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
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.
Aircraft grade birch plywood, styrofoam and epoxy
Aircraft Spruce and Specialty Company
P.O. Box 424
Fullerton, CA 92632
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
P.O. Box 440
New Brunswick, N.J. 08903-0440
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.
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.
Danboro, PA 18916
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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