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[ATM] The 15.5 Ultrathin Project, some lap notes
Doesn't Texereau have a pic of this lap in his book??:>)
-----Original Message-----
>From: atm-request@atmlist.net
>Sent: Jan 15, 2006 8:00 PM
>To: atm@atmlist.net
>Subject: ATM Digest, Vol 25, Issue 18
>
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>Today's Topics:
>
> 1. Re: wire spiders (Alan Scott)
> 2. Fwd: Re: Polishing to a sphere (Ken Hunter)
> 3. Stardust (Don Clement)
> 4. Acculap problems.... (Douglas Arion)
> 5. Re: Acculap problems.... (Mel Bartels)
> 6. Re: Acculap problems.... (Mel Bartels)
> 7. The 15.5 Ultrathin Project, some lap notes (vorblesnak@peak.org)
> 8. Re: Acculap problems.... (John Lynch)
> 9. Support for slumped mirror (Jerry Dove)
>
>
>----------------------------------------------------------------------
>
>Message: 1
>Date: Sun, 15 Jan 2006 00:37:08 -0700
>From: "Alan Scott" <alanne1956@hotmail.com>
>Subject: Re: [ATM] wire spiders
>To: atm@atmlist.net
>Message-ID: <BAY107-F5524216DA48486B308073CD180@phx.gbl>
>Content-Type: text/plain; format=flowed
>
>Ah, I missed that. Thanks, Mel.
>
>alan
>
>
>>From: "Mel Bartels" <mbartels@bbastrodesigns.com>
>>To: <atm@atmlist.net>
>>Subject: Re: [ATM] wire spiders
>>Date: Sat, 14 Jan 2006 09:31:34 -0800
>>
>> > Mel's scope has a single ring too! There is no requirement that the
>> > wires must cross - stability calls for some not too small angle between
>> > the wires, so if you let them have a common origin at the cage, you
>>
>>My scopes have 100% consisted of single rings since 1992. Look, the wires
>>need to have some angle between them. Once this is accepted, then it is an
>>engineering issue of how to create and distribute that angle. The optimum
>>is to cross the wires in the middle in the form of an X. It is optimum to
>>cross in the middle since that minimizes both the wire hub's length and the
>>single ring's depth (I use a small aluminum rail to give the single ring
>>depth). To use a V style, then the wire hub has to be doubled in depth or
>>length. So in other words, you have a set length and it is up to you to
>>distribute this length between the hub and the upper ring.
>>
>>Mel Bartels
>>
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>------------------------------
>
>Message: 2
>Date: Sun, 15 Jan 2006 08:25:40 -0800 (PST)
>From: Ken Hunter <atm_ken_hunter@yahoo.com>
>Subject: [ATM] Fwd: Re: Polishing to a sphere
>To: atm@atmlist.net
>Message-ID: <20060115162540.60376.qmail@web52715.mail.yahoo.com>
>Content-Type: text/plain; charset=iso-8859-1
>
>
>
>Gilbert Gagne <ggagne@clearwire.net> wrote: Date: Sat, 14 Jan 2006 19:05:59 -0500
>From: Gilbert Gagne <ggagne@clearwire.net>
>To: Ken Hunter <atm_ken_hunter@yahoo.com>
>Subject: Re: [ATM] Polishing to a sphere
>
>Ken Hunter wrote:
> "Position the Ronchi grating until you have only ONE line"
>Hi Ken!
>Your recommendation was on the mark! I adjusted the stage holding the Ronchi grating to display only one line inside of focus and the image was revealing. The mirror surface is quite rough with a slight central depression. I don't see any turned edge.
>http://www.atmlist.net/contrib/ggagne-at-clearwire-dot-net/114-1bar.jpg
>>From other comments received, I am tending to redo the lap with softer pitch. The cooler winter temperatures in my garage are undoubtedly contributing to the problem. My last mirror was a 12.25" x 2" pyrex and was polished in the summer in Florida with the same pitch which was definitely softer than at present.
>
>Thanks for your help.
>Gil Gagne
>Port Orange, FL
>
>
>---------------------------------
>
>
>
>---------------------------------
>Yahoo! Photos ? Showcase holiday pictures in hardcover
> Photo Books. You design it and we?ll bind it!
>
>------------------------------
>
>Message: 3
>Date: Sun, 15 Jan 2006 09:04:16 -0800
>From: "Don Clement" <clement.focuser@verizon.net>
>Subject: [ATM] Stardust
>To: "atml" <atm@atmlist.net>
>Message-ID: <000901c619f5$b8594d60$6401a8c0@hugo>
>Content-Type: text/plain; charset=iso-8859-1
>
>http://www.cnn.com/2006/TECH/space/01/15/stardust/index.html
> Congratulations NASA on the successful return of the Stardust capsule. A
>few years back at an SDAA meeting , a JPL representative gave a talk about
>the Stardust mission. He passed around a sample of Aerogel, (used on
>Stardust to collect dust samples). Aerogel is an amazing ethereal substance.
>Holding the Aerogel sample in my hand it was hard to tell if it was real or
>imaginary.
>
>Don Clement
>Running Springs, California
>
>
>
>------------------------------
>
>Message: 4
>Date: Sun, 15 Jan 2006 12:16:19 -0600
>From: "Douglas Arion" <darion@carthage.edu>
>Subject: [ATM] Acculap problems....
>To: atm@atmlist.net
>Message-ID: <web-31723320@carthage.edu>
>Content-Type: text/plain; charset="windows-1252"
>
>Hi, Everyone,
>
>Here's a conundrum for you: I'm teaching an ATM class (we
>have 18 college kids making 6" mirrors!)...and I'm using
>Acculap for the first time. After polishing for the 8-10
>hours it takes to clear pits, the kids started noticing a
>film on their mirrors. A few minutes of polishing with
>considerable pressure seems to take it off, but that, of
>course, plays havoc with the surface condition. So, has
>anyone else ever experienced this? It seems to be some kind
>of reaction between the Acculap and the plate glass (note,
>we're using plate, not pyrex)...or something similar. We're
>using CeO to polish. Suggestions?? I'd really like them to
>be able to finish their mirrors very soon.
>
>Doug
>
>
>
>
>
>_________________________________
>Dr. Douglas N. Arion
>Hedberg Distinguished Professor of Entrepreneurial Studies
>Professor of Physics
>Head Coach, Ice Hockey
>Carthage College
>2001 Alford Park Drive
>Kenosha, WI 53140
>262-551-5864
>262-551-6208 (Fax)
>
>
>------------------------------
>
>Message: 5
>Date: Sun, 15 Jan 2006 10:21:52 -0800
>From: "Mel Bartels" <mbartels@bbastrodesigns.com>
>Subject: Re: [ATM] Acculap problems....
>To: <atm@atmlist.net>
>Message-ID: <002701c61a00$8f964530$63012001@bbad>
>Content-Type: text/plain; charset="us-ascii"
>
>> Here's a conundrum for you: I'm teaching an ATM class (we
>> have 18 college kids making 6" mirrors!)...and I'm using
>> Acculap for the first time. After polishing for the 8-10
>> hours it takes to clear pits, the kids started noticing a
>> film on their mirrors. A few minutes of polishing with
>> considerable pressure seems to take it off, but that, of
>> course, plays havoc with the surface condition. So, has
>> anyone else ever experienced this? It seems to be some kind
>> of reaction between the Acculap and the plate glass (note,
>> we're using plate, not pyrex)...or something similar. We're
>> using CeO to polish. Suggestions?? I'd really like them to
>> be able to finish their mirrors very soon.
>
>The film is actually Cerium bound to the Oxygen atoms in the Silicon of the
>glass. This happens with certain combinations of pressure and wetness.
>Almost always it comes from too little wetness and too little pressure. So
>I suggest (for polishing out, not for figuring) pressing much harder and
>stroking slower. A bit of wetting agent like a drop of soap or glycerin
>will help too.
>
>A minute or two of polishing releases the Cerium atoms so it's a cosmetic
>issue, really.
>
>Mel Bartels
>
>
>
>
>------------------------------
>
>Message: 6
>Date: Sun, 15 Jan 2006 10:24:12 -0800
>From: "Mel Bartels" <mbartels@bbastrodesigns.com>
>Subject: Re: [ATM] Acculap problems....
>To: <atm@atmlist.net>
>Message-ID: <002801c61a00$e286e010$63012001@bbad>
>Content-Type: text/plain; charset="us-ascii"
>
>> > Acculap for the first time. After polishing for the 8-10
>> > hours it takes to clear pits, the kids started noticing a
>> > film on their mirrors. A few minutes of polishing with
>
>BTW, 8-10 hours is way too long. You should be able to polish out a 6 inch
>in an hour, two at most.
>
>For more on what might actually happen during polishing (not figuring) and
>why more pressure is better, see
>
>http://www.bbastrodesigns.com/tm/chemical_mechanical_polishing.html
>
>Mel Bartels
>
>
>
>------------------------------
>
>Message: 7
>Date: Sun, 15 Jan 2006 11:15:47 -0800 (PST)
>From: vorblesnak@peak.org
>Subject: [ATM] The 15.5 Ultrathin Project, some lap notes
>To: atm@atmlist.net
>Message-ID: <1121.64.28.60.9.1137352547.squirrel@webmail.peak.org>
>Content-Type: text/plain;charset=iso-8859-1
>
>I stripped the old 12 inch lap, and melted the pitch with some new stuff.
>I poured this onto a piece of paper and faceted it so I could break out
>squares of pitch. No pictures, sorry. I took the grinding tool and using
>a torch and an old chisel, I stripped the glass squares and epoxy off.
>Now I cleaned the took well and then drizzled very hot pirtch onto the
>tool and pressed the squares on, gluing them into place with the hot
>pitch. Here is a picture of the raw tool and lap after I was done ..
>
>http://www.atmlist.net/contrib/vorblesnak-at-peak-dot-org/15.5%20Lap/New%20and%20Chunky.jpg
>
>Now to tuning the lap. I got out an my wash tub and filled the bottom
>with about 6 inches of hot water from the tap. Three spacers on the
>batton and set the tool / lap on the spacers, submerging the lap in the
>hot water. The spacers, old jar lids, are there so I can get my fingers
>under the tool and lift it out. I checked the pitch for softness every
>now and then and when it was soft I pulled it out and pressed it with the
>mirror to shape it. I prepped the mirror with soap the first press as I
>knew it would go back into the water at least a couple of more times. The
>last press and tuning was done with cerium oxide on the mirror to charge
>the lap. Here is apicture of the lap in the "tuner" ...
>
>http://www.atmlist.net/contrib/vorblesnak-at-peak-dot-org/15.5%20Lap/Tuning%20the%20Lap.jpg
>
>Finally, a tuned lap. Good contact, good drag while polishing. I am
>concerned about glass flex while polishing so I am using a 20 pound ring
>weight to press the glass to the pitch while I polish. I just move it
>back and forth on the lap. I suspect this will take longer to polish out
>but hopefully I will not induce any astigmatism. Another possible source
>of astigmatism could be the heat of my hands on the glass. I move the
>glass with the ring weight and it is resting on a piece of foam shelf
>liner, so hopefully I am not inducing any odd shaped heat zones into the
>glass. Thin stuff. Here is a picture of the tuned lap with some cerium
>on it ..
>
>http://www.atmlist.net/contrib/vorblesnak-at-peak-dot-org/15.5%20Lap/Tuned%20and%20Frosty.jpg
>
>I will try and get a picture of the glass on the lap with the ring weight
>on it. Also, I have not forgotten my promise of some ronchi pictures.
>
>David Davis
>Toledo, OR 97391
>
>
>
>------------------------------
>
>Message: 8
>Date: Sun, 15 Jan 2006 12:34:50 -0800 (PST)
>From: John Lynch <john_lynch2006@yahoo.com>
>Subject: Re: [ATM] Acculap problems....
>To: Douglas Arion <darion@carthage.edu>, atm@atmlist.net
>Message-ID: <20060115203451.63168.qmail@web35701.mail.mud.yahoo.com>
>Content-Type: text/plain; charset=iso-8859-1
>
>Doug,
>
>I had a residual film with my 6" mirror when using
>optical rouge and Gugolz. I quickly took the mirror
>and washed it off with a water stream a paper towel
>and gentle wiping, and that solved the problem.
>Seemed that if I let it dry, I couldn't get it off
>with the same procedure.
>
>John Lynch
>
>__________________________________________________
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>------------------------------
>
>Message: 9
>Date: Sun, 15 Jan 2006 14:27:22 -0700
>From: Jerry Dove <jldove1@cableone.net>
>Subject: [ATM] Support for slumped mirror
>To: atm@atmlist.net
>Message-ID: <ouels117r6qdh0vvn5c31641q84qtkbmot@4ax.com>
>Content-Type: text/plain; charset=us-ascii
>
>
>
> Hi,
> I've got an 8"x3/4" plate glass blank that Richard Schwartz (sp?) slumped for me a few years ago. I haven't been
>able to work on it because of health and a couple of moves since then but I'm finally able to get started on it again.
>
> When I first started to do grinding on it, I made a hard plaster form to hold it in place that was formed to fit
>the back and then had blocks wood around the edge to keep it and the form from moving. But after all these years of
>watching the list I'm not sure this is the best way to do this.
>
> Any advice on this would be most helpful,
>
> Thanks,
>
> Jerry Dove
>
>
>------------------------------
>
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>
>End of ATM Digest, Vol 25, Issue 18
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