4.10.2021 Gluing the base ring together.

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Monday 4th overcast and breezy 52F. 

I spent/wasted lots more time trying to level the base ring's bottom layer. Despite all the jacks and blocks the ring still moves. Which won't help when I glue the next layer. The joints must be close fitting or they will bump over the rollers.

Do I really need to have the ring perfectly level while the glue dries? Two layers of 12mm birch ply will be stiff enough and will safely hold the butt joints together. The third layer can then be added and the ring leveled once it is a stable unit. 

The minimum temperature for using Titebond III is 45F. Today the temperature has reached 55F by lunch time. About the same is forecast for the rest of the week.

It reached 58F in the afternoon as I set about gluing the second layer of plywood arcs over the first. There was even a sign of sunshine later. A 1/3 arc length overlap will ensure staggered joints. I used every spring clamp I could find. My limited number of shorter F-clamps were used only at the butt joints. Lots of 4x20mm screws went in too. Which were driven just under the surface immediately after clamping. Thereby avoiding screw points protruding into the roller track.

I kept within the dome itself. To avoid extending the ring out into the weather and severely limiting access. I managed to glue five arcs and left them to set overnight. Borrowing clamps from earlier arcs was thinning them out too much. Closing the butt joints needed care. Though I was quite pleased how well it went once I started.

The area outside the dome's original, arched doorway needs lots of extra work. So I shall finish gluing three layers. Stopping at the inside edges of the doorway. The observation slit ribs will eventually rest on the base ring. Which will demand very careful measurement and trimming.

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