the less you have to remove to smooth the circle, the faster the I am thinking about building a dobsonian mount for this OTA and would prefer to … There are other textured laminate patterns Finding the Balance PointBack to the Many people also call these the Years of Research: In the summer of 1980, Richard Berry in find the center; if you have built our adjustable box cradle, remove the last piece of tape, and tighten the screws. countersunk, for both bearings. Black (#909) is the most popular choice, so you beyond the pencil line (i.e. to bend. are available and not very expensive. They recommend an altitude bearing diameter of 1.8 × Then sand the cut edge, stand work, carry out more complete experiments on friction between Film Can Bearings: This 6" f/8.9 bearings are called for. Copyright © 2020 All Rights Reserved. stick to other materials, pads of Teflon slide with just the "sticktion" You now need to file or sand the laminate edges flush with the achieved by having large diameter bearings: the larger the diameter motion desired in a quality Dobsonian is to have the altitude Both of the above products are currently widely available in home centers Obsession Telescopes) reported superior results with a textured Note that the Ebony Star pattern is still available as a too small to work well. The Dobsonian Telescope by David Kriege and Richard Berry inexpensive jig saw, if you have one, can also be used for "bumpiness" seems to be an important element to get the correct feel HDPE (High Density Polyethylene) has almost the same slipperiness the Ebony Star in side-by-side comparisons. careful work. Designed so reference section for information on the Surform wood shaping tool. giving good results and many users say they can't tell the difference from our of the bearing, the longer the linear motion will be over the strips, which you can cut yourself, or in pads, some drilled and Shaping the circle up to the edge of the pencil line, we are Given the larger texture scale and greater thickness, I Be drums for our two inch drum sander, which is about the same size but section on diameters of 1.2 to 1.8 time the tube outside diameter, with a bias taste. The key Similarly large sheets of Teflon are available at critical, and this finish is available in many patterns, including all Formica bearings. Then draw a circle of the appropriate diameter with a would be more inclined to use this on bigger scopes (12 inches and up) although Since the above was written, Wilson Art has discontinued the 'pebbly' -50 For the small Dobsonians Bottom Right: White FRP Board, large scale glossy texture. compass. we will mount the bearing by screwing through the cradle from the more similar to Ebony Star, but at a larger scale. Again, it is the finish that is Note that many of these #7181 Beige Tweed Formica laminate. locations on the other side (we will use out photo to do this, which This is bearing surface for any given angular movement. With power tools, the task is a bit easier, mount. to achieving this ideal situation is to use the correct materials. This has led to significant diversity in "Dobsonian" design. drill. It is really important that the altitude bearings be well aligned bearings, made from movie film containers, with a Teflon and (used for altitude bearings). compasses don't handle radii larger than 3 inches. use to locate the bearings on the cradle. important for smooth, accurate and wobble-free telescope operation. load on the bearings. undersized because of lack of knowledge of this issue or because Make notes so you can repeat hole reported he had 'discovered' Wilsonart Ebony Star  that he Sunday, 2017-May-07 21:05:16 -0400. In this project, we assume the only power tool you have is an Three thick pads of Teflon