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Cut Corners On Parts.

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Posted by Russell A. Hopkins on March 17, 2002 18:10:16 UTC

Okay, first, forget about photos for awhile. You need a lot more than $300 will buy to take photos. Build a Dobsonian. There are places where you can cut corners on parts. Mirrors are not among them. Try They make excellent quality mirrors at their factory in California. The mirror is the heart and soul of a reflector. You can upgrade accessories later.

Mirror cell: Cut an 8" circle from 3/4" plywood. Sand it. Drill three countersunk holes for the collimation screws. Put one flat-head machine screw in each hole. Make sure the screw heads are flush with the surface of the disk. Polyurethane disk. Cut equalateral triangle out of 3/4" plywood except that instead of corners, round off to conform to shaped of inside of the tube. Sand. Drill holes to match those on disk. Make sure machine screws in disk can move freely through them. Polyurethane. Drill holes in corners from the edges toward the center of the triangle (not all the way). Put threaded inserts into those holes. Drill corresponding holes in tube. Put compression springs on machine screws. Add triangle piece, screw-on with wing nuts. There is your mirror cell.

Remove the wax lining of the cardboard tube.

Secondary holder and focusers can also be fabricated. Also, you can get a helical focuser and mirror stalk from Discovery for $40. For a finder, get a BB gun red dot finder from Kmart for $14. You will need to build a mount, but it is not that hard.

Adorama has its own brand of eyepieces called Pro-Optic. The look like Language Removed, but optically they are very good. Dirt cheap $25-$35 (they gouge you on shipping, though). You will probably want to start with a 25ish and a 12ish.

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