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19094Re: Linear Focuser

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  • gjcaunter
    Dec 9, 2008
      Dear Anat,

      Hi, I'm Gareth and this is my first post on the WO Yahoo group. I was
      looking for information about the LinearPower focuser and this
      discussion caught my eye.

      I actually have a new WO Megrez 90 APO with the LinearPower focuser in
      my hands. Unfortunately there is a lot of backlash which I would like
      to try and correct. I had looked though all the documentation
      beforehand but found nothing relating to this design.

      Notable differences worth mentioning between the one pictured on the
      WO website and my own are: mine lacks the large silver ring (this is
      only relevant to SCTs I presume), and the central allen-screw and
      large thumb screw on the bottom are absent. There are threaded holes
      where both of these are located in the images on the website - the one
      that has the allen-screw is covered by a quality-control sticker on my
      Megrez. I'm 99% sure I haven't lost any screws (so to speak, you may
      disagree).

      Is it too early to ask if you or anyone else has experience with this
      focuser? I would appreciate any advice about how to adjust it.

      Best regards,
      Gareth

      --- In William-Optics@yahoogroups.com, "aruangra" <aruangra@...> wrote:
      >
      > Hi Timm
      >
      > Many thanks for the clear description. I am excitedly waiting for
      > Megrez 90 with the new linear power focuser.
      >
      > Regards,
      > Anat
      >
      >
      > --- In William-Optics@yahoogroups.com, "Timm Bottoni" <t.bottoni@>
      > wrote:
      > >
      > > Hi Anat,
      > >
      > > Yes, sort of like a rack and pinion, it has a steel rack and a nylon
      > > gear that turns with the focuser knobs, but it is different in several
      > > ways, more sophisticated compared to the rack and pinions focusers I
      > > have seen before because the entire weight rides on a steel bar with
      > > steel ball bearings at all times on both sides of the steel bar.
      > >
      > > Both ends are held in place by three inset screws, so the 2" piece is
      > > not threaded.
      > >
      > > The SCT threads screw onto the back of the C8 directly, and that is
      > > the silver part you see in pictures. That part is not threaded onto
      > > the rest of the focuser. There are three inset screws that hold it in
      > > place in a channel that allows it to rotate, and these three screws
      > > are adjustable for tension of the rotation. The focuser is locked in
      > > place by a thumbscrew.
      > >
      > > The end where the diagonal inserts also has three screws that allow
      > > the end piece to also rotate, but there is no thumb screw, it is held
      > > in place and tightened to the tapered flange by the three inset
      > > screws. WO stated that a custom adapter could be made to attach to
      > > this, but I have not seen any more info on what that might be.
      > >
      > > Another nice improvement is the dual set screws on the brass retaining
      > > ring, rather than only one like my refractor has.
      > >
      > > Does that answer your questions?
      > >
      > > Take care,
      > >
      > > Timm
      > >
      > > --- In William-Optics@yahoogroups.com, "aruangra" <aruangra@> wrote:
      > > >
      > > > Dear Timm
      > > >
      > > > Thanks for your review. So it is a rack and pinion focuser. Right?
      > > > I see that the 2" adapter can be unscrewed from the 2.5" tube. Could
      > > > you tell me the thread size of the 2.5" tube? The thread is very
      > > > useful to rigidly fix a camera and accessories with a proper
      adapter.
      > > >
      > > > Best regards,
      > > > Anat
      > > >
      > > >
      > > >
      > > >
      > > > --- In William-Optics@yahoogroups.com, "Timm Bottoni" <t.bottoni@>
      > > > wrote:
      > > > >
      > > > > Hi William,
      > > > >
      > > > > I'll try and explain it without picturesf for now, but will
      include
      > > > > pictures and details in my upcoming review.
      > > > >
      > > > > First - DON'T TAKE IT APART if you have one, trust me, I know.
      ;-)
      > > > >
      > > > > The Linear Power focuser uses a rack and pinion design to move the
      > > > > focuser forward and back, which is very different from any other
      > > > > focuser I have seen. The entire focuser tube runs on a steel rail
      > > > > that is sandwiched between two sets of ball bearings. I am
      not sure
      > > > > how the two speed focuser works, if it is on tension or gears,
      > but it
      > > > > is incredibly smooth.
      > > > >
      > > > > The tension is adjusted easily using an allen wrench, and is
      > locked in
      > > > > place using a thumb screw. The ability to adjust the tension
      > is very
      > > > > forgiving, and allows for easy adjustment to meet your weight
      > > > > requirements.
      > > > >
      > > > > I have never used a FeatherTouch or other brand of crayford or
      rack
      > > > > and pinion, but this design allows for the travel to stay
      incredibly
      > > > > smooth at any tension from too loose to too tight.
      > > > >
      > > > > It is a 2.5" design, and the thread on the SCT end, and the
      > inside of
      > > > > the draw tube is 2" internal. Everything is ultra flat black
      > inside,
      > > > > and the SCT is shorter in it's travel than the refractor ones
      I see
      > > > > pictured on the WO site, which makes sense since the travel tube
      > must
      > > > > stop at the threaded SCT ring, it can't go inside the back like a
      > > > > refractor one could.
      > > > >
      > > > > Based on my testing so far, this design is excellent and
      capable of
      > > > > handling a much heavier load than the Crayford design of the one
      > on my
      > > > > Megrez 80FD. If WO has a way to make it work on the ZS110, I
      think
      > > > > it will probably preform very nicely.
      > > > >
      > > > > I'll post the pictures and full review in the next couple of
      weeks.
      > > > >
      > > > > Timm
      > > > >
      > > > >
      > > > > --- In William-Optics@yahoogroups.com, "William Roy Penney"
      > > > > <penneywilliam@> wrote:
      > > > > >
      > > > > >
      > > > > > Hi Tim,
      > > > > >
      > > > > > Do you or anyone else have any details or information about
      > the new
      > > > > > linear focuser? Is it another crayford type or rack and pinion?
      > > > > > I would like to replace the focusser on my Z110, and maybe the
      > > linear
      > > > > > focuser is the "beefed up focuser" which was supposed to be
      > > available
      > > > > > soon from WO (several years ago) but did not eventuate.
      > > > > >
      > > > > > Merry Xmas
      > > > > >
      > > > > > William
      > > > > >
      > > > >
      > > >
      > >
      >
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