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JamesF's observatory build


JamesF

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I've posted these in DaveS's thread already by way of encouragement to work with Sketchup, but for the sake of completeness here is my design as it has progressed so far:

obsy2.png

obsy3.png

James

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9 hours ago, tobblerone said:

Wow thats awesome! How long did it take to draw the mounts and telescope? Looks really professional :) 

I can't claim credit for those :)  I downloaded them years ago when I did my first design.

James

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Whilst wood is generally my preferred option for construction, I have been pondering today on buying some 25mm-ish square section steel tube and welding up a frame for the roof.  I'm not sure I could bring myself to clad it Olly-style in wrinkly tin though.  It would also allow me to construct a more aesthetically-pleasing pitched roof without the need for additional bracing as I'd need to for a timber pitched roof of the size necessary (it will be about 4m long and not less than 3m wide).  Looks as though I could actually screw OSB direct to the metal frame as you can even get self-drilling self-tapping countersunk screws these days.

Just need to have a bit of confidence in my welding skills, I guess.  I might nip into the see the local steel fabrication chap next week (I need to take him a drawing of the pier for him to make anyhow) and see if I can scrounge some scrap to practice on.

James

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This is the sort of thing I had in mind:

obsy4.png

Creating this roof design has also made me thing that I probably only need four wheels, in which case I'd place them about 90cm from each end leaving a gap of a smidge over 180cm between them, so the wheels at the warm room end would be at most 275cm from the opposite end, meaning I'd not need such long rails extending behind the warm room -- almost a metre shorter than I currently have them.

I wonder if I need quite so many framing elements, too.  One of the advantages of timber is that I know what works.  With steel I'm not so confident.

James

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I have indeed been following Sara's build.  It's lovely.  Somehow I feel sure that if I tried to build something similar here someone would have the planning authorities all over me before you could say "Alpha Lacertae".  I particularly like the way the roof locks into the walls with pins when closed and will almost certainly steal that idea for mine.  Or if they're cheap I might look at the pins used for mounting tractor implements on a three-point linkage.  They have a cross-drilled hole through which a sprung locking pin fits which would allow me to permanently lock things up if I were going away for a while:

pin1.jpgpin2.jpg

And whilst I'm here I'll ping @ollypenrice for advice on what size steel he has used for his own metal-framed rolling roof constructions.

James

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One side of my observatory faces south and I made this lower.  Also have a drop down end in the form of a window made from twin-wall polycarbonate roofing.  I designed mine in SketchUp too.  I only have one pier and want three.  When I built my observatory I was less advanced in astronomy and particularly in astro imaging.  I could have had a bigger scope room and smaller warm room like you.  So I would advise sticking with the three piers.  I know it's a lot of extra work but you won't regret it.  I shall probably end up with three observatories to accommodate my three piers but two of them will not be human sized - just enough room for remote imaging. ?

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The drop-down end is one thing I still haven't really thought about yet.  I quite like Olly's design where it lowers automagically as the roof rolls away, but I'm not sure about the security of it.  Doubtless by the time I've got that far something will have occurred to me.  It may even  turn out that I don't need the end to drop down if it would just block the view of the house, but I suspect it will be worse than that.

James

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Today's progress:

I didn't really start until lunchtime as my priority for the day was finishing messing about with the plumbing after sorting our leak, but first I lowered the shuttering for the two concrete blocks that I'd already put in place so that the highest one will have its top at ground level.  After that I dug out the space for the two other corners, which didn't require a huge amount of digging as I found rock about four inches down.  In fact there's so much rock close to the surface that I gave up trying to get the pads square with each other.  As long as they're bigger than the obsy base, that will have to do.  The shuttering for the lowest pad looks huge as the ground level there is over two feet lower than at the highest one.  I may well re-use that shuttering for making the pier foundations.

obsy-build-7.jpg

obsy-build-8.jpg

The plan for tomorrow is to get the outer timbers of the floor made up and then get the concrete poured for these four pads.  The floor timbers will allow me to place the strapping (which may actually turn out to be some old radiator wall brackets) to tie the frame down accurately.

I have some stones and broken up concrete blocks that I'll also throw into the pads as I need to get rid of them and it will reduce the amount of concrete I need to make.  I do need to be careful that the shuttering doesn't "float off" given the weight of the concrete though.  I might have to rest a few more blocks on top just to stabilise things.

James

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What finer way could a blazing hot sunny day be spent than barrowing and shovelling a tonne of concrete? ?

I started the day by cutting some of the outer floor timbers to length and digging the afore-mentioned radiator brackets out of my pile of scrap metal to use to fix the timbers to the pads.  Then came the hard part: shovelling the ingredients for the concrete into the mixer, wheelbarrowing it to the right place and shovelling it out again.  I certainly won't complain about the weather because it's such a pleasure to be able to spend so much time outdoors, but by the time I finished my clothes were totally sodden with sweat and I was almost on my knees.

Very pleased to have got it all done though.  Here's how it looks now:

obsy-build-9.jpg

obsy-build-10.jpg

James

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Well, I could fudge around a bit with other stuff, but really now I need to get on with the concrete for the pier foundations.  I need to do the centre supports for the longer side but those are relatively trivial.  It's the pier foundations that are next on the "critical path".  The local engineering chap who has said he can make the piers for me is a bit busy at the moment (he mends tractors and farm gear generally so spring to autumn is his "busy" time).  If I can trust him to make the mounting holes for the pier in exactly the right places (eg. I want four 18mm holes centred on the corners of a square with 300mm diagonals) then I can go ahead and make the foundations using a template that matches.  I need to take the pier design down so he can see it.  I'll try to do that this week and see what he thinks.

James

Edited by JamesF
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Quotes for making the piers have come in at about £200 each.  Whilst that's significantly cheaper than some of the commercially produced ones, it still seems an awful lot.

As I'm kind of persuading myself to bite the bullet and weld up a frame for the roof I'm also therefore tempted to have a go at welding the piers myself.  I reckon I can buy the steel ready-cut for about £50 per pier.  I'd need to drill the holes and cut out an "owl's nest" (which might be the trickier part though I guess I could cut a rectangle out by drilling out the corners and then applying the angle grinder to join the dots).  It may not be the prettiest thing ever, but would save a fair bit of cash.

James

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I would use a MIG welder, it's pretty easy to get the hang of especially on new thick steel, it's worth getting a decent size welder that takes a sensible size gas bottle not one of those teeny ones that use disposable gas canisters.

It's also worth having a cut off saw, makes light work of cutting steel.

Dave

 

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On 03/06/2018 at 22:45, Astrokev said:

Wow, that must have been tough. I was only sawing bits of plywood and I was shattered (I blame my hay-fever ?).

Great progress James - at this rate you'll finish your obsy before mine!

I seem to recall starting mine at the same time as you. Must me getting close to a year now. ?

Edited by Adam J
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Like Gina, I've used concrete to fill 2 part, air conditioning ducting 300mm & 150mm. Nothing will move it now, & I pity the next owners who want to remove it as it goes 2m into the ground.

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