19.08.2021 Eye bolt plate and zenith board reinforcement.

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Thursday 19th 62F, bright start, became cloudy with a heavy shower at 12.00. I had to drop the tarpaulin over the slit in a hurry!

I found a piece of 15cm x 10mm aluminium plate suitable for hanging the eye bolt. I shaped the top to match the zenith board and will fit the plate vertically. 

The M16 eye bolt will pass through the middle of the lower, zenith brace board. Smaller bolts through the plate will ensure the it never moves under load. While tying the two zenith boards even more firmly together.

I have fitted two, 100x220mm, roofing, hole plates to further reinforce the joint. I shall buy some narrower plates, or angle brackets, to fix the ends of the brace to the slit ribs. Angle brackets could also be wrapped around the outside of these joints

The timber, slit, cross braces have been removed to allow easier access. I have left the two supporting posts in place to avoid dome sag during the construction phase. The bottoms of the slit ribs haven't been secured yet. Which means they cannot provide their contribution to supporting the dome until later.

I have to think more seriously about the base ring next. There are a lot of arcs to glue together. They must be flat and strong and accurately follow the curve of the dome. I have had a stack of neatly routed arcs awaiting my attention.  The ends need to be cut precisely at different angles to form staggered joints. 

The inside edge of the arcs forms the track for the steering rollers. Which keep the dome rotating concentrically. I have used skateboard wheels mounted on sturdy shelf brackets for this on my plywood dome. Once adjusted they have worked without issue.

As I mentioned earlier, I am going to hammer temporary battens into the soil around the inside of the dome. The 360° laser will provide accurate heights for supporting the ring. Once the ring is fully glued and assembled I have to fibreglass it to the dome. Which means I will need more resin and glass-fibre mat. [CSM.] Autumn has come early this year but still not too cool for fibreglass work. I can take advantage of any sunshine to work while the dome is warmed.

15.45[CET] Some sunshine prompted me to open up the observatory. The sun has not shone once since I switched on. So I can't point at the sun nor focus. There isn't a blue patch in the sky now! Nor was there by 17.40 as I update this post. I have been tidying the timber off-cuts stored in the dome again. So I can access the entire, internal perimeter of the dome.

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