nytecam
Postmaster
Reged: 08/20/05
Loc: London UK
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Re: Building a 24' Dome
[Re: DeanS]
#5454547 - 10/04/12 03:28 AM Attachment (102 downloads)
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Nice work Tom  Quote:
Aren't you suppose to build the dome around the scope?  Sort of like a ship in a bottle.
Yeh - anyone done a Dob-in-a-Dome where the Dob is physically attached and supported by the dome eg top end of the Dob pivots on the shutter for 'altitude' and rotation of dome for 'azimuth'  Now that would be neat but may need a fancy viewing platform - also attached to the dome - a sort of updated Leviathan of Parsonstown from the 1850 
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Tom Clark
professor emeritus
Reged: 11/14/07
Loc: North of Deming, NM
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Re: Building a 24' Dome
[Re: crazyqban]
#5461738 - 10/09/12 08:36 AM Attachment (113 downloads)
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On the last dome I used 1/4 x3 x3" angle iron rolled into a circle and welded together. It rode on 10 steel "V"-grooved wheels. The observatory quickly acquired the name "The Thunder Dome" because of the sound it made when rotating.
This time I am using 2" wide 6" diameter wheels rolling on a flat aluminum plate. It should be a bit quieter. The casters have a weight bearing capacity of 750 pounds each.
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David Pavlich
Transmographied
Reged: 05/18/05
Loc: Mandeville, LA USA
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Re: Building a 24' Dome
[Re: Tom Clark]
#5461875 - 10/09/12 10:34 AM
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Really cool execution, Tom!!
David
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Tom Clark
professor emeritus
Reged: 11/14/07
Loc: North of Deming, NM
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Re: Building a 24' Dome
[Re: Tom Clark]
#5465109 - 10/11/12 10:25 AM Attachment (118 downloads)
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Yesterday the base ring for the dome was reassembled on top of the walls. The inside of the ring has an aluminum strip around it, and the base of the ring has a 3.5" wide aluminum strip to provide a smooth tract for the wheels to ride on. Another two 8" diameter wheels will be used to drive the dome in rotation.
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Tom Clark
professor emeritus
Reged: 11/14/07
Loc: North of Deming, NM
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Re: Building a 24' Dome
[Re: Tom Clark]
#5465130 - 10/11/12 10:43 AM Attachment (104 downloads)
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All of the hold downs were welded from 1.5" angle iron, and ball bearings are attached to ride on the inner ring. This keeps the dome from sliding around as it rotates.
Saturday morning - if it is not too windy - will be the big day for reassembling the dome parts in place. Wish us luck, as there will be a lot of ladder work involved.
I realize not many of you will be running out and building a 24' dome in your back yard next week, but all of these ideas would be very good for using on smaller domes of 12' and up. Any smaller observatory would be a real easy project after building this monster.
A commercial dome of this size runs over $50K, and the projected cost of this project is a more far more affordable at under $10K, including the motors to rotate the dome and open and close the shutters. Of course all of the details are not worked out yet, but that just makes the building exciting.
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nytecam
Postmaster
Reged: 08/20/05
Loc: London UK
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Re: Building a 24' Dome
[Re: Tom Clark]
#5466321 - 10/12/12 04:11 AM Attachment (98 downloads)
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Excellent work Tom - main rollers and side restraint rollers looking good and a model for anyone dome building of any size. How is the dome anchored down to stop it lifting under storm conditions? Do the plates above the restraint rollers do that
ps: couldn't but help note the difference of aspect from your vast NM horizons to my cosy London backyard [below] containing my M12 astrograph that no faint DSO escapes its eagle-eye
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Tom Clark
professor emeritus
Reged: 11/14/07
Loc: North of Deming, NM
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Re: Building a 24' Dome
[Re: nytecam]
#5467920 - 10/13/12 09:28 AM
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"All of the hold downs were welded from 1.5" angle iron, and ball bearings are attached to ride on the inner ring. This keeps the dome from sliding around as it rotates."
Sorry, I should have been more clear. The black angle iron posts that hole the ball bearings also extend over the dome ring, so the dome cannot lift during high winds.
By the way, your yard is beautiful. We could use a bit of that greenery around here - but what the heck - we did move to the desert for the 300 clear nights a year along with the wonderful transparency of the air. You just can't have everything…
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EricGraham
member
Reged: 01/19/11
Loc: New Mexico
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Re: Building a 24' Dome
[Re: Tom Clark]
#5467949 - 10/13/12 09:52 AM
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I guess I lucked out. I have a 30 year old established garden almost as lush as Nytecams and a great observing site not too far from Tom's.
Eric
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Tom Clark
professor emeritus
Reged: 11/14/07
Loc: North of Deming, NM
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Re: Building a 24' Dome
[Re: EricGraham]
#5472084 - 10/15/12 06:43 PM Attachment (104 downloads)
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After taking a couple of days off to have a little star party, a bit of progress has finally been made. Next up is sheeting the dome and then fiberglassing it.
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David Pavlich
Transmographied
Reged: 05/18/05
Loc: Mandeville, LA USA
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Re: Building a 24' Dome
[Re: Tom Clark]
#5472425 - 10/15/12 10:34 PM
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Hey Tom...I have a request. Do you have any pictures of your crew and you setting the dome section? I'd love to see it! 
David
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dmdouglass
professor emeritus
Reged: 12/23/07
Loc: Tempe, AZ
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Re: Building a 24' Dome
[Re: David Pavlich]
#5473333 - 10/16/12 01:38 PM
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Hi Tom...
We have never met, but i would like to say that your project is absolutely FANTASTIC !!
I am really looking forward to photos of your continued construction. Keep up the GOOD WORK !!!
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Tom Clark
professor emeritus
Reged: 11/14/07
Loc: North of Deming, NM
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Re: Building a 24' Dome
[Re: David Pavlich]
#5473412 - 10/16/12 02:51 PM
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Quote:
Hey Tom...I have a request. Do you have any pictures of your crew and you setting the dome section? I'd love to see it!
David
David,
A friend set up his camera to take photos every minute while the dome was being reassembled on the walls. I haven't seen them yet but will one of these days, and will post a couple. At first I tried to put up the main arches with just a crew of guys, but after a bit, realized how stupid that was, so I halted work and got a crane out to lift the arches. That made putting the ribs back up a piece of cake.
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Tom Clark
professor emeritus
Reged: 11/14/07
Loc: North of Deming, NM
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Re: Building a 24' Dome
[Re: dmdouglass]
#5473419 - 10/16/12 02:57 PM
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Quote:
Hi Tom...
We have never met, but i would like to say that your project is absolutely FANTASTIC !!
I am really looking forward to photos of your continued construction. Keep up the GOOD WORK !!!
David,
Thanks for the nice note. Jeannie and I look forward to inviting local astronomy clubs over for observing after the project is finished, so maybe we will see you then. In 2010 we visited Steve Coe and the Saguaro Astronomy club, where I gave a talk. Keep in touch.
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Wmacky
Pooh-Bah
Reged: 11/24/07
Loc: Florida
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Re: Building a 24' Dome
[Re: Tom Clark]
#5473942 - 10/16/12 08:00 PM
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Tom, I'm envious as I'm still back in the great state of humidity! You mention using a center nail, and plumb bob to align the ribs. I'm having trouble visualizing. Can you elaborate?
Any insight on laying out the ribs, hoops, and rings on the plywood sheets? Is there a place to gain such knowledge or did you dig formulas out of old trigonometry text books? I'm finding little info around on calculating the dimensions of the dome framing members, not to mention those gores!
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Tom Clark
professor emeritus
Reged: 11/14/07
Loc: North of Deming, NM
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Re: Building a 24' Dome
[Re: Wmacky]
#5474172 - 10/16/12 11:04 PM
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Look at the photo above of just the dome sitting on the concrete. The center of the concrete had a piece of wood screwed down, with a nail sticking up out of the floor, in the center of everything. Note where it says that every rib points to the center of the dome. I used a straight edge that went from the center nail to a mark on the outer ring, where an ink mark was made where every rib was to be attached. Now all you have to do is mark where the top of the rib hits the main arcs high above.
How do you do that? l piece of string holding the plumb bob is held until the weight is hovering over the straight edge - and then mark the arc where the top of each rib is to be attached.
No rocket science or fancy math. Just a simple way to figure where things go.
If you are seriously are considering building a dome, when I built the first one back in '01-02, I wrote a two part article with lots of photos in Amateur Astronomy Magazine. Issues 33 & 34 I think. Back issues are still available…
To lay out the ribs and other parts, draw out your dome with dimensions. If you need 120 pieces with a 144" radius on the outside, and with a 140.5" radius on the inside, make a compass and draw a template. Then cut out the template and use it to draw the 120 pieces on the plywood. That is where the 4 days of bandsawing went.
You have to build the dome in your head, then jay it out on paper. Once you do that, all the pieces become clear, and the dimensions of each piece are arrived at. Sure the project may seem hard at first, but just like anything, it's one piece at a time, and before you know it, your yard contains a skeleton that looks something the dinosaur that is in my back yard at the moment!
By the way - you live in N. Florida. Go visit my old dome at Chiefland. When I was getting ready to build that one, I visited every home-made dome around the country I could find, took some of the good ideas of each, and that really helped me to figure out how I wanted to build mine.
Edited by Tom Clark (10/16/12 11:14 PM)
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Tom Clark
professor emeritus
Reged: 11/14/07
Loc: North of Deming, NM
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Re: Building a 24' Dome
[Re: Tom Clark]
#5477979 - 10/18/12 11:29 PM Attachment (106 downloads)
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As the sheeting goes on the project starts to give an impression that it will be finished one of these days. Picked up 40 sheets of lauan 1/4" plywood at Home Depot yesterday, and today the roofing started.
Also, today the building inspector signed off on the framing inspection. He even gave us a pat on the back and said that it looked like we were building a solid building.
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dmdouglass
professor emeritus
Reged: 12/23/07
Loc: Tempe, AZ
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Re: Building a 24' Dome
[Re: Tom Clark]
#5478114 - 10/19/12 01:06 AM
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"He even gave us a pat on the back and said that it looked like we were building a solid building."
Indeed you are !!!
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dobsoscope
sage
Reged: 05/24/06
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Re: Building a 24' Dome
[Re: dmdouglass]
#5478243 - 10/19/12 04:41 AM
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Excellent progress Tom!
The cladding is coming nicely. Did you consider using 1mm thick aluminium sheeting instead of plywood to have it withstand more the test of time and need less maintenance? I would assume it will not be an easy-everyday task to reach all the way up the dome to carry out maintenance on the cladding (joints etc.).
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Keith Howlett
Pooh-Bah
Reged: 03/06/07
Loc: Northumberland, UK
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Re: Building a 24' Dome
[Re: Tom Clark]
#5478302 - 10/19/12 06:33 AM
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Hi Tom,
That's looking great. how are you joining the edges of the gores prior to fibreglassing?
Cheers,
Keith
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EddWen
scholastic sledgehammer
Reged: 04/26/08
Loc: Here or There
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Re: Building a 24' Dome
[Re: Keith Howlett]
#5478682 - 10/19/12 11:46 AM
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Looks good!
Seems like it is already drawing the clouds out of Arizona, Thanks ;-)
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