Dome build: Shutters: More shutter ribs.

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I need to decide what to mount at the top of the slit to take the heavy drawer slides. There is presently very little room above the top tier of panels at the top/back of the slit. So I shall have to sandwich some thick plywood tall enough to take the slides. Failing that I might have to cut the panels back to allow a taller plywood plate across the full width of the slit. Or replace the present one with something taller and thicker. That would save me losing some of the opening beyond the zenith.

This plate will have to be strong and well attached. Not just to carry the weight of the shutters but to cope with the inevitable drag from gales plus potentially heavy snow loads. A couple of 15mm birch plywood strips laminated together should do. Though three layers, to achieve odd numbers of veneers, might be preferable. 3x12mm? I could bolt on some serious, roofing angle brackets for a better fix to the observation slit ribs.Then there is always 10mm aluminium for a top crossbar to carry the slides. Would it become a lightning conductor? Not likely when there are more metal domes than wooden ones.

I was just removing the zenith board when there was a heavy shower. So I scrambled to cover the slit with a smaller tarpaulin. I need another 55mm of height on this board for the top, drawer slides. Though I really don't think it needs to be quite so massive as I suggested above.

I didn't have any aluminium wide enough so used 18mm birch ply instead. It is further reinforced by a curved strip of 15mm ply which supports the top tier of panels.

I bent some rectangular roofing plates to 90° and screwed those to the corners between the top board and obs. slit ribs. I also made the central shutter ribs and placed them in the shed for safety from the frequent showers.

The ladder was obstructing the shutter when the dome was turned. So I reset the big ladder to its original slope and re-fixed the near horizontal bracing ladder.

Making a skirt for the dome will be more difficult than expected. When I stapled some wide DPC to the bottom of the dome it dragged on the support wheels. Though it did look acceptably smart as a temporary measure it needs to be further out. Perhaps a wide moulding with a sloping top produced on the table saw? It would be attached at the bottom of the dome to give it a wider footprint.

The difference in diameter between the dome and octagon was due to the change to a 16 sided dome. A round dome cleared the octagon but the flats of the 16 sided one fell just inside the top, outer "corners" of the octagonal building's top ring. I can't cut off the corners because this is where all the rotation rollers support brackets lie. A wider dome base ring would help but would collect rain.

Yesterday evening I was using a router trimming bit to match the central shutter ribs. The shavings were flying up in the air like a fountain! I am aching all over today after my recent activities. There was a lot of lifting and climbing involved and it went on for hours. My back, hands and elbows are aching from the constant physical demands being placed on them over the last year or probably two. My left hand has been feeling 'sprained' for ages. It is actually a struggle to unscrew the top of the toothpaste these days.

Click on any image for an enlargement.

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