Converting Plastic Water Tank for astro shed .

[Den]

Hi folks,

I would like to convert a 5000L water tank into a astro shed any ideas. Has anyone done this before.

Thanks

Den

[MrB]

Not done it before but I like the idea, would you be cutting the top off to make it rotatable? I reckon that would remove a lot of strength and the walls would then flex a lot, so would likely need a ring of some sort around the rim, which you would likely need for running wheels anyway.
What are the diameters of the tanks shown?

[rmuhlack]

the second picture there looks like a poly tank from Mastertanks in Adelaide. The 5000L (which I actually had in my garden when I lived there) is 1.8m in diameter, and 2.05m high.

http://mastertanks.com.au/wp-content/uploads/2012/02/Poly-Rain-Water-Tank-Adelaide-Sizes-Measurements.png

[Den]

Hi Simon,

I was thinking something like this.

5000L tank is about :
Diameter 1700mm
Height 2225mm

2 aluminium flat bars inside and outside diameter bolted together with a giant plastic bead washer for frictionless movement.

[multiweb]

:lol: Everytime I drive in the bush past one of these big water tanks I'm thinking the same thing. :) The big ones can be quite expensive though. When you think about it you'd only need the top part.

[Kunama]

Cut the aperture for your scope but rather than cutting the top off the tank, cut all but the outside 150mm of the floor out and have the whole tank rotating, much stronger, less chance of water getting in the top and any water that gets in will then go out the bottom. Then you can have your bearing surface on a slab of concrete and the whole tank held down by L brackets.

You will also need a door hatch of course.

A bit like Zane's Observatory only not so round!

[Den]

I like the Idea of having a complete seal around the bottom for bugs and dust.

[Den]

Hi Matt,

Good point about strength being on the bottom good for centre of gravity as well but how to seal for bugs. (on top)I was going to put a outside flashing for bad weather.


Den

[Den]

How about this?

[cfranks]

When I first came to Aus, in 1961, I rented a house in Hope Valley, SA that had a homemade 14" in a metal observatory. The obs. rotated on rails at the base and the builder kept the bugs out by having a 240v live rail under a flap all around the base! Worked very well!!

Charles

[Den]

I wonder if you could use 12V like a electric fence only using a quicker pulse rate.

[LewisM]

You could keep 2 legged bugs out by electrifying the door hatch when not in use ;)

[Den]

:lol: , The only trouble for me is I would forget to turn it off for my self.:eyepop:

[LewisM]

What a shocking predicament that would be :) :D

[bojan]

I would be very cautious about using watertank instead of proper dome.

The problem will be when the opening is cut - the tank supporting structure (actually, there is none) may collapse and you may end with wobbly and useless pile of plastic.

Instead, we (I am also considering all sorts of options for my future observatory) may try to talk Col into manufacturing some more of his very interesting 2.4m or 3m metal dome http://www.astrodomes.com/ (he is looking into retirement right now and the availability of his products is pending on sale of the business).

Geo-dome (https://www.google.com.au/search?q=geodesic+dome+kit&hl=en&client=firefox-a&hs=dIt&rls=org.mozilla:en-GB:official&tbm=isch&tbo=u&source=univ&sa=X&ei=PuMvUZ36KOmaiAfGy4CAAQ&sqi=2&ved=0CFEQsAQ&biw=1765&bih=775) approach is also very interesting one.. I am looking into sourcing the criitical elements of the construction, mostly the connectors, like in attachment (5-way connector is shown, 6-way is also needed for 3V dome.. something like on other attachment.)

Some interesting links:
http://www.strombergschickens.com/product/2-Inch-Bolt-Kit-and-Starplate-for-2X2/Starplate-Dome-Kit (2v dome)
http://www.geo-dome.co.uk/article.asp?uname=gd15_dome_kit
http://www.geo-dome.co.uk/article.asp?uname=GD5_babydome

[Den]

Here is a playground built with tanks, it uses metal to help support weak areas. eg flat bars & angle on door frames. It was very strong and roomy.

Den

[bojan]

Well, maybe this is OK for playground, but our dome must rotate as well. So there is no support on the lower part.
Also, cut needed for astro-dome is longer (zenith!)

My point is (probably 2c worth or even less), that it may prove to be more expensive to try and adapt the watertank, than building something more suitable from the scratch.

[Den]

Nice brackets, depending on how much they are I had a similar idea a while back using triangle brackets spread around evenly on a round plate. (see picture). I can weld this my self.

[Den]

I love those Geodesic dome kits, You could rotate the base on some aluminium angle on concrete.

[CDKPhil]

I have a 3m metal Astrodome, I think it was the last one that Col manufactured.
They are very good.

A little more expensive than a tank conversion but well worth it.

Dennis if you wanted to come and have a look and get some ideas, I am in the Canberra region, feel free to contact me.

Phil

[bojan]

Exactly right.
This particular one is suitable for me (right size), the only problem is there is no connectors, so the building is somewhat complicated.. it can be organised, though - there are 3 variety of spokes, that can be manufactured separately.
The cover plates (Al or galvanised steel) will add to the structural strength of the whole thing.

I am thinking along those lines because of relatively high price of the commercially available domes (like Sirius or Kiwi domes - they are ~10k for 2.3m diameter), and this is not all - you still have to have the building to mount the dome on.

That is why Astro Dome is interesting: very little else is required for the observatory, see here:
http://www.astrodomes.com/adome3000.php
But, as I mentioned earlier, it is not available at the moment

[Den]

Can keep the original base strength and have a good seal.
Have a hole for pier.
only need to strengthen the top area.
$ 750.00 for 5000L tank

[Den]

Sent PM

Den

[bojan]

You can't see anything below 45° above horizon (as per your drawing).

I still think watertank is not a good idea. Too many issues to sort out, simply because watertank is meant to be watertank and nothing else.

[Den]

I thank you for your imput those links are really helpfull.
My location I have only Zenith to 45 Degrees due to 2 story building.
I am going to visit someone with a metal Dome and get extra ideas.
I still like the idea of the water tank though, something about it maybe because of the challenge..
And price of 5000L tank is only $750 leaving extra cash.

Thank you again.

Den

[bojan]

Well, then perhaps the garden shed (https://www.google.com.au/search?q=garden+shed&ie=utf-8&oe=utf-8&aq=t&rls=org.mozilla:en-GB:official&client=firefox-a) (with removable roof... but easier to do here than on plastic tank with no support) could be the best option for you ?

[Den]

I have attached some pictures provides some perspective of area.
My wife likes the look of the round tank (clean appearance).

Garden shed maybe better, but does not look as nice.
Maybe bunch of flowers might help.:D

[kinetic]

Geodesic of mine: (foam triangles clad with concrete render)
http://jfbo.webs.com/observatory.htm

pros:
cheap! , practical for someone handy with basic powertools,
lightweight (one person can lift my 9ft dome, 2 very easily.
Can be torn down easily and moved. Insulates well(keeps scope , computer
cool). Traditional dome benefits of low horizon and wind off scope.
Geodesic very strong. 3 people fit inside mine easily with 12" F5 Reflector.

cons:

Insulates too well, use of fans for cool down helps this!
I wish I had made it bigger! 9ft is fine but 12 ft would be sweeeeet!
See Chris M's geodesic 2 storey.....now that is classy (http://www.iceinspace.com.au/forum/showthread.php?t=36222)

Steve

[bojan]

How about this approach? it is half way to the full enclosure..
http://www.iceinspace.com.au/forum/showthread.php?t=84067&highlight=water+tank

[bojan]

Hi Steve,
Very interesting, something like this is on my list as well!

How did you cut the triangles, did you have some sort of jig for that job?

[Den]

How about this It comes with astro seat and door.


http://totalsanitationsolutions2-px.rtrk.com.au/portable-toilets-and-showers/

:)

[bojan]

Well, jjjnettie found something of thar size earlier..
http://www.iceinspace.com.au/forum/showthread.php?t=77319&highlight=tardis

[Den]

Hi Steve,

I like this Idea as well .

Den

[Den]

Bojan,

Great :) a little humour is good for the soul.

:question: Your other link :
http://www.iceinspace.com.au/forum/s...ght=water+tank (http://www.iceinspace.com.au/forum/showthread.php?t=84067&highlight=water+tank)

With concrete footing and metal pier with small water tank cover is a lot easier for now. Perhaps a little larger tank like in my picture, I can even keep mount parked in home position. (Just add a solar vent fan)

Tank picture is 700mm diam.

[bojan]

I am glad its been helpful.. .
BTW, the mount fits nicely inside, and I am leaving it all the time like this.

Back on the geo-dome, this mob (http://www.sonostarhub.com/sonostar-hubs.html) sells PVC hubs for geodomes relatively cheaply..
3V dome connectors (with one section more below upper half) can be purchased for ~US$500.
Not sure about structural strength, as they are made of PVC.

Of course, one has to add pipes and cover sheet material on top of that.. plus mechanism for rotation, plus convex shutter for slit, plus...

Not cheap!

So, perhaps, the other attachment is the answer...

[Den]

I need a telescope shed. So I decided to go ahead with my water tank idea.
I have done some work on it, but the weather is quiet warm so it may take some time. The roof will be popped off like a biscuit tin lid.
The door is almost finished.

Regards

Den

[Den]

Has anyone used one of these on their telescope sheds.
(Solar vent ventilator). I am thinking of using this one on the dark round roof section in the image.

[mswhin63]

They look interesting, I may look at this for mine. With yesterday's 44.4 deg heat, I am not sure how my setup handled the heat.

[glend]

They are common in the boatng world where they are used on cabin tops to circulate air into cabins from outside or exhaust hot air - the fan blade is reversible. They don't move a lot of air but can help bring down internal temps alitte and importantly for boats they prevent moisture buildup in a closed cabin. Works best with a louvre vent located to provide across flow.

[multiweb]

Love it. I've often wondered, looking at those water tanks. Great project. :thumbsup:

[Den]

Hi Malcolm,

It should start to operate first thing as the sun hits the panel.
There is a 3" to 4" hole on the side of the tank to provide extra ventilation.

[Den]

Hi glen,

This is what I was hoping for.
On a 35 deg/c day at 15:00 I measured the temp inside the tank and it was 1 deg lower on the bottom of the tank and 1 deg higher at its highest point.

[Den]

Thanks Marc,

It is going to be a nice little project. I have got the Aluminium flat bar to go around the top section to reinforce when I cut the top off. Like a biscuit tin. Dig a hole place the tank over it. And drop the pier in with concrete. Pop the top section off and have a open sky.

[Den]

Here are some images for ideas, if anyone is trying to start a astro shed.
I have almost completed my shed.
I have been very busy trying to finish this project. Very hard with shift work and family.
I will add some thoughts and experiences very soon.
Image 1 from left shows tank area with lifting hoist for roof.
Image 2 roof swung to side out of the way.
Image 3, 4, 5, and 6 how gear looks inside tank.
Den

[Den]

Some more images.

[rustigsmed]

it looks awesome.
looking forward to the writeup, interested in the hoist,how easily the roof goes on and off and wall strength.

regards,

rusty

[astronobob]

Well on your way Dennis, nice work on a very good concept ! !
Looking on with interest ,,,,

[Den]

Thanks guys for your comments. :)

Well where do I start :question:.
I guess what attracted me to the water tank idea was the shape, it looks like a real observatory and has a sealed floor (To keep out bugs).


Door area:
I knew that the tank would lose strength when it was cut. So I used 80 x 6mm aluminium flat bar for the door areas (in and out) and top of tank rim. I also used a 40 x 25 rhs steel tube for both sides of the door for added strength. For me this was enough strength and it kept the price down as well. My first cut (door area) was with a jigsaw it was not ideal for cutting this material very shaky. I made the door first while the tank strength was still was intact. The aluminium was bent by hand on a metal frame (kids climbing frame) not perfect but close. Rollers would be nicer!. The end part of curved sections was bent with a large hammer between 2 points (blocks). The door making went ok but to hang it I had some movement even with supports under the door. two persons would be better.


Roof:
Now the roof section had to be cut. Not liking the shaky cutting of the jig saw made me purchase a mini rotorazer saw for $50 a bit like a grinder with saw blades. This made cutting the top section very easy. I chose to cut along the seam plus 50mm giving me as much wall height as possible. This was a mistake for 2 reasons. Firstly I should have made the cut at 100mm from the seam, my scope is a little low because of the wall height. Lucky I have extra room on the puck and I will get bigger longer bolts to compensate. Secondly the roof section would have been less wobbly. When the side hoist lifts the roof aprox 20kg it flexes and 2 sides sag about 200mm. This is because of the thin rim on top my 50mm cut not 100mm this would have made it more stable. To compensate I use a second lifting rope placed over the lifting arm with a hook on the sagging sides to support the roof keeping it flush (level) all round. Its not hard but could have been avoided.


The top rim:
The aluminium flat bar was made in 2 sections for the top section where the roof sits on. It made attaching much easier. It has made a lot of difference in the wall strength. When the roof is off the wall has some flex but for me no extra strength was needed. I guess one could add another aluminium bar further down.

The lifting hoist:
The longer larger diameter hoist pipe is attached to the wall in 3 places with cut flatbar washers it seems to hold ok. And is around 600mm above the tank. The second shorter smaller diameter hoist pipe fits inside the other longer pipe and is resting on the top support bolt giving about 1m height for the metal cables to be attached to. The arm that extends out across the tank is made of aluminium pool cover roller pipe (second hand). It was drilled with a hole saw to fit over the smaller diameter pipe resting on a aluminium plate which was hole saw cut as well.


One thing I found frustrating is the coloured silicon does not stick well on the poly tank so I used a clear silicon ( Selleys all clear ).


More to come!.
:)


Den

[Fox]

Hi Dennis
I have several polytanks for my garden, a 1000L and 4000L. Anyway, during my research into tanks, I also considered steel tanks as well: tankworks.com.au. They make to order, according to customer specified dimensions, so I wonder if you could get one made without the top cover? Just a thought... Although they tend to be more expensive than their plastic counterparts. cheers, Fox.

[Den]

Hi Fox,
You should give them a call and tell them your plans.
What materials would you build your roof out of.
I know some one who has a metal shed it is a very nice setup.
I feel that a metal roof would make more noise when handling it.

Den

[Den]

Hi Rusty,
Thank you, The roof comes off very easy. Putting it back on requires me to line up one of the bolts which can be a little fiddly due to my 50mm cut instead of a 100mm cut (flex). then the other bolts line up much easier.
It takes about 3 to 5 min to get the roof on. I am getting better each time. :)
Plus its harder because I am tired 2-3 am in the morning.
The old way took me at least 30min to pack up mount and gear and the next morning sorting out optics from kitchen table.
This makes thing a lot easier.

Den

[Den]

Thanks Bob.

[Den]

I have attached three more images:
Tank2b image is where the top is off and two hooks are being attached.
Tank4 & 5 images are showing the roof swung to the side with the two hooks and rope. This keeps the roof level.

Den