6 ms·

Pouring the 200 inch disk at Corning Glass Works

189 points by DoreenMichele 4y ago

ggm 4y ago
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.
- bruce511 4y ago
  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.
  - defrost 4y ago
    > 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.
  - martyvis 4y ago
    And grinding and polishing away the 4½ tons of glass in the blank to make it parabolic took 14 years!
    - gambiting 4y ago
      It says the mirror was installed 4 years after being made, where did you get 14 years from?
      - martyvis 4y ago
        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/palomar/about/history.html https://sites.astro.caltech.edu/palomar/about/history.html
- anotherboffin 4y ago
  > 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-geeks-an-in-depth-tour-of-nikons-hikari-glass-factory https://www.imaging-resource.com/news/2018/04/17/glass-for-g...
  - tony_cannistra 4y ago
    Not the OP, but that was a great article - thanks.
- thanatos519 4y ago
  > 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 4y ago
    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.
jamiek88 4y ago
mind.blown. now I HAVE to go that observatory. I wonder if they do public tours?
- bombcar 4y ago
  https://sites.astro.caltech.edu/palomar/visitor/ 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 4y ago
    The longer term effects of lost opportunity and science are the most saddening.
    - CharlesW 4y ago
      It's just been closed for tours and public events. It's not the same, but you can take a virtual tour here: https://sites.astro.caltech.edu/palomar/visitor/virtualtour.html https://sites.astro.caltech.edu/palomar/visitor/virtualtour....
      - cplusplusfellow 4y ago
        I think when we have people going to basketball games, we can tour science facilities. It’s absurd anyone would be so terrified of covid at this point.
        CharlesW 4y ago
        My guess is that it's less about being terrified of COVID and more about wanting to avoid the irrational members of the public (you've seen the videos) who are performatively careless about taking even minimal precautions at best, and an active danger to others at worst.
        4y ago
minhmeoke 4y ago
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 https://www.youtube.com/watch?v=KdqaC8pLixY&t=15s Transport: https://sites.astro.caltech.edu/palomar/media/slideshows/mirrortravellog.html https://sites.astro.caltech.edu/palomar/media/slideshows/mir... Polishing: https://sites.astro.caltech.edu/palomar/about/telescopes/images/OpticalShop.jpg 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.
- kumarvvr 4y ago
  The site says that the first mirror cracked due to breaking of the mould.
- Gare 4y ago
  Video of recent recoating: https://www.youtube.com/watch?v=lkBgQaJVKjc https://www.youtube.com/watch?v=lkBgQaJVKjc
- insane_dreamer 4y ago
  > they spent 11.5 years polishing it down to 14.5 tons wow, talk about a long-term project
- yborg 4y ago
  >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.
CobrastanJorji 4y ago
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.
KingOfCoders 4y ago
There where these days where Corning and Gorilla was a selling feature of phones.
kumarvvr 4y ago
A YEAR for annealing ! Amazing how they came up with that timeline, or if they were being overly cautious.
- bell-cot 4y ago
  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."
patrick0d 4y ago
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.
basicplus2 4y ago
Story of Palomar - 1948 https://m.youtube.com/watch?v=4miVqgNSRVY https://m.youtube.com/watch?v=4miVqgNSRVY
- DrFell 4y ago
  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 https://www.youtube.com/watch?v=4miVqgNSRVY&t=1223s
tinco 4y ago
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.
- bayindirh 4y ago
  Starting early. Like Zeiss, Bosch and others.
- trentnix 4y ago
  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.
- analog31 4y ago
  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 4y ago
    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
beowulfey 4y ago
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 4y ago
  +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 4y ago
  > 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-project-for-steve-jobs-helped-define-the-iphone https://www.fastcompany.com/40493737/how-cornings-crash-proj...
  - xhkkffbf 4y ago
    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.
flir 4y ago
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.
AlbertCory 4y ago
There's also the Lick Observatory's refracting telescope, still usable: https://www.lickobservatory.org/explore/36-inch-lick-refractor/ 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 4y ago
  You can still go look through it! I went a couple months ago.
ninefathom 4y ago
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 4y ago
  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.
brookst 4y ago
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.

189 points by DoreenMichele 4y ago

ggm 4y ago

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.

bruce511 4y ago
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.
- defrost 4y ago
  > 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.
- martyvis 4y ago
  And grinding and polishing away the 4½ tons of glass in the blank to make it parabolic took 14 years!
  - gambiting 4y ago
    It says the mirror was installed 4 years after being made, where did you get 14 years from?
    - martyvis 4y ago
      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/palomar/about/history.html https://sites.astro.caltech.edu/palomar/about/history.html
anotherboffin 4y ago
> 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-geeks-an-in-depth-tour-of-nikons-hikari-glass-factory https://www.imaging-resource.com/news/2018/04/17/glass-for-g...
- tony_cannistra 4y ago
  Not the OP, but that was a great article - thanks.
thanatos519 4y ago
> 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 4y ago
  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.

jamiek88 4y ago

mind.blown. now I HAVE to go that observatory. I wonder if they do public tours?

bombcar 4y ago
https://sites.astro.caltech.edu/palomar/visitor/ 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 4y ago
  The longer term effects of lost opportunity and science are the most saddening.
  - CharlesW 4y ago
    It's just been closed for tours and public events. It's not the same, but you can take a virtual tour here: https://sites.astro.caltech.edu/palomar/visitor/virtualtour.html https://sites.astro.caltech.edu/palomar/visitor/virtualtour....
    - cplusplusfellow 4y ago
      I think when we have people going to basketball games, we can tour science facilities. It’s absurd anyone would be so terrified of covid at this point.
      - CharlesW 4y ago
        My guess is that it's less about being terrified of COVID and more about wanting to avoid the irrational members of the public (you've seen the videos) who are performatively careless about taking even minimal precautions at best, and an active danger to others at worst.
        4y ago

minhmeoke 4y ago

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 https://www.youtube.com/watch?v=KdqaC8pLixY&t=15s Transport: https://sites.astro.caltech.edu/palomar/media/slideshows/mirrortravellog.html https://sites.astro.caltech.edu/palomar/media/slideshows/mir... Polishing: https://sites.astro.caltech.edu/palomar/about/telescopes/images/OpticalShop.jpg 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.

kumarvvr 4y ago
The site says that the first mirror cracked due to breaking of the mould.
Gare 4y ago
Video of recent recoating: https://www.youtube.com/watch?v=lkBgQaJVKjc https://www.youtube.com/watch?v=lkBgQaJVKjc
insane_dreamer 4y ago
> they spent 11.5 years polishing it down to 14.5 tons wow, talk about a long-term project
yborg 4y ago
>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.

CobrastanJorji 4y ago

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.

KingOfCoders 4y ago

There where these days where Corning and Gorilla was a selling feature of phones.

kumarvvr 4y ago

A YEAR for annealing ! Amazing how they came up with that timeline, or if they were being overly cautious.

bell-cot 4y ago
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."

patrick0d 4y ago

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.

basicplus2 4y ago

Story of Palomar - 1948 https://m.youtube.com/watch?v=4miVqgNSRVY https://m.youtube.com/watch?v=4miVqgNSRVY

DrFell 4y ago
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 https://www.youtube.com/watch?v=4miVqgNSRVY&t=1223s

tinco 4y ago

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.

bayindirh 4y ago
Starting early. Like Zeiss, Bosch and others.
trentnix 4y ago
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.
analog31 4y ago
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 4y ago
  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

beowulfey 4y ago

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 4y ago
+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 4y ago
> 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-project-for-steve-jobs-helped-define-the-iphone https://www.fastcompany.com/40493737/how-cornings-crash-proj...
- xhkkffbf 4y ago
  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.

flir 4y ago

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.

AlbertCory 4y ago

There's also the Lick Observatory's refracting telescope, still usable: https://www.lickobservatory.org/explore/36-inch-lick-refractor/ 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 4y ago
You can still go look through it! I went a couple months ago.

ninefathom 4y ago

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 4y ago
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.

brookst 4y ago

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.