Doc--

A piece of chain attached to the mirror box is one of the most effective, and
cheap, ways to balance a large dob when using heavy lenses such as a 20mm Nagler
with a Big Barlow. As you tip the dob toward the horizontal, you lift more chain
off the ground--it works!

Clear skies, Andy

R. A. Greiner wrote:

> The use of a chain is rather clever I think. I suggest a possible experiment.
> Use a chain with a rubbery coating. The links will provide some mass and the
> rubbery coating some friction (dissipation or damping). It might also be
> possible to make a passive, dynamic damper for reducing the gross oscillations
> of the OTA. The damper can actually be designed to reduce vibrations at the
> resonant frequency of the OTA. This is 10 to 20 Hz for the 10" and 12" scopes.
>
> The above are interesting things to consider and work on. Perhaps some ME out
> there will come up with a nice damper attachment for our rather wobbly scopes.
>
> Doc G <http://www.mailbag.com/users/ragreiner>

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