Intro: Dome Connection Clip
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Update 12/11/15 The pictures now show the new scissor stainless steel clip made with a CNC process that is stronger and more universal for strut frames than the spring clip. The pivot hole can be adjusted easily to fit any size pipe or square tubing PVC, aluminum or metal. We've used these to replace and extend broken conduit ends that were used in event domes due to many set ups and take downs. The struts are saved and the new self aligning connection is installed easily. There is no need to calculate geodesic strut angles anymore as once the hub is bolted solid in relation to all the connected struts they align themselves between the hub placement.
I'm getting ready for a production run on the clips, I'd like to get some of these out there in the DIY market to show folks how easy it is to build a dome or any strut type structure such as a greenhouse. This clip can also be fixed at a set position into pipe or tubing by adding one more hole and tab on the clip.
In building domes I felt the need for a better and simpler connection. I've looked at numerous geodesic hub connections for PVC & EMT and none of them had the angle self aligning adjustment needed for a geodesic application. Lighting wire or sprinkler lines can be run continually alongside the clip into each tube and the reusable clip will work in PVC as well as EMT tubing. For instance, in a greenhouse dome that required steel or aluminum tubing you would use the PVC in the bottom row for corrosion resistance buried under the soil and the metal tubing above that.
Another way to explain the flexible connection joint is that proper geodesic struts ONLY experience tensile and compressive loading. There is NO lateral pressure IF the strut is exactly the correct length between the rigid hub centers. Any mis-alignment of the strut due to improper length, variation from a straight line or bent hub connection ends will create lateral pressure and degrade the natural triangular strength in the geodesic design.
Patent 9151035 and others.