BillD's corner of the Universe
Building the Serenity Observatory
When I started getting into Astrophotography, I found I was spending much of my time setting up, aligning and then packing up my gear. So I decided to build an observatory in my backyard.
I highly recommend either having an observatory or at least a permanent pier under cover.
Clearing an area and pegging out the site
The first step was to clear out the area and peg out the location.
Eventually the large lemon tree to the left will be trimmed to make way for the roof to roll across the top.
After much deliberation, I decided to go for a concrete pier as it as it is generally cheaper than a metal pier and I could do most of the work myself.
Preparing the Form Tube
The pier will be shaped using a 12″ diameter concreting formtube. This will will be braced above a large hole which will form a separate base for the pier.
To make room to run some cables internally, I insert some PVC tubes. I also create a temporary cap that will be placed on top once the concrete is poured. This will be used to correctly position the threaded rods needed to attach the scope mount.
Preparing for the concrete pour
The main slab area has been framed, so we can now start digging the hole for the isolated pier foundation. It was originally planned that we would have a hole 600 x 600 x 1000 deep. But at about 800 mm deep we hit rock solid ground. Probably stabilised ground from sewerage that is supposed! to be about a metre away and a metre further down. So we could not go any deeper. I decided to go a little wider making it 700 x 700 x 800.
We then brace the form tube over the hole which contains a re-bar cage and 12 mm re-bar rods run most of the way up the tube. There was a lot of work in setting up the rig, this was by far the hardest part to get right. Constantly remembering that we need to have all that concrete in the hole isolated from the main slab that will be put down in a few days time.
The Pier
There is no turning back Now. She is full of concrete, so we are committed.
We will let this set for a few days and then remove the jig, The concrete foundation that protrudes from the ground will be surrounded by several layers of expansion foam before the main slab is laid for the rest of the floor. The top of the main slab is about one inch higher than the top of the pier foundation. This allows for the cables that come out of the bottom of the pier to be run below floor level to the back wall.
After a few days we can unwrap the pier and remove the supports.
Tada! Some scraped knuckles and a few expletives later…I have a pier. There are a few bubbles on the surface but its a lot better that I thought it would be considering that we had to use used very dry concrete to stop it flowing out from the bottom, and it was difficult to agitate in the tube. (A little bit of rendering will fix that before I paint it in a few weeks). I will let it completely dry first and I can also cut off the excess wiring tubes sticking out of the top of the pier.
Lay the rest of the slab
Here the slab has been poured with the frame still around the pier base to keep it isolated from the rest of the floor and hopefully reduce vibrations. Once it has dried, the frame is removed and the pier foundation is packed with several layers of expansion foam.
Before it completely sets a gouge a channel running from the pier base to the back wall, so I can run cables under the flooring.
Starting the Frame
while giving the slab a week to dry, I started building the frame and also get all of the roof trusses together…
I could not do this on my own so my good neighbour Max, came by to give me a hand.
After day one we managed to get the frame for 3 of the walls built and put into place. This is my first attempt at building a frame, but Max has a lot of experience and was able to give me some advice and help with the lifting.
One big mistake I made is that I bought some of the timber I required weeks before I was ready to use it. This was a VERY BAD idea. By the time I was ready to use it, most of it had turned into bananas and was pretty much useless. So I had to go out and buy more timber.
And on the 7th day they rested.
On the Sunday I got the rest of the frame into place and decided to have a break before getting the to work on the Roof Trusses. And of course that will be made more complex as the roof will need to move.
With the last wall in place, my neighbour Max, inspects our work while having a beer.
Let’s put build some roof trusses
Here I have finished the roof. For the time being the trusses are temporarily attached directly to the frame walls. This allowed me to completely assemble the roof structure and stop anything from going out of shape until the next weekend when I can start the next phase of making the roof move.
Making the roof move – part one
This was the most challenging part of the build.
The mechanism I was going to use to make the roof roll, is to use the same parts they use for panel roller doors.
I went to a local roller door manufacturer and and purchased the overhead channels and skates that are used when a panel roller door is opened and slide along the ceiling. They where kind enough to cut the curved ends off so I just had straight roller channels.
The next step was to create rails with the holders for the skate rollers. These rails will be what the roof trusses sit on.
After fitting the skates, they are flipped over. I the lift the roof trusses and secure them to these rails.
As there were only two of us working on this project, we originally constructed the roof in place on top of the walls and attached them to the wall frame.
For this next step, we simply jacked up the roof about 30cm, so it gave us room to install the rails and rollers.
There are five roller braces on each of the rails. 10 in total for the whole roof.
The wheels on axles are inserted into the braces and the entire rail is then lifted into the tracks under the roof, which is currently up on blocks. The Roof is then lowered onto these rails and bolted on to these rails.
The roller rails are now fitted in place and the roof lowered and attached.
Making the roof move – part two
At the same time we also had to add beams that run along the side of the observatory and extend out the back. On the inside of these beams is the galvanised C-channel the the roller are secured into.
This does two things. The first of course, is that the roof can now roll back along the tracks. However this also solves another problem. It reinforces the walls adding rigidity. If you have walls and no trusses directly attached, it can suffer from the “floppy box” syndrome. It would be like having a shoe box without a lid and the longer walls could lack rigidity without the roof attached.
Voila ! The roof moves.
Finishing off
The final parts of the build are more traditional:
- Adding the weather proofing and tin to the roof,
- Lining the walls,
- Adding the weather boards
- Building the door frame and installing a door,
- Painting.
- And finally, filling it with technology 🙂
