More work on the chamber.

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Once the concrete platform had hardened and while the good weather lasted,  attention shifted again to the chamber and its roof. The aperture of the roof would of course be covered over by the steel dome itself but the four triangular corner sections would be fully exposed to the elements and also receive the water draining from around the dome.  So the joints in these marine ply sections were sealed with wood-filler and waterproofed with several coatings of the fiberglass resin/acetone mixture. The point were the circular beam overlapped the inside border of  the corner triangles was then dabbed with resin and a fiberglass strip was worked in between the two and and over the joint circumferentially all the way around the whole beam. Resin mixed with hardener was painted and dabbed on the fiber.2015-05-01 12.52.23

On drying the excess fiber was clipped off with a sharp knife and the edged finished with sandpaper. 

The end result provided a smooth, hard and impermeable surface for the strip of aluminium skirting that was later added to the lower edge of the dome to complete the enclosure.

The corner of the each of the four triangles at their apex was drilled at an angle and  four small lengths of brass tubing were inserted with their upper ends flush with the roof and their lower openings pointing outwards towards the ground outside. These drains provided an escape for the rain water that collected there. the space around these drains was sealed with silicone sealant and the corner sheet sections were then finished with  undercoat and white enamel paint.

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The door was installed and  next the  front left  side panel which needed to have notches cut into it to allow for the door hinges.

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As an afterthought it was considered safest to actually anchor the frame of the observatory to the concrete platform itself and not rely on gravity alone to hold the structure earthbound ( The Wizard of Oz has left a lasting impression on me:) ).  So back to the garage and 13 rugged angle shaped long brackets were welded up, drilled to take 8 mm bolts and given generous coatings of galvacoat before being painted white. These would be bolted to the lower horizontal square hollow steel sections of the frame all around and anchored by stainless steel bolts  drilled into wall plugs in the concrete floor.

2015-05-11 19.49.42
Anchoring brackets drying off their galvacoat

 

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