diagonal holders
Greg Granville (gag1@psu.edu)
Wed, 1 Mar 1995 23:11:29 -0400 (EDT)
Last year, when I was building my 6" dob, I obtained a spider and diagonal
holder from university optics. The holder they sent for my 1.3" secondary
was constructed with a piece of 1.5" aluminum tube with a 45 degree angle
cut on the end. This seems to be an old design, as I've seen this type of
secondary holder pictured in several ATM books and magazines. I stuffed some
cotton inside the tubing to hold the mirror in place - snug up against three
little retaining clips on the front of the tube.
But now I'm thinking of fabricating my own secondary holder. The plan is to
get a 1.3" piece of solid aluminum bar and mill a 45 degree angle on the
end. Then I figured I'd just glue (RTV - silicone seal) the mirror
directly to the end of the 1.3" aluminum piece. I'll reduce the obstruction
from 1.5" to 1.3" while keeping exactly the same secondary mirror.
Kinda makes me wonder why the tube-style of secondary holder is so common in
the first place ???
________________________________________________
Greg Granville - N3SPE - (day)814-865-3310
ARL-PSU gag1@psu.edu (eve)814-339-7244