Shutter
Initially I
considered to build
bi-parting shutters, like those on Mount Palomar observatory, but I gave up because although they are simpler to make, they catch
the wind and I had designed a large shutter opening
(850mm). I
decided to build it in two
separate sections having a separate drop down flap at the bottom. The top section runs in two aluminium tracks. The bottom section flaps
outwards when I need to observe near the horizon.
The shutter is made from
1200 mm radius arcs
and is 2 ply. The bracing in the shutter was made from pine wood . For the shutter skin I applied 3.2 mm thick plywood.
Shutter Tracks
The dome shutter rides on
two
parallel aluminium tracks. Each 2.7 m length of 25 x 19.5 aluminium channel was screwed down
against a 50 mm wide aluminium strip previously fastened against the 1100 mm
radius dome arches to provide a smooth and firm base.
At the
end of each track is a small bolt that provides a
shutter stop.
Weather Skirts
Two skirts made from 180 mm wide lengths of masonite are attached to the
observatory. One is hung from the dome and the other is attached to the top
of the base. This provides a trap to keep out blowing dust and
rain. The dome skirt was
attached after the dome was put on the base.
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