12.04.2021 Shutters cut out. More cladding ply.

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Monday 12th 38-46F, bright, but with high cloud after an overnight frost. Continued cool but sunny.

I'd like to make more progress on the shutters. To be rid of the huge [spare] segment taking up lots of space. It is still draped over the car trailer and filling the entire area. First, I must confirm how long the shutters need to be. This is critically important not to waste the material available.

I chose to cut the centre line of the segment to 3.60m long. First I cut the unwanted pointed end off the segment. Then I used ratchet straps to stop the halves of segment falling apart as I cut with the jigsaw. The two halves didn't want to fall apart. They wanted to collapse inwards. So no problem at all. 

Now I just have to saw the shutters out. Which is two, roughly half width cuts out of the remaining strips. I shall lift them onto a workbench at halfway to make life easier than grovelling on the ground. The image [left below] shows two half segments nested after cutting along the centre line. I was using the pallet, in the foreground,  to protect the huge "aerofoil" from the gusty wind.

Later in the morning I went to the DIY store in town for more 12mm cladding plywood. They had new stock at a slight discount. This time I had help from a staff member so bought 12 sheets. Though I still need more. That was the limit of what would fit on their panel trolley.

Then, when I arrived outside, a builder was waiting by his car. Right beside where I was parked. He cheerfully volunteered to give me a hand to load my trailer. It was completely effortless with his help. So it all went perfectly! I just had to secure the load and drive home for a late lunch.

Despite being very tired, by now, I decided to go ahead and cut out the shutters. I could not get my head around the strange shape. The outer edge looked like a crescent. I was almost afraid to go ahead. So I held up a straight edge and moved my head until I could make the cut line look straight.

Once cut out, I could stand the shutters up over the observing slit of the dome. With a struggle! The shutters are still very heavy and remarkably flexible! The shutters are both rotated outwards. Higher in the middle, where they meet and lower on the outer edges. The cut, outer edges then became vertical. The shutter and slit ribs will have to be be made deep enough to provide this difference in height.

The image [right] has the resting shutters several inches too low, too far out at the bottom and too flat on the dome. I still need to cut them level, straight across their bottoms. They are standing on their outer corners at the moment. Which makes them very unstable. 

I have thrown a ratchet strap over them and left them clamped in place overnight. I didn't have the strength to get them safely back down to the ground again. 

I think you can see how the shutters nicely follow the curve of the dome in all planes. They should do as they came from a spherical panel. Providing an ultra-low profile instead of the usual projecting, outer ribs. Which stand well out on many "classical" domes. Including my own plywood dome.

The jigsaw "eats" blades when cutting GRP. The "Wood" blades end up with a completely smooth section after cutting for only a foot or two. This is only where the teeth have been in contact with the fibreglass. The "Laminate" blades take longer to wear the much finer teeth away. 

Only HSS "Metal" blades last long enough to make any progress. Even then I was pushing the back of the saw body to keep it moving along.  My arm was really aching by the time I had finished cutting 10.8m of shutter edges. Lot's of dust flying about too in the gusty conditions. I positioned myself upwind as much as possible.

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