The Plan: To build a fully functional, computer controlled, domed observatory for astrophotography. The goal is to build, using materials that will be salvaged or bought as economically as possible. The labor will be supplied mostly by myself and my girlfriend, with occasional brute force supplied by friends and family members.
5/25/08 Building begins. We form and pour the foundation for the observatory base.
5/30/08 The dome build begins. I decide on a template for the dome. I will be building a 3V 5/8 geodesic dome with a radius of 43.25 inches. The tank has a 42 in radius and I want the dome to overhang the outside edge of the tank. We used the Geodesic Dome Calculator but realized the calculations were from apex to apex, not flat to flat. So the dome calculations had to be reworked to insure the dome would fit over the tank wall.
6/4/08 Building the dome begins. I made a plywood template for both triangles. I undersized both templates the width of my Skill Saw base to blade dimension (1 1/2in) Then I stacked up 3 layers of OSB, screwed the template to the top of the stack with drywall screws and started ripping. 105 triangles seems like a lot, but I was finished in one long evening. I made sure to mark all the edges, A, B or C with a sharpie. This is a very important step.
6/5/08 Looking forward to putting all these triangles together. Good thing I printed out the diagram in color (you will find this on the progress photos page.) Matching up A to A, and B to B, doesn't sound too hard, but in reality, it's good to have the diagram and two sets of eyes to double check everything.
We determined that the fastest and easiest way to attach the triangles was with sheet metal strips and 1/2" sheet metal screws. This worked very well. It also gave the added benefit of a backing for the epoxy filler later. Three screws per side, with a total of 6 screws per join, seemed adequate. I worked on inside with the cordless drill, and Liana worked on the outside, placing the triangles in the correct position and hold them while I attached them from the inside. We finished all the pieces in two evenings.
6/8/08 Using the sheet metal strips and no glue, was fast, but the whole structure was flexible at the bottom edge. So, I drew a circle on the concrete shop floor, and used it to aligned the bottom edge of the dome. The dome slit is not cut yet. I do not want to weaken the structure until it is fiber glassed and solid.
7/1/08 My fiber glass and epoxy resin have arrived. I also ordered a bag of cabosil to use as thickener. Mixed into the epoxy, to the consistency of peanut butter, makes for a very hard and strong glue. I putty this into all the joints between the triangles, from the outside. The next morning, the epoxy/cabosil filler is set and there is no more flex in the dome. I then lift it up onto buckets, so I can crawl under and work on the inside.
7/5/08 Next comes the fiber glassing. I use the same epoxy resin and fiberglass mat to cover every inch of the outside. The easiest method was to cut the fiberglass mat into triangles a couple of inches larger than the OSB triangles. Then I paint them on to the outside, one at a time, overlapping the edges, with the epoxy resin.
This takes some time to do. But, in the long run, I do not want to have to stand on a ladder, 20 feet in the air, wishing I had done a better job the fist time around. I do not want to have to do maintenance on this dome for a long time.
7/27/08 Another trip to Pueblo for building supplies, this time paint for the outside of the dome. Stopped at a yard sale on the way and bought 25 pre-fabed floor trusses for $1.00 each. These will be used for the dome floor and the warm room floor. The dome is almost finished and ready to be moved out of the shop.
7/29/08 Get word that next weekend will be "The Tank Raising". I know you have been wondering just what am I going to set this dome on. Well, I have had this old steel tank, I salvaged from a gas station underground fuel tank. It is 7 feet in diameter and 14 feet long. It's rusty, but strong, and the perfect height to see over the trees. I just need my buddy to bring his tractor over, drag it up the hill, and stand it on end on the cement pad.
In the meantime, I need to paint the outside of the dome, and finish the dome slit assembly.
9/4/08 The tank is installed on it's concrete foundation. A few hair-raising moments, but it went better than expected. The tank looks taller standing on end. I plumb the tank, and fill the bottom two feet with sand and gravel.
9/17/08 The dome comes out of the shop and is placed near the building site. It needs to cure in the sun, and I need the room in my shop.
10/27/08 We have come up with a set of building plans, and start construction. I one long day, we got the foundation formed and poured the concrete floors inside the tank and warm room.
11/05/08 The warm room framing is under way and almost complete. Framing a 7 sided room is not that hard, we just need to cut accurate angles. The framing inside the tank, for the first floor is coming along. The days are getting shorter and there's not much time to work in the evenings, so I am relying a lot on my helper.
11/08/08 The roof joists are installed on the warm room and the roof and wall plywood goes up. I am thinking of using composite shingles on the roof. I have a roofing buddy, who has some extra squares of shingles lying around. Right now, it looks like I will go with stucco on the warm room walls. It's cheap, quick, and stops any air movement.
11/15/08 After a cold, snowy Friday, the sun came out and we went to work. One long weekend later, the wiring is in, the first floor of the tank is finished, and the second floor is done, except for the hatches. I have an idea of how I can get the dome to the top of the tank, using ramps and a boat winch.
11/26/08 The second floor is finished, so I have a place to stand and work on the top of the tank. I mount an old caster wheel to my torch as a depth guide and cut the top 3 inches off the tank. I have built a temporary ramp from the left over TIG's that reaches the nearby hill. I use this to lower the tank top. It will go down to the shop for further work this weekend. I will cut off all but 5 inches of the top ring, where the dome will be bolted. My drive chain has arrived, and it will be easier to mount in the shop. I also have to fabricate and weld on the mounting brackets for the wheels. Then the whole assembly will be slid up the ramp and back onto the top of the tank.
11/27/08 Turkey Day, and we have the muscle available to move the tank ring down to the shop. Then, we carried the dome to the top of the hill and placed it at the end of the ramp.
12/6/08 The rollers are welded and weather stripping are added. The top ring is set in place and the dome goes up.
2/14/09 The weather is co-operating, and I am motivated to pour the pier. I have been procrastinating because this means carrying cement, in 5 gallon buckets up to the 2nd floor of the observatory. But the Lulin Comet is due on the 24th of this month, and I am determined to do some astrophotography. So I fire up the cement mixer and drag out the buckets. After too many trips up and down those spiral stairs, I am tired, but satisfied.
The warm room has been painted white, with a dark blue ceiling. The ceiling inside, is faceted just like the roof. That was a bit of tricky work with cardboard templates, but the ceiling looks great. I am talking Liana into painting stars, galaxies and nebula on the ceiling. Would look great with my collection of Star Trek ships, hanging from the ceiling.Last update, December 6, 2008 www.nightskyobservatory.com