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Wednesday 19th 38F very heavy overcast. Wet and windy.
I only needed a lower curve on the [studs] threaded rods I used to reinforce the top channel stays. The rods then passed vertically through the 10mm holes in the outer ends of the channel.
I did not mention that I added a plastic wedge between the top of the dome and the channel. The curvature of the dome had leaned the channel away from the zenith board. Which made the skate wheel hubs drag on the top edge of the channel. So I brought the channel more upright to combat this problem. I have lots of these carpenter's wedges. Which I had used to match the shelf brackets to the base ring. So I can increase the tilt if it proves necessary. They are very robust under compression.
The lower channel has yet to be fixed to the base ring. I am trying to achieve an accurate idea of the required spacing and degree of parallelism with the upper channel. More on this later after testing the shutter movement.
The shutters proved to be variable. Sometimes they would open effortlessly. At others the tops would stick. I removed the bottom channel. Then clamped spacers to fix the plank on which the skate wheels now ran. This was a definite improvement. I have been deliberately using overlapping channels of different sizes. Which meant aluminium rubbing against aluminium with the slightest misalignment.
There is a high point on the shutter ribs. At which pushing and pulling produces the smoothest movement at both top and bottom. I'm going to think about this problem before trying to fix anything. The shutters are usable, but a nuisance, as they are. There is no obvious way to stiffen them diagonally. Because the inside of their [spherical] curves is swept by the slit ribs.
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