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Re: Slipping 1:10 focuser

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  • Kelliot1@aol.com
    Hi I have attached below a solution I gave in April for the ZS105, which I assume has the same focuser. I hope this is helpful. Keith I have, broadly
    Message 1 of 4 , Jul 14, 2007
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      Hi
       
      I have attached below a solution I gave in April for the ZS105,  which I assume has the same focuser.  I hope this is helpful.
       
      Keith
       
       
      I have, broadly speaking, been happy with my ZS 105. I say broadly,
      because although delighted with optics and build quality, I have never
      been able to get the focuser to work as advertised.

      Out of the box it felt `notchy' and I found that there were places on
      the tube travel where the fine adjuster would rotate without either
      rotating the larger `gold' knob or moving the shaft. I have searched
      in vain to find owners who had managed to correct the problem and
      fiddled for hours with the large fluted screw and its central
      tensioning screw without success, maybe nobody else has had this
      problem, anyway, here is what I did, perhaps it will help somebody.

      I finally took the thing apart using the WO website instructions for
      retrofitting a dual speed focuser and discovered the problem. There
      is a threaded locking ring which (seems to) adjust the friction
      between the fine and course focuser which I very carefully tightened
      with about 2 or 3 degrees of clockwise rotation. This needs to be
      tight enough to give free rotation of the `course/fine' knobs for
      their entire rotation and yet tight enough to give engagement. If
      you over tighten it will start to feel `lumpy'; too loose and it will
      not engage all the way around.

      I had to make a couple of disassemble/ assemble iterations to get it
      right but `hey presto' the focuser now works as beautifully as I had
      always hoped it would. Interestingly the black fluted screw does not
      need to be extremely tight, as I have read elsewhere, just normally
      so, and the tensioning screw can be used to get the tube friction
      just right.

      As usual this process comes with a warning: be very very careful and
      make only very small adjustments before checking all is ok.

      A (now) very happy ZS105 owner.

    • Timm Bottoni
      Hi, Good instructions! Thanks! My original report was the one that included instructions regarding getting the black thumbscrew tight. The tightening of this
      Message 2 of 4 , Jul 16, 2007
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        Hi,

        Good instructions! Thanks!

        My original report was the one that included instructions regarding
        getting the black thumbscrew tight. The tightening of this really
        only affects one aspect of the focuser, which is to make sure it is
        perfectly alligned with the main shaft, which helps keep it smooth.
        Otherwise if it's not tight enough, it will slightly flex or warp the
        main focuser knob shaft, which can cause it to sometimes exhibit a
        smooth-rough-smooth pattern as it turns. It does vary from model to
        model a bit as to what adjustments provide the perfect tensions and
        smoothnesses so if you are willing to experiment a little, it is
        likely that you can get things perfect if you are willing to.

        Depending on the model there are three places that could cause
        slipping, which have all been mentioned so I will summarize in case
        it helps anyone.

        1) The little allen head that tightens to the main shaft that turns
        may be round or may be a half circle, but either way it should be
        tight so that it doesn't accidently allow for slippage.

        2) The little allen tension screw that adjusts the tension of the
        actual focuser draw tube needs to be tight enough to prevent slipping
        (note, that the focuser lock should always be loose when adjusting
        the tension, or the two will fight with each other)

        3) The small brass slotted tension ring on the inside of the two-
        speed focuser adjusts the tension of ONLY the two speed part of the
        foucser relative to the main focuser.

        Through a series of steps, trial and error will allow you to
        determine which part is slipping, or too firm, but once all three
        things are properly set it is a wonderful focuser.

        One other thing to note, is that if you adjust things for the warm
        temps of summer, and have cold Winters like I do, you will likely
        need to adjust the tension harder for the Winter as the metal parts
        will contract as it cools down resulting in the focuser potentially
        slipping in the Winter.

        Hope this helps,

        Timm

        --- In William-Optics@yahoogroups.com, Kelliot1@... wrote:
        >
        > Hi
        >
        > I have attached below a solution I gave in April for the ZS105,
        which I
        > assume has the same focuser. I hope this is helpful.
        >
        > Keith
        >
        >
        > I have, broadly speaking, been happy with my ZS 105. I say
        broadly,
        > because although delighted with optics and build quality, I have
        never
        > been able to get the focuser to work as advertised.
        >
        > Out of the box it felt `notchy' and I found that there were places
        on
        > the tube travel where the fine adjuster would rotate without
        either
        > rotating the larger `gold' knob or moving the shaft. I have
        searched
        > in vain to find owners who had managed to correct the problem and
        > fiddled for hours with the large fluted screw and its central
        > tensioning screw without success, maybe nobody else has had this
        > problem, anyway, here is what I did, perhaps it will help somebody.
        >
        > I finally took the thing apart using the WO website instructions
        for
        > retrofitting a dual speed focuser and discovered the problem.
        There
        > is a threaded locking ring which (seems to) adjust the friction
        > between the fine and course focuser which I very carefully
        tightened
        > with about 2 or 3 degrees of clockwise rotation. This needs to be
        > tight enough to give free rotation of the `course/fine' knobs for
        > their entire rotation and yet tight enough to give engagement. If
        > you over tighten it will start to feel `lumpy'; too loose and it
        will
        > not engage all the way around.
        >
        > I had to make a couple of disassemble/I had to make a couple of
        disass
        > right but `hey presto' the focuser now works as beautifully as I
        had
        > always hoped it would. Interestingly the black fluted screw does
        not
        > need to be extremely tight, as I have read elsewhere, just normally
        > so, and the tensioning screw can be used to get the tube friction
        > just right.
        >
        > As usual this process comes with a warning: be very very careful
        and
        > make only very small adjustments before checking all is ok.
        >
        > A (now) very happy ZS105 owner.
        >
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