Unbuilding a two storey observatory.

[Rusted]

I thought it might be interesting to see the construction l used. As I dismantle my 14 sided, enlarged, 4.3m/14' observatory building.
Which I literally built around my original 10'/3m octagon. The larger building was offset by 1.3meters to the west. The 4.3m dome is now sold. [£5!]
Once the plywood cladding is removed the construction details of the skeleton can be clearly seen.
4x4 [10cmx10cm] full height, timber for uprights. Then the "sides" are cross-braced in 2x4 and 2x6. Using screws throughout.
I always use Torx screws because things can then be dismantled later. Without destroying the timber. [Recycling!]
A DeWalt sliding miter saw was ideal for obtaining close fitting joints. The plywood cladding acts as a stressed skin.
Providing triangulation without using diagonal timber braces provided enough fixing screws of adequate size are used.
Gluing in addition to screws is a safer option but I prefer to be able to take things apart in case they don't work out as intended. 
Diagonal bracing plus stressed skin is the belt and braces approach. My building never flinched during storms.
Its rounded form probably helped. A rectangular or square building has no such natural stability. Excuse the mess! 

[Mr H in Yorkshire]

Everything has its time! Interesting to see the construction and deconstruction.

[Rusted]

28 minutes ago, Mr H in Yorkshire said:

Everything has its time! Interesting to see the construction and deconstruction.

Thanks.

My memory isn't what it probably never was. The uprights of the outer building are paired 2x6s. [50x150]
Screwed firmly together and beveled on the outer faces. To match the angle of the plywood cladding.
I used a DeWalt table saw for this. Great fun with such long and heavy pieces. Working outdoors.
A handheld, circular saw might have been better but I never liked the great weight of these.

Had the plywood dome been waterproof I might never have bothered with the bigger dome.
I used expensive cartridges of marine sealer but this didn't keep the water out of the countless joints.
A shame because the dome was quite attractive and unusual.
On of Peter Drew's, half cylinder "domes" would have been an easier thing to seal.

Access was far too difficult and dangerous, at that height, to have clad the dome in GRP in situ.
In retrospect I could have had the dome lifted down with a crane to work from ground level.
Unfortunately access for any crane was simply too difficult on my long [200m] and narrow drive.
Just getting a modest tipper truck to deliver gravel proved to be quite a trial.
The local, lorry mounted, crane hire uses an even bigger truck. It could never have reached me.

 

[Mr H in Yorkshire]

We conversed about this all a while back - I know the problems you faced. Hope it all goes well and no mishaps.

[Rusted]

Thanks. The dismantling of the outer building is going very well.
The large Torx screws have all responded to a key or the rechargeable driver.
 

[Alan White]

Sad to see this deconstruction,
you take care and be safe in doing this Rusted
 

[Rusted]

Thanks.
I keep it firmly in mind that there is nobody to stick a plaster on any injuries.
Probably nobody would find me for weeks out here in the sticks.
It gives one a proper sense of fragility and vulnerability.

[900SL]

Nice bit of work there, Rusted. Good it can be recycled.

I've been lifting exterior decking that has reached the end of its life. It's a PITA, all nailed, needed a crowbar to lift the planks and had to use my big circular saw to cut the bearers and strutting below. Torx are the best

[Rusted]

Thanks. For some reason I wasn't notified of your response until today.

Living in fear of a demand for removal [by my very tolerant wife] guided my selection of materials and construction methods. My two storey domed building is half hidden by the house but still visible from certain angles. There are no near neighbours with clear oversight. The height was required because of constant tree and hedge growth. I was careful to stay within the very lenient planning rules for garden structures.

It was quite magical to do my imaging up there for hours on end. My wife preferred my being nearby. Rather than many miles from home on yet another cycle ride. The front garden is rather too small and limited to allow a reasonable sized [domed] observatory. Solar imaging would be reduced to only a few hours in winter. A white dome would also be highly visible to my neighbours and the distant road.

Light coloured, round objects stand out like a sore thumb in the mostly green countryside. While a white caravan can go completely unnoticed. I have erected quite small, TV dishes in the front garden and could easily see them from over 200 meters away. I just didn't want to draw attention to my hobbies. Nor cause an accident. When some motorist was "rubber necking" at my distant observatory. Which I soon painted green. After an exploratory coat of white primer. The primer was a serious mistake and caused the high quality timber protection paint to peel rapidly.

I have had a serious "man cold" for the last week or more. So deconstruction has been on hold. I have now discovered I have a heart problem. So must be very careful with heavy work. Normally I would have worked for hours. Like a very fit person in my 20s. Just as I have done all my life.

[scotty1]

You must of felt very proud and excited when you finished building such a grand observatory. 

Is there going to be another observatory to replace the dismantled one? 

Edited yesterday at 06:47 by scotty1

[Rusted]

1 hour ago, scotty1 said:

You must of felt very proud and excited when you finished building such a grand observatory. 

Is there going to be another observatory to replace the dismantled one? 

Thanks, but no new observatory is likely now. I'll explain why. Because it may help to guide other builder's decisions. I have years of hands-on experience at this.

My own back garden is no longer fit for solar imaging due to excessive tree growth. Only a narrow angle is clear around the south and the house lies on that path. A hot, tiled roof ruins the seeing! The only cool roof is white. This limits the choice of covering materials and is not usually considered very pretty. White corrugated cement sheeting and white glazed tiles are sometimes used by architects. The rest of us are unlikely to get away with it!

Shelter, from the sun, for the imager themselves is vital IMO. Sitting for hours exposed to the hot sun is very, very unpleasant and even dangerous. [Cancer & heatstroke.] A dome can provide vital shade but sets tight physical limits on size and wall height. I could hide behind my massive mounting, pier and instrumentation. This required I sit at an imaging desk with my large monitor[s] fixed to the huge pier and facing north. Some shifting about of my chair, to avoid the direct sunshine, was still necessary at certain times of day and year.

The size of my 6" refractor, with H-alpha filtering extensions, sets a minimum size for any permanent shelter. I am no longer able to lift such a heavy and unwieldy instrument onto a mounting unaided. Which means permanent mounting of the instrumentation. Even an E-W parking position set tight limits on dome size. Once the scopes are pointing high, the large swept radius must lie within the dome's supporting structure. [DIY dome ribs and observation slit ribs usually extend inwards.] A smooth interior is fine. If the structure is stiff enough. Which requires thicker and much heavier GRP. Or a perhaps a GRP-foam-GRP sandwich. I would never choose any other colour but titanium white for an observatory. Green painted plywood and self-coloured GRP absorb considerable heat. The heat is built up inside the dome. Then escapes through the observation slit and ruins the seeing.

Raising the solar telescope above the sun-warmed ground helps improve solar seeing conditions in the heat of the day. Grass is fairly, thermally neutral. Tarmac, dark stone, metals and painted surfaces anything but! I spend hours wandering around with remote sensing thermometers and IR cameras checking different surfaces. White is usually good. Depending on its absorption and emissivity across the entire solar spectrum.  Draping white tarpaulins or shades externally can be helpful but are usually wind intolerant and look very untidy.

A smaller, roll off [roof?] housing for the telescope and separate shelter for the imager would work. Having a continuous view of the telescope is vital IMO. To avoid cable tangles and obstructions. The camera end of the telescope can swing very low when the sun is high. Causing unforeseen obstructions on the imaging desk and furniture. Even though my dome was 10' [3m] in diameter and the walls my nose height it set severe limits on freedom of movement. I would often be tracking the sun continuously from just after sunrise to local sunset.

The cost of commercial domes rises rapidly with size. Making DIY the only way forwards for many of us. Which means the risk of failure is very high indeed. Unless one has lots of DIY experience. Long term weatherproofing is very difficult for most amateurs! Tar felt roofing is fairly foolproof but absorbs enormous amounts of heat. It is also very heavy!  A Peter Drew, barrel shaped 'dome' in aluminium would be my first choice. If I had my long life all over again.

[scotty1]

Could the trees be coppiced or trimmed down? 

Edited yesterday at 12:04 by scotty1

[Alan White]

Rusted, I never thought I would see a structure to compete with your build, but by utter fluke today and I think I have.

Sorry if this slightly off topic, but I had to share the image.

[TiffsAndAstro]

11 minutes ago, Alan White said:

Rusted, I never thought I would see a structure to compete with your build, but by utter fluke today and I think I have.

Sorry if this slightly off topic, but I had to share the image.

Doctor evil located

[ollypenrice]

Strewth, you weren't messing about when you built that. Very impressive.

Olly