> Our society's 20" f/4 has a multi (12?) section wooden tube, mounted on
> a massive fork mount. Being f/4, it is EXTREMELY sensitive to
> miscollimation. The wood proved to be totaly inadequate. It shows
> enough motion (buckling?), whether thermally or humidity induced, that
> the scope is constanly out of allignment - almost unusable. We are now
> going to make a truss for it.
> In short, for smaller longish amateur scopes it migh be OK. For large,
> fast telescopes (or photographic instruments) - forget it.
>
> Bratislav
>-- End of excerpt from Bratislav Curcic
Bratislav,
Is the tube made of solid, "real" wood, as opposed to plywood? When you say multi section, do you mean in the sense that a cross section of the tube is a 12 sided polygon? I'm the one who originally asked the stability question, and I'm still unsure of whether I should construct a wood tube for my 6" f/8. I've seen many made of plywood, which should be far more dimensionally stable than "real" wood, but I'd kind of prefer to turn a multi-section tube on a lathe to obtain a cylindrical section. Maybe I should just play it semi-safe and construct a multi-section tube out of decent plywood and be done with it.....
John