The leaky dome roof is very depressing. Five tubes of marine sealant consumed and it still leaks like a sieve! I have started having repetitive dreams about taping the seams, fiber-glassing and cladding the dome in heat welded tarpaulin. Shrink wrapping plastic doesn't last long enough to be worth the expense and effort. Only shrink wrapping would keep the facets crisp.
The afternoon was spent correcting the shutters. First I lined up the outside edge of all four ribs. That meant a 2" outward movement for the inner ribs. Then I reset the height so all were level on top. I discovered that non-parallelism made the slides "sticky" at the far end of the shutters.
Careful examination from above showed that the inner slides were being pulled, or pushed, inwards or outwards at only one end. This was due to the timber to which they were screwed being skewed by the misaligned ribs.
I replaced the original [roofing] battens with 2x4s to have more meat to screw into. Then I had to trim back the ribs up at the top to clear the zenith board. Then all the slide screws had to be replaced because the originals would not run through the slides without the oversized heads hitting them. Ironically they could cope with the big screws when incorrectly aligned.
Eventually the shutters could be closed, or opened effortlessly, from anywhere along their length. A frustrating but still interesting exercise involving endless ladder climbing. In retrospect I could have left the ribs untrimmed but thought I had no choice at the time. When I first fitted them the ribs were stretched tightly between the slides. With no way to free them except to trim them back on the inside.
Monday: A drive to collect some galvanized T-hinges, some latches and another sheet of grooved, plywood for the observatory doors. During the afternoon I fitted the upstairs, double doors out to the veranda. Except for the latch to hold them closed. I'm using the same 1/2" [12mm[ grooved plywood as the rest of the building. Still bare ply at the moment but I shall add thin frames to the insides to prevent them warping over time.
I hope to avoid adding any [weather] framing above or below the doors because it would impede my ducking under the octagon top rail. The door height is 135cm. Just over 4'5". Having ducked under the bar literally hundreds of times during the build I don't find it too onerous. Though I would not want it being the main point of access. I have a habit of losing concentration and hitting my head. Which is why I usually wear a hat while working on the observatory.
It was quite a hard decision deciding where to place the hinges on the octagon posts. There seemed to be too many options. I finally settled for a recessed position on the inward slopes. This provided plenty of overhang above to reduce the impact of wind driven rain. The veranda doors face west towards the prevailing wind and winter rains. The doors had to open outwards since the ladder handrails bump against the doors in their closed position. Quite deliberately I might add. There is just room to push past the open doors when walking along the 60cm wide veranda. The doors each ended up 52cm wide.
I have discovered there are much wider versions of my plastic DPC roll which I used as a mini skirt on the bare midriff. 30cm would be more than enough. Then my wife suggested I cut strips from some heavy, rubber pond liner. This would be much stiffer and heavier than the thin plastic strip. Which would help to keep it in place compared with the plastic. Which blows inwards far too easily in windy weather. Being much too short does not help. First I need to add some heavy sloping mouldings to push the skirt out to clear the octagon top ring. This would reduce potential friction issues with the skirt on the roller brackets.
Click on any image for an enlargement.
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