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Ho Hum again... stir the pot, add eye of newt, double bubble, toil and trouble.

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  • Ken Hunter
    There just has to be someone doing something?! Let us hear about it! Ken Hunter
    Message 1 of 6 , Aug 15 2:40 PM
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      There just has to be someone doing something?!
      Let us hear about it!

      Ken Hunter
    • James Lerch
      Ok Ken, here s one for you. A few weeks ago myself and an associated welded up a 25*25*11 ID steel box out of 1/2 thick sheet steel. Ordered 15 feet of 10mm
      Message 2 of 6 , Aug 15 3:34 PM
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        Ok Ken, here's one for you.

        A few weeks ago myself and an associated welded up a 25*25*11" ID steel box out
        of 1/2" thick sheet steel. Ordered 15 feet of 10mm O-Ring cord to use as a door
        gasket and base-plate gasket.

        Were currently working on the door hinge and O-Ring seal system.

        Once that's done, were going to use an 18 point evaporator setup. If I did the
        math correctly, we can use the system as follows

        #1 12" diameter or less mirror only needs 6 of the 18 evap points

        #2 12 - 14" diameter mirror uses 12 of the 18 points

        #3 14 -24" gets all 18 points ;)

        Once the box and all the wiring is done, I plan on use my existing base plate
        and plumbing, by just lowering the box onto the baseplate, where the mirror will
        physically rest on supports in the door, and be coated while on edge.. (IE the
        box is tall and wide, but not very deep)

        I'm a little concerned my poor little HVAC pump won't be able to pump the
        chamber down very fast, but we'll cross that bridge when we get there :)

        BTW, I've successfully coated the following materials

        Glass (duh), Plastic, and Cured Silicone and Epoxies. The one thing I've found
        so far that I couldn't coat, was some painted wood (I know, big surprise! At
        the time I was trying to see if I could coat my secondaries with the wood
        support still siliconed in place <g>)

        Take Care,
        James Lerch
        http://lerch.no-ip.com/atm (My telescope construction,testing, and coating site)

        "Anything that can happen, will happen" -Stephen Pollock from:
        "Particle Physics for Non-Physicists: A Tour of the Microcosmos"

        ----- Original Message -----
        From: "Ken Hunter" <atm_ken_hunter@...>
        To: <VacuumX@yahoogroups.com>
        Sent: Friday, August 15, 2003 17:40
        Subject: [VacuumX] Ho Hum again... stir the pot, add eye of newt, double bubble,
        toil and trouble.


        > There just has to be someone doing something?!
        > Let us hear about it!
        >
        > Ken Hunter
        >
        >
        >
        >
        > To unsubscribe from this group, send an email to:
        > VacuumX-unsubscribe@yahoogroups.com
        >
        >
        >
        > Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
        >
        >
      • Ken Hunter
        Hi James... Have you done any fall-off experiments to see just how much ONE FILAMENT will coat? The TV tube coating machine I saw would do a 27 tube with
        Message 3 of 6 , Aug 18 12:15 PM
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          Hi James...

          Have you done any "fall-off" experiments to see just how much ONE
          FILAMENT will coat? The TV tube coating machine I saw would do a 27"
          tube with one filament approximately 15 inches away from the glass
          faceplate. I have no idea of the coating uniformity requirements for
          a TV tube but it all looked very shiny inside after blasting the one
          filament.

          I've also seen 24 inch mirrors done with the (one) filament offset
          half way and the mirror rotating to reduce the filament
          requirements. That is what I'll probably do in my chamber for the
          larger sizes and just try centering everyting for the smaller
          sizes... What have you tried? What works, what doesn't?

          How big is your Diff pump? I have 3 pumps, valves etc gathering
          dust. They are 6 inch size... Photo's are in the photo section I
          think.

          Ken Hunter

          --- In VacuumX@yahoogroups.com, "James Lerch" <jlerch1@t...> wrote:
          > Ok Ken, here's one for you.
          >
          > A few weeks ago myself and an associated welded up a 25*25*11" ID
          steel box out
          > of 1/2" thick sheet steel. Ordered 15 feet of 10mm O-Ring cord to
          use as a door
          > gasket and base-plate gasket.
          >
          > Were currently working on the door hinge and O-Ring seal system.
          >
          > Once that's done, were going to use an 18 point evaporator setup.
          If I did the
          > math correctly, we can use the system as follows
          >
          > #1 12" diameter or less mirror only needs 6 of the 18 evap points
          >
          > #2 12 - 14" diameter mirror uses 12 of the 18 points
          >
          > #3 14 -24" gets all 18 points ;)
          >
          > Once the box and all the wiring is done, I plan on use my existing
          base plate
          > and plumbing, by just lowering the box onto the baseplate, where
          the mirror will
          > physically rest on supports in the door, and be coated while on
          edge.. (IE the
          > box is tall and wide, but not very deep)
          >
          > I'm a little concerned my poor little HVAC pump won't be able to
          pump the
          > chamber down very fast, but we'll cross that bridge when we get
          there :)
          >
          > BTW, I've successfully coated the following materials
          >
          > Glass (duh), Plastic, and Cured Silicone and Epoxies. The one
          thing I've found
          > so far that I couldn't coat, was some painted wood (I know, big
          surprise! At
          > the time I was trying to see if I could coat my secondaries with
          the wood
          > support still siliconed in place <g>)
          >
          > Take Care,
          > James Lerch
          > http://lerch.no-ip.com/atm (My telescope construction,testing, and
          coating site)
          >
          > "Anything that can happen, will happen" -Stephen Pollock from:
          > "Particle Physics for Non-Physicists: A Tour of the Microcosmos"
          >
          > ----- Original Message -----
          > From: "Ken Hunter" <atm_ken_hunter@y...>
          > To: <VacuumX@yahoogroups.com>
          > Sent: Friday, August 15, 2003 17:40
          > Subject: [VacuumX] Ho Hum again... stir the pot, add eye of newt,
          double bubble,
          > toil and trouble.
          >
          >
          > > There just has to be someone doing something?!
          > > Let us hear about it!
          > >
          > > Ken Hunter
          > >
          > >
          > >
          > >
          > > To unsubscribe from this group, send an email to:
          > > VacuumX-unsubscribe@yahoogroups.com
          > >
          > >
          > >
          > > Your use of Yahoo! Groups is subject to
          http://docs.yahoo.com/info/terms/
          > >
          > >
        • James Lerch
          ... From: Ken Hunter ... Hi Ken and All ... When I first started playing with my chamber I had one filament about 10 above a
          Message 4 of 6 , Aug 21 10:40 PM
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            ----- Original Message -----
            From: "Ken Hunter" <atm_ken_hunter@...>

            > Hi James...

            Hi Ken and All <g>

            > Have you done any "fall-off" experiments to see just how much ONE
            > FILAMENT will coat?

            When I first started playing with my chamber I had one filament about 10" above
            a 10" diameter mirror. It took two consecutive evaporative runs to get an
            opaque coating all the way to the edge. With just one run, the center ~30% was
            opaque and the last 1/4" of edge made for a nice beam splitter (maybe 75%
            coated.)

            After the "catastrophic drip" incident, and subsequent re-grinding, polishing,
            and figuring to "erase" the drip damage (It's soo nice that glass is so
            forgiving!) I re-built the chamber to a multi-point evaporative setup (with the
            filaments out by the edge, so if another drip happened it would miss the
            mirror!)

            To help me figure out the filament layout, I wrote a near field evaporative
            simulator. I've had great results playing and working with it. If you haven't
            seen it you can download a copy from here:

            http://lerch.no-ip.com/atm/nearfieldsim3.zip (9KB Exe only)

            The above code can simulate mirrors upto 24" in diameter, and have 3 various
            radius evaporative rings, with as many filaments as you'd like on each ring.
            (Careful! this can turn into a serious CPU Hog!)

            BTW, my simulator is based on the work of Jim Hill who wrote the code to figure
            out the layout for the In-Situ aluminization of the 6.5m Mt Hopkins MMT mirror,
            See link for some Fascinating reading!! <g>

            http://cfa-www.harvard.edu/cfa/oir/MMT/www.mmto.org/MMTpapers/pdfs/tm/tm03-8.pdf

            I ran my near field sim on their data (Scaling everthing down), and if you refer
            to the above figure 3, they report a 1.6nm deviation, and my sim shows a 1.8%
            deviation, which turns out to be 1.69nm with a coating thickness of 94nm (their
            target). OH, the reason for the slight difference? I model the mirror as a
            sphere, since in usual ATM hands the difference in Path Length between a sphere
            and a parabola is really small :) Here's a screen cap of my simulation results:

            http://lerch.no-ip.com/atm/6.2m_MMT_Evap_Sim.jpg (119KB)

            > I've also seen 24 inch mirrors done with the (one) filament offset
            > half way and the mirror rotating to reduce the filament
            > requirements.

            You can use my simulator to simulate this arrangement. Enter the following

            Mirror Radius = 300
            Mirror Roc = "whatever your test subject is"

            Ring 1
            # of evap points = 10 (or more, depending on how long you want to wait for an
            answer)
            Evap point Rad = 150mm (50% radius)
            Height of EVP (height above mirror center)

            Ring 2 & 3, set # of evap points to zero.

            BTW, I played around with this, and to make it work reasonably well means your
            going to need a fairly tall chamber!

            > That is what I'll probably do in my chamber for the
            > larger sizes and just try centering everyting for the smaller
            > sizes... What have you tried? What works, what doesn't?

            I know for certain a single point doesn't work to great unless your chamber is
            really long.

            So far, my 6 points with a radius of 140mm about 120mm above mirror surface,
            works really good on 10" F/5 there abouts.

            What's interesting is if I change the height difference (move mirror closer to
            filaments) I can actually add a "little" extra correction to a mirror. Even
            more amazing is Robo is able to measure the change in figure, and it agrees with
            the near field simulations (were talking a VERY small change, like a 2nm or so!)

            > How big is your Diff pump?

            6" inside diameter, with 4 electric heaters at the bottom, of which only 3 of
            the heaters work (I burned one out thinking the pump was 220V, when it was only
            110v (ooops!). Still pumps my 12"id x 11" tall chamber down in under a minute
            (once the rough pump is done) I may have to replace that bad heater once I get
            the Larger chamber finished, but I'll wait and see :)

            Take Care,
            James
          • Ken Hunter
            James, Thanks for the GREAT INFO... It s going to take me a while to digest all that and check out the links but it s nice to have on file here to refer back
            Message 5 of 6 , Aug 22 7:30 AM
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              James,

              Thanks for the GREAT INFO...
              It's going to take me a while to digest all that and check out the
              links but it's nice to have on file here to refer back to!

              OK on your diff pump size... I thought from your photo of the mobile
              coater that was about the size you had but it could have also been a
              4 inch pump in which case I might have been able to help increase
              the size of your system a bit.

              I'm curious why you are sticking to a filament above the glass and
              taking a risk of sputter damage or as before, drops of molten metal
              hitting the glass?

              My tank is 24 inches diameter and approx 30 inches tall. There's a
              photo in my junk folder and I'm still not into a house yet so have
              made NO PROGRESS in regards to getting anything done. Maybe by
              Christmas???

              Again, thanks for the info for the group!

              Ken Hunter

              --- In VacuumX@yahoogroups.com, "James Lerch" <jlerch1@t...> wrote:
              > ----- Original Message -----
              > From: "Ken Hunter" <atm_ken_hunter@y...>
              >
              > > Hi James...
              >
              > Hi Ken and All <g>
              >
              > > Have you done any "fall-off" experiments to see just how much ONE
              > > FILAMENT will coat?
              >
              > When I first started playing with my chamber I had one filament
              about 10" above
              > a 10" diameter mirror. It took two consecutive evaporative runs
              to get an
              > opaque coating all the way to the edge. With just one run, the
              center ~30% was
              > opaque and the last 1/4" of edge made for a nice beam splitter
              (maybe 75%
              > coated.)
              >
              > After the "catastrophic drip" incident, and subsequent re-
              grinding, polishing,
              > and figuring to "erase" the drip damage (It's soo nice that glass
              is so
              > forgiving!) I re-built the chamber to a multi-point evaporative
              setup (with the
              > filaments out by the edge, so if another drip happened it would
              miss the
              > mirror!)
              >
              > To help me figure out the filament layout, I wrote a near field
              evaporative
              > simulator. I've had great results playing and working with it.
              If you haven't
              > seen it you can download a copy from here:
              >
              > http://lerch.no-ip.com/atm/nearfieldsim3.zip (9KB Exe only)
              >
              > The above code can simulate mirrors upto 24" in diameter, and have
              3 various
              > radius evaporative rings, with as many filaments as you'd like on
              each ring.
              > (Careful! this can turn into a serious CPU Hog!)
              >
              > BTW, my simulator is based on the work of Jim Hill who wrote the
              code to figure
              > out the layout for the In-Situ aluminization of the 6.5m Mt
              Hopkins MMT mirror,
              > See link for some Fascinating reading!! <g>
              >
              > http://cfa-
              www.harvard.edu/cfa/oir/MMT/www.mmto.org/MMTpapers/pdfs/tm/tm03-8.pdf
              >
              > I ran my near field sim on their data (Scaling everthing down),
              and if you refer
              > to the above figure 3, they report a 1.6nm deviation, and my sim
              shows a 1.8%
              > deviation, which turns out to be 1.69nm with a coating thickness
              of 94nm (their
              > target). OH, the reason for the slight difference? I model the
              mirror as a
              > sphere, since in usual ATM hands the difference in Path Length
              between a sphere
              > and a parabola is really small :) Here's a screen cap of my
              simulation results:
              >
              > http://lerch.no-ip.com/atm/6.2m_MMT_Evap_Sim.jpg (119KB)
              >
              > > I've also seen 24 inch mirrors done with the (one) filament
              offset
              > > half way and the mirror rotating to reduce the filament
              > > requirements.
              >
              > You can use my simulator to simulate this arrangement. Enter the
              following
              >
              > Mirror Radius = 300
              > Mirror Roc = "whatever your test subject is"
              >
              > Ring 1
              > # of evap points = 10 (or more, depending on how long you want to
              wait for an
              > answer)
              > Evap point Rad = 150mm (50% radius)
              > Height of EVP (height above mirror center)
              >
              > Ring 2 & 3, set # of evap points to zero.
              >
              > BTW, I played around with this, and to make it work reasonably
              well means your
              > going to need a fairly tall chamber!
              >
              > > That is what I'll probably do in my chamber for the
              > > larger sizes and just try centering everyting for the smaller
              > > sizes... What have you tried? What works, what doesn't?
              >
              > I know for certain a single point doesn't work to great unless
              your chamber is
              > really long.
              >
              > So far, my 6 points with a radius of 140mm about 120mm above
              mirror surface,
              > works really good on 10" F/5 there abouts.
              >
              > What's interesting is if I change the height difference (move
              mirror closer to
              > filaments) I can actually add a "little" extra correction to a
              mirror. Even
              > more amazing is Robo is able to measure the change in figure, and
              it agrees with
              > the near field simulations (were talking a VERY small change, like
              a 2nm or so!)
              >
              > > How big is your Diff pump?
              >
              > 6" inside diameter, with 4 electric heaters at the bottom, of
              which only 3 of
              > the heaters work (I burned one out thinking the pump was 220V,
              when it was only
              > 110v (ooops!). Still pumps my 12"id x 11" tall chamber down in
              under a minute
              > (once the rough pump is done) I may have to replace that bad
              heater once I get
              > the Larger chamber finished, but I'll wait and see :)
              >
              > Take Care,
              > James
            • James Lerch
              ... From: Ken Hunter ... The new 25 chamber will be in a vertical orientation, to avoid the above mentioned problem! In the mean
              Message 6 of 6 , Aug 22 9:16 AM
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                ----- Original Message -----
                From: "Ken Hunter" <atm_ken_hunter@...>



                > James,

                > I'm curious why you are sticking to a filament above the glass and
                > taking a risk of sputter damage or as before, drops of molten metal
                > hitting the glass?

                The new 25" chamber will be in a vertical orientation, to avoid the above
                mentioned problem!

                In the mean time my 11" chamber, vertical coating is the only way to go
                unfortuantly. On the plus side, I've never had a "Sputter" problem when
                evaporating (Ie stuff Flying off the tungsten). With the existing 6 point
                layout, drops of molten Al are also not a problem, as they would miss the mirror
                (as long as I keep things realativly centered). Another odd thing is, since I
                have 6 points, I don't have to put very much Al on each tungsten filament,
                consequently I have NEVER had a drip problem with the new layout :)


                Take Care,
                James Lerch
                http://lerch.no-ip.com/atm (My telescope construction,testing, and coating site)

                "Anything that can happen, will happen" -Stephen Pollock from:
                "Particle Physics for Non-Physicists: A Tour of the Microcosmos"
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