Re: telescope tubing
Bratislav Curcic (epabcc@epa.ericsson.se)
Thu, 20 Apr 95 13:38:51 EST
Get the lightest carboard tube / sonotube. Peel off waxed layers
(if there is any) and epoxy two layers of Kevlar or Carbon fibre
(one outside, one inside). Give another layer of Kevlar/Carbon in
stressed areas (around focusser, primary etc.). You'll end up
with lightest and strongest tube you've ever seen !
I've made tube out of balsa wood and Carbon fibre for my Wright.
It hardly has any weight (around 300 grams for tube 8X23"), but it is
unbelievably strong (no trace of flexure whatsoever)! Another plus is
that Carbon has almost zero coefficient of thermal expansion.
PVC tubes sag, attract dew, and are just too heavy. They will also
expand/contract under temperature by few mm !
Bratislav