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Hole design observatory build


wimvb
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Part 1:

About one and a half year ago we moved from the Stockholm suburbs to just outside the small village of Lindholmen in Vallentuna municipality. The night skies are much darker here (estimated magnitude 20.5 vs 17.5 in the suburbs), and I decided to build an observatory. Just to get me through the winter, I bought a tool shed kit that I set up to house the SW AZ-EQ6 with 150PDS, with the intention to build a more permanent obsy at a later date.

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This worked well for the 150PDS, but when I got the MN190, it got a bit tight.

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After the first winter at our new location, we also found out that we needed to reenforce the slope around our house. This meant I would either need to move the entire shed, or decomission it. Time to plan for something more permanent. My property is large enough, and is situated on a south slope overlooking a field. I spent early spring to plan for a good location and a proper design.

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Part 2:

The design of a permanent roll off roof observatory.

A friend of mine, @Firas, lives in central Stockholm, and despite bad light pollution, he manages to create very good images. When he visited me at my new location, he was blown away by the sky quality, which allowed him to capture better data in just a few hours than he would be able to in Stockholm. So I suggested that he move his gear over to me, and house it in the obsy I was planning. This meant that the obsy would need room for two piers, not just one.

I use Ekos/Kstars for equipment control, and one of its features is that it allows for robotic operation of an imaging rig. I decided that the new obsy would be controlled from the house and not from an adjacent warm room. This way I could keep the area and cost down.

But now I needed a roll off roof design, with a large roof. Since my property is on a south slope, the piers would need to be located next to each other East and West, and this meant a wide roof, rather than a long one. The slope also makes a long roof difficult, because the south side of the observatory will be high.

Other constraints are the weather. In this part of Sweden, the snow load can vary a lot, and the obsy roof needs to be strong enough to cary wet snow. I've also noticed that the ridge where my house is located causes strong local winds and the obsy will need to blend in with the environment and be as low as possible.

Design 1:

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The obsy is about 3.6 m East-West and 2 m North-South. The sloping ground means that the roof will be very close to ground level when opened.

This design has a lot of difficulties associated with it.

After some discussions with @gorann, I decided to build one similar to his. The obsy would have a roof that rolls off to the south, on sloping rails.

This is what I call the Hole design, because the area where Göran lives is called Hole (pronounced Hoo-le) and his obsy is named "Hole observatory".

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But a 3.6 m roof like this will become too heavy if it is to withstand a snow load. Plus, if only one imaging rig is used, the other rig is unnecessarily exposed to the elements. The roof needed to be split.

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This is a rough sketch of the design I settled on.

Next: watch your back!

Edited by wimvb
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Man that looks really good! A well thought out design by the look of it. I particularly like that split roof design.

Also your current shed is very nice as well.

 

I hope it's ok I ask a few questions, since I am planning on building something (much smaller) come spring / summer and you clearly are further along in the planning stage than I am. :)

  • Are you planning a concrete floor or is it a raised wooden construction?
    • If a raised wooden construction, are you worried about moisture comming up from below, making it hard to keep a low moisture environment when not in use?
  • Are the piers "disconnected" from the rest of the floor?
    • I was considering pooring a concrete floor in mine, and then bolting a todtmorten pier to the floor, but I wonder if that is going to be stable enough. Maybe the pier foundation needs to be seperated from the rest of the floor.
  • What software are you creating your drawings in?
Edited by jjosefsen
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3 hours ago, jjosefsen said:

Also your current shed is very nice as well.

It's a roll off shed. I bought a tool shed kit and assembled it without the flooring on a frame.

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I had to move it last spring when we reenforced the slope behind it.

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Part 3, the Dig

Sweden is mostly one big rock with smaller rocks on top. My property is no different. The area is old moraine on which there used to be a forest. This means that the ground is made up of organic material (roots), and sand. Mixed with that are stones, anything from pebbles to boulders. And since this material was polished during the ice age, it is embedded in clay. Groundwork for the obsy started in April, with hand tools. After a few hours, the first serious obstacle saw the light of day.

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This was the topic of a previous thread:

I bought tools to remove this stone, but in the end I decided to keep it and use it as the foundation for the west pier. The tools came to good use on other rocks.

Here are a few more pictures from the dig.

The beginning of a pile of rocks (this would grow)

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This is about the size of the dig and observatory, with a view towards the south. The hole for the east pier isn't dug yet.

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This picture shows the approximate size and level of the floor beams. @jjosefsen: that should answer one of your questions: the floor will be a raised wooden floor.

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I removed more material and dug the hole for the east pier. No images though.

Next step: filling this excavation site again.

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Part 4, construction begins

After a lot of digging, it was time to do something constructive, pouring the plinths. This was done in June. This image is from just before pouring. The tubes were covered to protect them from the occasional rain shower.

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One thing I hadn't fully figured out yet was the material to use for the pier. I wanted ventilation tubing filled with concrete, but it turned out that for some reason dimensions larger than 160 mm are only sold to professional builders. Fortunately, Göran had just built his second obsy and had almost 4 m of plastic tubing left over, which I could get for free if I collected it. This was just enough material for two piers.

By the end of July, the plinths and piers were poured.

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Finally, the excavation site was filled in. Here's the floor frame under construction. The length of the long side is 3.9 m, and the short side is 2.2 m

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Once the frame was in place, laying the floor was easy. The floor is insulated with 10 cm styrofoam blocks.

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The floor boards are 38 mm thick, leftover from when the house was built. Btw, the holes around the piers were filled in later with smaller pieces of insulation.

Next: up, up.

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Part 5, framed

Once the floor was finished, it was time to erect the walls. First I thought of building these indoors and then lift them into place. But since I did most of the work alone, this was impractical. Everything was constructed on site. August had its showers, and as soon as the frames were up, I used a tarp to cover the build.

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I didn't take any pictures of the roof design, but it's very similar to Göran's second obsy. In stead of ball bearings, I used rubber wheels.

https://stargazerslounge.com/topic/337156-just-finished-my-second-obsy/

Fast forward from mid August to mid October, the roof is in place.

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Here's a view from the very North-East corner and the highest point of our property

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Edited by wimvb
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Part 6, a screatching halt

With the roof in place, it was time to start with inside work. First off, the piers needed finishing. I made pier adapters out of aluminium. It turned out that the AZ-EQ6 and EQ6-R mounts can have the same adapter design. Here's my solution.

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This is my AZ-EQ6 in place on the west pier, and the east pier ready to accept @Firas EQ6-R.

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My gear will be controlled from a Rock64, which is the same size as a Raspberry Pi, and sits on top of the scope. But Firas has a Windows PC that needs to be mounted next to the pier. Here's a mock up of my solution.

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Next step: getting electricity installed.

Here I hit a snag. Sunday afternoon on November 10, I went out to the obsy to do some electricity work. That morning we had some light snow which had all but disappeared, leaving the ground wet. Just outside the obsy I slipped and hit my knee on a large rock. I thought I had dislocated my knee cap, but an x-ray the next day showed that I had actually broken my knee cap. I had surgery on November 25, and am now on crutches. Work on the obsy has come to a screatching halt. Fortunately for me, the weather has also been very poor this autumn/winter, so I haven't lost any imaging opportunities. Hopefully I will be mobile enough for galaxy season. The obsy is operational (kind of), and I only have to install the scope and camera. Finishing the obsy is planned for summer recess.

"That's all, folks!" (For now at least)

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1 minute ago, jjosefsen said:

Sorry to read about your knee, I hope you make a full recovery. 🙂

Thanks. So far so good. I'm still not allowed to bend my knee at all, it's in a brace. Healing will take a while, but it'll be allright in the end. As I haven't been able to work for more than a month (I'm a teacher, so lots of moving between classes), I was able to put together a weather station and a sky quality meter for use with the obsy.

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Fabulous thread Wim. It's great when a design turns into a practical solution., although I'm sorry to hear of your mishap and hope the recovery is 100%. Your next design is a "safe" path from your house to the Observatory.

Steve

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On 02/01/2020 at 11:30, Gina said:

Good luck with your recovery Wim.

Thanks, Gina

18 hours ago, Swoop1 said:

A very good thread to read Wim. A propper bummer about the knee though. Be careful out there matey.

Thanks, @Swoop1

1 hour ago, sloz1664 said:

Fabulous thread Wim. It's great when a design turns into a practical solution., although I'm sorry to hear of your mishap and hope the recovery is 100%. Your next design is a "safe" path from your house to the Observatory.

Steve

Thanks, Steve. I've already started to plan for that. For one, the plugs & feathers I bought to deal with that large boulder will come to good use on the rock that busted my knee. Revenge! 😁

Edited by wimvb
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Great thread Wim! You need to add to it when you finally get fit for finnishing off the build. I suspect that you, like I have now done, at a later time will fully insulate the obsy so that you cheaply can keep the equpiment dry at a few degrees above ambient temperature. You have already insulated the roof and floor, so it will be a small investment to do it to the walls.

Then I am of course very pleased that my Hole Observatory design was adopted:hello2:. At least it works quite well for those of us that are fortunate enough to have some space for the build and not a cramped backyard.

And yes, a priority must be to get your revenge on that rock and make a safe path to the obsy!

PS. My Lizard Island AP adventure is over for this time and we are sitting in a hotel room in Cairns waiting for the flight home. I hear from my neighbor in Sweden that I have no snow to worry about - just wet muddy grounds and roads. Then I just need to bring the clear skies:glasses9:

Edited by gorann
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Thanks, Göran. I will have my revenge eventually. I think for our conditions, and especially on a south facing slope, the Hole design is superior to a traditional ror. 

Yesterday we had a clear night, but with the moon out and strong winds. I've ordered a wind speed meter to add to my weather station, because it can get very windy locally. Probably the ridge funneling air currents. I at least should have gone out to do a sky quality reading, but totally forgot. It will be clear later this week according to CO. I'll do a reading then and send your meter back.

So far, this winter has been unusually mild, with almost no snow. 

7 hours ago, gorann said:

Then I just need to bring the clear skies:glasses9:

Yes, please.

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  • 2 weeks later...

Fixed a basic video surveillance. I had a wireless camera lying around which I mounted on the south wall between the piers. However, hooking it up and getting it to stream was an entirely different matter. D-link are lousy at supporting their own devices. The built in software isn't supported by any web browser, although they claim that IE and Firefox have support. MyDLink wouldn't connect to it, and D-LiveView isn't even proper windows, and doesn't support the camera (which I bought new a few months back). In the end I got it to work with an older version of D-LiveView, but I have no idea if the motion detection actually works.

Anyway, here's a screen shot before I figured out how to set the proper date and time. D-link seem to think that their software is sooo good that it doesn't need a manual.

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6 hours ago, Firas said:

Dear god! One almost forgets how much work was put into this observatory build. 

Great write up Wim! 

Can't wait for a galaxy hunt! 

 

3 hours ago, Miguel1983 said:

Very nice Wim !

Thanks, guys. Tonight was clear from about 10 pm, so I opened the roof and managed to do a polar alignment. Had a mishap with a usb cable to the guide camera, which caused kstars to crash. But I managed a pa error of less than 1' according to Ekos (not sure how accurate that is, but it was repeatable) . Also focused the imaging camera, but hfr values indicated that sky quality wasn't that good. Ekos acted strange when I tried to create a pointing model near the neridian, so I have to figure that out. I don't think it's a balance problem, but I will check for that anyway. 

@Firas: I got a long ethernet cable, so will have internet access from the obsy network.

The obsy wifi just reaches the dining room in my house, so once everything is set up, I can control from there. 

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Like the Death Star, my observatory is operational but not yet finished. Here it's waiting for some action tonight.

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To the East, the other roof half is an obstruction when closed. I will see how it goes, otherwise I can always open that half too. But there will always be the fixed beam. A good thing is that the roof can be closed with the telescope in any position. In case of an emergency, I don't have to park first. With the opened roof in the position it is, I have a free view of the forrest on the other side of the field. If it turns out that the scope is positioned too low, I can always extend the pier adapter a few inches. Better a pier that is too low than one that is too high. It's future proof.

"It's not a bug, it's a feature."

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On 01/01/2020 at 21:58, wimvb said:

thought I had dislocated my knee cap, but an x-ray the next day showed that I had actually broken my knee

Bad luck Wim, I broke my kneecap many years ago and had it removed, they didn't replace it with anything, apparently in earlier times they fitted silver replacements for rich people, about twenty years later as a result I had to have a replacement knee joint fitted this has lasted about 35 years and still working fine so you may have this to look forward to in the future 😁

ATB

Dave

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3 hours ago, Davey-T said:

Bad luck Wim, I broke my kneecap many years ago and had it removed, they didn't replace it with anything, apparently in earlier times they fitted silver replacements for rich people, about twenty years later as a result I had to have a replacement knee joint fitted this has lasted about 35 years and still working fine so you may have this to look forward to in the future 😁

ATB

Dave

Mine is wrapped in wire. Although not silver. Titanium is more likely. 

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