Here is my idea: Make a fixture with circular disks that you can strip plank around, but on the ends place floor pipe flanges at the center. Insert short sections of pipe to act as bearings to rotate the tube on. Design a fixture to this that a router can be placed in and slowly moved the length of the tube. When the adhesive on the strip planking has cured, slowly rotate the tubing, and with the router running carefully plane down the thickness to the desired dimension. When finished remove the internal fixture finish sand all surfaces and paint with the desired finish.
I have also been thinking about doing this to make a form for casting resin re-enforced fiberglass tubes.
Bob
):-{])) <---- madden@netcom.com madden@svpal.org Remember amateur astronomers: "keep looking for the next Universe"
On Thu, 3 Aug 1995, John Q. Runchey wrote:
> On Aug 3, 9:52am, Bratislav Curcic wrote:
>
> > 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
>
>
>