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First things first.
The Pier and its footings. There are several schools of thought. This is the one that I chose. The footing should be a minimum of 220kg of concrete, more is better. This is roughly 500 x 600 x 500mm. The hole should be belled out at the bottom of the hole. This hole should be completely isolated from any other concrete and therefore poured first with a rubber strip running around the pier concrete. Then the pier should be a minimum of 140mm in diameter. It needs to be precision welded so that top and bottom plates are 90 degrees exactly.
Anyway, you can see all the tips that I made on the thread for Blackwood Observatory.
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