Mowbs's Observatory Build

[Mowbs]

Well here we are. For as long as I can remember and since getting my very first telescope I have had a burning ambition to have my own observatory. OK, that's around two and a half months now but this is an itch that is just not going to go away.

I have had great pleasure and taken a lot of inspiration from reading about many of your observatory builds over the last couple of months and hope I can give some of this back through this thread. I have a good idea of what I'm aiming for but I'm going to be winging it a lot along the way.

I have moved around my garden and set up my scope in various places and I think I've found the best site I have available taking all things into consideration.

It feels like a huge step forward to start this thread but don't be holding your breath to see the finished (or started ) article just yet. I work offshore on a month on month off rotation so work will hopefully progress quite quickly when I'm at home but will obviously stop when I'm at work. I leave on Tuesday so I wont be starting until I get home in the middle of April but I'll be doing a lot of research, planning and pondering while I'm away so I appreciate any comments, ideas or criticisms.

I plan to make a concrete pier first and I will be able to use that while the rest of the build is underway. I was initially going to have the obsy raised up on wooden legs but I'm now thinking I will lay a slab base around my pier and build on that. I want to make it reasonably substantial and aesthetically pleasing, I don't really have a budget but I will try to build it as cheaply as I can without scrimping or cutting corners.

I have been setting my scope up inside the area I've staked out with posts in the photos below and I realise height of the side walls will be a compromise between protection from the elements, obstructing my views of the horizons and head height.(I want to make a warm room / man cave at the back) and I have found the bigger the obsy gets greatly reduces the obstruction of the sides, the main downside I can see with this is that the roof is going to get heavy.

As you can see in the photos I have trees on most horizons, the south view is fairly open but I do have to wait an hour or so for planets to move from the horizon to be visible above the trees, my north view is the most restricted but I can see Polaris no problem and it's probably not as bad as it seems once it gets dark and the stars come out. The roof will roll towards the North too so hopefully it will only obstruct my view of the trees and not the precious skies.

The footprint I have marked out is approx 3.5m wide and 4m long but I might make it a little bit longer to give me plenty of space for a warm room, the roof will roll back but still partly cover the warm room although the warm room will have it's own ceiling to keep the warm in.

Photos of location

1] Proposed footprint

2] South view

3] East view

4] West view

5] North view

I'm not too hot on CAD or Google Sketch Up so here's a couple of old fashioned sketches of the plan

And with the roof rolled back

[r3i]

Looks like you've got great views pretty much all round and I would imagine not a lot of light pollution.

Interesting design for the observatory - looking forward to seeing how it develops.

Wishing you every success - you do right to take your time, there's no rush.  Enjoy the process of building - hopefully you'll find it as rewarding as the end result.

[Tinker1947]

Interesting set of angles your going to have there, good luck look forward to watching your build....

[Mowbs]

r3i, I just spent ages looking at the photos and reading about your build on your website. That looks amazing and is very similar to what I am planning with the exception of a hexagonal frontage but it was hugely informative and interesting. I have bookmarked your page and I will be referring to that a lot during my build I suspect. The roofing material is something I haven't really decided on yet, the EDPM rubber sheeting sounds like a great option. I imagine I will be giving myself additional challenges making a hexagonal front to my roof so that could restrict the material I am able to use.

Is there anything you would change if you were doing it again and do you find the size is alright?

Tinker1947 are you referring to the angles in my plan or in my sketches? If it comes out too close to the sketches I could be in trouble, I probably should have used a ruler hopefully the real build will have at least 2 lengths of wood approximately the same length!

[laser_jock99]

Looks like a good site- keep us posted with progress.

[A40farinagolf]

You're so fortunate to have such a good site available to you and your plans look superb.

I've just started planning my observatory, not quite on your scale as I've only got a 5' x 5' spare plot available.

Anyone got any plans for a pent roof shed conversion where the roof pivots about the highest point of the shed?

[r3i]

Glad you enjoyed my build pages.  I've been pretty happy with the way it turned out, it's about a year old now - the only disappointment has been the lack of clear skies but that's been the same for everyone.  The size of 4.8m * 2.4m split in half between the scope room and the warm room has given me plenty of space. 

There's been some fantastic builds documented on this part of the forum that I used for inspiration so I'd recommend working through them for ideas, though you've probably done that already.

Quite a few of us have gone for an EDPM roof - it's quite a bit more expensive than traditional felt, but is a lot easier to install and looks to be more durable in the long run, so I'd definitely recommend it.

[Mowbs]

Here's an update of the plan, much the same as before but this one looks like it might stand up to a breeze slightly better and the pitched roof has been shortened over a flatter warm room roof, influenced by r3i's build. A ruler was found and used for this one. Hopefully I can find a tape measure before I start on the real thing or it will look more like the first sketches

[dmahon]

One worry with the hexagonal front is that, as it rolls off, it may need a horizontal support brace - which will lose all the headroom you had gained by having the hexagonal front in the first place. I'm sure there will be some kind of engineering way around it though.

[yesyes]

That is a nice site! I wish I had those horizons.

Interesting design. Good luck with the build. I'll be watching

[Bizibilder]

That looks very interesting and you certainly seem to have a good site to start with.  I would be concerned about the "hexagonal end" as it could be very difficult to build and to retain adequate strength.  You may also find that the "missing corners" inside the observatory will restrict your movement around the scope - It is amazing just how large you become on a cold night with several layers/coats etc to keep out the cold.  I also went for an EDPM roof and it was installed in under an hour (with the help of Mrs Bizibilder - bless her!) - it has proved to be an excellent investment and not that much more expensive than decent roofing felt.

[Fordos Moon]

All the best for a successful build! Just nearing the completion of mine and it is fantastically rewarding!!

[nightvision]

Great locaton and an interesting design. 

Have you checked out the drainage in that area?  Given that you re putting it very close to that mound it might be an idea to dig out some kind of drain-away.  If you don't bother the obsy foundations may behave as a focal point for any run off.

Like the asthetically pleasing design, makes a change from the usual boxes. 

[twintin]

Looking forward to seeing how this progresses. Keep the pics coming.

[Beulah]

Love these build threads, going to keep an eye on this one. Some of you guys have enviable views from your garden. I'm not jealous in the slightest.  

[nytecam]

Envy at your open skies site and good luck with the RoR project - I'm a dome man myself ;-)

[jambouk]

Why not have the external door opening into the observatory rather than the warm room, so then you'd have more wall space in the warm room for shelves or cuboards or desk space, and it would be less drafty and "warmer".... That's what i plan to do.

But it looks smashing and the location great!!! Well jel.

Jd

Sent from my iPhone using Tapatalk

[yesyes]

That's what I've done for exactly the same reasons...

[Tinker1947]

If a opening door is a problem, go for a sliding option built on the scope room side and made wider than the opening it would only require a bolt top or bottom to keep it open or closed......

[Stevp]

Looking forward to seeing this project unfold!!

Sent from my iPhone using Tapatalk

[Mowbs]

Thanks everybody,

There are some great suggestions and things I hadn't really thought about in those replys and it's given me a lot to ponder on. I agree the hexagonal front will affect the strength of the structure, I've also been thinking of fitting 3 drop down flaps on the 3 front panels which would again comprimise the structure but I'm sure as dmahon says, it could be engineered out.

Anyone who has used the EDPM for roofing material, do you think it would be possible to use it on a roof of that shape? I was thinking about the possibility of folding the excess at the angles of the roof and glueing the flaps down but I don't really want it to look like a pigs ear. Perhaps I could fit the 2 smallest angled sections as seperate pieces and then glue the main part over the top. I'm sure that wouldn't be ideal and it would comprimise the integrity of the sheet and would 2 pieces glued together give a waterproof seal? Failing that I could install some kind of ridge tile or go with a completely different material. (Profiled sheeting, plastic roof tiles, etc?)

Either way, I know this hexagonal end is going to be a PITA but I'm determined to keep it.

I have started looking to source parts for the pier. My plan is to fill a section of 200mm plastic pipe with concrete and rebar and fit an Altair Astro type mount adapter directly to the top with no adjustment plate.

http://www.hampshireastronomy.co.uk/product/skywatcher-pier-adapter-eq5

Accessing the mount bolt in a similar way to the pier in this build

http://www.philchris.co.uk/pier.htm#Lower%20Pier%20Construction

With a space for a hand or a couple of dainty fingers (that wouldn't be my fat sausages then) to fit the bolt and tighten it with a ratchet and socket.

I have been considering welding 'L' angle steel to the nuts of the allen head bolts and burrying them in the cement to form a captive nut (held in place with slightly longer bolts (so the actual ones don't bottom out on the concrete) through a ply wood template)

I don't see a way of fitting the mount adapter in the more conventional way of concreting protruding threaded bar out of the top of the pier because the adapter would need the heads of the nuts to be recessed.

Does anyone know what size of thread are on the nuts / bolts of the allen head cap screws supplied with these mounts? I have emailed the company but haven't had a reply yet. I will try another supplier if I don't hear soon.

I'm sure this design will have some flaws, perhaps 200mm is not a big enough diameter if I am loosing a quadrant the best part of 100mm wide at the OD but I will make some kind of mock up before I start to see how much pier I will be left with by the time I can get my hand in there. I can always increase to 300mm like the pier build above.

I also have concerns about concreting captive nuts into the pier, probably not the cleverist thing in the world and it could be difficult to get a good anchor that's not going to pull out or crack the concrete above it as soon as I tighten the bolts. Again though perhaps with the right sections of angle welded on it and burried deep enough into the pier it 'could' work.

I have a wedding next time home and a stag do, that's seriously going to eat into build time since I'm only off for 3 weeks before I start a new job. That's the downside of having a sister who's been married more times than Zsa Zsa Gabor, but I'd like to at least get the pier built.

Thanks again for all your invaluable input, I'd be interested to hear any suggestions to improve on the ideas above. (the pier stuff, not the bit about my sister)

[Tinker1947]

The EDPM rubber roof i took it round the edge on the roof so it overhung the timber then trimmed it off, its help in place with stainless steel staples every 3" or so, the corners very folded and stapled then GripAll run along the small gap this has lasted the winter so i suspect will last as long as the roof, the stainless steel staples are still silver and shiny after the wettest winter on record.....I would keep the rubber sheet in a single piece as a join might not leak, but then again if it does...

[Mowbs]

The pier is taking shape. The main hold up has been that I wanted to align my azimuth stop bolt with Polaris and I haven't seen Polaris in quite a while. Yesterday was a beautiful sunny day but the fog started rolling in from the south as it was getting dark. Luckily I had enough time to mix up a batch of concrete and align my captive nuts.

I used a 1.5m length of 8" plastic duct (£20 from eBay) for the pier, 1 bag of cement and 4 x 1.5m of 10mm re-bar hammered into the ground.

I got the welder from work to knock me up anchors for the M8 nuts of the adapter plate to concrete into the top of the pier

You can see the wooden block I've concreted in to give me access to the M12 mount bolt

I had to cut a lot of my adapter plate template away to give me access to pour in the last of the concrete. The missing bolt is to allow room for the space to access my mount bolt.

I'll give it a few days to a week for the concrete to go off, the main fill was done a week ago so I only had to fill the last 6 inches last night, there shouldn't be too much shrinkage. When I remove the wooden template I will put bolts back into the captive nuts and fill and smooth the last few mm. The top of the plastic pipe is perfectly level so I'm expecting the adapter plate to sit level. If it needs any adjustment I could use washers between the pier and adapter or buff off or build up the concrete.

[jambouk]

Looks really good. It is going to be fun watching this evolve.

Jd

[Mowbs]

The pier is complete!

I mixed up some mortar - (3 parts building sand to 1 part cement) and filled the last few mm, it was much nicer to work with than the concrete and gave a really nice finish to the top of the pier. I might give it a coat of white masonry paint later to blend it in to the plastic pipe but I'm really happy with how the white pier looks with the Skywatcher.

The level of my adapter plate is very slightly off. From previous posts I read while researching my build the general opinion is that the level being slightly off will not affect the scope when it is set up but I would like to get it as close as I can. I buffed down a couple of the washers that are between my adapter plate and the top of the pier and it is much closer to level but it could do with a little more buffing to level it perfectly, it's really not much off though but I think it would be worth the extra time just for the piece of mind.

The captive nuts concreted into the pier

The adapter sitting on the mortar

The scope fitted to the adapter plate

The scope fitted to the adapter plate with the footprint of the observatory marked out

Next step will be lifting the turf and setting the slabs for the base of the observatory