7Wells Observatory Build

[old_eyes]

As previously announced I am actually going to bite the bullet and build an observatory.

 

So this will, I hope, be the record of the journey.

First things first - location. We own the fields around our house, and one of them is not overlooked and is well screened by hedges and trees. However, it is my wife's nature reserve, so there was a certain amount of compromise based on where unusual wildflowers and wild orchids grow, where various trial plots are, which trees cannot be touched, which areas get boggy when it rains etc. All perfectly reasonable. 

So after walking the field with Jan, the best location looks about here:

That is already about 60 metres from mains power (which my electrician says is fine) so I don't particularly want to go further east.

A quick panorama from a level camera at the expected scope height looks like this:

And the angle to the horizon with the trees as they are at the moment looks like this:

The main problem is the trees and hedge to the south and east. I have about a 45 degree zone where the altitude to clear the hedge and trees is about 26 degrees. However, the trees do need trimming. It is supposed to be a hedge, not a wood, so I could take the view to the south down to about 16 degrees.

East is great, but that way lies my nearest town with its skyglow. West is good although there are some mature trees, and I am looking over the house. North is my nearest major city. Some way away, but with a distinct skyglow.

Given the murky air at lower angles, is this good enough, or should I negotiate harder about location?

 

Edited April 6, 2019 by old_eyes

[Gina]

I think if you can trim that hedge well down as you say, it doesn't seem too bad.  Lots of people have a far worse outlook.

[mikeDnight]

Looks good! How far will you have to walk to the observatory in winter, and don't say the same as in summer?  I'm thinking that if you've to walk some distance th tough the snow, you might be put off somewhat. Losing a little horizon may be worth it if you have easier access. Just thinking out loud!

Edited April 6, 2019 by mikeDnight

[Startinez]

Happy to help out with electrical calculations and advice should you desire. As for the astronomical outlook, I'm not so experienced!

[old_eyes]

2 hours ago, Gina said:

I think if you can trim that hedge well down as you say, it doesn't seem too bad.  Lots of people have a far worse outlook.

Indeed I know how lucky I am. Spoilt for choice. Just trying to make sure I don’t commit any obvious howlers. I am probably only going to do this once?

[old_eyes]

2 hours ago, mikeDnight said:

Looks good! How far will you have to walk to the observatory in winter, and don't say the same as in summer?  I'm thinking that if you've to walk some distance th tough the snow, you might be put off somewhat. Losing a little horizon may be worth it if you have easier access. Just thinking out loud!

It’s about 100 metres from the nearest house door. I don’t anticipate a huge problem. We rarely get that much snow here. (There does not seem to be an emoji for ‘fingers crossed’).

[old_eyes]

2 hours ago, Startinez said:

Happy to help out with electrical calculations and advice should you desire. As for the astronomical outlook, I'm not so experienced!

Thank you. I might double check with you. I totted up the total load with my electrician, then we doubled it, then picked the next cable up in size. My kind of Engineering!

[Startinez]

12 minutes ago, old_eyes said:

Thank you. I might double check with you. I totted up the total load with my electrician, then we doubled it, then picked the next cable up in size. My kind of Engineering!

Have you thought about a career as an electrician? ?

[JamesF]

I'd agree with Gina.  If you can tidy up the view to the south a bit then it looks pretty good.

James

[old_eyes]

Here are some initial design thoughts. I have tried to learn from as many plan and build threads as possible, and also from visiting @ollypenrice at Les Granges.

Because I am building in what is intended as a nature reserve, I want to tread as lightly on the landscape as possible. So the concrete block for the pier will be flush with the ground, and the observatory itself will be standing on decking pedestals supported on paving slabs on the ground. No deep foundations. So the whole thing can be removed if necessary leaving only the pier block.

The decking pedestals are things like this

Height adjustable so I should be able to keep the observatory level and not in contact with the pier.

The designs I am showing are fairly crude to try and get a sense of the key elements and the different boxes in the structure. Most of the strengthening structure is missing and no roof or cladding.

Floor area in the telescope room 2.3m x 2m

I like the drop sides that @ollypenrice uses, and that will give me a good horizon. Wall height is 1.3m from floor level. Warm room height 1.8m. I plan to use F H Brundle track and wheels. The moving roof structure I would like to make out of square section steel tube. My engineer next door neighbour reckons that it should be strong enough for a span of 2.6m with a lightweight roof.  I am looking at the kind of multiwall polycarbonate they use for conservatories which is available in opal and other finishes. By insetting the wheels by about 70cm at each end, I don't need the track to project too far beyond the rear wall and should be able to avoid additional support posts.

With all those caveats about the early stage of the design, and the fact that this is the first time I have used SketchUp (what a learning curve!), this is what the initial skeleton might look like:

The grey sphere shows the maximum area swept out by the scope and mount, and fits the general advice - make sure the roof can close with the scope in any position, 'cos if it can collide it will!

Lots more detail to put in yet. Slope on roof, other strength components, folding south wall etc.

I am thinking of using polyester coated corrugated steel as the cladding for as much as possible - I like the low maintenance aspects and it fits with the rural environment. There are sheds like that all over the place! Not sure of cladding for the asreas where the roof runs as corrugated steel would stick out too much. Possible half-timbered?

Any immediate thoughts, particularly looking for the stupid mistakes that more experienced eyes immediately spot.

Cheers!

[JamesF]

Looks like a good start to me.

I'd definitely agree with having a bit of a slope on the roof sections to allow rain to run off rather than pooling on the roof and increasing the weight.  Thinking about how the folding section of the south wall will work and be held in place when upright is probably a good idea.  Also how you seal around the edges.

I've never used the polycarbonate stuff so I've no idea what it's like, but you might find it still allows too much heat into the scope room during the day.  If that turns out to be the case however it may well be possible to fit insulation internally as long as you still have clearance for it as the roof moves over the warm room.

I guess you're pretty much stuck with putting the door in the end wall of the warm room unless you want to crawl in   It's probably worth thinking about the layout of the warm room and where the doors go so you can use the space the way you'd like.

Guesstimating from the drawings, the pier looks as though it's about 90cm to a metre high from the scope room floor?  If you allow another 30cm for the mount (perhaps more depending on how you intend the top of the pier to work, that would get you pretty close to level with the tops of the walls.  That being the case, I'd suggest the walls of the scope room can be a little higher because you're unlikely to want to view all the way down to the horizon.  Once I had the frame for my floor in place I actually set a mount up on a tripod (on some bits of scrap timber resting on the joists) with a length of batten clamped in the mount to see how high I could make the walls:

In the end I decided 1500mm was actually quite feasible.  My piers are possibly closer to the walls than yours will be, too.

In order to make the roof as easy to work with as possible (ie lighter) I might also be tempted to make the gap between the roof rails and the top of the scope room walls smaller.  A small drop there will be useful for stopping rain driving in, but it probably only needs to be a couple of inches.

James

[Astrokev]

Great site you have there! Looking forward to following your project. SketchUp's great once you get used to the main tools and quirks  

[old_eyes]

21 minutes ago, Astrokev said:

Great site you have there! Looking forward to following your project. SketchUp's great once you get used to the main tools and quirks  

The thing that drives me mad is trying to rotate a component. I have looked at the tutorials, but it doesn’t seem to behave rationally in my case. So far, since all objects have been aligned with a principle axis it has been easier to remake the component in the correct orientation than to rotate. I’ll get it eventually!

[JamesF]

Oh, yes, I remember having all sorts of fun rotating stuff.  It's not too bad when you just want to rotate a component, but if you want to rotate it in place it can be a bit of a pain.

James

[Gina]

I found SketchUp had all sorts of strange quirks!!

[Astrokev]

I rotate components well away from the final location, then move into place.

[JamesF]

Yes, in most cases I think I found it easier to do that.

James

[Astrokev]

That said, my SketchUp days may be at an end. I've just had to install a new HDD in my main PC and have therefore lost my SketchUp install file (my data is fully backed up so all is OK on that score. I recall reading on an SGL thread that the free version is no longer available.  I haven't checked yet, but does anyone know if this is right?

[Gina]

I think I still have a SkrtchUp Make install file.

[Yawning Angel]

SketchUp trick 1) The keyboard cursor keys can select axis, saving all the vague waving of mouse pointer in the hope it gets it right

[old_eyes]

1 hour ago, JamesF said:

Looks like a good start to me.

I'd definitely agree with having a bit of a slope on the roof sections to allow rain to run off rather than pooling on the roof and increasing the weight.  Thinking about how the folding section of the south wall will work and be held in place when upright is probably a good idea.  Also how you seal around the edges.

I've never used the polycarbonate stuff so I've no idea what it's like, but you might find it still allows too much heat into the scope room during the day.  If that turns out to be the case however it may well be possible to fit insulation internally as long as you still have clearance for it as the roof moves over the warm room.

I guess you're pretty much stuck with putting the door in the end wall of the warm room unless you want to crawl in   It's probably worth thinking about the layout of the warm room and where the doors go so you can use the space the way you'd like.

Guesstimating from the drawings, the pier looks as though it's about 90cm to a metre high from the scope room floor?  If you allow another 30cm for the mount (perhaps more depending on how you intend the top of the pier to work, that would get you pretty close to level with the tops of the walls.  That being the case, I'd suggest the walls of the scope room can be a little higher because you're unlikely to want to view all the way down to the horizon.  Once I had the frame for my floor in place I actually set a mount up on a tripod (on some bits of scrap timber resting on the joists) with a length of batten clamped in the mount to see how high I could make the walls:

In the end I decided 1500mm was actually quite feasible.  My piers are possibly closer to the walls than yours will be, too.

In order to make the roof as easy to work with as possible (ie lighter) I might also be tempted to make the gap between the roof rails and the top of the scope room walls smaller.  A small drop there will be useful for stopping rain driving in, but it probably only needs to be a couple of inches.

James

Yes the roof slope is essential, I just haven’t put it in yet. I could also include a slight fall to the rails to help shed water.

wall height was calculated for a 15-20 degree horizon, but it was based on preliminary numbers so the walls could be higher.

the polycarbonate is strong and light. We have two conservatories roofed in the material, and it has stood up to everything North Wales weather can throw at it, including a storm that neatly removed a garage roof. I wondered about overheating, but you can paint it, or add shading film. I have some spare sheets to play with.

the folding south wall is work to be done, but there are good discussion here on how to approach it and what might go wrong.

Yes I am stuck with a door in the north wall, or go for a Japanese tea-house entrance. The key for me is to make the roof work well.

By the way, your thread has been one of my inspirations, so thank you very much!

 

[old_eyes]

5 minutes ago, Astrokev said:

That said, my SketchUp days may be at an end. I've just had to install a new HDD in my main PC and have therefore lost my SketchUp install file (my data is fully backed up so all is OK on that score. I recall reading on an SGL thread that the free version is no longer available.  I haven't checked yet, but does anyone know if this is right?

I used the online version. The menus are less conveniently laid out than the desktop version, but seem to work OK.

[old_eyes]

3 minutes ago, Yawning Angel said:

SketchUp trick 1) The keyboard cursor keys can select axis, saving all the vague waving of mouse pointer in the hope it gets it right

Ooh! I must try that in the next iteration!

[Astrokev]

3 minutes ago, old_eyes said:

I used the online version. The menus are less conveniently laid out than the desktop version, but seem to work OK.

I must try that if I can't download the free version

[JamesF]

28 minutes ago, old_eyes said:

By the way, your thread has been one of my inspirations, so thank you very much!

You're very welcome.  My own has been inspired by the builds of many others I've followed.  I think it's one of the great things about the DIY section of SGL.

James