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Construction of Base & FloorAs long it's not square ..... !!! taking shape 22 june 2006 My
dear lady wife insisted that the observatory would not be a "square
wooden shack messing up the garden"
and she "suggested" the octagon - bear in mind I have never built
anything like this before!. I used 3" x 2"s for the outside
of the
base and 2" x 2"s for the internals. The pieces were securely
screwed together with a mixture of 2" and 1.5" woodscrews.
Keep off the grass  breeze block foundation 02 july 2006 My
garden is composed of firm clay and the breeze block foundation was
more than adequate. The blocks were levelled and the base
laid on
top. Note that I subsequently added more supporting joists to
the
base (as per the original
plan) to give it more support.
 base complete 02 july 2006 The
base and plinth with the mount and scope fitted - just to get a feel of
how it would eventually turn out. I was able to use it as an
observation platform at this stage. Note that there is a gap
between the plinth and the hole in the base so that no vibrations would
be transmitted to the plinth while walking around.
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Holding
it all together
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 This
allows you to calculate the dimensions of the octagonal "rings" for
constructing both the dome base and supporting rail.
Dome base  octagonal base ready for mounting geodesic dome and "skirt" 23 august 2006 Each
side of the base octagonal was joined using a combination of two wooden
dowels, staples, and ..... yes, you've guessed it ..... PVA wood
adhesive.
Dome support rail  octagonal rail "trimmed" (16 sides) to ensure dome "skirt" clearance for rotation 23 august 2006 I
worked out in advance that I would need to further trim the rail to
ensure clearance of the dome skirt which would eventually be fitted.
In fact, I had to trim a further centimetre or so off eight
of
the corners once the dome was placed on the rail casters to get the
right clearance - not a difficult job though !
Dome support rail  dome rail fixed to side frame with 45° wooden braces 26 august 2006 3"x2"
wooden braces attached to each upright using 8mm diameter carriage
bolts and ..... PVA wood adhesive. An extremely strong
combination and I didn't have to add the "cantilever" braces I thought
I might have to in the original plans. The dome rail was
checked
for level and attached with two 4cm woodscrews at each support.
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Side
panels fitted just the door to do - will have it finished this week ! 28 august 2006 Knock to enter  door on & painted, joints silicone-sealed, rail casters fitted many thanks to my long-suffering wife for her help here ! 16 september 2006 Run rabbit run  close-up of dome rail caster 16 september 2006 Initially
I attached the casters to the base using small woodscrews but I later
replaced them with nuts & bolts and raised the height a couple
of
millimetres off the base using washers. This ensured the dome
skirt cleared the roofing shingles applied to the "watershed" (see
below) and provided a much more secure fixing.
Water off a duck's back  "watershed" being installed 17 september 2006 The
watershed was constructed using eight cut-to-shape segments of OSB
board.
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