The 3-D printer salami-slices the CAD model into electronic slices, one on top of another, where each slice might be about 20 microns thick.
Although all of the slices are 3-D because they have thickness (or length) as well as width and height, the 3-D printer treats each slice as a 2-dimensional cross section showing precisely what the object would look like if it were carefully cut through.
The 3-D printer prints out each slice—starting with the lowest—just like a printer would a 2-D image. But instead of squirting ink onto paper, it produces all the details in each slice as a 20-microns-thick layer of “stuff.”
The material for one slice dries and hardens, then the 3-D printer indexes (moves up) and produces the next slice as another 20-microns-thick layer on top of the previous one.
This process is repeated over and over until all the slices of the CAD model have been printed one on top of another to produce a real 3-D object!
20 microns—or 1/50th of a millimeter—is approximately 25% of the thickness of one of the hairs on your head! A CAD model of an object that is 10 cm (4 in.) high would therefore be salami-sliced into about 5,000 electronic slices!
Facts about 3-D printers
• The most common material used is plastic, as it can be easily squirted out in very small amounts as a liquid and will quickly harden into a solid. It is also ideal for making prototypes (models of new things like buildings or cars). As modern machines can use several different kinds of plastic at the same time and can print in color, prototypes can be very realistic. This is still the biggest application for 3-D printers.
• There are two common types of 3-D printers used today:
Extrusion Machines: the material is forced through a nozzle, rather like using a piping bag to ice a cake. These machines are especially good when using more than one type of color of material, since more nozzles can easily be added.
Bed Machines: these are most commonly used with powdered metals. Enough powder is poured out to completely fill one slice, then a power laser fuses (melts and joins) the powdered metal into a solid shape at precisely the right places in the slice. Once the model is complete, the excess powered metal is brushed away.
• Over the next few years scientists expect that machines using plastic will become more common in peoples’ homes, allowing you to download patterns and 3-D-print things like made-to-measure bike helmets or fun personalized toys. Imagine printing yourself as a Star Trek or Harry Potter figure!
• 3-D printers in factories use materials like metals and ceramics—for example, to print out parts for jet airplanes that are lighter and stronger, thereby making the airplanes safer and more fuel-efficient.
• Medical devices like implants for new hips and teeth, and cranial plates (used to repair holes in heads), can also be 3-D-printed, because this process allows them to be made specifically for the person they will be fitted into.
Robots of the future?
Today’s 3-D printers are still quite slow and can only make things out of a few different materials at the same time—it would not yet be possible to print a complete robot since you would need complicated interlocking parts made of many materials: metal parts, gears and motors, magnets, wires, plastics, oil, grease, silicon, gold—even weird things like yttrium and tungsten!
But 3-D printers could easily make parts for robots within a fully automated factory. The parts could then be unloaded from the 3-D-printers by unloading robots, polished by polishing robots, and then assembled by assembly robots …
Robots using 3-D printers (with other technology too) to make robots? Is this something you will see in the future?
It was as if they were in a spherical, clear glass bubble, floating through space. At regular points around the perimeter, openings led into more corridors: these tubes curved away from the central room to an outer circle, like the spokes of a bicycle wheel.
Apart from these, the room was completely transparent. When they looked down, they saw that even the floor (or was it the ceiling? It was hard to know in space) was made of the same glasslike material.
It was the most amazing thing George had ever seen; for a second it took his breath away. He had dreamed of diving through space; now, he realized, he was probably as close to this as he could ever get—suspended in a glass bauble with an awesome view of the universe on all sides.
But when George gazed out, it wasn’t just the emptiness of space or the dark sky peppered with stars that grabbed his attention. It was something far more beautiful: a jewel-like blue-green planet, clothed in a thin wispy veil of atmosphere. It was their home.
“It’s the Earth!” breathed George as he and Annie drifted around the room. A lump came into his throat. He reflected that it would be difficult to explain this feeling to someone who had never flown in space. When you left the Earth and then looked back and saw it—fragile, ancient, mysterious, and enchanting, suspended against the blackness of space—it made your heart burst with protective, homesick feelings. You wanted to stay in space forever, but you also wanted to rush home and look after your beautiful planet, hanging there so courageously in the vast emptiness.
But George didn’t have long to gaze in wonder. The angry robots had ushered them into the middle of the room and then taken up posts around the edges, where they lurked, silent and impassive.
Then, from another round opening, a figure emerged.
“Ebot!” cried Annie.
The android was no longer in Eric’s space suit—he was now just wearing Eric’s trademark tweed jacket, pants, and brightly colored shirt.
George felt a rush of relief to see Ebot again in this strange place—he’d become oddly attached to the robot. More importantly, he was their route out of the alien spaceship.
“Ebot!” Annie shouted to him. “We found you!”
But Ebot seemed to be asleep; he just floated into the room; and, they saw, he was not alone. The kids hadn’t noticed his companion at first—but when they did, their mouths fell open in amazement.
Dressed in a onesie that was striped like the planet Jupiter, a peculiar figure rolled around the spherical room, flicking the tail of his suit and chuckling to himself. He orbited Annie and George and their robot, looking a little like a small planet. Holding on to each other for support, the friends gazed at him in astonishment.
“Hello!” the man—for it was indeed a man—cried, throwing out his hands in a gesture of welcome as he came to a stop in front of them. “And welcome! I am so pleased you could join me. This has made my day! No—wait … not just my day! My week, my month, my year! I’m so happy you are here,” he continued, smiling broadly.
George felt himself relax a little. At least they seemed to be guests rather than prisoners now, and he knew which he preferred. Was this strange man I AM? Was this the voice they had heard on the radio? It certainly sounded rather familiar.
“George and Annie, right?” he continued, beaming away. “From twenty-three and twenty-four Little Saint Mary’s Lane, Foxbridge. George is 106 days older than Annie, who has the blood group AB positive, is working on a project to identify the elements of life, and was recently diagnosed dyslexic by a child psychologist. She was sent to see a psychologist because her marks have plummeted and she has slipped down in the class rankings, losing out to her main rival, Karla Pinchnose. This has given her a complex, and she is determined to prove her intelligence and her ability to overcome her educational issues.”
Two pieces of information stood out for George. “You’re dyslexic?” He turned to Annie in surprise. “You’re doing badly at school? You told me you only went to the psychologist to have your IQ measured and they said you were probably a genius!”
Suddenly he realized why she had been trying so hard with her vacation project. She was attempting to reclaim her position at the top of the class—which George didn’t even know she had lost. Now it all made sense: why she had started so many weird experiments, and why she had been unable to give up on the quest for life until c
ircumstances had forced them to take another tack.
“The IQ test was part of the dyslexia assessment,” she said with great dignity. “I didn’t realize I had to tell you everything.”
“George,” continued their host, “is harder to pin down in terms of information, which makes me think he is a less prolific user of technology than Annie. I know that he is a fan of computers and doesn’t like humans nearly as much as machines. But given what I have also gathered of his parents—infamous eco-warriors with a marked dislike of the electromagnetic spectrum in domestic situations—he probably only gets to use the computer at school, and frankly I can’t be bothered to wade through every single inane statement typed into a school computer.”
“You’ve been reading our private messages!” gasped Annie.
“Well, no,” chuckled the mystery onesie wearer. “I think that’s a bit too much to ask, don’t you? I know about you because you tap away on Cosmos, and Cosmos is a computer that greatly interests me. I only investigated George because he is a registered user of Cosmos.”
“But how could you get into his system?” asked Annie, frowning. “It’s not possible!”
Their new friend chuckled. “You’re right,” he confided. “There is no computer on Earth that could break into Cosmos.”
“Then you can’t have done it!”
“Look around, dear clever girl, with your very high IQ and the partial disability that you are so eager to keep hidden from your friends and peers,” he murmured. “Can you see what the answer is? Can you spell a seven-letter word?”
The color rose in Annie’s cheeks.
“Don’t be horrible!” said George angrily. He hated seeing Annie being taunted like this.
“Me? Horrible?” said the man, swishing the tail of his onesie and simpering. “I wouldn’t know how! I’m full of love and kindness and joy. Just trying to help your little friend here work out the solution. She won’t get it—I always said girls were no good at science.”
“Space,” said Annie defiantly. Inside, George cheered. “You’ve got a space computer,” she continued doggedly. George gave her a double thumbs-up. “No computer on Earth can break into Cosmos, so it must be a computer in space.
“And”—she thrust out her chin belligerently—“I’m going to take a guess. It’s ‘quantum.’ Which is seven letters when ‘space’ is five. That’s the answer.”
“Can you spell that?” said the man sweetly. “Or shall I do it for you?” He waved his tail, and in a loopy script, the word “Quantum” appeared on the clear surface of the bubble in red, blue, and green lights.
“Now, children,” he purred. “For a special prize … Who can tell me—where is the quantum computer?”
George looked around. Apart from the people, Ebot, and the robots, the room held nothing at all apart from amazing views. He looked at the word “Quantum” spreading out across the transparent sphere, and a light went on in his brain.
“This is it, isn’t it?” he said. “This is the quantum computer… . We’re inside it! I don’t know how it works, but I just know that this is it.”
“Oh, so clever!” said their host. “As you’ve made what some people would erroneously describe as a quantum leap, I shall fill in the rest for you. Embedded in the crystalline structure of this chamber are the billions of quantum dots that make up the quantum computer. The whole spaceship has them throughout, but in other locations they are ordinary non-quantum computer particles. This room is special because in here we have my quantum computer.”
“But what powers it?” For a moment George was lost in wonder at the technological brilliance of this achievement.
“Solar power, of course. The millions of dots inside the infrastructure of the spaceship scavenge power from the Sun.”
“Well, we know what you’re using it for,” said Annie, sounding very unimpressed. The sharp tone of her voice woke George up and reminded him that they were not here to marvel at the technology and the view.
“Do you?” The man floated over to position himself right in front of them. They could just see the blue, yellow, green, and white of their home planet, outlined against a dark sky, the view only slightly spoiled by the madman in a Jupiter-striped onesie.
He twitched his tail again, and the glass sphere around them lit up with tiny pinpricks of light. George and Annie felt as though they were suspended in the middle of a crowd of fireflies. “It really has been the most extraordinary week so far,” the man told them. “I can’t remember when I last had such a good time. Who would have thought the dear old Earth would react so quickly to my little modifications? They were just supposed to be tiny tweaks to make it a better place. But—oops—I wonder if I overshot the mark, just a teensy little bit …”
The two kids looked astonished. George felt his jaw drop.
“Make the Earth a better place?” echoed Annie, having recovered the power of speech first. “That’s soooo not true! Who are you, anyway?”
“Take a guess!” said the onesie wearer. “You did so well last time.”
“You’re I AM,” said George.
“I AM coming to save you… .” Annie realized now just what the voice had meant by this sentence.
“Oh, so many delightful possibilities!” said I AM. “You see now how clever I am.”
“Yes, we do,” said George, hoping to get some more information by playing along. “But you see, we’re not so clever—at least, not as clever as you. We’d like to learn to be, if only you could teach us… . To start with, could we know your name?”
“My name,” I AM replied, clearly pleased by George’s compliment, “is Alioth Merak. I, Alioth Merak—”
“Hang on,” said Annie. “That’s not a real name. That’s two of the stars of the Big Dipper!”
“Exactly!” crowed Alioth Merak. “I don’t really exist. That’s the exciting part. That’s why I’m so hard to find. You could search and search for me—and you won’t find me anywhere. Not a single mention … It’s the true luxury of our age—complete anonymity. Almost impossible in this era of information. But yet I have managed it.” He preened for a second, stroking his arm with his tail and looking extremely pleased with himself.
“Easy,” said George, “with an invisible spaceship and a quantum computer.”
“Easier,” corrected Merak. “Not easy—after all, I had to make the spaceship and the computer first.”
“Are you very rich?” asked Annie bluntly.
“Excessively so,” said Merak casually. “That’s what makes it all such fun!” He turned a few somersaults in midair to express his joy and happiness at being him.
George and Annie exchanged glances. It seemed very unlikely, thought George; he was talking to an adult, but he felt like the grown-up compared to the juvenile Alioth Merak.
“If you’re so rich,” persisted Annie, “why don’t you get a better onesie? That one is really uncool.”
Merak turned on her, furious, all the smiling good humor wiped off his face in an instant.
“How dare you, you horrible little girl!” he spat. “How dare you—you insignificant, ridiculous vile little worm—make a comment about me, the amazing, the magnificent I Am! Don’t you know, I am saving the world!”
“How are you doing that?” George intervened, anxious to screen his friend from further attacks by this cranky and probably very dangerous man.
“The Earth,” Alioth Merak began, sounding serious now, “our beautiful planet, is beset with terrible evils: inequality, unhappiness, hoarding of resources; great wealth, great poverty. The rich have to police their land, their countries, their possessions with weapons, armies, and guards, while the poor starve. No one is happy. No one is having fun.”
“So your plan was to make people have more fun?” Annie wrinkled her nose. “That’s the solution? Are you for real?”
“No,” said Merak, throwing her a scathing look. “I would have thought it was perfectly clear that there is nothing ‘real’ about me, idiotic sm
all girl with intellectual pretensions.”
He turned to George and smiled. Clearly Merak had decided that he liked one of them and hated the other. “My plan was, simply and brilliantly, to make the world a better place… . What’s that you say … ?” Suddenly he appeared to address some invisible person. “Can you repeat? … Copy. I read you… . What do you mean, the penguins have been exterminated?”
“What!” shouted Annie. “You can’t exterminate penguins!”
“Too late, I’m afraid,” said Merak. “It seems they’re already dead.”
“Who were you just talking to?” said George, horrified. It seemed to him that this man was becoming more deranged by the second.
“My head is a cell phone,” Merak told him. “I had an implant robotically inserted, deep into my brain, which means that I have no need of a handset to communicate with my mechanical troops.”
“Where are your troops?” said Annie, thinking of her mom and George’s family in the basement and suddenly feeling very afraid. “And do you just have robots or do you have people too?”
“People!” snorted Merak. “Are you kidding? Why would I need people when I’ve got my own robot army? I think you’ve seen one or two of them already. A couple of them are in Foxbridge. For now, they are few and strategically placed, but soon they will be far more numerous. I just have to give the command to my network of 3-D printers on Earth, and they will appear, as if by magic, ready to take control and make the world a better place!”
“I get it now,” murmured George to Annie. “I see the link.”
“What’s that, boy?” cried Merak. “Speak up so everyone can hear you!”
“I get it!” said George loudly. “The banks and the free money—the supermarkets and the free food, opening the dams, stopping the military aircraft, cutting off networks that might hurt people. You think all these things are nice things to do!”
“Clever boy! They were random acts of kindness,” replied Merak, thrilled to see that George had finally worked it out. “They were poor, so I gave them money. They were hungry, so I gave them food. They were thirsty, so I made water in the desert. They were scared, so I made the bombs stop.”
George and the Unbreakable Code Page 18
