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Dear Fred and Bill,
Bill's message is very interesting.

I don't know whether the problem I experienced has
a similar explanation.
What I really DO NOT like about SNO-T and
Freiberger is exactly this enclosed drum
construction. They claim it is designed to
protect the worm assembly.
But it prevents any inspection or cleaning of
this assembly. (And the manual prohibits to mess
with this part, though the special wrench is supplied
to disassemble the trommel).
In the factory they did not open the drum.
The drum fits the arc tightly, and it is
hard to imagine that any insect could penetrate inside.
But dust could. When the sextant arrived, its rubber parts
were covered with a thick layer of talc,
and of course this talk (very fine powder) was everywhere,
even inside the telescope. Some of it could penetrate the drum
and build up on the arc or on the worm.

I oiled the teeth of the arc once or twice with very small
amount of oil.

I also noticed some black substance (probably old oil)
on the teeth which definitely came from the drum, expecially
in the first months.

Index error I measure frequently.
Before the repair it was usually 0, but sometimes closer
to 0.15'. Now (after the adjustment made in Freiberg) it is 0.6'.

Alex.



On Sat, 28 May 2005, Fred Hebard wrote:

> Here's a physical explanation for Alex' previous results, where his
> readings were too large.

   

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