2.04.2021 Run out of cladding ply.

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Friday 2nd 37-50F. Some sunny periods but becoming cloudy. 

I trimmed and fitted the eighth sheet of cladding in the NE. Then added more screws along the top edges of all the panels working from a ladder. There followed some tidying up of the remaining sheet material and off-cuts. Talking of which: The DIY chain store has run out of the 12mm cladding plywood. They promise to have more next week. Probably DIY fans making carports and sheds over the Easter break.

Further to the suggestion for scribing the observation slit from the inside of the dome: I was finally able to reach some lengths of slotted angle right at the back of the shed. I assembled a well triangulated, 2m x1m rectangular frame with all the material I had. Which is heavy but not perfectly stiff. However, provided no resistance or twisting forces are applied to the frame it should be good enough. 

The difficulty will be in setting the pivot points for the frame to rock in. These want to be perpendicular to the external [ridged] mouldings. It sounds easy enough but isn't. Connecting the internal and external surfaces may only be possible with a drilled hole near the zenith. This will let me centre the frame. The "exit" is at the top of the open doorway and a marker can easily be carried around the edge. 

The subtlety of the external "facets" probably suggests I make a shallow V-form jig. With a guide hole at the centre for the drill. I have tied laying a straight edge over the crest [for making with a pencil] but this is not accurate. i.e. Not instantly repeatable without any change [or error.] 

The shed tidying has revealed yet another forgotten but very useful tool. A multi-bladed profile or contour gauge or copier. The arrow shows my pencil line drawn over the green laser line. The subtlety of the "faceted" dome profile is obvious. Until, that is, the gauge is moved even slightly to left or right without pressing down. The change in position is immediately obvious and unmistakeable. Another positioning hurdle overcome. For which I must thank my wife.

A 4.3m long 2x4 can be lifted up to the dome skirt on blocks. To form the long baseline for the frame pivots. This will allow subtle changes in [compass] orientation for frame alignment with the dome's external features. The interior of these features are even more subtle. This is due to the chopped strand mat & cloth being thickly laid-up inside the GRP mould. [8-10mm thick at the edges.]

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