How to build a 12.5 inch closed tube Dobsonian telescope. I placed my telrad, optical finder, and an eyepiece on the focuser end of the tube and, using a broomstick as a balance point, found that the tube balanced 22 inches from the bottom. This content is created and maintained by a third party, and imported onto this page to help users provide their email addresses. "The whole thing was made out of junk. This book will expertly guide you through every step of design, construction, and mirror making. Over how many nights did this photography session take place? I even began taking careful notes about needed supplies and plans for each piece of the truss tube scope. The side bearings are each made from 2 identical semicircles of 5/8 inch plywood glued together to make a thickness of 1 ¼ inches. Fast forward a few months to the next time I had the tube outside. At some point in the building process, my goal became to finish the scope by RocheStar Fest, an annual event of the Rochester Astronomy Club. On that noteWARNING:do not look directly into the sun and never point a telescope into the sun without proper filtration you can damage your telescope and burn your retinas and possibly go blind i am not a astrophotographer so i cant comment on the quality of the pictures since there is so much doubt on the photos i will gladly take them down. The pivot bolt consists of a 1 1/8 inch brass spacer with an 11/16 inch outer diameter, a 3/8 inch bolt 2 inches long, a stop nut, and two large washers. To hold the tube in place within the tube box, I used a combination of pieces of felt inside the box and wooden shims between the tube and the box. I laughed, packed up the cell with a long letter describing the series of events that led to the return, and put it in the mail. I was still doing some construction on the morning of the event, but I succeeded in making first light on that clear, dark night in late July. I drilled the holes in the center of the ground board and rocker bottom using a 9/16 bit, thinking that I needed the extra 1/16 so that the spacer could move. The mount works via friction, just little enough to easily move the telescope, but yet enough that the telescope remains pointed. The last chapter of the book describes a plan for an 8 inch sonotube dob with a few design elements from their truss design, and, as I read that chapter, the simplicity of its construction was very appealing. When I brag that the plastics supply store where I finally found Teflon gave me some scrap for free, he exclaims, "Good for you!". I got no response to phone calls or emails after another week, and decided to wait until the primary would be finished in another two weeks. How to build a 12.5 inch closed tube Dobsonian telescope. Plans for Building a Dobsonian Telescope. At their suggestion, I also ordered a 2.6 inch secondary mirror. I had initially allowed for more of a gap, but realized once I cut the pieces and held the tube inside them that my gap was too large. Did Scientists Just Find a Way to Reverse Aging? Lining up this center point with the center of the top of the side bearing, I brought the corner of the side bearing up to the edge of the tube box and attached it with screws. brought to you by: The San Francisco Sidewalk Astronomers : Yes, it "looks like a cannon," but the above is really a ten-inch (measured by the diameter of the objective) Newtonian telescope that almost anybody can build. Thicker walls also required thicker side bearings so that the outside of the bearings would line up with the outside of the rocker sides. I told them to take their time and get it right. This allows for a small clearance between the outside of the tube and the inside of the tube box (14 3/8). Finally, I glued a strip of Ebony Star laminante to the curves edge of each side bearing using contact cement, using a flush edge bit on a router to bring the edge of the laminate even with the edge of the wood after the cement had set. This allowed me to cut perfect identical circles. On the cutting diagram, you can see that the side bearings were cut 26 inches long. Two such companies would not give me a price because the order of a single tube was too small. The Focuser and other items: (Scope Stuff). Since my plan called for purchasing the mirrors and mechanical parts there were several decisions to be made and several vendors to contact. ScopeStuff is awesome!! I had nearly completed the base and put things together for the first time. And you can tell it's not a mosaic because the stars at the corners show coma/field curvature artifacts. Share it with us! The design isn't intuitive or obvious, but it is wonderfully elegant. I marked the spot and moved things back inside to install the mirror. on Step 3. Using heavy grit sandpaper I brought back the surface of the keeper enough for the side bearings to fit inside the felt pads. The cardboard tube can be cut down to the desired size, have the needed lens installed in each end, then embellished as desired. In essence, it's a telescope built onto a gun mount, which balances through friction as it swivels on an LP record. Have you made any mods on it since you built it? A week later the cell arrived (on schedule) from University Optics. on Step 5, After much debit and doubt i have taken the photos down cause i cannot be 100% sure that they were taking from my scope as i was not there to verify them and i do not want my contest entry to be based on photos and not the build process. I redrilled the holes for the mirror cell and got ready to wrap it. Step 4—Attaching the Side Bearings and assembling the Rocker.