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RE: Back plate of mirror cell on XT8

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  • Ken Coates
    Message: 1 Date: Thu, 30 Nov 2000 06:21:02 -0600 From: Wrighter, Don A. Subject: RE: XT8 Obs Rpt: Mirror cooling, Cassiopeia Tour,
    Message 1 of 5 , Dec 1, 2000
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      Message: 1
      Date: Thu, 30 Nov 2000 06:21:02 -0600
      From: "Wrighter, Don A." <dawright@...>
      Subject: RE: XT8 Obs Rpt: Mirror cooling, Cassiopeia Tour, Planets, Leonids

      > Ken Wrote:
      >
      > >I'm also planning on drilling some holes in the metal plate on the back
      > of
      > the mirror cell of the XT8. It doesn't touch the mirror, but it keeps air
      > from getting to the back of the mirror.
      >
      > I wrote:
      > If yours is like mine, the entire plate can be removed.

      I didn't realize that, but I've put the felt pads as suggested by the Sky &
      Telescope review article to support the mirror better to prevent
      astigmatism. So I'm going to leave them in place and drill holes around
      them.

      Ken
    • Wrighter, Don A.
      I created a T bracked to support the mirror instead of using the S&T suggesstion. This allowed me to remove the back plate. I replaced it with a plastic disk
      Message 2 of 5 , Dec 1, 2000
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        I created a T bracked to support the mirror instead of using the S&T
        suggesstion. This allowed me to remove the back plate. I replaced it with a
        plastic disk that fits outside of the the end ring. This disk is painted
        flat black with a 3" center hole and a 3" cooling fan. the T bracket lifts
        the mirror far enough away from the lip of the mirror cells to allow pretty
        good circulation past the mirror. I havend had a chance to use the new setup
        yet...
        > -----Original Message-----
        > From: Ken Coates [SMTP:ken@...]
        > Sent: Friday, December 01, 2000 12:18 PM
        > To: 'skyquest-telescopes@egroups.com'
        > Subject: [skyquest-telescopes] RE: Back plate of mirror cell on XT8
        >
        > Message: 1
        > Date: Thu, 30 Nov 2000 06:21:02 -0600
        > From: "Wrighter, Don A." <dawright@...>
        > Subject: RE: XT8 Obs Rpt: Mirror cooling, Cassiopeia Tour, Planets,
        > Leonids
        >
        > > Ken Wrote:
        > >
        > > >I'm also planning on drilling some holes in the metal plate on the back
        > > of
        > > the mirror cell of the XT8. It doesn't touch the mirror, but it keeps
        > air
        > > from getting to the back of the mirror.
        > >
        > > I wrote:
        > > If yours is like mine, the entire plate can be removed.
        >
        > I didn't realize that, but I've put the felt pads as suggested by the Sky
        > &
        > Telescope review article to support the mirror better to prevent
        > astigmatism. So I'm going to leave them in place and drill holes around
        > them.
        >
        > Ken
        >
        >
        > http://www.egroups.com/group/skyquest-telescopes
        >
        > To unsubscribe from this group, send an email to:
        > skyquest-telescopes-unsubscribe@egroups.com
        >
        >
      • Brad
        Don and Ken, Could you see any improvement after doing the mirror mount modifications? Brad
        Message 3 of 5 , Dec 1, 2000
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          Don and Ken,

          Could you see any improvement after doing the mirror mount modifications?

          Brad


          On Fri, 1 Dec 2000 12:06:12 -0600 , you wrote:

          > I created a T bracked to support the mirror instead of using the S&T
          >suggesstion. This allowed me to remove the back plate. I replaced it with a
          >plastic disk that fits outside of the the end ring. This disk is painted
          >flat black with a 3" center hole and a 3" cooling fan. the T bracket lifts
          >the mirror far enough away from the lip of the mirror cells to allow pretty
          >good circulation past the mirror. I havend had a chance to use the new setup
          >yet...
          >> -----Original Message-----
          >> From: Ken Coates [SMTP:ken@...]
          >> Sent: Friday, December 01, 2000 12:18 PM
          >> To: 'skyquest-telescopes@egroups.com'
          >> Subject: [skyquest-telescopes] RE: Back plate of mirror cell on XT8
          >>
          >> Message: 1
          >> Date: Thu, 30 Nov 2000 06:21:02 -0600
          >> From: "Wrighter, Don A." <dawright@...>
          >> Subject: RE: XT8 Obs Rpt: Mirror cooling, Cassiopeia Tour, Planets,
          >> Leonids
          >>
          >> > Ken Wrote:
          >> >
          >> > >I'm also planning on drilling some holes in the metal plate on the back
          >> > of
          >> > the mirror cell of the XT8. It doesn't touch the mirror, but it keeps
          >> air
          >> > from getting to the back of the mirror.
          >> >
          >> > I wrote:
          >> > If yours is like mine, the entire plate can be removed.
          >>
          >> I didn't realize that, but I've put the felt pads as suggested by the Sky
          >> &
          >> Telescope review article to support the mirror better to prevent
          >> astigmatism. So I'm going to leave them in place and drill holes around
          >> them.
          >>
          >> Ken
          >>
          >>
          >> http://www.egroups.com/group/skyquest-telescopes
          >>
          >> To unsubscribe from this group, send an email to:
          >> skyquest-telescopes-unsubscribe@egroups.com
          >>
          >>
          >
          >
          > http://www.egroups.com/group/skyquest-telescopes
          >
          >To unsubscribe from this group, send an email to:
          >skyquest-telescopes-unsubscribe@egroups.com
          >
          >
          >
        • Wrighter, Don A.
          It removed a slight astigmatism that I seemed to have when I was star testing the mirror. However, at the time I was testing I could not get a very readable
          Message 4 of 5 , Dec 2, 2000
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            It removed a slight astigmatism that I seemed to have when I was
            star testing the mirror. However, at the time I was testing I could not get
            a very readable star test. It could have easily been due to a bad
            collimation. I was not very experienced at the time. Tube currents also make
            it difficult to get a star test. The outer rings looked like the teeth on a
            saw blade and the inner rings shimmered real bad.
            It just so happened that the method I used to support the mirror
            should allow the fan to cool the mirror better. I haven't been able to try
            it since I finished the work because of the weather.
            After the experience I would highly recommend trying to solve the
            tube current problem and getting a realiable collimation before star testing
            the mirror. If you find after this that you have an astigmatism problem then
            I would try changing the mount.
            If you look in the files section on our egroup, you will see a
            diagram of the modification that I made to my mirror cell. I used paint
            stiring sticks, epoxy and fender washers to make it. You will really need to
            use c-clamps while assembling to get the best results. Mine is very strong.
            My 3 year old stood on it before I put the mirror in and the bracket didn't
            even bow.

            > -----Original Message-----
            > From: Brad [SMTP:brad@...]
            > Sent: Friday, December 01, 2000 2:16 PM
            > To: skyquest-telescopes@egroups.com
            > Subject: Re: [skyquest-telescopes] RE: Back plate of mirror cell on
            > XT8
            >
            > Don and Ken,
            >
            > Could you see any improvement after doing the mirror mount modifications?
            >
            > Brad
            >
            >
            > On Fri, 1 Dec 2000 12:06:12 -0600 , you wrote:
            >
            > > I created a T bracked to support the mirror instead of using the S&T
            > >suggesstion. This allowed me to remove the back plate. I replaced it with
            > a
            > >plastic disk that fits outside of the the end ring. This disk is painted
            > >flat black with a 3" center hole and a 3" cooling fan. the T bracket
            > lifts
            > >the mirror far enough away from the lip of the mirror cells to allow
            > pretty
            > >good circulation past the mirror. I havend had a chance to use the new
            > setup
            > >yet...
            > >> -----Original Message-----
            > >> From: Ken Coates [SMTP:ken@...]
            > >> Sent: Friday, December 01, 2000 12:18 PM
            > >> To: 'skyquest-telescopes@egroups.com'
            > >> Subject: [skyquest-telescopes] RE: Back plate of mirror cell on XT8
            > >>
            > >> Message: 1
            > >> Date: Thu, 30 Nov 2000 06:21:02 -0600
            > >> From: "Wrighter, Don A." <dawright@...>
            > >> Subject: RE: XT8 Obs Rpt: Mirror cooling, Cassiopeia Tour, Planets,
            > >> Leonids
            > >>
            > >> > Ken Wrote:
            > >> >
            > >> > >I'm also planning on drilling some holes in the metal plate on the
            > back
            > >> > of
            > >> > the mirror cell of the XT8. It doesn't touch the mirror, but it keeps
            > >> air
            > >> > from getting to the back of the mirror.
            > >> >
            > >> > I wrote:
            > >> > If yours is like mine, the entire plate can be removed.
            > >>
            > >> I didn't realize that, but I've put the felt pads as suggested by the
            > Sky
            > >> &
            > >> Telescope review article to support the mirror better to prevent
            > >> astigmatism. So I'm going to leave them in place and drill holes around
            > >> them.
            > >>
            > >> Ken
            > >>
            > >>
            > >> http://www.egroups.com/group/skyquest-telescopes
            > >>
            > >> To unsubscribe from this group, send an email to:
            > >> skyquest-telescopes-unsubscribe@egroups.com
            > >>
            > >>
            > >
            > >
            > > http://www.egroups.com/group/skyquest-telescopes
            > >
            > >To unsubscribe from this group, send an email to:
            > >skyquest-telescopes-unsubscribe@egroups.com
            > >
            > >
            > >
            >
            >
            >
            > http://www.egroups.com/group/skyquest-telescopes
            >
            > To unsubscribe from this group, send an email to:
            > skyquest-telescopes-unsubscribe@egroups.com
            >
            >
          • Ken Coates
            Brad, I didn t know enough about observing to decide whether I had mirror astigmatism before I put the pads in, but it was so easy to do, that I decided to go
            Message 5 of 5 , Dec 4, 2000
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              Brad,
              I didn't know enough about observing to decide whether I had mirror
              astigmatism before I put the pads in, but it was so easy to do, that I
              decided to go ahead and do it. I also put the milk jug washers on the center
              bolt which improves the azimuth motion of the XT8.
              I haven't drilled holes in the back plate yet. I decided to put in
              the Protostar flocking paper at the same time in the tube and I haven't been
              able to find a block of time to do it yet. Now that the moon is up, I'm
              going to try and get that done soon.

              Ken
              =================
              Date: Fri, 01 Dec 2000 13:16:20 -0600
              From: Brad <brad@...>
              Subject: Re: RE: Back plate of mirror cell on XT8

              Don and Ken,

              Could you see any improvement after doing the mirror mount modifications?

              Brad
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