weight vs.balance problems
Jim Kendrick (jkendrick@astral.magic.ca)
Mon, 3 Jul 1995 12:04:46 -0400
I am building an 8", F8, 2 truss dobsonian. The scope is almost finished
but is seriously top heavy and therfore very difficult to balance. In order
to obtain a better balance I am considering using one truss to hold the
focusser board, instead of the two now required. I will be rebuilding the
focusser board out of foam core board and laminating it with fibreglass. I
also plan to drill holes into the spider vanes to lighten them up. This
should lighten it up considerably.
My question is this: What material can I use as my truss that is
lightweight, strong and rigid. Presently I am using 2" OD x 1/16" wall
aluminum tube but this is simply too heavy. Going to 1/32"wall may do it
but I am concerned about flexing in the tube putting the secondary out of
alignment. Another alternative may be graphite tubes. Does anyone have any
experience with this material? Any suggestions are welcomed.
Jim Kendrick