Flying Dobsonian
Parts and Construction Details

The following suppliers were used to obtain hardware and materials used in the Flying Dobsonian.

Composite panels, fiberglass sheets

Aerospace Composite Products
14210 Doolittle Drive
San Leandro, CA 94577
510-352-2022
http://www.acp-composites.com

1/4" graphite/balsa laminated panels were used in the 18 point mirror flotation cell and the sides of the diagonal cage. The pieces were cut from LP-26 12"x24" panels with an ordinary band saw. The triangular panels for the mirror supports are made of single 1/4" panel pieces. The cross bars supporting the triangles were made of two laminated 1/4" pieces. The diagonal vanes are made of 5/32" thick graphite/foam composite, P.N. LP-28.

Aircraft grade birch plywood, styrofoam and epoxy

Aircraft Spruce and Specialty Company
P.O. Box 424
Fullerton, CA 92632
800-824-1930
http://www.aircraftspruce.com

The side bearings were made of 1" Styrofoam, P.N. 01-09700, laminated with 1/16" plywood. The plywood was glued to the Styrofoam with Elmers glue. 1/2" Finnish Birch aircraft grade plywood, P.N. 02-208-50, was used for the mirror boxes and the ground board. The base of the rocker box was made of sandwiched 1/4" plywood and 1" Styrofoam core. See Rob Pike's description, "On the Making of Foamcore Telescope Parts" in Telescope Making #28.

Plastic cabinet latches, plastic thumbscrew knobs, 1/4 turn fasteners and teflon sheets

McMaster-Carr P.O. Box 440
New Brunswick, N.J. 08903-0440
http://www.mcmaster.com

I used 1/8" Teflon bearing pads. P.N. 8545K24, or you can get it etched on one side for glueing, P.N. 8711K15. The plastic thumbscrew knobs were press fit knobs on 1/4 x 20 socket-head cap screws, P.N. 94052A053.

The plastic cabinet latches are no longer available at McMaster Carr. They are Southco, P.N. 07-99-161-12. I chose them because of their low profile. See http://www.southco.com.

The 1/4 turn captive fasteners are no longer available at McMaster-Carr. A good substitute is their knurled head quick action captive screw, P.N. 93765A125. Check the PEM Fastener catalog for ideas.

Penn Manufacturing
Danboro, PA 18916
215-766-8853
http://www.pemnet.com

After some experience with the 1/4 turn fasteners on the ends of the truss poles, I am more in favor of screw-type captive fasteners because you can tighten them more securely. Captive fasteners are specified based upon the thickness of the panel to which they are attached. It is difficult to adjust the thickness of the flattened end of the pole to get a uniform tightness with the spring loaded 1/4 turn screws. Remember to use very light fasteners for this application. There are 8 of them and they are at the end of a long lever arm.

The focuser is a Lumicon 2" Helical, Low Profile Focuser. Note in the photographs that there are small triangular spaces in the corners of the top half of the mirror box into which the octagonal diagonal cage nests. The focuser is attached to one of the diagonal faces and just fits into the space. Keep in mind that the truss pole blocks are in that s pace too. There is very little room. I screw the helical focuser in all the way and it leaves about .050" to spare.

Many different telescoping poles including custom sizes are available from Testrite in Newark, NJ.

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