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Build a Dobsonian Base
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Click thumbnail for larger picture
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The problem with smaller sized Dobsonian telescopes is you are too low to the ground while observing. This can be a real pain in the... umm... back. You can use an observer's chair, but you're constantly moving it around as you observe different objects. It's also in the way often and can be a tripping hazard to you or others nearby in the dark. (You don't want anybody tripping near your telescope do you?) The best solution that I've found is to use a base to get the scope up to a comfortable height while observing. When the scope is pointing straight up you're standing straight up. When the scope is pointing off to the side you're bending over a little, but not enough to be uncomfortable, and probably less than you would be in a chair. It isn't in the way any more than your telescope in its factory mount is when setting on the ground. Below you will find instructions on how I made a simple one for just a few dollars in a couple of hours. You can adjust any dimensions to fit your telescope. |
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The plans for the base
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The materials: are few and cheap, a few 2x4's, some 3/8" plywood, screws or nails, wood glue, paint, handles and furniture feet (or pegs... pads...).The tools: needed are a table saw, miter saw, drill, screw gun or hammer (Depending on if you use screws or nails, your choice) Helpful, but not necessary is an electric sander and a biscuit cutter/joiner.
To build a base for your Dobsonian telescope the first thing that you have to figure out is the height. Set up your telescope and point it at the zenith. Measure the distance up from the telescope's eyepiece to your eye. This will be how tall to make your base. The width will be just a couple of inches wider than the manufactures base of your scope. I made mine an octagon instead of a square so that no large corners would stick out and be in the way. First miter cut 16 pieces of 2x4's at 22 1/2 degree angles and assemble octagon frames for top and bottom. (See Bottom inside view & Bottom view close up ). I cut mine 8 1/2" long to end up with a base 22" wide. Adjust your length to fit your desired width. I cut grooves for wooden biscuits and wood glue, plus screws (or nails), but glue and screws alone will hold fine. Take another 2x4 and cut from the centerline of the wide side a 45-degree angle off all the way down the length. This will leave you with a 2x4 with one edge at a 135-degree angle. This is the angle of the outside corners for the inside framing.Next take the measurement that you figured out for the height of the base, deduct 4", (1 1/2" for the top octagon, 1 1/2" for the bottom one, 3/8" for the plywood on top plus 5/8" for the pegs on the bottom equals 4") Cut 8 pieces this long out of your 2x4 that you cut at an angle. These are the inside corners of your frame. Glue and screw in place to the corners of the octagon frames. (Once again see "bottom views" on Photos page) Next is to cut the sides out of 3/8" plywood. (3/8" is plenty strong on the short span of 2x4 framing. Thicker plywood will only add to the weight and make it heavier to carry around). Cut and attach one side at a time to the framing with glue and nails before measuring the next one. Each side might vary in size slightly. When all 8 sides are attached to the framing set the base upside-down onto a piece of plywood, then trace the outline of your base onto the plywood. This is easier and more accurate than trying to measure the octagon top for cutting. Cut out the top and attach to the base framing, again with glue and nails. Next, if your manufactures dob base has feet (and/or a center bolt sticking out of the bottom) set it on your base and trace them onto it. Drill out holes for them to rest in (see Top view of base. The holes are there, it's hard to see the outside 3 because of the black paint). This makes the telescope setup sturdier, and also keeps the telescope from sliding around (or worse - off) your base.Sand all the edges down smooth. Next is to seal it up with a clear exterior finish, or exterior paint. You just want something to protect it from the moisture outside while observing. Don't cut corners and use spray paint.... it just won't seal up the wood very well. (A quart of black rustoleum exterior paint works great. I had some left over from my swimming pool deck rails. This stuff is HARD when it dries. It's been on my iron pool rails through 7 years of summer pool water, and winter snow and ice, and it still looks good! Be sure to use an exterior primer first). All that's left is to add a couple of handles to opposite sides, (utility handles are cheapest and strongest) and on the bottom nail in 3 of those pegs made for the bottom of furniture legs. Space them evenly. Plastic or stainless, your choice. It seems like you would want 4, one on every other side, but 3 makes the base more like a tripod and not wobble on uneven surfaces. Your finished product should look something like this:
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