10 replies to this topic

[wavefront]

Hi everyone ........... I would like to build a 12 foot diameter observatory this Spring that has a shutter that rolls back.  Bi parting shutters are okay but can act like sails when the wind picks up.  I don't quite understand how to have it roll back and still remain water resistant.  If someone has some carefully drawn plans I might be willing to send you some money for them. The diagrams below might be helpful.  I'd like to end up having something for a Newtonian that would allow me to see objects that are lower in the sky. Also I wouldn't have to fuss with any ladders. The old color pic from a catalog kind of explains it.  Thanks

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Edited by wavefront, 17 January 2021 - 07:20 PM.

[Oberon]

You might like to consider a 5/8 dome that is more than a hemisphere. That way there is enough space on the rear of the dome to store the opening section (the shutter).

[PETER DREW]

Before retirement I built observatories as part of my astro equipment business.  I made several domes up to 30 feet diameter and several half cylinder versions.  The half cylinder units are easier and cheaper to make.  I have tried up and over doors and bi-parting doors, I wouldn't go back to the former, too many long term problems.  

[duck]

 

20ft diameter.  Up and over shutter.  Lower fold out section at the limit of what can be opened/closed by hand using a rope and pulleys.  1/4 hp shutter motor with huge reduction.  Takes several minutes to open/close the shutter.  Shutter is only captive at the ends of travel, about 2 feet.  Shutter is driven by a sprocket engaging a rack made from a strip of perforated steel.  Sprocket teeth were enlarged from a standard sprocket by welding and grinding to shape.  All moving/mating surfaces have lips to prevent rain from getting in.  

[Beeham]

One thing to think about - "watertight" is a tough requirement, but what you want is "no water intrusion", which is slightly different.

 

I would do the sliding top as a tambour-door style construction, then nest it in a pair of "C" tracks for motion, kind of like a garage door.  If the lower portion of the C has an upturned flange, the whole thing will act like a gutter, and any rain that sneaks around the edge can be channeled to a drain at the lower edge.

 

Auto sunroofs are typically done this way - it's easier to engineer a solution to manage water that gets in, rather than one that is 100% watertight.

 

Maybe helpful, maybe not...but something to think about.

 

Cheers!

[gregj888]

Might want to move this to "Observatories"....

 

My favorites

 

Google "Geodesic foam observatory" .  Probably the cheapest way to get a dome.  I visited this one and was impressed.  Should get you here:

https://users.eoni.c...itzj/observ.htm

 

And on Youtube, search for "Arduino observatory" my current favorite,  Flat pieces, good use of materials, looks a little like the ESO enclosures and with small mod could have the exhaust behind the slit out of the observing path.  12 sides...   here: https://www.youtube....h?v=FR5WsE8gGSk

Edited by gregj888, 17 January 2021 - 06:51 PM.

[wavefront]

One thing to think about - "watertight" is a tough requirement, but what you want is "no water intrusion", which is slightly different.

 

I would do the sliding top as a tambour-door style construction, then nest it in a pair of "C" tracks for motion, kind of like a garage door.  If the lower portion of the C has an upturned flange, the whole thing will act like a gutter, and any rain that sneaks around the edge can be channeled to a drain at the lower edge.

 

Auto sunroofs are typically done this way - it's easier to engineer a solution to manage water that gets in, rather than one that is 100% watertight.

 

Maybe helpful, maybe not...but something to think about.

 

Cheers!

I had to laugh at "water tight" because I forgot it's not a submarine    Thanks for your thoughtful explanation

[Bob4BVM]

Having used domes of all sizes from 10' to 36' for long periods, i can easily say that i much prefer the ROR type of roof.  Can't beat that wide-open-sky feeling i get when i roll the whole roof back. I understand the advantages of a dome when it comes to sheltering the gear & person, but i still feel claustrophobic in there compared to a full-sky situation.  Just my take

CS

Bob

Edited by Bob4BVM, 17 January 2021 - 10:02 PM.

[Foundationer]

I was going to follow this gentleman's plan until I decided to go with my Nexdome.

 

https://va3ngc.weebl...s---dome-1.html

[wavefront]

I was going to follow this gentleman's plan until I decided to go with my Nexdome.

 

https://va3ngc.weebl...s---dome-1.html

You're right.  These will last for a long time if you keep an eye on it and use a glossy oil base paint.  Thanks for sending this   

[Taosmath]

Alan,

 

How about a low elevation ROR like mine.....

 

 

I designed it for my 18" F4.5 Dob & to see objects with altitudes down to 20 degrees .

 

Works well for me and at half the cost of a commercial dome.

 

(PS - I love the 8" Celestron Star Hopper you sold me a couple of years ago - still one of my favorite scopes to use!)

 

Colin