The Pinhead Observatory
I live in Acton, California and the wind can blow pretty hard out here and it gets real cold. So I decided to build a small observatory. I played with several designs, roll off, square base with a dome, among others, before deciding on a 12 sided building. This worked best for my size, which is approx. 8 feet in dia., because the width of each panel is just under 2 feet. Combine that with a wall height of 4 feet and I was able to get 4 panel's from 1 sheet of plywood.
I started by digging a hole, 3' x 3' x3', dug a smaller hole down another foot in the middle. This may sound easy, but we have very hard and rocky soil. As you can see, I came across a large one. We fought a long hard battle. The Rock thought he won, but he is now under a cubic yard of concrete.
I had a friend weld a plate to a 4" round 7' long steel pole. I filled it with concrete, placed it in the hole, then filled the hole with a yard of concrete. Note the absence of "The Rock". All the concrete was mixed 2 bags at a time, by me and my wife, in a mixer, you can see it to the left in this picture. The top plate of the pier was roughly aligned to north and has elongated holes in it, so when I'm finished and mount the wedge, I will have several degrees of movement to allow precise polar alignment.
After the concrete in the hole cured for 2 weeks, I framed and poured the slab. Again 1 yard, mixed by me and my wife. I figured out that by the time we had moved the concrete bags to and from my shop, we had lifted 9 tons of concrete, not counting the water. The wood around the pier is to isolate it from the slab. I was on call during this, you can see the pager on my right hip, luckily I didn't get paged.
I can't find the pictures that show the base in the framing stage, but I'm still looking. If I ever find them I will update this page. There isn't much to it though, just 12 panels with the top plate and sill ends cut at 15 degrees so when they are placed together they make a 30 degree angle. I just set them on the slab and adjusted them around until they formed an 8' circle centered on the slab, then attached them to the slab using Redhead anchor bolts.
The dome was a little harder. I really wanted a true dome, but since this was a budget observatory and I don't know anybody that does fiberglass work, I decided to use wood. I gave the roof a slight slope so the top plate of every panel has a compound angle, and each one is different. This made cutting them a pain, but I like figuring those kind of things out so it was fun. Next I needed to find something to cover it with. Since it is made of wood and pretty heavy, I needed something light. After searching for days for something light and inexpensive, I settled on 26 ga galvanized aluminum. The aperture opening is covered with a clear fiberglass panel to allow some light to enter when it's closed. It's held in place with 4 latches and just lifts off. There was one design flaw. I thought I made the opening long enough, but when I first put the scope inside, I found I couldn't look straight up. Oh well, if I wait a while, whatever I want to look at will come into view. When I get rich, I want to buy a real dome, like a Home Dome. I should be able to adapt it to the existing base.
Well, here is the semi finished product, I'm going to paint the inside black. Not pretty but it keeps me out of the wind. There are 12 panels, 2' x 4' on the base and 2' x 2' on the smallest of the top. The roof slopes up slightly, about 6", so water will run off. The top rotates on 22 2" heavy duty casters. I'm having trouble keeping the top from shifting when I rotate it. Right now I have electrical conduit with a piece of PVC over it. A piece of plywood cut in a circle is attached to the bottom of the dome and rubs against these pipes. The problem is the pipe won't stay in place, so to top shifts as I move it. Any suggestions would be greatly appreciated.
The dome in the picture's above was just to heavy and hard to rotate, so I built a new one. The plans are from Joe Garlitz, he has detailed plans at his site, thanks Joe. My dome is smaller, so I modified the plans slightly, which is very easy to do, and I used a different kind of foam.
Construction was pretty easy. The hardest part was putting all the pentagons and hexagons together to make the dome. I used a thinner foam than Joe did, 1 inch high density, so there was not much surface area to glue. So when I was putting the dome together, in the left picture below, I would add a few pieces, then wait a day, and add a few more.
After it was all together and turned over, I reinforced all the seams with metal tape. I figured that would help keep the pieces together plus help with sealing them. I sealed the dome with 5 coats of rubberized paint, like they use to seal the roofs of RV's. I went with a one piece door that I take off and set on the ground when in use. The trouble with that is that with the dome sitting on 4 foot walls, I need to stand on a chair to un-latch it and take it off. I may redo it and make it a 3 piece door like in Joe's original plans, but for now it works.
The dome rides on the same rollers as the last dome, but is so much lighter it rolls much easier. I still need to attach strips of rubber around the out side edge to protect and seal the opening between the dome and base, but I couldn't wait to get it in use, besides, there is no forecast for rain in the next week. It took a while to build, and sometimes I felt like smashing it, but I think it was worth the effort. If you are thinking of building your own observatory and going with a conventional style dome, I strongly suggest downloading the plans from Joe, if you click on his name in the first paragraph it will take you to his site. If his site ever goes away, let me know and I will send you a copy of his plans. Just remember, Joe gets all the credit for this design, thanks Joe!
For some reason, the Ravens decided they liked the taste of my dome and started eating holes in it. To stop them from landing on the dome, I installed a few rows of bird spikes on top. When I was all done it reminded me of the guy from the movie "Hellraiser", so we decided it should be called "The Pinhead Observatory".