Let’s
begin construction with the tubes – At pickup the guys dropped the 12 foot tube
(before cutting) from a 15 foot high rack onto a concrete floor and “ dented”
about 4 inches of one end. Then they cut
the two halves crooked, so we’ll need square things up at the ends and figure
overall length – the mirrors have focal length of 60 inches +- ¼ inch. The light path will have to take a right
angle turn at a secondary mirror and then another right turn at a tertiary
mirror to reach the eye. This will use
up 7 inches from secondary to tube wall, 2 inches from wall to tertiary mirror,
and about another 4 ½ inches from tertiary to the eye, for a total of 12 ½
inches, reducing our mirror to secondary distance to about 50 inches. Let’s allow about 6 inches for safety, for an
overall initial tube length of 56
inches. We need a rotating end to allow
interocular adjustment, so we will cut off 8 inches for the rotating part,
leaving the main tube 48 inches long. The tubes will fit in the Jeep!
End
to end copy paper used to mark
true line small hand
saw/wedge 60/120 grit sandpaper
Thin
bead Elmer’s glue rubbed into all
rims beginning of insert second cut w/tin snips
insert
ready to glue to inside of
upper ring tube & upper ring
w/insert tube/ring weighs 10#
When
I got the upper ring insert installed it was too tight, as ring wouldn’t turn, so
peeled off a single layer of cardboard on the insert which resulted in snug fit
in the tube that allows ring to turn.
I
had read about “peeling” the waxed layer from the tube interior, but with thin
wall to begin with, was hesitant to try, so attacked the wax coating on tube
interior with 3 different solvents, HD steel wool, a drill powered wire brush,
80 grit sand paper – sure was hard work and sure made a mess of the tube
interior, so went ahead a “peeled” what turned out to be a layer about
thickness of a sheet of paper. And it
took all of 5 minutes to do the whole tube!
Wax is gone and interior “virgin cardboard” is ready for flat black
paint.