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Equipment Discussions >> Observatories

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averen
Vendor Main Sequence Software
*****

Reged: 01/20/09

Loc: Austin TX
Pico Dome (it's that small)
      #5411733 - 09/09/12 02:21 PM Attachment (504 downloads)

I've wanted to build an observatory for as long as I've been interested in astronomy...it always seems to be the holy grail! My wife and I bought a house a little over a year ago out "in the burbs" of Austin TX. So while it's not pitch black (or even remotely close) it's "dark enough."

I'm mostly an imager and from home I typically do narrowband because of the light pollution so I don't need to be in the dome. Plus the best spot for the observatory is near the front of our backyard and the HOA would have a fit about it rising over the fence line being that close to the front of the house.

So I've decided to make a VERY small dome. Essentially the bare minimum required to fit my equipment and give me a tiny bit of room to grow (very tiny). The diameter of the dome will be 5 feet (1.5 meters). And the entire structure will be around 6 feet (1.8 meters)tall. This keeps it just under the fence line and out of the HOA's control :-) The diameter of 5 feet was chosen for a couple of reasons. First, I'm planning on using a gore type construction with 1/8" masonite for the dome. At 5' I can build the entire dome from 2 pieces of masonite. I also plan on fiberglassing the exterior and possibly the interior of the dome as well. This will give it added strength as well as weather proof it. Second, at the smaller diameter I should be able to lift the dome off if needed by myself or with the help of one person. Since it will be unlikely that I'll be able to get into the dome (at least not comfortably) I'll need a way to do periodic maintenance and access the equipment.

I initially considered building a roll off roof as I could lay the scope on it's side and make the entire setup even smaller. But where I'm at is fairly windy so the added wind protection of a dome is a nice plus. And I like building things like this so the challenge of building the dome was a big part of the decision as well...one which I may regret later!

I'm also planning on automating the dome (eventually). Initially the azimuth will be automated but I'll likely forgo automating the shutter until a later time. I plan on building all the control hardware as well and writing an ASCOM driver for the dome controller. I believe there is already an Open Source Dome Controller out there so I may check that out as well.

Attached is an initial drawing that I have done with a G11 inside of the mount for reference. Everything is to scale to give you an idea how small the dome is.

Hopefully I'll get some pictures of the actual dome construction up fairly soon. I'm headed to the lumber store to pickup materials to start on the dome here shortly.

Jared


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Mirzam
Post Laureate
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Reged: 04/01/08

Loc: Lovettsville, VA
Re: Pico Dome (it's that small) new [Re: averen]
      #5411932 - 09/09/12 04:45 PM

A similar project:

http://www.cloudynights.com/ubbthreads/showflat.php/Cat/0/Number/3024780/page/0/view/collapsed/sb/5/o/all/fpart/1/vc/1

Kevin does some amazing AP with this setup.

JimC


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averen
Vendor Main Sequence Software
*****

Reged: 01/20/09

Loc: Austin TX
Re: Pico Dome (it's that small) new [Re: Mirzam]
      #5412271 - 09/09/12 08:26 PM Attachment (186 downloads)

I considered a "Dog house" as well but like the roll off roof it still doesn't block as much wind. Which is the primary reason for the dome. I lose a lot of nights to imaging because of wind, hopefully the dome will help that! Plus it gets really dewy here and the dome should help to keep that under control as well.

I started on the lower ring for the dome. The center is 5' across. I'll cut a notch for the gores to rest in. Currently this is just rough cut and not glued up. I'll likely get to that later this week.

Jared


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Mirzam
Post Laureate
*****

Reged: 04/01/08

Loc: Lovettsville, VA
Re: Pico Dome (it's that small) new [Re: averen]
      #5412362 - 09/09/12 09:30 PM

I can offer some advice on the lower ring. Make it much stronger than you think is necessary. I would laminate at least three layers of plywood like you have shown.

What will happen over time is that the ring will sag in between the wheels. Also be sure you use at least 6 wheels and even 8 would be better.

Sag will distort the slit opening and possibly cause leakage.

JimC


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dobsoscope
sage
*****

Reged: 05/24/06

Re: Pico Dome (it's that small) new [Re: Mirzam]
      #5412726 - 09/10/12 02:42 AM

I would strongly recommend you follow the guidelines given here by Nytecam for the ring beam rather than a layered ring.

http://www.cloudynights.com/ubbthreads/showflat.php/Cat/1,2,3,4,5,8,9,10/Number/4783794/page/0/view/collapsed/sb/5/o/all/fpart/all/vc/1


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astrovienna
Carpal Tunnel


Reged: 12/04/06

Loc: The NoVa White Zone
Re: Pico Dome (it's that small) new [Re: Mirzam]
      #5413533 - 09/10/12 03:02 PM

Quote:

A similar project:

http://www.cloudynights.com/ubbthreads/showflat.php/Cat/0/Number/3024780/page/0/view/collapsed/sb/5/o/all/fpart/1/vc/1

Kevin does some amazing AP with this setup.




When I read "keep it below the fence," I knew exactly where Jared was coming from!

I'd love to have a dome to keep out the wind, Jared. But as anyone who's seen my doghouse-style obs could guess, I don't have dome building skills. Good luck, and feed us with pictures.

Kevin


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averen
Vendor Main Sequence Software
*****

Reged: 01/20/09

Loc: Austin TX
Re: Pico Dome (it's that small) new [Re: dobsoscope]
      #5413799 - 09/10/12 05:39 PM

Quote:

I would strongly recommend you follow the guidelines given here by Nytecam for the ring beam rather than a layered ring.

http://www.cloudynights.com/ubbthreads/showflat.php/Cat/1,2,3,4,5,8,9,10/Number/4783794/page/0/view/collapsed/sb/5/o/all/fpart/all/vc/1




Thanks for that link. I like the idea of the box beam but I'm not sure if that's necessary for this size of dome. I may consider it though as it doesn't seem all that complex and it would be easy to implement that at this point since the rings are not glued together yet.

Jared


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Starhawk
Space Ranger
*****

Reged: 09/16/08

Loc: Tucson, Arizona
Re: Pico Dome (it's that small) new [Re: averen]
      #5414092 - 09/10/12 08:58 PM

I'd suggest one of the small shed conversions into ROR observatories for Arrow metal sheds folks have been doing. You'll have room to move around inside, and if the HOA peeks over the fence, it just looks like a garden shed.

Otherwise, you might as well get a robodome.

-Rich


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Starhawk
Space Ranger
*****

Reged: 09/16/08

Loc: Tucson, Arizona
Re: Pico Dome (it's that small) new [Re: Starhawk]
      #5414104 - 09/10/12 09:05 PM

Here's a robodome link:

http://www.homedome.com/store/product_robodome.htm

I'm trying to remember who here on CN recently built a metal shed ROR. He did a really good job on it.

-Rich


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averen
Vendor Main Sequence Software
*****

Reged: 01/20/09

Loc: Austin TX
Re: Pico Dome (it's that small) new [Re: Starhawk]
      #5416392 - 09/11/12 11:23 PM

I had looked at the Robodome but it's too small to to house my setup I need a minimum of 24" all the way around the RA axis and the Robodome is only 42" wide. 24" is pretty tight even. Plus it's well over what I want to pay for a dome.

Doing a RoR has it's benefits...it's definitely easier and faster to build but at the moment I'm still set on a dome.

Thanks,
Jared


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Starhawk
Space Ranger
*****

Reged: 09/16/08

Loc: Tucson, Arizona
Re: Pico Dome (it's that small) new [Re: averen]
      #5418867 - 09/13/12 10:14 AM

The dome has to be synchronized with the mount, you know.

The mini-ROR gives you room to work on the gear, and the synchronization collapses to park and open/close.

-Rich


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averen
Vendor Main Sequence Software
*****

Reged: 01/20/09

Loc: Austin TX
Re: Pico Dome (it's that small) new [Re: Starhawk]
      #5421224 - 09/14/12 04:23 PM

Quote:

The dome has to be synchronized with the mount, you know.



Yes, I'm aware. I'm planning on motorizing the azimuth initially and will just use a manual shutter for the time being. Eventually, when time allows, I fully plan on motorizing the shutter as well which would give me a completely automated dome at that point. I'll be creating the software as well as the hardware to do this. I have experience with both of those things so it's not out of my wheelhouse.

The equipment to do this is still TBD but I will likely use an Arduino or AVR for control. I want it to be used through a PC but I also want it to be standalone as well so I can open the observatory in case the PC is powered down. I also plan on having at least one door in the base of the Obs. I may put in two smaller doors on opposing sides so that access is easier with I need to do maintenance.

Quote:


The mini-ROR gives you room to work on the gear, and the synchronization collapses to park and open/close.




This is one of the main draws to the RoR to be honest. The dome will not give me a ton of room to work around the scope if something were to go wrong of if I needed to setup equipment. I had initially thought of hinging the dome since it will be fairly small. That way if I need to get into the obs I can simply unlock the dome and flip it over. I may still do this but that definitely complicates the design since domes aren't generally flipped over like that. It would require some way of locking the dome onto the base (which I will already have...but it will need to be stronger to withstand the lateral forces of the dome being on it's side and then upside down.

I have also considered making the dome lift off from the base after removing some clamps...but this scares me because if I drop it then I drop it directly on my gear! At least the hinged approach would provide a path for the dome and worst case I just destroy the dome!

Jared


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nytecam
Postmaster


Reged: 08/20/05

Loc: London UK
Re: Pico Dome (it's that small) new [Re: averen]
      #5421350 - 09/14/12 06:02 PM Attachment (105 downloads)

Quote:

Quote:

I would strongly recommend you follow the guidelines given here by Nytecam for the ring beam rather than a layered ring. http://www.cloudynights.com/ubbthreads/showflat.php/Cat/1,2,3,4,5,8,9,10/Number/4783794/page/0/view/collapsed/sb/5/o/all/fpart/all/vc/1




Thanks for that link. I like the idea of the box beam but I'm not sure if that's necessary for this size of dome. I may consider it though as it doesn't seem all that complex and it would be easy to implement that at this point since the rings are not glued together yet. Jared


A boxbeam is overkill for a 5ft dome - my 5'.6" DIY dome is strong and lightweight [walked it down garden on my back!] and brilliant for both me and my M12" SCT as link below. Pico dome - very cool


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averen
Vendor Main Sequence Software
*****

Reged: 01/20/09

Loc: Austin TX
Re: Pico Dome (it's that small) new [Re: nytecam]
      #5421701 - 09/14/12 10:38 PM

Very cool domes! What did you skin them with? I considered aluminum but assumed it would be too expensive. I guess tin sheets would do the job too.

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nytecam
Postmaster


Reged: 08/20/05

Loc: London UK
Re: Pico Dome (it's that small) new [Re: averen]
      #5421865 - 09/15/12 02:55 AM

Quote:

Very cool domes! What did you skin them with? I considered aluminum but assumed it would be too expensive. I guess tin sheets would do the job too.


The big 10ft dome is frameless from 1/8" marine ply clad in 0.25mm ali Roneo plates as 'tiles' with ply boxbeam base ring and current 5'-6" picodome in 1mm sheet ali on lightweight ply frame and here on Youtube. If I was doing a picodome today I'd do this simplified wooden octagonal dome which can be rescaled to any size [and even a sphere!]

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averen
Vendor Main Sequence Software
*****

Reged: 01/20/09

Loc: Austin TX
Re: Pico Dome (it's that small) new [Re: nytecam]
      #5422664 - 09/15/12 05:26 PM

I was initially planning on doing this frameless...I'm not really convinced one way or the other at the moment. Frameless does have the advantage of being a little less expensive and I would assume lighter weight...it also seems like it would be potentially faster to build. Although I would still need the inner pieces for the shutter. I was initially thinking of attaching the shutter ridges on the outside of the dome. They would add some additional structure but not as much as a frame. It also seems like there is less room for error when building a frameless dome.

The other option is something like this, which I'm also contemplating just scaling the outside to 6' or 5'6" rather than 8'.
http://users.csolve.net/~jilldwr/dome.html

My initial plan was to use 1/8" masonite on the exterior and use a parachute gore generator to create the cutting template. I was planning on keeping the gores "together" at the bottom to form a skirt. Using this method I would need 2 sheets of masonite to cover the dome and would have a single full seam in the back (and another in the front...but that's where the shutter would go).

I'm thinking of going the "framed" route at the moment. I like the idea of the octagonal dome but I think I would need to size it a little larger to accommodate the straight sides. I'll likely start cutting out the frame pieces tomorrow.

Jared


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averen
Vendor Main Sequence Software
*****

Reged: 01/20/09

Loc: Austin TX
Re: Pico Dome (it's that small) new [Re: averen]
      #5428431 - 09/18/12 10:59 PM Attachment (100 downloads)

I haven't been able to make a lot of progress, which is sad because we've had a nice cold front and it's finally under 120 (not an exaggeration!) in my garage.

I was able to get the rings glued together and I made a jig to trim them to size. I've also decided to go with a frame which will allow me to make the dome a little bigger.

Here's a quick shot of the jig I created...nothing fancy. I'll use a router to dimension the ring to it's final size. I'm also going to cut a couple of shallow channels in the bottom to run a couple of copper or aluminum wires to carry power for the shutter.

Jared

Edited by averen (09/18/12 11:05 PM)


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dobsoscope
sage
*****

Reged: 05/24/06

Re: Pico Dome (it's that small) new [Re: averen]
      #5429044 - 09/19/12 11:11 AM

If you skin with tin you have to prevent galvanic corrosion from happening at every point where you screw in the panels into the arcs.

With aluminium sheet you can use stainless steel screws with no problem.

Then you use something like SIKA MULTISEAL a.k.a FLASHBAND to go over the joints. I would suggest overlapping adjacent panels over each other the full thickness of the arcs and screwing once through both aluminium sheets into the wood.

Instead of the Flashband tape you may also seal with proprietary waterproofing products.


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Starhawk
Space Ranger
*****

Reged: 09/16/08

Loc: Tucson, Arizona
Re: Pico Dome (it's that small) new [Re: dobsoscope]
      #5434941 - 09/22/12 07:04 PM

Aluminum with stainless is a strong galvanic couple. The aluminum will erode the stainless fasteners- this is why cadmium plated bolts exist.

-Rich


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Mary B
Vendor - Echo Astronomy and Electronics
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Reged: 05/21/10

Loc: Minnesota
Re: Pico Dome (it's that small) [Re: Starhawk]
      #5436698 - 09/23/12 06:25 PM

Amateur radio antennas are typically aluminum with stainless fasteners. I have never noticed any corrosion when taken down for cleaning/tune up.

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