October 2014 – Prime time

After finishing and trying on all the side arches and supports, all these were dismantled again and primed with a series of coats including dilute fiberglass resin, wood preservative and oil based undercoat.

A formula I  picked up from the internet that I have found very effective in priming wood meant for the exterior consists of :-

6 parts Acetone
1 part Fiberglass resin
few drops of Fiberglass hardener

This mixture is painted on the wood or ply in several coats. It soaks in and dries very quickly and  if I intend to do any overpainting I tend not to overdo it or it might be difficult to get other paint coats to stick. I have used it on ordinary plywood and it seems as though it matched marine grade in durability and in its tolerance to the exterior. The wood preservative/ primer I use is Cuprinol and I apply two coats of that . This is followed by an oil based undercoat of the appropriate color (black in this case) and then two coats of finish. 

Picture44

A matt black color was chosen as this was considered least reflective.

…from paper to cardboard

Having worked out from the scale models the shapes and dimensions of the four broadly triangular sheets required to cover the four quadrants of the dome, the next step was to cut out the full- size shapes in thick builders’ cardboard and lay these out on the ribs themselves for the final trim. About 2 cms. was added to the width of each sheet to allow for the overlap.

Picture46
First cardboard template being sized up and trimmed to fit

…from cardboard to hardboard

After having trimmed and tried the four cardboard templates on all four quadrants, which fortunately they fitted without any great discrepancies, the next step was to convert these relatively fragile shapes into more rigid and durable hardboard ones that would subsequently be used as the  actual templates on which the metal sheets would be fashioned. Four templates were enough for all the sections required because of course these could be turned over and serve for both left and right faces of the dome.

Picture50
Four hardboard templates copied from cardboard ones

…from hardboard to steel

Four copies of each of the four patterns were next cut out from sheets of galvanized steel, using mostly hand shears and elbow grease! Some help was obtained from powered metal shears and scissors but by and large the manual approach seemed to be the simplest and best overall. 

 

Picture55
First sheet metal sector cut, fitted and clamped in place
Picture56
Second sector in place.
Picture57
Fourth sector in place.
Picture58
Fourth and fifth sectors showing overlap

… some local inhabitants of my garage stood watch while I toiled through all this. I don’t mind them at all.

Picture45

Picture45aThey’re pretty harmless and after all they represent my star sign 🙂 …and a beautiful constellation …home of Antares.

 

I considered their presence as an auspicious appearance on the set.

 

10
Constellation of Scorpio
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