In another thread, I discussed one aspect of the alt-azimuth mount of
an 80mm Meade Model 312 telescope, namely the fine adjustment controls
of the mount. In this posting, I'm interested in another aspect of the
mount. The mount can rotate on a certain base shaped roughly like a
frustrum of a cone. The base has a cylindrical chamber at the top
and the bottom of the mount is a matching cylindrical tube that drops
into it. It is not a perfect cylinder: the outer diameter of the cylinder
has been reduced at one place to allow a set screw in the conical base
to penetrate it. This prevents one from removing the mount from the base
without loosening the screw, but at the same time allows the mount to
rotate.

When one removes the mount, one smells the lubricant that is used between
the cylindrical chamber of the base and the matching cylindrical tube but
I don't recognize the smell. The fit is snug and it doesn't rotate quickly,
and that might indicate the preferred lubricant. At any rate, what I'd like
to know is how to identify the lubricant without having to guess at it. This
question is motivated in part by trying to learn how things are done by
studying finished products and in part motivated by a desire to know how
to maintain and repair the scope if, unlikely as it seems, anything happened
to the lubrication and I wanted to replenish it.

There are other parts of the scope that have knobs for adjustment and which
are either rusty (e.g. set screws in the fine adjustment mechanism) or which
tend to get stuck in certain places (for example, the knob and rack for
extending or retracting the eyepiece). Ultimately I'll be interested in
cleaning and lubricating those parts, which I also don't know much about.
--
Ignorantly,
Allan Adler
* Disclaimer: I am a guest and *not* a member of the MIT CSAIL. My actions and
* comments do not reflect in any way on MIT. Also, I am nowhere near Boston.

Allan Adler wrote:

.. like a frustrum of a cone ..
^^^^^^^^

Perhaps you meant "frustum"? - GWE

I suspect the lubricant is some sort of damping grease, often used in
optical instruments where you want smooth movement but with some resistance
and no backlash.
Nyogel is a good product, which I have used in the past to relube the
focusing eyepieces on binoculars. I get mine from www.micro-tools.com
As to cleaning, xylene and a toothbrush will remove all traces of the old
grease. It might take a few passes with clean xylene to get it perfectly
clean.
For just about all other moving parts, I use teflon grease. Here in
Florida, I don't have to worry about the grease freezing....
Dan

"Allan Adler" wrote in message
...

In another thread, I discussed one aspect of the alt-azimuth mount of
an 80mm Meade Model 312 telescope, namely the fine adjustment controls
of the mount. In this posting, I'm interested in another aspect of the
mount. The mount can rotate on a certain base shaped roughly like a
frustrum of a cone. The base has a cylindrical chamber at the top
and the bottom of the mount is a matching cylindrical tube that drops
into it. It is not a perfect cylinder: the outer diameter of the cylinder
has been reduced at one place to allow a set screw in the conical base
to penetrate it. This prevents one from removing the mount from the base
without loosening the screw, but at the same time allows the mount to
rotate.

When one removes the mount, one smells the lubricant that is used between
the cylindrical chamber of the base and the matching cylindrical tube but
I don't recognize the smell. The fit is snug and it doesn't rotate
quickly,
and that might indicate the preferred lubricant. At any rate, what I'd
like
to know is how to identify the lubricant without having to guess at it.
This
question is motivated in part by trying to learn how things are done by
studying finished products and in part motivated by a desire to know how
to maintain and repair the scope if, unlikely as it seems, anything
happened
to the lubrication and I wanted to replenish it.

There are other parts of the scope that have knobs for adjustment and
which
are either rusty (e.g. set screws in the fine adjustment mechanism) or
which
tend to get stuck in certain places (for example, the knob and rack for
extending or retracting the eyepiece). Ultimately I'll be interested in
cleaning and lubricating those parts, which I also don't know much about.
--
Ignorantly,
Allan Adler
* Disclaimer: I am a guest and *not* a member of the MIT CSAIL. My actions
and
* comments do not reflect in any way on MIT. Also, I am nowhere near
Boston.