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19102Re: Linear Focuser

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  • aruangra
    Dec 9, 2008
    • 0 Attachment
      I uploaded some photos in this folder:
      http://groups.yahoo.com/group/William-Optics/photos/album/1438929508/pic/list
      and show some dimensions.

      My initial evaluations:
      1) The focuser is a 2" focuser, not a 2.5" focuser.
      2) The two setscrews on the top are not used. You can see that they
      are not extended to the drawtube.
      3) Three plastic setscrews are used to hold the focuser assembly to
      the OTA and three plastic setscrews are used to hold the 2" adapter to
      the drawtube. I think it is not secured to use plastic setscrews. I
      understand that they are used to prevent scratches but the strength is
      more important than cosmetic issues in this case. I will replace them
      with stainless steel setscrews.

      This focuser is a BIG improvement for AP because:
      1) the drawtube can be locked.
      2) the microfocuser is very SMOOTH.
      3) the 2" adapter can be removed. So a ccd camera can be fixed rigidly
      to the drawtube by a custom-made adapter.

      Regards,
      Anat




      --- In William-Optics@yahoogroups.com, "gjcaunter" <gjcaunter@...> wrote:
      >
      > 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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