Collecting  Photons

1) Lying down the base (1).

Some thought went into deciding the dimension of the observatory. Some factors going into the decision are obvious (how much space have I got?), others are less obvious at first and require some advanced planning. For example, it is important to consider the available length of the beam that we are going to use: if they are 3 m long, it would be wasteful to design an observatory 3.3 m long.

After MUCH thinking I decided for a 2.96x2.36 m base.

2) Lying down the base (2).

The base sits over large concrete pads (50x50 cm) about 25 kg each. I levelled the ground underneath as well as possible but, on a side I had to resort to a strange sandwich of dirt and concrete blocks to attain proper flatness. The idea is that growing grass will stabilize the contraption. Time will tell.

3) The beginning of growth

The vertical beams are 8x8 cm, and they are anchored with iron angles at the base and wooden braces higher up. At this stage verticality and alignment of the beams are VERY important. I used a bubble level and a long straight beam to align the pieces.

4) Mounting the main support beams.

This is a detail of the way they are mounted. The 45° braces are screwed (long screws! 12 cm) through the floor in the beams that form the base of the observatory. Once that the braces are set the rigidity of the vertical beams is quite remarkable. The back wall is formed with long planks screwed to the 4 vertical supports.

5) Closing the box (1)

More vertical beams are added. in total there are 4 corner supports, 2 supports on each long side and 1 support on the short side.  Most of the floor is laid down. The door will be placed on this side of the observatory.

At this stage it was critical to check for parallelism between the sides. This is especially important, because this is going to determine the parallelism of the tracks for the sliding roof.

6) Closing the box (2)

The short sides are closed by vertical planks. This is for esthetical reasons and also because it simplify the door construction. The vertical planks requires two horizontal supports for better rigidity. They are visible on the left side, while on the right side the was is already covered up.

The upper beam on the short side of the observatory were carefully levelled. This required adding about 40 mm of height to the vertical beams on the left side. This is because of the fact that the entire floor slopes down to the left.

7) Lateral support for the entrance door.

A close up view of the lateral supports.

8) Another look to the lateral supports

A close up view of the supports on the back wall.

9) Reinforcing the corners

The corners are reinforced with a steel angle and 45° braces. In winter my site can be subjected to fierce northern winds and I really worry to see the collapse of everything. Reinforced joints and large beams: this is my recipe.

On top of the vertical support the small block of crossed laminate has been added to level the top beams.