[HN Gopher] Pouring the 200 inch disk at Corning Glass Works
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Pouring the 200 inch disk at Corning Glass Works
Author : DoreenMichele
Score : 175 points
Date : 2022-10-23 04:18 UTC (18 hours ago)
(HTM) web link (nyheritage.org)
(TXT) w3m dump (nyheritage.org)
| ggm wrote:
| The length of time they annealed for is staggering. I believe it
| was continuously rotated throughout that time, to ensure even
| thermal and mechanical load.
|
| I also like that they pressed on with annealing the first cast
| even though it was a reject. Avoid the unknown when you repeat
| for the final one.
|
| There's a blog post I can't find any more about a camera nut
| visiting one of the last Japanese refactories capable of making
| lenses and the excruciating processes they go through to make
| complex zonally variant glass. Mirrors seem almost simple by
| comparison.
| anotherboffin wrote:
| > There's a blog post I can't find any more about a camera nut
| visiting one of the last Japanese refactories capable of making
| lenses and the excruciating processes they go through to make
| complex zonally variant glass.
|
| Was it this one?
|
| https://www.imaging-resource.com/news/2018/04/17/glass-for-g...
| tony_cannistra wrote:
| Not the OP, but that was a great article - thanks.
| bruce511 wrote:
| Yes, I was struck by the length of cooling as well. A year
| sounds like an arbitrary period, but seems long.
|
| I mean, assuming the glass starts at like 1000 degs, (I have no
| idea) that means cooling about 2.5 degrees per day. Which I
| assume means inside an active furnace.
|
| The additional energy, and hence cost of the finished glass but
| have been massive.
|
| Presumably they learned this would be necessary from the test
| piece, which presumably cracked at some point.
| martyvis wrote:
| And grinding and polishing away the 41/2 tons of glass in the
| blank to make it parabolic took 14 years!
| gambiting wrote:
| It says the mirror was installed 4 years after being made,
| where did you get 14 years from?
| martyvis wrote:
| I haven't read this through thoroughly, but a lot of the
| final polishing must have been done after it was in
| place. It was only moved from Pasadena to Mount Palomar
| in 1947. There is both a '47 and '49 as being when
| figuring was done. https://sites.astro.caltech.edu/paloma
| r/about/history.html
| defrost wrote:
| > I mean, assuming the glass starts at like 1000 degs, (I
| have no idea) that means cooling about 2.5 degrees per day.
|
| It's relevant to remember that this is a _gradient_
| tempreture throughout the mass that declines and not a
| uniform fall throughout.
|
| An analog might be to think of a porous spongy material
| (clay, heavy peat moss, etc) and water .. annealing is the
| process of slowly leaching out the tempreture (or water) with
| no abrupt gradient changes that lead to cracking.
|
| As the temp. in the annealing furnace is staged down, there
| must be a pause to allow the heat to flow out from the mass
| centre to match the furnace before the next reduction.
|
| > Which I assume means inside an active furnace.
|
| Ideally a very well insulated furnace so that little energy
| input is required to maintain the desired furnace mean.
| thanatos519 wrote:
| > I also like that they pressed on with annealing the first
| cast even though it was a reject. Avoid the unknown when you
| repeat for the final one.
|
| If only we did this for software instead of just keeping the
| reject.
| lloydatkinson wrote:
| Instead, every "MVP" project I've been on has ended up as the
| final shipped product. Often with no further improvements at
| all, let alone anything the user asked for. Big Agile really
| has poisoned the industry.
| CobrastanJorji wrote:
| They cast the mirror in 1935, brought it to Cal Tech in 1936,
| finished assembling the telescope in 1939, tested and adjusted it
| for another ten years (they took a break to fight World War 2),
| and so it was not until 1949 that they got the first image out of
| it. Very soon the telescope would discover that the Andromeda
| galaxy was twice as far as we'd thought. The giant lens is still
| there and is still making discoveries today. It found a new mini-
| moon of Jupiter in 2010.
| jamiek88 wrote:
| mind.blown. now I HAVE to go that observatory. I wonder if they
| do public tours?
| zdw wrote:
| Not this location, but the University of Arizona mirror lab
| does tours as well starting sometime next year:
| https://mirrorlab.arizona.edu/content/tours-tickets
|
| They pour somewhat larger mirrors - most recent ones are 8.4
| meters (330 inches) for the Giant Magellan Telescope.
| pfdietz wrote:
| These larger mirrors can also be made thinner now because
| their shape is actively controlled. They don't have to be as
| stiff as the mirror at Palomar, which was about at the upper
| limit for such mirrors (anything larger would sag too much
| retain its optical figure as the mirror was tilted.) Being
| thinner, these modern mirrors can be cooled more quickly.
| MengerSponge wrote:
| They spin their glass while melting it, which generates a
| parabolic surface that only needs polishing/coating. It's so
| very rad.
| caboteria wrote:
| I've known people who did something similar with epoxy and
| an LP record player, but doing it with molten glass is
| next-level!
| [deleted]
| bombcar wrote:
| https://sites.astro.caltech.edu/palomar/visitor/
|
| They used to do campouts for students - it was a 6th grade
| trip.
|
| Looks like it's closed for Covid for now.
| cplusplusfellow wrote:
| The longer term effects of lost opportunity and science are
| the most saddening.
| CharlesW wrote:
| It's just been closed for tours and public events. It's not
| the same, but you can take a virtual tour here: https://sit
| es.astro.caltech.edu/palomar/visitor/virtualtour....
| RosanaAnaDana wrote:
| They do tours. I took astronomy at Palomar college.
| aae42 wrote:
| Corning's Museum of Glass is a nice stop, too, if you're in the
| finger lakes area of New York.
| pfdietz wrote:
| More Southern Tier than FLX. But do go a bit north to see the
| lakes, especially if you like wine or geology.
| beowulfey wrote:
| My dad worked as an engineer at Corning in the 80s and 90s. In
| addition to their general glass expertise (the museum is really
| incredible and I highly recommend it) Corning's importance in the
| early days of the internet is pretty amazing and I think not as
| well known. They basically built all the earliest fiber optics
| cabling for communication networks. We lived in the town of
| Corning and had a fiber internet connection in our house that my
| dad was testing back then. They are a super cool company and I
| will always appreciate them as an example of one that does one
| thing, really well (glass) but managed to grow by finding more
| and more uses for their speciality.
| trentnix wrote:
| +1 on the museum
|
| I did some consulting for Corning back in the late 2000s and
| took an afternoon to visit the museum. I can't recommend it
| enough.
|
| Corning is an exceptional company and so much of our
| technology, from fiber-optics to monitors and screens to
| Gorilla Glass, is thanks to the brilliant minds at work there.
| eastbound wrote:
| > Corning's importance in the early days of the internet is
| pretty amazing and I think not very well known
|
| After the fiber optics, they repeated the performance with the
| Gorilla Glass. See, we don't understand it anymore today but
| having glass screens on "smartphones" was a revolution - we
| didn't do touchscreens earlier because screens were plastic,
| like in the Palm Pilot; they were plastic because people pushed
| insensitively, people did that because the touch wasn't
| sensitive at all (cursor would always land at the wrong place,
| or not be sensed at all).
|
| What Corning built for Apple was a glass screen, almost
| unbreakable, and thin enough to have an amazing touch
| resolution.
|
| https://www.fastcompany.com/40493737/how-cornings-crash-proj...
| xhkkffbf wrote:
| Having broken many smartphone screens, I have to disagree
| with the characterization of "almost unbreakable." Sure, the
| screens are tougher than, say, house glass but that doesn't
| make it unbreakable. The number of screen repair stores at
| the mall pretty much testify to the accuracy of this phrase.
| jaynetics wrote:
| In earlier smartphones fractured screens were indeed very
| rare, because the glass did not reach so close to the edges
| of the phone, i.e. to the impact zones. My "Razr i" took a
| hell of a beating. The iPhone 3 was also quite robust.
| Galaxy S4, iPhone 4 were probably the turning point in
| terms of robustness vs aesthetics.
| unethical_ban wrote:
| iPhone 5 was my first fragile phone. I sat on my iPhone 4
| all the time, it being in my back pocket. The 5 thinned
| out and I warped the frame.
| NikolaNovak wrote:
| Yeah, I felt that earlier phones had more flex in the
| shell vs innards, which absorbed the impact; my Galaxy S2
| and S5 were also famous for scattering parts all over the
| floor upon impact (case, battery, etc:), which was
| hilarious but I also felt (perhaps wrongly) it helped
| dissipate the energy of the impact. They also tended to
| have a very very tiny "lip" where the shell of the case
| would touch surface rather than screen if you put them
| upside down.
| eastbound wrote:
| Before the era launched by Gorilla Glass, phones weren't
| even made out of glass. So, yes, I broke several phones
| (Android, never iPhone despite having been less careful
| about those), but it's still better glass than before.
| gmoes wrote:
| I recall visiting the museum many years ago and seeing a demo
| where they heated a glass rod and pulled a fiber. This was
| probably when fiber optics was in its infancy. It was
| definitely a highlight for a young science nerd. I would love
| to go back some day.
|
| Along those lines I highly recommend the episode of the show
| "How we Got to Now" about glass [0]. It tells the story of how
| clear glass was developed, something I always took for granted,
| but early glass was not clear and took a major effort to
| create. The show then goes into how Corning took it to a new
| level for fiber optics. The whole series is excellent and
| similar to James Burke's excellent series "Connections". [1]
|
| [0] https://www.imdb.com/title/tt4160136/
|
| [1] https://www.imdb.com/title/tt0078588/
|
| [1]
| https://www.youtube.com/watch?v=XetplHcM7aQ&list=PLf02uWXhaG...
| technothrasher wrote:
| I had a great time a while back visiting the museum with a
| friend who works for Corning, trying my hand at glass blowing
| for a couple hours, and then wandering around some of the cool
| places in the Corning buildings, before going to have some
| drinks at the appropriately named "Glory Hole" pub on Market
| Street, but I think that one is long gone now.
| KingOfCoders wrote:
| There where these days where Corning and Gorilla was a selling
| feature of phones.
| kumarvvr wrote:
| A YEAR for annealing ! Amazing how they came up with that
| timeline, or if they were being overly cautious.
| bell-cot wrote:
| IANAME (Mech. Engineer) - but I'd bet it was mostly known &
| boring physics (rates of thermal conduction, coefficients of
| thermal expansion, etc.), experience with the material being
| used (stress-strain curves, crack propagation, and such), and
| some differential equations that weren't all that hard to get
| approximate solutions to. A _lot_ of things like this are "If
| you could get an "A" on the Mech. Engin. 407 final, then you
| could pretty much figure it all out."
| basicplus2 wrote:
| Story of Palomar - 1948
|
| https://m.youtube.com/watch?v=4miVqgNSRVY
| DrFell wrote:
| At about the 20 minute mark, they show the Foucault testing of
| the mirror, and actually put a camera at the test focus, so you
| can see a Foucaugram of the mirror. It's of poor quality, but
| still. You see the donut. To anyone who was into amateur
| telescope making, ground their own mirror, used the Foucault
| test, and was as interested in mirror metrology tests as I used
| to be, this is absolutely fascinating.
|
| https://www.youtube.com/watch?v=4miVqgNSRVY&t=1223s
| patrick0d wrote:
| There is a book called "The perfect machine" about building this
| observatory.I found it very interesting since you might think
| it's not as hard as it is to make a piece of glass a few meters
| across and make it reflective.
| flir wrote:
| First Light, by Richard Preston, is well worth reading. Technical
| details on the Hale telescope balanced with stories of the
| astronomers who use it.
|
| Two standout passages for me are the construction of the
| parabolic primary (by the end they were polishing it with the
| ball of their thumb, knowing how much glass each pass would wipe
| off), and the support mechanisms that account for flexing in the
| mirror, which sound like absolute black magic to someone trained
| on digital systems.
| tinco wrote:
| What's Corning's secret? It seems they have been at the forefront
| of innovations in their industry for almost a hundred years. Has
| no one ever disrupted them with a crucial patent? Almost
| everything in the world changed in the past hundred years yet
| they're still world leader.
| analog31 wrote:
| Among other things, that region of the country was a hot bed of
| innovation, with multiple companies big and small, maybe an
| early silicon (dioxide) valley. Polaroid, Kodak, and many
| smaller companies. University of Rochester was and is a top
| school for studying optics.
| asmithmd1 wrote:
| Polaroid was started in, and grew around Cambridge MA. It was
| kept alive on life support by a $1B settlement paid by Kodak
| for infringing their instant photo patents
| trentnix wrote:
| They have some of the best minds in the world working for them.
| Their knowledge of glass, the physics of light, materials, and
| related manufacturing is unmatched.
| bayindirh wrote:
| Starting early. Like Zeiss, Bosch and others.
| brookst wrote:
| My favorite part of the story is the first attempt, which failed,
| but Corning continued on with it as an experiment. And that's the
| one in the museum now.
|
| That is how you accelerate learning anything. In a large multi-
| stage, multi-disciplinary project, there is always a temptation
| to give up and start over the first time a stage fails.
|
| But that means you always enter new stages with perfect inputs
| and no experience. Way better to keep working on flawed WIP to
| build experience and test new processes with lower stakes.
| ninefathom wrote:
| This is still an impressive technical achievement nearly a
| century later.
|
| As another commenter has already mentioned, there really is
| something to be said for a business picking one thing- just a
| single specialty- and doing it really d**ned well.
|
| Maybe Corning can give me some pointers on how to get a modest
| 3'x3' piece of glass for my coffee table back from my local home
| improvement store without having it shatter into a million
| pieces...
| fencepost wrote:
| _Maybe Corning can give me some pointers on how to get a modest
| 3 'x3' piece of glass for my coffee table back from my local
| home improvement store without having it shatter into a million
| pieces_
|
| Simple, hire having it delivered. People who deal with decent-
| sized chunks of glass or other brittle materials like stone
| countertops have vehicles with structures built to support
| what's being transported safely. For a 3x3 piece, a rack in the
| back of a pickup truck would likely work fine, if it was a
| larger tabletop then a glass contractor vehicle with a larger
| carrying space on the side would be needed.
|
| A thicker piece of glass might also work better.
| AlbertCory wrote:
| There's also the Lick Observatory's refracting telescope, still
| usable:
|
| https://www.lickobservatory.org/explore/36-inch-lick-refract...
|
| The lens was built in France in the 1880s and transported to San
| Jose. I don't know about COVID closures now, but I looked through
| it in the early 00's.
| reid wrote:
| You can still go look through it! I went a couple months ago.
| minhmeoke wrote:
| Additional pictures showing how the 20 ton, 200 inch (5.1 meter)
| diameter glass disk was transported across the country by train
| to Pasadena, CA, polished, and eventually trucked up to the
| Palomar Observatory:
|
| Video of the pouring process:
| https://www.youtube.com/watch?v=KdqaC8pLixY&t=15s
|
| Transport:
| https://sites.astro.caltech.edu/palomar/media/slideshows/mir...
|
| Polishing:
| https://sites.astro.caltech.edu/palomar/about/telescopes/ima...
|
| Click the slideshow and press the left/right arrows to advance
| the slides or go back.
|
| It seems like the first mirror cracked, so they manufactured a
| second mirror in Corning, New York (taking 10 months to cool it
| down and anneal it after it was poured), moved it across the
| country to Caltech in Pasadena, then they spent 11.5 years
| polishing it down to 14.5 tons... wow! And finally trucked it
| over to its current location in the Palomar Observatory in San
| Diego. I can't imagine being the crane operator while loading and
| unloading this thing.
| insane_dreamer wrote:
| > they spent 11.5 years polishing it down to 14.5 tons
|
| wow, talk about a long-term project
| yborg wrote:
| >It seems like the first mirror cracked
|
| Firebrick bolted to the base of the mold to form the void
| spaces broke loose and floated to the top of the mirror blank.
| Gare wrote:
| Video of recent recoating:
| https://www.youtube.com/watch?v=lkBgQaJVKjc
| kumarvvr wrote:
| The site says that the first mirror cracked due to breaking of
| the mould.
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