24.04.2021 Limping wounded!

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Saturday 24th 40-53F, another sunny day but cool and breezy from the north. 

I obviously overdid it yesterday because I can hardly walk on my right leg. Probably due to crouching on one leg from the short roof ladder for hours on end. Sensibly, I decided to avoid too much exercise for today. So I tidied the observatory of all the accumulated detritus, bits of timber, screws, etc.

Then I measured the outside diameter of the building's 2"x6" top ring with the surveyor's, fibreglass tape. The largest measurement was 4.18m over opposing points. Average around 4.15m. All safely within the 4.30m of the dome. Though without the danger of being too small. A laminated plywood top ring will be added on top of the 2"x6" timber ring for reinforcement.

The centre of the new dome will be at the present, westerly pier edge at obs. floor level. The new, westerly, "2x6" is 100cm beyond the octagon's matching top timber ring. Suggesting that the huge, pyramidal pier needs to move 50cm to the west. [If I keep it!] 

As mentioned earlier, I plan to build a very large, cross-axis mounting. With the hope of mounting my three refractors, 180/12, 150/10 and 90mm f/11. All balanced by the 250mm [10"] f/8 Newtonian. Or some other instrumental combination to achieve balance. 

The cross-axis mounting allows large and long instruments to be used on opposing ends of the Declination axis. Without their being obstructed by the [now completely missing] central pier. There is also no need to do meridian flips unless desired for greater viewing comfort. 

The image shows a better geometry than earlier attempts. The north and south piers are based on timber A-frames edge on in the image. I want to maintain maximum clear headroom downstairs to avoid head injury. While still resisting thrust loads on the south PA bearing. Meanwhile the obs. upstairs needs clear floorspace [in the south] to move past the telescopes without having to duck under anything. Though it should be possible to walk under or behind the telescopes at many pointing angles.

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