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Gina's Observatory


Gina

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Yes, this is a delightful site and I know how lucky we are :) I love the rural way of life and I love the countryside round here. And being relatively low in light pollution it would be a waste not to take advantage of it for astronomy IMO.

I looked at the cost of sheds and I reckon I can do it at less than half the cost - and get what I want at the same time :p

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Of those positions for the obsy, one, no. 4, comes out miles ahead from the point of view of sky area and general aesthetics. Only a minimal part of our wonderful view from the lounge window will be obstructed. With this orientation some of the prevailing SW wind will be blocked by the roof and apple tree leaves will tend to be blown away from the obsy. And as the ground slopes north/south there will be less digging out required for the shed foundations. This will partly counteract having to re-dig the pier foundation hole. The shed itself will be relatively light and will not house any heavy equipment so only light foundations will be required.

So... the decision is practically made. The apple trees will block some of the sky but the one closest to the site is smaller than the others and a good pruning will help considerably. The pier position will need to be such that the view dead north is not obstructed but initial measurements show that this will be near enough to the boundary anyway. I'll check the clearance well before starting building.

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Sorry, somehow the diagram didn't attach to an earlier post. I've added it now but I'll repeat it here. Without this diagram and the colour key my later posts would not have made much sense :)

The orange line around the apple trees shows what can be pruned.

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Before doing any digging, I'm going to clear the site and set up the scope and mount on the tripod to check what I can see and determine the best position in that general area. I think I'll look into the possibility of borrowing or hiring a mini digger - the ground here is hard digging, being clay and stones below the topsoil which is only about a foot deep. In fact I'm wondering if a larger area but less deep concrete foundation would do for the pier.

Checking the photo of the trees shows that the obstruction will be less the 30 degrees above horizontal once pruned.

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I think I'll look into the possibility of borrowing or hiring a mini digger - the ground here is hard digging, being clay and stones below the topsoil which is only about a foot deep. .

Oh I would recommend you do... our neighbor took just hours to dig out the trench for the footings for my obsy, and he said that doing it by hand would of taken him and his workmate 4 days solid as it was so hard going. If you are thinking of laying a 6" slab I would guess it should take less around a morning to excavate with a mini digger - well worth the cost.

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I wasn't thinking of a slab but footings for the walls and the pier foundations. I'm thinking of having a wooden floor using OSB sheets.

As for digging equipment, I shall ask around - we have several farmer friends.

I have made the decision - it's location no. 4 in the diagram above. OK, so I spent many long hours digging out the hole for the pier. I was decidedly over-keen to get a pier up. I have calmed down a bit now and looking to the longer term. Learned from experience! As others have said, best to get it right now before I put too much effort and cost into it. After all, there's plenty of time before the long winter nights. In any case, the tripod that comes with the NEQ6 Pro mount is pretty substantial and will do for now.

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Hi Gina

Enjoying the thread, but agree with an earlier post - you need to be careful you don't suffer from "paralysis through analysis". The upsides/downsides of the different options you've been deliberating on seem relatively minor to me. You have a great site that beats those of most of us on here, so I'd just pick one and get on with the build!

Looking forward to seeing some construction.

Kevin

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Enjoying the thread, but agree with an earlier post - you need to be careful you don't suffer from "paralysis through analysis". The upsides/downsides of the different options you've been deliberating on seem relatively minor to me. You have a great site that beats those of most of us on here, so I'd just pick one and get on with the build!
I've made the decision and I'm happy with it.
Looking forward to seeing some construction.
Me too :) Unfortunately, the actual building will have to wait until I have enough money. But I shall be getting on with the site clearance when I have time. I'll post photos as things progress. Oh, and I'll post the plans too when I've done them.
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Just to make things clear, this diagram shows where I've decided to put my obsy and warm room shed. It also shows how the apple trees will be when pruned.

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I have made the decision - it's location no. 4 in the diagram above. OK, so I spent many long hours digging out the hole for the pier. I was decidedly over-keen to get a pier up. I have calmed down a bit now and looking to the longer term.

Shame the existing pier isn't outside the line of the new position for the obsy. You could have left it in place and had a free-standing outdoor pier for those times when you absolutely, positively have to have two telescopes on the go at once :)

James

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Shame the existing pier isn't outside the line of the new position for the obsy. You could have left it in place and had a free-standing outdoor pier for those times when you absolutely, positively have to have two telescopes on the go at once :)

James

Very true. When I've cleared the site I shall be able to take exact measurements but as things stand I think the warm room would have to shrink a bit too much to get the old pier position outside. OTOH I would then have to have two decent mounts. (£££££).
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I've now had a chance to measure the long beams we have in the shed and they aren't long enough for the runners. So that's two 100x47x3600 timbers from Wickes to add. Current total is £300 and I haven't finished yet!. However, those beams may still be usable for something.

Although the runners would ideally be 4.8m long, I can manage with 3.6 since the bogey will have 8 wheels. At either end of it's travel it will be sitting on 3 pairs of rollers.

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Just a thought... Wouldn't it be possible to swap the scope room and the warm room and then use the existing half-done pier location? You would need to observe over the opened roof but with a good roof design (pent, not apex) that should be OK...

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If you're after hardware, screwfix have a clearance sale on at the moment. Could be that there's some cash to be saved there?

James

Thank you for that, James :) I'll check it out.
Just a thought... Wouldn't it be possible to swap the scope room and the warm room and then use the existing half-done pier location? You would need to observe over the opened roof but with a good roof design (pent, not apex) that should be OK...
A good thought but I looked at that and the roof would block 30 degrees of sky whereas I have a clear view to the distant hilltop eastwards over fields from the site. The west is blocked by houses and trees, with rising ground. If fact the site is 16 degrees from the compass points so the direction is actually 106 eastwards and 286 westwards ie. south of east and north of west. Unfortunately I can't see any way of not losing a large chunk of useful sky,
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I promised to post photos as I make progress, well, I've started preparing the site.

Stage 1. Removing the grass, using a Rotavator.

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A bit more done. Removed a roll of pig netting that grass an nettles had grown into making it difficult to pull out. However, I managed it with a block and tackle and some careful cutting round the bottom. I then was able to do some more grass and soil removal.

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Been working on the design drawings and sorting out which way to slope the roof, how everything joins up, etc. I looked at having the roof slopes such that the water ran off the obs roof onto the warm room roof and then collected in guttering. But this presented problems so I've gone back to sloping the roof to run off to the south side. (Same as Darren's design.)

I've also been looking at materials again. Plywood v OSB. 11mm exterior OSB is actually cheaper than 6mm exterior plywood. I imagine OSB is of similiaer density to plywood so would make a much heavier roof. Also, I presume it would need wider roof beams to support that extra weight. 63x38mm studwork has a discount on 20+ and was what I'd planned for the walls and roof using 6mm plywood. We very rarely get snow here so a lightweight roof would be alright. With 11mm thick OSB I think it might want 89x38mm studding for the roof beams. Wickes don't list a quantity discount on this size. So it's a close call between 6mm ply and 63x38 beams or OSB and 89x38 beams. I could use either OSB or plywood for the walls and 63x38 studding. OSB is cheaper in 10+ quantity, plywood is cheaper in 5+ quantity.

Looking at info on the net, it seems OSB is preferred to plywood as being more consistent, having no voids (ply can have knot holes) and not subject to the possibility of delamination.

Any of you builders and experienced DIYers have any comments, please?

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I built a chicken house from OSB having used ply beforehand and I've not been very impressed with it. The water does seem to get in eventually -- perhaps the fact that the surface isn't smooth, making it easy for the rain to collect and sit on the surface, doesn't help. I've gone back to using decent ply for my chicken houses and I think they're much better.

The other thing I didn't particularly like about OSB was the integrity of the cut edges. They seem to break up rather too easily.

Were you planning on painting the walls and covering the roof with felt, leaving them "natural", or something else?

James

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Thank you James :D I was planning on covering the roof with felt and painting (or maybe varnishing) the walls. I imagine the roof will be much more prone to wet problems, particularly as it will need a join in each section.

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My "off-the-shelf" 10x6 obsy uses felt-covered, OSB over (fairly complex) 2" timber, roof trusses, spaced every 2'. A ruddy great "main spar" runs the whole length. LOL. There is a "join" since OSB is 8x4'? At the limit of two-man (overhead!) lifting capacity, but still movable with one hand, when on wheels. :D

Dismantling the *previous* shed - with a LEAKING felt roof, revealed a LOT of soggy felt and timber. However, the former house owner had botched repairs over many years. I sense WELL-LAID felt is fairly fine? You might look at this "corrugated bitumenous sheet"(?) though... :p

No expertise, all a voyage of discovery... ;)

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I don't rate OSB either. I'm opting to use exterior grade ply for the roof sections, and 18mm for the flooring. I did consider cladding the exterior frame work with 6mm ply, but have managed to source some 7" feather edge boards for a decent price.

Having said that, our locations seem different, in that I'm in suburbia so want it to look as shed like as possible, and to fit in with the rest of the garden, where you are some what remote, so aesthetics may not be a high priority for you ? - In which case painted or varnished OSB is an option

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