Plans for Building a Dobsonian Telescope
brought to you by: The San Francisco Sidewalk Astronomers
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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. Here you will find plans to build this telescope, or a smaller one--either a 4.5", a six-inch, or an eight-inch--of identical design. These plans are only slightly modified from the plans The Sidewalk Astronomers have been sending to interested parties for a mere $2.00 via snail-mail. I have kept as close to this design as possible: One, because this is--hands down--the cheapest and easiest way to make a quality telescope; and two, because I walk in the shadow of John Dobson, who invented many of these designs which have revolutionized amateur and professional astronomy alike... Besides, Los Angeles Sidewalk Astronomer, Pam Reid, did most of the work by writing and typing the procedures, as well as gathering the drawings--which, by the way, were done by Earl Jungians (from photographs of John at work by Molly Lusignan). Most of my "work" consisted of scanning and re-typing Pam's work... though I do interject my two-cents here and there. If you would like to grind, polish and figure your own mirror, I suggest Victor's Telescope Making page as well as the late Sam Brown's book , All About Telescopes, which may be ordered from Orion Telescope and Binocular Center.
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Introduction
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The plans you will find on these pages, are, by and large, the result of years of trial and error on the part of John Dobson, one of the founders of The San Francisco Sidewalk Astronomers and a prolific telescope maker. John has, quite literally, helped thousands of people make telescopes of this design! Only in the past few years have commercial telescope manufacturers adopted the Dobsonian approach to make affordable, alt-azimuth Newtonian telescopes... However, the three top manufacturers (henceforth referred to as: "The Big Three"), Celestron, Meade, and Orion, continue to fall short mechanically of the simple designs found on these pages. All of The Big Three, for example, use Melamine; a kind of coated particle board, which is heavy, not durable, in short; not as strong or light as plywood, which, of course, we recommend. All of The Big Three have undersized pivot bolts, do not use Teflon as bearing surfaces (there is no substitute!), and have shoddy mirror cells (tailgates). The list goes on... They do look "pretty," especially in photos; I'll give them that. If you happen to own one of these scopes; you might well peruse these pages to find ways to tinker and fix up your mass-produced Dob: you can only improve what you got! It ain't rocket science! The designs you find on these pages are also open to improvement by you: the builder. Not only will you discover the ins and outs of Newtonian / Dobsonian telescope design, but you are encouraged to come up with your own modifications. We include plans to make your own Primary Mirror Cell (we call it a "Tailgate"), Secondary Diagonal Mirror Holder and "Spider," and Eyepiece Holder/Focuser. These are items even the most seasoned TM (telescope-maker) usually buys from small telescope part manufacturers: you may opt to do the same (although John's designs are perfectly functional--some ingenious--and very inexpensive to fabricate). Contact your local astronomy club, there are usually at least a handful of TM's that can help you out. Also, check my Sources page for materials and accessories you will need, or, might want, to purchase. I think you will find these plans pretty clear, simple, and straightforward. If not, let me know. Have fun!
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Ray Cash