V geodesic structure there will be 6 pentagon connections and all the others will be hexagon connections. There will be 2 different triangles in the Domekits 3V geodesic frame.
Your outside sheathing is the most important structural part to any structure not just geodesic structures. If you dont plan on gluing, screwing or nailing any plastic or other rigid material please use some type of steel strapping or connector on the lower connections. Once you have your spherical geodesic structure completed you can create the openings for your doors and windows. The reducer washer work very well for these connections.
The lower levels of your geodesic dome structure carry all the weight of the structure. This adds a great deal of pressure pushing downward and outward on your connections. One off the best ways to enhance the structural integrity of your connection and geodesic structure is to add a piece of 3 plastic pipe or coupling for the ends to rest on. This also helps you during construction to keep your strut ends the same distance from the center.
The simplest and least expensive connector for this geodesic structure comes from the Electrical Contractors supply house . These are called Reducer Washers. For the inside connection Dome Kits prefers the 3 outside diameter 1/2 inside diameter center hole. The self-Tapping (drilling ) screws are needed to screw threw the heavy steel connector. Also the self-drilling screws keep from splitting the small lumber.
For the outside connector Domekits uses a larger Reducer Washer, 4 outside dia. with a 3 center hole. The larger reducer washer is needed on the outside connection of the structure to allow for the 24 degree angles at the ends of the struts. The 3 center hole allows the reducer washer to lie flatter on the outside surface. One of the added advantages is the extra strength but they are also flexible enough to be adjusted with a hammer or pliers so they dont interfere with your exterior sheeting.
This is possible Dome Kits easiest wood connection system. You will cut 12 degrees on the ends of all your wood struts which can be done with a hand saw. Your cord lengths (struts) will be measured on the same side and longest side. When all six 1 1/2 struts come together corner to corner you will have a 3 hole in the center of your node point.
If you have any spherical design, engineering or building code questions please send us an e-mail and we will try to reply as quickly as possible.
In Dome Kits framing diagram you will notice all the A struts make up the Pentagons. The Icosahedrons geodesic structure uses the same major triangle to create the total geodesic frame. Starting from the top of the sphere where all five A struts meet and follow it down from the A-B-A struts to the next pentagon corner of the major triangle. Now if you travel horizontal across the A-B-A struts you will meet the third pentagon corner of the major triangle. Bellow this major triangle you have the same triangle turned upside down. You have five major triangles at the top of your Icosahedrons geodesic frame (the icosa cap). Around the middle of your spherical structure you have ten major triangles facing each other. And to complete the spherical ball shaped structure you would have five major triangles (the Icosa cap) at the bottom facing up. In the major triangles there is what is called the Frequency ( the total number of struts from the pentagon center to pentagon center). This is Dome kits 3V (frequency) Icosahedrons A-B-A.
This diagram is to represent a 36x 72 piece of plastic (Lexan) storm window or any other sheet material you wish to use. In our 3V geodesic frame we have optimized the strut length to create 36 tall triangles to build the 16 geodesic structure.
The diagram is showing one of the ways to optimize your sheet goods. You have two triangle combinations; A-A-B, B-C-C. You can save some time and materials by cutting the triangles to align the equilateral sides.
The cord lengths are calculated by multiplying the formula X the diameter you wish to build.
Your measurements are calculated in decimals. Using our A-strut length of 2.788 the 2 stands for 2 and if we multiply the numbers after the decimal point .788 by 12 we will get 9.456. The 9 is 9 and to create our final fraction of an inch we can multiply .456 x 8 (8th of an inch) = 3.648. I would round this off to 4/8 or 1/2. If you round them off to the nearest 1/4 you should be fine. The 16 diameter was chosen because the longest strut is the C strut with a final length of 39-1/2. Using precut treated handrail balusters with a length of 42 we could not go much longer. This also created our largest triangle with the total height under 36.