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    Re: Maintenance of SNO-T's Was Re: on washing sextants
    From: Joel Jacobs
    Date: 2004 Aug 4, 02:40 -0400

    Thanks for your comments.
    You have a big leg up on the rest of us since you can "read the friendly
    manual".  I can't read Russian so I have no idea what it says. And the
    manual I have is for a SNO-M which is made differently.
    If your SNO-T has three screws on the lower portion of the index arm that
    holds the cylinder in place, then it mounts exactly like the Freiberger. It
    goes on and off quite easily so I don't understand why you would be hesitant
    to remove it, but only if it was necessary. Also, the tangent screw must
    make contact on the arc. For it to do that, there has to be a slot that runs
    the whole length of the barrel. This slot is not water tight along its
    length, and its been my experience that water added at one end will run out
    the length of the slot carrying and dissolved salt with it. In my personal
    experience, I've not seen sextants used in places where they would pick up
    dirt and grit. The enemy has been salt.
    If you have had success in what your doing to maintain your SNO-T, without
    the tightening of the quick release clamp or when turning the micrometer
    wheel which happens over time, then keep doing it.
    Courtney, what Lee describes as to the three screws means that the procedure
    for removing the barrel is the same as with the Freiberger so that answers
    your question.
    Joel Jacobs
    ----- Original Message -----
    From: "Lee Martin" 
    Sent: Tuesday, August 03, 2004 8:45 PM
    Subject: Maintenance of SNO-T's Was Re: on washing sextants
    > Joel, I am not so sure about some of your suggestions, my comments below.
    > ----- Original Message -----
    > From: "Joel Jacobs" 
    > To: 
    > Sent: Wednesday, August 04, 2004 2:56 AM
    > Subject: Re: on washing sextants
    > > Courtney,
    >   Sometimes it pays to
    > > remove the aft leg which will allow the index arm to move backwards off
    > the
    > > arc. There maybe some kind of a stop which has to be removed.
    > On my 1988 SNO-T the index arm sits within the frame and it is impossible
    > move it off the arc.
    >  Take the index
    > > arm and move it all the way to the back of the arc. In a SNO-T the
    > underside
    > > of the cylinder in which the tangent screw is housed has a slot which is
    > > wide enough to see the teeth of the screw.
    > Not on my SNO-T...the drum completely "seals" the tangent screw in all
    > positions of the index arm. It is clear that is the purpose of the
    > design....the drum completely encloses the tangent screw and the drum fits
    > snugly on the arc, all to prevent the ingress of dirt. The only way to get
    > at the tangent screw is to unscrew the 3 screws holding the drum onto the
    > index arm, and remove the drum....something I would not want to do often.
    > I have always found a RTFM to be a useful thing to do when these sorts of
    > questions arise. In this case, the SNO-T manual suggests the only
    > maintenance necessary is a careful brushing of the arc after each use
    > supplied) to remove all particles of grit and salt. And a very occasional
    > lubrication of the arc with the lubricant supplied (no idea what it is).
    > Clearly, any but the lightest lubrication will pick up grit and
    > have never lubricated mine, prefering to rely on stringent cleanliness. It
    > seems to me that one would only access the tangent screw or internals of
    > drum when normal maintenance had failed, or wasn't carried out at all.
    > Trying to wash the drum in situ on the arm doesn't seem very useful to me,
    > because there is no way to flush water in and out of the drum, to carry
    > dirt and salt away.
    > The manual has nothing to say about preserving the eyecups. I have used
    > occasional talc, which I suspect is what was placed on them in the
    > factory.In any case, I suspect the eyecups might be relatively easy to
    > replace at a camera/binocular store.
    > Lee Martin
    > >
    > > ----- Original Message -----
    > > From: "Courtney Thomas" 
    > > To: 
    > > Sent: Tuesday, August 03, 2004 10:52 AM
    > > Subject: Re: on washing sextants
    > >
    > >
    > > > Joel,
    > > >
    > > > I have a SNO-T with the barrel enclosed tangent screw.
    > > >
    > > > How do I properly gain access to the tangent screw ?
    > > >
    > > > Also, what should be done to preserve rubber eye cup pliability ?
    > > >
    > > > Appreciatively,
    > > >
    > > > Courtney

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