… one ring to bind them

It was considered cautious to reinforce the top wooden doughnut ring that would carry the dome, with an outer ring of steel that would provide a strong belt around its periphery helping to maintain structural integrity especially during rotation.

The mating beam underneath required no such support as it was firmly bolted to the roof frame of the observatory square chamber.

…time to bend metal…again

Picture19
Forming the band of 25mm x 3mm flat bar to go round the outside of the Dome base doughnut beam

Picture20

Now up until this point I had planned to build the frame for support of the galvanized shell out of a circular row of 15mm width flat bars arrayed vertically around and rising up from the metal band on the periphery of the doughnut

…a giant bird-cage

Picture21
15mm angle brackets tack welded to the top edge of the ring on the inside

These would bend inwards as they rose, to form a sort of giant bird cage of twenty risers to which the sheets of metal would be riveted.

For this reason a series of equally spaced 15 mm wide angles were welded to the top of the metal ring belt and a metal ‘spider’ was hooked on to a length of pipe to provide for temporary anchorage of the ribbing to allow their eventual welding together at the top.

Picture22
‘Spider’ crown positioned in the center of the ring. Brackets seen spaced around the base perimeter tack welded to the outside ring.

 

Picture23

The ‘Crown’ was made from a ring of flat bar to which were welded 20 radial horizontal lags. These were intended  to anchor the vertical ribs of the cage, arising from the base ring…. a cunning plan, as Blackadder would say,  but…

 

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