It uses a primary mirror to capture and reflect light, a secondary mirror to direct light into an eyepiece, and a focuser to make fine adjustments for viewing. Dobsonian Bearing Materials A discussion of why certain materials are used for Dobsonian Bearings, mechanical issues for Dob bearings, and where to obtain these materials. Now sink in the screw heads , and you will get one right side and a left side board. Other plans may make other perfectly valid choices, or may have different design goals. The Newtonian OTA will be built in the classic Dobsonian-style cardboard concrete form tube, and while we plan to mate it to our Dobsonian Mount, it could certainly be attached to other types of mounts if desired by making a suitable set of tube rings or a tube cradle.
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We will strive to produce something in the middle: The box should be deep enough to allow the mirror box to swing all the way down. We break the project into two major pieces: You will get boards in a few colors and patterns There is a special tool for this For a mm F6 primary, a 40 mm minor axis tp is needed.
Nothing to install on your computer - you just need an up-to-date web browser. Plan ahead by carefully weighing all components and approximating the center mass of the optical assembly. As the telescope tilts toward the horizon, the mirror must be supported on its edge. Make sure the shroud can slip on and off of dobsoniaj assembled scope, buile that it stretches along the circumference not lengthwise.
Mark 3 drilling holes per strip, 30 mm from the edges, and one in the middle.
They need to be at least 25 mm tall to provide enough clearance on uneven ground. Put 3 on the outer edge of the disc, deg apart, and 2 near the 8 mm axis hole green dots on sketch above On the other side of the board, attach 3 rubber feet, near the edge, deg apart. Using plywood, make 4 attachment blocks to pair the trusses together and create a small ledge for the secondary cage to rest on while you secure it.
Similarly, the Dobsonian mount we describe could be sized to fit an existing OTA, so if you have a telescope tube and want to mount it as a Dobsonian, you can just start at dobsoniann mount project.
Build a Backyard Dobsonian Telescope
This is how a finished altitude bearing box looks like: Now sink in the screw headsand you will get one right side and a left side board. Same goes for the mm mirror, only here you need the mm OD tube.
Education How making is transforming learning. Photo by Carrie Fay Amaro. In this section we will show you how to build a complete Dobsonian Eobsonian.
Going for a shorter focal length will give you a shorter, more compact tube, easier to transport. The plywood Dobsonian mount is simple to build and very functional.
Stellafane: Build a Dobsonian Telescope
On the other hand, the faster focal ratio will want more expensive eyepieces, and is more demanding on collimation. Given any mirror measurements, PLOP will provide the ideal support layout and how much distortion to expect for any number of flotation points. Draw the outline of the upper part of the mount on the azimuth bearing board.
The optical judges told me on their second visit I had the best collimated scope and the easiest to point and hold Dobsonian mount on the filed that night - so if you have any doubts about the curved vane spider or mount design, rest assured they work well.
Move the jigs until you can comfortably place a variety of eyepieces in the focuser and get a sharp image, then carefully measure the separation distances. Whatever source that works for you will work in this telescope. Your changes have been saved. I found a used 16" primary on eBay.
PVC plugs are cheap and work very nicely as altitude bearings. You can follow the instructions strictly, or make modifications to suit dobsoniaj needs, available materials, and skills.
Build a Dobsonian Telescope
At about the inch size, it is more practical to switch to a truss-tube design, which we will not cover at this time see [Kriege97] for very good plans on building large aperture truss-tube Dobsonians. By adjusting the bolts, the mirror can be pointed toward teoescope correct spot. Drill a 4 mm hole in the center, and find the center of the even sided boards by drawing diagonal lines, corner to corner.
Use 4x50 mm wood screws, and some carpenters glue in-between teoescope contacting surfaces.