Have a idea for DIY Dome

[RickK]

I was looking at how to get a small home dome set up fairly cheap, I was thinking about using a water storage tank as the dome and lower half / floor. Using a 80" dia x 90"H poly dome tank, cut a few inches below the rib to make the dome cap and use the lower half for the walls and floor then the top could be lifted off for use. The top @ 55 lbs. would be farly easy to lift off for use. There are other tanks I've looked at also and may look at a shorter tank.

[peroni]

This looks like a pretty neat idea. I'll be interested to monitor the progress you make 

Do you have any thoughts on how the two parts would be joined together after cutting? Hinges to flip the top over? Or a gutter/channel so top sits nicely on the bottom part. You'll want to keep the rain out.

[Bizibilder]

Some folk used to use the hemispherically shaped tops of grain silo's as observatories.  However that was when I was younger (and plastic hadn't been invented yet  ).  Looks like a good idea as long as the cost is reasonable.

[RickK]

I was thinking you could use a ribbed type tank, maybe a 1400 gal. It would be around 700 USD, for the 80"x 90"H. Cut the tank just below the top rib (Red in the picture), then it would be like a cap. Then it could be a lift off or flip off, but I think any type would be fairly easy. Plus its water tight, and UV proof.

[RickK]

Just a picture I found to give a idea of size, and I was thinking more about white as a color. It would be water proof and you could use the screw in caps as a point to add wiring. 

[RickK]

Some folk used to use the hemispherically shaped tops of grain silo's as observatories.  However that was when I was younger (and plastic hadn't been invented yet  ).  Looks like a good idea as long as the cost is reasonable.

I had thought about that and it would make a good dome, in my area they are hard to come by. Another Idea was to use a old large type satellite dish for a dome.

[spaceboy]

I'm aware of people having used the bottom of a septic tanks for domes http://www.thesun.co.uk/sol/homepage/news/142356/I-see-Uranus-from-my-tank.html . I looked in to it and while it would have been ideal it wasn't going to be within my budget.

Edited August 28, 2014 by spaceboy

[nytecam]

Great idea Rick:-) I can't guess their size but had you considered cutting off the base ( or top!) and rotate the 'dome' with a door for entry and a slot in the 'roof' to observe through eg a true domed obsy with complete protection for you and the scope

If you just lift the lid off eg RoR-like you've no such protection !

Edited August 28, 2014 by nytecam

[tekkydave]

An interesting possibility. I thought about making a geodesic dome.

[RickK]

I had thought about different ways, there are lots of options and even tanks with open tops more like a tub. You could do any configuration you wanted, for a few hundred you could get a tub type and a smaller dome tank and use both, or even the large dome tank and a smaller (less volume) tank with the same dimensions for parts make the shutter. Make the top rotate, then half the dome (shutter half) rotate on top.

[JamesF]

It's an intriguing idea.  I think you may find that once you cut the top off the tank that it loses much of its inherent strength however.  For example, in one piece the sides will resist deforming sideways relatively well.  Take the top off however and they'll probably wobble all over the place.  You may well need to take measures to reinforce the new lip of the "wall" so it will carry the weight of the top and the hardware required to allow the dome to rotate.  Cutting a door in the side may weaken it further.  I don't think that means the idea won't work, just that it may need a little more consideration

James

[RickK]

That is a possibility, I haven't looked at one up close. Where I retired from they used 55 gal drums with the tops cut off for trash cans and they were pretty rigid.  I like spaceboys idea as well.

[JamesF]

I have a similar 2500 litre (about 730 US gallon, I think) tank that I'm turning into an anaerobic digester.  The walls really aren't very thick at all.  Only a few millimetres.  I suspect that once you start destroying the integrity of the form it will lose much of its strength.  I guess the six million dollar question is whether you can restore that more cheaply than building the observatory another way.

James

[RickK]

I will need to check, I have looked at the pickup truck tanks and it was 1/4" (6.35mm) thick but if the larger tanks are that thin it would be a problem. Another choice I had was a custom metal building that is about the same price.

[zillah]

I'm slowly coming to the conclusion that this isn't a straight forward hobby, lateral thinking seems to be a huge part of what we do. In what other hobby would you look at a septic tank and a giant water container and think...'yeah, that'll work', although I'm now looking for the parts myself!!

[zillah]

Dear RickK, I am currently no longer talking to yourself or anyone else in this thread, due to you opening my thinking to a wider range of problem solving on a budget! In revenge, I was wondering if you had seen this.....

http://m.ebay.co.uk/itm/251630134644?cmd=VISPEC

[RickK]

Dear RickK, I am currently no longer talking to yourself or anyone else in this thread, due to you opening my thinking to a wider range of problem solving on a budget! In revenge, I was wondering if you had seen this.....

http://m.ebay.co.uk/itm/251630134644?cmd=VISPEC

No, I've never looked at a steel tank but if I had a way to cut and weld it I probably would. I always found it funny, anytime I was out driving and see a grain silo or a TV satellite dish I though "That would make a great dome".  

[zillah]

An angle grinder or a friend with a plasma cutter should be fine for cutting it, plus you (hopefully) wouldn't lose as much rigidity when cutting off the top and the doorway! I'm currently popping into charity shops looking for old Lego technique sets (with no luck), just to had a go at building a focus controller for my old scope..

[Richard Popovich]

I have the same idea using a 1550 gallon, white water storage tank, using a geodesic dome kit sold on Amazon.  The diameter of the tank would be just under eight feet.  To keep the weight of the dome to a manageable weight, I am thinking of using corrugated,  plastic panels used for greenhouses.  At first i thought of using the greenhouse materials because it can be purchased as a continuous roll, and then formed around an aluminum frame.  Then I thought about the floor and making the unit waterproof, and I dismissed the idea.  The water tank seems like a better way to go because it is all one piece and waterproof.

The only specification I haven't been able to find is the wall thickness, which would determine the weight of the dome it would handle, as well as the mechanical track to rotate the dome.  I drew rudimentary plans for this water tank observatory shown in the attachment.  If anyone has information on the wall thickness of these tanks and the mechanical track to rotate the dome please post your ideas/solutions.

 

water tank observatory.psd

[Cozzy]

Richard, just in case your not aware, you have posted on a very old thread.

[rodrigol]

This shows anything is possible 😊 There are many ways of adding doors, slots and of further stabilising the tank once cut. To ame a success of this project you need to take into account temperature control inside the tank and importantly ways of dealing with condensation. Ignoring these will ruin the entire project. But you are here and there are plenty of posts regarding ventilation, dehumidifiers and insulation. 

Great idea. I wish you good luck and lots of fun!

R.

[AlexK]

A hemispheric dome shape is used to minimize the material it is built from to reduce the weight as you want to move it around rather easily (by hands in the distant past). The OP idea looks like just a round shed with the removable roof, not really a dome.

So for a shed, there might be cheaper and more practical and convenient options (e.g. a ready to use plastic garden storage shed, just don't attach the roof completely). Migt be cheaper as well (surely, unless you can find a used/broken/defective tank, though a used one might be smelly  )

For the actual rotating dome-like roof, the easiest to make and most useful for our purposes approximation of a sphere is the rhombicuboctahedron:

I know it built from wood pieces and from welded metal scraps. It's easy to cover the surface for waterproofness with wood, metal, or most any other sheet roofing solutions, as well as equipped with sliding or hinged doors opening a large slit window from horizon to zenith (just cut or remove 3 squares).

Just my 2 cents.

Edited January 22, 2021 by AlexK