10.10.2021 Shutter rib trimming and lunar imaging.

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Sunday 10th 40F

Having shortened the bottoms of the outer shutter ribs I laid out the arcs of the base ring. Now I have to trim the inner shutter ribs because the base ring passes through them. Or, rather, under them when trimmed. There would be a narrow section which avoids the circle. 

Interestingly, the GRP shutter covers are getting a reprieve from their former mini-skirt look. Trimming the ribs has brought the covers ever closer to the shutter's final length. I feared I would have to add an extensions to the bottoms of the shutters but it seems increasingly unnecessary. I fiddled about [sic] too long with the shutter height.

The inner shutter ribs are not visible in the image. Once the drawer slides are mounted on the shutters the covers may even extend past the ribs.

Lunar imaging? My wife spotted the crescent moon on the horizon from an upstairs window. I brought my G9 with the 100-400mm lens up to the window. Then just managed a couple of snaps before the moon was gone. 

The reflections from the twin panes of the window are clearly visible. I was aiming at  around 45° to the window glass. It was sheer luck I caught it in a narrow gap between a building and a tree. With further trees on the horizon. 

Back to working on the dome. I followed up on the base ring, drainage gap. First I loosened the brackets to get some slack. Then I screwed the brackets to the base ring. Finally I dropped a plastic wedge between every bracket. Behind the base ring and against the dome. Then when I tightened all the nuts, the brackets pulled the dome inwards against the wedges. Which helped to ensure a minimum gap all around.

So now any condensation can run freely down behind the base ring. To drip off the skirt outside the building. Rather than gathering on the base ring and causing puddles. Or damage to the ring. Moisture on the underside of the base ring can cause wheel spin on the friction drive roller.

This image is looking down at the bottom of the inner shutter ribs. The base ring cannot pass through the ribs without trimming them away. The base ring shown here is a mock-up of of several arcs. The short arc is just ensuring the longer arcs meet evenly. The joints have yet to be marked and cut on the miter saw.

I have hammered a steel pipe into the middle of the dome floor. To give me a guide for checking the base ring overlap at the doorway was both concentric and round. 

The base ring steers the dome [in a circle] via vertical rollers. So it is vital that it is truly round. Without the steering rollers the dome would quickly fall off the rotation rollers and on down to the ground. The steering rollers rotate against the inside curve of the base ring. I have eight on the plywood dome. There will be fourteen on the new one.

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