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Dome vs Roll off ?

Astrokev

By Astrokev
in DIY Observatories

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swamp thing

swamp thing

Posted
Posted

Hi

I built my own domed obsy years ago. As I'm a builder this was neither hard nor costly but if you buy one they are pretty pricey.

TBH I never really liked observing from it that much. It felt like you were cut off somehow from the night sky. I wouldn't want another. As a visual DS observer though I neither want or need one.

If I was to start imaging I think, much as I really enjoyed building the dome I would go for a RO-RO one, as being out in the night sky always appeals to me.

Not sure my comments are much help though :)

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TheThing

TheThing

Posted
Posted
I opted for an ROR observatory for the following reasons
  • Even the chavs and yobs of today associate a dome with telescopes and thus in a town environment at least, advertises the fact that there is something of value inside. A ROR looks like a shed and most of the aforementioned arn't interested in lawn mowers or garden sheers

Actually, they are MORE likely to be interested in those as they are easier to sell on. Come the spring, break-ins to garages and sheds treble. Take a trip to any car boot sale and you will find 2nd hand garden equipment for sale. Not all of it has been obtained by legal means!

Chavs are more likely.to know the value of a Flymo than a SW.

TheThing

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malc-c

malc-c

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Posted

I agree that the cost of wood is expensive. Last year my build cost me £1200 in timber alone, with the total material cost of £1850. This is about the cost of the Pulsar 2.2m DIY kit, but then you still have to build the walls. Even if you factor in the additional costs such as mixer hire, tool purchased (compound mitre saw in my case) it still came out £500 cheaper than the 2.2m full height dome observatory, and my build included all the fitting out costs such as electrics, desk etc right down to the knobs for the built in cupboards. So in comparison, whilst wood construction is expensive, it's nothing to the cost of GRP.

Mind you maybe the comparison isn't the same as the Pulsar products are commercial so we should look at the alternative products on the market from commercial wooden ROR observatories. The commercial equivalent for my build was (is) £2795, an additional £1000 (ish) more than the total material cost, and then you still need to provide a decent flat and level base on which to place it. My £1850 cost included all the bricks and concrete foundations, and all construction materials. But it was a lot of work. I had the help of my son (17 at the time) and his friend who bagged up and help dispose of 1 tonne of earth, and moved two tonne of ballast etc from the drop off point. It took me best part of a week full time (12 - 14 hrs a day) in hot sunny conditions.... so a real labor of love.... but more importantly there isn't a day that goes past without me taking a look out of the bedroom window when I wake up and saying to myself......

....... I Built that !!

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ollypenrice

ollypenrice

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What a load of tosh, sorry to be so critical of your comment but I have a "small" dome on my observatory and it is great, loads of room. I obtained a SW 200 a couple of weeks ago and although I cannot now put that extra coat of paint on it fits perfectly. Now I know it has been described as part Dalek but I don't mind, it has helped me enormously, was cheap to get made and is fun (for others) :).

Jim

Be as critical as you like. Just don't be rude.

Olly

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The Sailor

The Sailor

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Be as critical as you like. Just don't be rude.

Olly

Rude, I suggest you keep you pretentious comment about other peoples equipment to yourself, you apparently have the money to splash out I don't so it's small and enough for what I want and can afford and it also does the job.

Jim

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Davey-T

Davey-T

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I think the original poster said he was strapped for time and as I said my plastic shed version could be built in a weekend and there is no chance of the roof blowing of as it

uses the original roof fixings of the shed, it also has a plastic floor so retains the waterproof integrity of the original shed when closed

Like Gina I like making stuff out of wood and have been doing it since before power tools became the norm' working on sites with no power so had to use hand tools.

Great sense of achievement when youv'e finished but you need the time.

Dave

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Gina

Gina

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That roof fix and it's mates on the other corners were added after an absolutely enormous gust of wind sucked the whole roll-off section up high into the air and carried it some 20 yards and deposited it upside down on our boundary fence - which it totally demolished. It was closed at the time. Three strong men were needed to recover it and replace it in it's proper place! Force 4 is nothing we often get that here and very much more. Force 9 or 10 are not that uncommon on this south-east facing side of the hill, exposed to the weather.

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ollypenrice

ollypenrice

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Posted

I think that roll offs are, in fact, cheaper and easier to make than domes. I've made five, all on tight budgets. The smallest and cheapest structure is the one with the smallest volume so this is the full roll-off which offers no protection to the scope once opened but can provide a sheltered space for the imager, though not for a visual observer. This can have a footprint of about 1.5 metres on a side plus space to roll off on floor based rails. Being structurally a bit doubtful they might be best with a simple welded up steel framework. You can pick up a MIG welder for £100. Bolting a plastic shed onto a welded steel U shaped chassis looks like a simple and cheap solution to me.

Next up comes the roll off roof shed which needs about 2 metres on a side if it is to be workable for visual and imaging. It doesn't need full head standing height so can be pretty low and unobtrusinve. An extended computer bay makes for more room if the objective is imaging. The raised rails do need space, of course, though I dug mine into a slope which happened to be there so the roof sits on the high ground.

And finally there's the roll off with warm room. Don't forget that the roof can roll back over the warm room, reducing the overall footprint.

Perfectly fair points earlier about the dew protection and stray light elimination of domes and I retain the right to think they look sexy!

Carole, don't the Pod people now do a device which allows the pod roof to move backwards a little once opened, so as to give access to the zenith?

Olly

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ollypenrice

ollypenrice

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But what do you do about wind + roll-off roof.. ?

Sorry, should have replied to this in the same post. What I do with all my roll offs is have a tongue on the rolling part that passes under a fixed steel flange or hoop on the ground part so that it 'can't' lift in the closed position. I've also added quick release guy chains. Now, of course, anything can lift if the wind is strong enough but we get raging winds up here (3000 feet) and nothing has ever moved. Over the last few years I've stopped bothering with the guy chains.

If you really were worried it would easy to make the roof entirely captive using interlocking flanges along the length of the shed. The same problems apply to domes and the same solutions present themselves, I imagine.

Olly

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Davey-T

Davey-T

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Posted

Roof of the six by six shed is so light that before I made it roll off I just used to lift it off and lean it against the side, that way it wouldn't add to the overall footprint if you were stuck for room

Have to be fit though.

Just noticed the edit buttons back, hurray.

Dave

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Gina

Gina

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Posted

Roof of the six by six shed is so light that before I made it roll off I just used to lift it off and lean it against the side, that way it wouldn't add to the overall footprint if you were stuck for room

Dave

Bit different from mine then!! :D
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The Sailor

The Sailor

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I went through quite a few changes with my 6x7 shed, slide back (into a tree) no, slide forward (rob more garden) no , cut roof down the centre (slide sideways) and that proved to be the best option, my only problem with all this was my equipment was getting bigger and heavier and was proving unmanagable in putting up so in the end came the Dalek dome :). Still there and functioning well, it is proving it's monies worth and can if needed be put on a new frame :).

Jim

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fwm891

fwm891

Posted
Posted

Been thinking a lot around a new housing for my scope now we have moved house. I originally had a RoR and warm room at the previous house, now I have a smaller garden with good south vistas so I have thought about a dome all be it on a square base. The practicalities however have taken me back to a RoR but minus the warm room as I can work from the conservatory (that's the plan)

See animation post #35

This is the basic arrangement I'm going to build - drop down front wall and RoR.

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JamesF

JamesF

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That roof fix and it's mates on the other corners were added after an absolutely enormous gust of wind sucked the whole roll-off section up high into the air and carried it some 20 yards and deposited it upside down on our boundary fence - which it totally demolished. It was closed at the time. Three strong men were needed to recover it and replace it in it's proper place! Force 4 is nothing we often get that here and very much more. Force 9 or 10 are not that uncommon on this south-east facing side of the hill, exposed to the weather.

A problem I share. To the north east there's absolutely nothing to slow the wind down between us and the Bristol Channel ten miles away really. When the wind is from that direction in the winter it feels like it really could go straight through you. It's not a whole lot better from the south west (the prevailing wind direction) either, although the house is built just off the top of the hill and gets a very small amount of protection from that direction. Twenty-five years ago or so there was a large stable with a hay loft here (originally for the working horses for the farm). One day the wind lifted the entire roof off and dropped it back down causing the entire building to collapse. I was working here as a builder's labourer at the time, but heard rather than saw it. Just as well no-one was inside when it happened.

As a result my construction methods might appear a little "over-engineered" :)

James

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