29.09.2021 Base ring bracket spacing.

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Wednesday 29th 59F heavy overcast. 

Another thought: Toothed, plastic wedges are readily available in many different forms. Used by builders and carpenters for fitting floors, doors and windows.

One could be fixed behind every bracket to fill the gap and resist the pressure from the bracket fixing bolts. 

These wedges have very high load capacity. The toothed texture, intended to allow secure stacking, should grip the inside of the GRP dome like a clam.

The 150mm x 25mm, yellow wedges are too tall. There is a 90mm tall wedge [in brown] only 15mm deep. These would fill the gap nicely. Without pushing the brackets any further over the inner edge of the base ring.

I sawed a yellow wedge to 90mm long x 15mm deep. Just to see how it would fit. The spring in the shelf bracket is easily taken up by the lower bolt. I was able to achieve this even with a spring clamp. Note how the bracket no longer [sic] protrudes over the inner edge of the base ring. The brackets could be sawn off shorter but would then be prone to rust.

Having decided to continue with the shelf brackets I needed to mark their position. First I double checked the bottom edge of the skirt was level using the universal laser level. Then I checked the height to the lower screw hole in the brackets while resting on three arcs. 22 cm up from the lower edge. 

 

There followed measuring of the external circumference, at that height, using a surveyors, fiberglass, tape measure. The doorway proved to be 3m wide at skirt level. Each half circumference measured from the edge of the doorway was 5.15m. Allowing fifteen brackets at 34cm spacing. Making 29 brackets in all. I marked the center of the middle [roof] segment. There isn't room for two brackets. So 14 each side and one in the middle.

 

Then it was time to mark out the dome using a pencil in a beam compass. Measure up 22cm and scribe an arc at that level. Repeat. Repeat again. Lots of crouching and sideways shuffling. Multiple arcs creeping ahead of each other. I should have started at the back center instead of from the doorway! A couple of  millimeters, per arc, adds up when there are fourteen of them. 

 

Today's effort was finished off by drilling three, very small, pilot holes at the intended bolt height. I could then confirm the holes lay on the laser, level line inside the dome.

 

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