Dome build: Fitting the trapezoid covering panels.

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Dare I start on the covering panels with the sky looking so threatening? There was light rain for about half an hour but I plodded on with the covering panels. Finished the bottom row by 16.30pm. It is finally beginning to take its proper shape again.

The skeleton had changed only a little on its long journey "upstairs." Just an 1/8" of an inch, here and there, where the pre-cut panels needed to be adjusted for position. Though I wasn't tempted to get the circular saw and sled out.

Perhaps I should have waited for the dome skeleton to stabilize. The base ring now rises and falls on the rollers as it goes around. I had to pack up some of the hold down disks because they were dragging on the base ring.

Later I realised that I could "let down" the base ring in the "high places" with some metal angle brackets. Though I'll see how it behaves first before making any hasty adjustments.

The sections not in contact with the support rollers will tend to more heavily load those which are. The roller have massive over-capacity so I'm not worried. I'm glad I went oversized and upwards in quality. This will hopefully provide long term satisfaction as my strength is lost with advancing age.


I just need to ensure the lift stop disks don't foul the base ring or the ribs. It was this which was causing the tight spot. There will be a tendency for the dome to climb uphill and roll down the other side. I had already noticed this. Sometimes the dome moves too easily when I lean on it accidentally. At others it needs a bit of a shove to get going. 

It is surprisingly difficult to spot errors in the base ring as it rotates. The eight steering wheels provide self centering. Which makes checking for eccentricity almost impossible. I can't watch all eight wheels simultaneously. So have to work my way around them while ducking under the stepladders.

The arches of my feet were hurting after days of working from ladders. I have now used nearly two whole cartridges of the Sikaflex 591 marine sealant. Though no great skill is required to run a small bead as an adhesive the "mastic" dispensing gun has proved adequate to the task. As I have one tube left I should finish the next two rows of panels with plenty of sealant to spare.

Then it is on to making thicker plywood panels for the top section between the dome and the observation slit framework. Now I have to drag myself back up there to cover the dome for the night.

Sunday: Cooler but sunny. First I finished the second row. Then almost the third row of panels by lunch time. Only a couple of panels wouldn't fit. So they will have to be trimmed using the sled on the table saw. Duly done. I messed up a lower panel with the adhesive when I tried to reach the top with a glued panel. I was doing quite well until then.

Monday: Pouring with rain and blowing a gale. I had to throw some ropes over the dome to keep the tarpaulins from flapping wildly. I couldn't tie them onto the skeleton because the panels have covered the struts. Flat sheets don't lie flat on a hemisphere. Which is why I chose a trapezoid dome.

These old, lightweight tarpaulins are leaking like a sieve in places! I have put down some storage tubs to catch the worst of it on the obs. floor. At least the DPC plastic seems to be shedding run-off outside the lower walls.

Click on any image for an enlargement.

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