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Equipment Discussions >> Observatories

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Mike I. Jones
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Reged: 07/02/06

Loc: Fort Worth TX
Re: Observatory progress update new [Re: Mike I. Jones]
      #5528781 - 11/19/12 08:48 PM Attachment (53 downloads)

Finishing up welding the rafters at sundown.

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Mike I. Jones
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Reged: 07/02/06

Loc: Fort Worth TX
Re: Observatory progress update new [Re: Mike I. Jones]
      #5528810 - 11/19/12 09:05 PM Attachment (57 downloads)

So, after welding up all the rafters, we decided to try giving the roof a roll up and down the track. It moved about six feet then seized up on the track. One look down the sides of the V-groove casters told the reason: the new added weight of the rafters was bending the ridge down and the roof baseframe outwards at the middle. The ends are fully trussed and can't change their dimensions, but out in the middle, there are no trusses to hold their shape. We never figured 11 gauge 2x6 gauge steel beams could bend much in 6" plane direction, but they do! The outward bending was about 3-4 mm, enough to cause drag on the sides of the track, anyway. The attached diagram shows what is happening.

The fix is easy - use a Come-Along to winch the sides back together and parallel so that the roof rolls smoothly, then weld one ceiling joist across the central span to keep it in shape. I had originally not wanted anything across the middle to keep it nice and open, but this central joist is about 6'5" above the floor, so it won't be running into any telescopes as long as I stow them properly.

I'm glad we discovered this and will have this fixed before attaching the roof R-paneling, which will add nearly 500 pounds!

LESSON 1: 11 gauge 2x6 steel beams will bend a lot more than you think!


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mikey cee
Postmaster
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Reged: 01/18/07

Loc: bellevue ne.
Re: Observatory progress update [Re: Mike I. Jones]
      #5529178 - 11/20/12 12:05 AM

You can temporarily jack the ridge up in several places until the flat plane of the roof panels are fully installed. The rafters can then no longer spread thereby keeping the ridge up. When raising the ridge you want to over compensate slightly so when things "settle" it will be nice and tight. Mike

Edited by mikey cee (11/20/12 12:08 AM)


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Mark Harry
Vendor
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Reged: 09/05/05

Loc: Northeast USA
Re: Observatory progress update new [Re: mikey cee]
      #5533493 - 11/22/12 07:58 AM

I was thinking this might happen.


M.


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kfrederick
Carpal Tunnel


Reged: 02/01/08

Re: Observatory progress update *DELETED* new [Re: Mark Harry]
      #5533547 - 11/22/12 08:53 AM

Post deleted by kfrederick

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rimcrazy
sage


Reged: 03/03/12

Loc: Overgaard, AZ
Re: Observatory progress update new [Re: kfrederick]
      #5533567 - 11/22/12 09:11 AM

This is probably too late but you really don't need V-Groove wheels on both tracks. If you put flat wheels and just flat stock as a header on one of the two sides then any small inconsistencies in your distance between both sides of your track become irrelevant and your roof will not bind.

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Mike I. Jones
Post Laureate
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Reged: 07/02/06

Loc: Fort Worth TX
Re: Observatory progress update new [Re: rimcrazy]
      #5533679 - 11/22/12 10:20 AM

Now THERE's a good idea! If I ever build another ROR I will do that.

Mike

PS: Hey Mr. Markus - any more thoughts you have that you could like maybe share with me BEFOREHAND?


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HunterofPhotons
Pooh-Bah


Reged: 04/26/08

Loc: Rhode Island, USA
Re: Observatory progress update new [Re: Mike I. Jones]
      #5533894 - 11/22/12 12:40 PM

Put in more than one center joist, it's needed.
You can't depend on roof panels to maintain the structural integrity of your roof framing.
If you wanted a cathedral ceiling, you should have put in a properly-sized ridge beam. The roof would not have sagged then.
I would recommend putting in some diagonals to prevent racking in your roof structure, too.

dan k.


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Mike I. Jones
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Reged: 07/02/06

Loc: Fort Worth TX
Re: Observatory progress update new [Re: HunterofPhotons]
      #5534100 - 11/22/12 03:34 PM

Good point on the heavier ridge beam. Oh well, too late now. 'Tis what it is.

By racking do you mean bending in the horizontal plane into a parallogram?


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rimcrazy
sage


Reged: 03/03/12

Loc: Overgaard, AZ
Re: Observatory progress update new [Re: Mike I. Jones]
      #5534982 - 11/23/12 08:10 AM

Something else Mike. I was planning on making a ROR for my observatory and I was going to use the motor and control system from BYO. They have a fine motor and gear system but in looking at the design, many people put the motor and gear to one side. This causes and automatic torque around the center-line of your roof which will add to your bind issues. While I ultimately changed to a dome, we were planning on running the gear right down the centerline of the roof. This placement will essentially remove any torque on the mechanical system, which should also reduce the load and any wear & tear on the motor. We had planned for this with the design of the roof joists but if you have enough clearance and if you were planning on using a motor/gear system to move the roof you may want to consider this kind of placement.

Nice work though. You have a stunning building and it should be a real class setup when you are all done.


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Mark Harry
Vendor
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Reged: 09/05/05

Loc: Northeast USA
Re: Observatory progress update new [Re: Mike I. Jones]
      #5535014 - 11/23/12 08:38 AM

Sorry, Mikey, I didn't see the recent posts until yesterday.
But it immediately came to mind; 1 track with -V- grooved wheels, and the other side a flat-track. Can be quite accomodating with any variance in width or flex.
******
Welding ain't as precise as most dudes think. I used to straighten car axles by placing welds in strategic spots after preheating, etc with 180k psi tensile welding rods---
bla,bla.... Runouts in the .00x", etc.
Maybe next time?
M.

PS one question- did you chaulk-line the tracks to see if the welds pulled the tracks 'concave' a bit??? I find it a bit hard to fathom a triangle 'truss' flexing that badly to bind if everything is straight.....? Just an idea.


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HunterofPhotons
Pooh-Bah


Reged: 04/26/08

Loc: Rhode Island, USA
Re: Observatory progress update new [Re: Mike I. Jones]
      #5535359 - 11/23/12 12:09 PM

Quote:

...By racking do you mean bending in the horizontal plane into a parallogram? [sic]




Mike,
Each roof slope is a rectangle now. There is nothing to prevent that from distorting into a parallelogram in the future. Corner braces or large diagonals will stop that distortion.
Large diagonals would be the strongest solution at this point.
Run two on a side, each from an outside corner to the midpoint of the opposing line of the roof.
Since one diagonal will always be in tension, they don't have to be that beefy.

dan k.


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Mike I. Jones
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Reged: 07/02/06

Loc: Fort Worth TX
Re: Observatory progress update new [Re: Mike I. Jones]
      #5545216 - 11/29/12 10:10 AM Attachment (27 downloads)

Here's Orion, rising above the finished roof frame.

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Mike I. Jones
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Reged: 07/02/06

Loc: Fort Worth TX
Re: Observatory progress update new [Re: Mike I. Jones]
      #5545220 - 11/29/12 10:12 AM Attachment (23 downloads)

Cygnus and finished roof frame.

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Mike I. Jones
Post Laureate
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Reged: 07/02/06

Loc: Fort Worth TX
Re: Observatory progress update new [Re: Mike I. Jones]
      #5545227 - 11/29/12 10:16 AM Attachment (16 downloads)

We got the insulation and roof on today. It was dark by the time we finished, so the full Moon made for nice illumination. Fomalhaut is peeking just over the rail.

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Mike I. Jones
Post Laureate
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Reged: 07/02/06

Loc: Fort Worth TX
Re: Observatory progress update new [Re: Mike I. Jones]
      #5545246 - 11/29/12 10:23 AM Attachment (34 downloads)

Finished roof, with Cygnus setting, Delphinus above the roof, and Vega low on the horizon.

You can see one of the remaining details I need to take care of, my neighbor two houses over with a yard light shining on the building. She seems agreeable to my paying for a light shield.

Next to do: side panels on roof, install cable system to roll the roof, finish the door and apply weatherstripping. Once I know this thing is weather-resistant (but aiming for weather-proof), I'll hook up the juice, run the wiring, and build the warm room, then I'll be ready to move in.

Mike


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David PavlichAdministrator
Transmographied
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Reged: 05/18/05

Loc: Mandeville, LA USA
Re: Observatory progress update new [Re: Mike I. Jones]
      #5545350 - 11/29/12 11:19 AM

Nice pictures and she's coming along nicely! Maybe I missed it, but have you given it a name?

David


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Starman27
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Reged: 01/29/06

Loc: Illinois, Iowa
Re: Observatory progress update new [Re: David Pavlich]
      #5546971 - 11/30/12 10:57 AM

Impressive build. Thanks for keeping us up to date.

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Mike I. Jones
Post Laureate
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Reged: 07/02/06

Loc: Fort Worth TX
Re: Observatory progress update new [Re: Starman27]
      #5551081 - 12/02/12 09:19 PM

The final delivery of steel R-panels has arrived. Gonna get that up, then start squirting the building from above with the garden hose and nozzle to find and caulk water leaks. Already started painting the inside walls "Celestial Blue", similar to "Mary B"'s color. I'll start building the warm room next, then get the wiring started. Still aiming for moving in over the Christmas break. I'll post more progress pictures Thursday or Friday.
Mike


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Mirzam
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Reged: 04/01/08

Loc: Lovettsville, VA
Re: Observatory progress update new [Re: Mike I. Jones]
      #5551628 - 12/03/12 08:14 AM

Sounds like you are building a Faraday cage. Hope you have your internet service hard wired!

JimC


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