My observatory

In this section I want to show you how I've build my observatory.

It isn't a tutorial but I'm sure that the pictures will give you a lot of ideas when you're planning to build a observatory.

The dimensions:

The base unit is 3,55 X3,55 mtr (square) and it is build out of wooden cabin profiles (28 mm thick).

The dome is almost 3,00 mtr diameter and is a geodesic dome (made out of 75 triangles, wood 4 mm thick).

The dome and the roof of the base structure is coated with 500 gr/m2 polyester glass roofing to make it water resistant.

Drawings

For those who want to build a observatory like this one: SORRY I DON'T HAVE DRAWINGS !

I always work with quick handmade sketches.

This is how my garden looked like when I started building my observatory.

I also wanted to change the look of my garden.

In the middle you can see a hole , in the next picture you can see how deep it is.

By the way, I've already put 4 conduit tubings into the ground, you can see them on the right edge of the foundation, coming out of the ground. They end in my sellar where I can easily connect them to : 220 Volt, telephone, intercom etc..

This is a closer look at the hole in the middle. It is about 100 cm deep (lmost 40 inches).

To fill it, I have to use about 1 m3 concrete, this should give a good stable footing for the pier.

In the left corner you can see my right foot !

Here you can see the pier. It is a plastic tube with 25 cm diameter.

It goes about 65 cm into the concrete foundation, and will stand almost 140 cm above the final floor of the observatory.

The sand for making the concrete. This is just over 3 m3 sand. At the end I've used almost twice as much, because I made a mistake in the calculations ( grhhhh) . In total more than 5 m3 sand and 30 bags of cement (25 kg) were used.

Luckely I had some help of a neightbour and my twin brother, and within a day the job was done.

By yhe way, I first filled the hole for the pier and the pier itself, let it dry for several days and put on top a layer of sand. Then I made a wooden box to make sure that the floor isn't in direct contact with the concrete of the pier.

All the concrete is made.

In this picture you can also see four conduit tubes mounted on the pier and ending near the four corners of the concrete base. These tubes are laying under the concrete floor, and make it possible (future) to make connections between the telescoop and the equipment without all those cables on the floor.

This is how my garden looks at this stage. It is 19 may 2002

Still a lot of work to do......

After another long day, the first of my holydays, the observatory looks like this.

Hey, it won't be in camouflage colors ! I just painted all the parts that I cann't reach when it is mounted together. Also it is worth to mention that it is made of wooden planks with a thickness of 28 mm.

The technic I've used is similar to the technic used to build wooden blockcabins, so no bolts or screws are used in this stage of the building.

This is the central piece of the roof. It is build out of two layers underlayment (18 mm thick), and the measurements are 294 by 294 cm. I have to split it into two pieces to get it out of my garage.

At this stage the inside isn't round yet !

Here you can see the two layers. Notice that the lower layer is wider then the top layer.The lower layer is going to be used as a support for the rest of the roof.

Also notice the overlap between the to layers, so they can be gluid and screwed together

This picture shows how the central piece of the roof is mounted.

It will take some time to centre it equally to the walls, but it is worth the effort. Making the other pieces of the roof is much easier when they are almost the same.

The central roof piece is mounted. Also you can see that the innerside is round now.

I've also mounted a small band of thin plywood (4 mm thick) inside the inner circle, that should prevent the observatory for flooding with water when thewind is blowing. This band is almost 1 cm higher than the central roof piece.

THE DOME

This is a small model I've made of the geodesic dome I wanted to build.

It is made out of paper and took me almost one day to build. I think it is worth the extra time spent on this model, because I've leart a lot only by making it and also by looking at it !

There are some good sites where you can find more info on how to build a geodesic dome.

Interested? Look here or here.

I've made my dome out of 4 mm woodand I had to saw a lot of triangles. For this dome you only need two different shapes of triangles. In fact the dome consist of pentagons (5 triangles) and hexagons (6 triangles).

Look at the previous picture: see the different colors !

In total there are : 6 pentagons = 30 triangles and 5 hexagons = 30 triangles and 5 half hexagons = 15 triangles. ======> total 75 triangles !

This is one of the 6 pentagons.

This is the outside------------------------------------------------and this is the inside

The lighter strips on the inside are small strips cut out of offset plates, this is thin (0,2 mm) aluminium. Using these strips makes the building of a geodesic dome much easier ! Lay your triangles on a flat floor, glue the strips in place and then bend together the last joint, also with a strip.

Here is a detail picture of these offset strips.

The final hexagon or pentagon is still flexibel, but already very strong.

On the outside there is some space between the triangles, I've filled it with waterproof woodglue.

The total structure (each hexagon or pentagon) get very stable then.

This is the basic ring of the dome. It is also made out of two layers of underlayment wood (18mm).

To get a full circle I needed 8 segments of wood.

I first made a mold out of a piece of old wood, and cut the segments out with a electric saw. Before mounting them together, I draw a circle on the garage floor so that it was already almost a perfect circle when the segmentas where glued and screwd together.

I've also made a halve circle that is also needed for the dome.

To get these circles perfect round I've used a construction like in the next picture.

This picture shows how the router is attached to the piece of wood.

The piece of aluminium is adjustable in lenght to get the desired diameter.

The first circle is already "compassed" at a depth of about 4-5 mm.

The first pentagons and "half hexagons" are put in place and glued together.

Thanks to the "offset strips" this is an very easy job !

At the inside it looks like this.

Notice the use of the "offset strips".

In this picture you can also see the aluminium rails where the dome will stand on ( on 8 wheels, mounted on the base structure) so it is possible to turn the whole dome to each desired direction.

Voila !

The dome is almost ready, I just needed a afternoon to get this far.

All this is done without help ! The diameter is as planned before: almost 300 cm !

Putting in the last central pentagon on top was a bit tricky, but in the next picture you can see that I left out some triangles where the shutter is planned, so that I could reach the top easily !

This is where the shutter is planned.

You can also see some lines where the triangles will be cut away.

Make sure that the lines are parralel to each other and reach further than the top of the dome to make it possible to look at the zenith also ! The shutter wide is almost 70 cm.

Here you can see how I made the connection between the base ring and the dome.

Later I removed these connections !

At all the joins I've glued some "offset plate" circles.

Looks better, and makes the dome also "light tight"!

Yep, this is the dome opening, now you know why I made a half circle before.

By the way it is somewhat more than a half circle (emember we wanted to look at the zenith also ).

At the bottom of the shutter opening I've put in two layers of underlayment.

This is to prevents water getting (blown) into the observatory.

It also makes the construction more stable because I had to split the dome in two halfs to get it out of my garage. I hope you don't have to do the same, it makes the building of the dome more difficult.

During the dome building I've also done some work on the roof of the base structure.

It took some time to draw and saw all those pieces (16 ) . Looks like a big jigsaw puzzle, but it was worth the effort.

ALso notice the amount of weeds: they grow like hell !

Until now (19 nov 2002) there hasn't got any water into the observatory, and believe me : we have had some very bad wether with storm - rain and hail.

The hatch is made. As you can see I've shosen to move it to the side.

In my opinion it is easier to construct and in future to motorise it (maybe).

To make the movement easy, I've made some teflon bearings; you can see them on a picture that comes later.

The same situation, but the hatch is closed !

It moves so easy that my brother's youngest daughter (she's 7 years) can open and close it easily.

The dome is now ready, it can be put on to the roof of the base.

It is coated with one layer of 500 gr/m2 polyester roofing and a topcoating to make it UV proof, that was a nasty job to do (smell).

With just two people ( my neightbour and me) we managed to get the dome in two pieces out of the garage. We estimate that the weight is about 100 kg ( without the hatch).

The girl in the yellow T-shirt is my brother's youngest daughter, the other girl is his oldest. She is also very interested in astronomy !

The teflon bearings as mentioned earlier !

The hole is bigger as the diameter of the slide tubes, so it want get trapped. Also it is very difficult to get both tubes exact parallel, believe me: it took me some time to get it wright!

Finaly the dome is on top of the base structure.

It wasn't that difficult, with 7 people it was a "piece of cake" !

After some painting and also constructing a door, this is how it looks like on 1 september 2002.

This picture showes one of the 8 wheels with a ball-bearing.

The aluminium strip prevents the dome from flying away, which could happen when the wind gets under it ! Due to these strips I had to remove the connection triangles between the dome and the base ring, as mentioned earlier.

You can also see the aluminium rail mounted to the dome. This is made out of several pieces alu 3 by 30 mm. Thanks to this construction it is easier to motorize the dome, because the motor can stay in the same place. The wheels I've made myself ( I posses a metal lathe ).

In each corner of the base structure there is a lot of room for tables.

To get these illuminated I've used 2 groups of four halogeen lights. One group is with a red light and can be dimned. With a switch you can quickly change between the two groups. As can be seen in this picture and also in the previous one: I've chosen to make the inside blue. Due to the flashlight (I had to use for these pictures), it looks lighter than it is in real.

In each corner I've made a electric point, so there won't be problems with powering up all the equipment I want to use.

The vertical conduit tube comes from the central pier and goes under the concrete floor, so it won't be messy inside the observatory due to cables on the ground. By the way, as mentioned earlier, there are four of these tubes ( to each corner one !).

As mentioned earlier, I've changed the edge of the roof, so the water of the roof doesn't drip on the side walls anymore.

This pictures showes a part of the roof and the dome.

Like the color ?

This is going to be the main instrument / telescoop. It will have a lens of 15 cm and a focal lenght of 180 cm (so f12).

If I succeed, I want to build the equatorial stand also by myself, with steppermotors and "goto" function, but

that's another story and will take more time..

At the moment I'm working on the tables and I also have mounted a alarm to protect the equipment !

The telescoop I'm using at this moment.

New pictures (15 feb 2003)

	This is, at the moment, the main computer. It's a Pentium2 200 Mhz. At top of the picture you can see a DCF clock, so I've always the wright time. Just at the right side of the PC you can see the twelve volt power suply for the telescope At the right side there are a telephone , a intercom and the alarm installation. You can also see how much room there is in a square basic building without diturbance of the free room needed to look through the telescope.
	In another corner I've placed this old lady ! It's a 386 with 16 MHz. I want to use it to collect the suns radio signals.
	Yep, this is my telescope. Look at the wooden adapter I've made to put it on the central tube. It works great and is very stable.
	Same telescope and adapter, viewed from another angle.
	Just another picture.

Will be continued............