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Saturday 26th. Another grey day with rain. 45mph gales forecast for tomorrow Sunday 27th. So I have lashed the dome down to the massive pier with ratchet straps. Several hundred kilograms of reserve loading will be added to the eight, dome restraining disks which constantly overlap the base ring.
I have been looking back over my last dome build and the extraordinary way I went about it. Nothing was really planned and it simply evolved as I went along. An interesting fact which I rediscovered was the weight of the bare wood and plywood dome.
The bare shell, without the hefty base ring and shutters, weighed about 300 lbs. So one can estimate that it weighs as much as the much larger [but still bare] fibreglass dome. The shutters and base ring, of that too, will add to the overall weight. I can still remember how covering the dome with 4mm ply added to the difficulty of rotating the dome. Which quickly led to my adding the friction roller drive.
I hope the new dome will have been much better thought out than the last. Reducing the modification time to perhaps, only a few months. I plan everything in my head and write it down here. Almost as I go along. This way I can fix details for onward consideration until that stage draws closer. Thereby avoiding the making of costly or time wasting mistakes. New ideas constantly pop into my head.
The entire building must be enlarged before the dome can be lifted into place. Though the original building now offers stability and a safe working platform which was completely lacking when the first was built. It would be ideal if I can get the larger top ring safely fixed up there. To guide the position of the new, upright posts. In comparison, the last build was more like constructing a castle in the air while working at arm's length from the ground. Which was hugely wasteful of time as I constantly erected and moved my few ladders.
Being able to raise the larger building around the first is a huge advantage. I can add support struts for the building's top ring wherever they are deemed necessary. Which will give me an accurate guide for spacing and fixing the new, upright posts. Further layers of plywood ring can be laid on top of the first for increased strength and stiffness. The last building used heavy, 2x8s laid flat with mitre joints between them.
As mentioned before, I plan to use 2x4s fixed side by side this time. Instead of the massively heavy 4x4s x 4 meters of the last build. Which were rather prone to twisting and cracking as they dried. I may even add diagonal 2x4 struts to help spread the loads more evenly into the smaller panels.
The cladding of decoratively grooved 12mm plywood adds a strengthening and stiffening, stressed skin effect. Which could be considerably increased by lining the new building with matching 9mm ply. Some of the original plywood panels could be cut down to clad the larger building.
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