More telescope stuff...vibration damping

Factual Questions
21

But I will go out and clamp it in my welding vise. Thanks.
.
For those interested in the bed rail experiment: No good. I’ll have to try something else. All it did was make my counterweight too light.

22

I attached the tube to a hardwood block, which I then clamped in my welding vise. I’ve definitely isolated the vibration to the tube. So now, it’s a matter of fixing the tube. Somehow.
Oh, and by the way, welcome to the SDMB, Moe Mentum!

23

If the tube is buckling at the mounting screws, you could probably fix the problem by building a ~1 foot long cradle for it with 2" straps that go around the tube and hold it in place. That’d spread out the stress more.

24

I found a interesting picture
of what appears to be the same model I’ve got.

25

Those straps look too thin, and I’ll bet you can’t tighten them enough to minimize vibration without buckling the tube.

26

As it happens, mine has been modified such that it is held on the mount by 1/4 20 bolts from inside the tube(sorry, I should have made that clear). There are no straps, but I assure you that the mounting is FIRM. I have also tried hose clamps in place of the straps in the picture, to no avail. It is the tube itself that vibrates; that’s what I have to figure out how to damp. Next guess: I’ll build a replacement cradle a bit longer than he existing one, say 2’ vs 12" (amazing the excuses you can find to own a lathe, drill press, welding kit, etc).

27

Thank you.

Welcome to the wonderful world of amateur astronomy. As you seem to be finding out, it’s a great excuse to spend time tinkering out in the garage.

28

I’ve tried a new tack: bracing from part of the mount. It has made a fair improvement. This was suggested to me last night by a member of the Central Maine Astronomical Society. Nice folks. For those who are interested, I’ve taken a few pictures.

http://img.villagephotos.com/p/2004-7/767107/brace.jpg
http://img.villagephotos.com/p/2004-7/767107/top.jpg
http://img.villagephotos.com/p/2004-7/767107/mountbrace.jpg

29

That ought to do it. Nice solution.

30

For what it’s worth, what you’ve added to your telescope is called a Hargreaves strut, named for F. James Hargreaves a former president of the British Astronomical Association. There was a short article on this subject in Sky and Telescope , Sept. 2001, p.114-5.