Horse
Today on "how it's made"... Horse-drawn carriages... Artificial eyes... Dog and cat food... And mirrors. Nothing takes you back to the past quite like a ride in a horse-drawn carriage, a timeless vehicle in both appearance and construction. Building one today still requires the expertise of several traditional craftspeople, from ironworkers to wheelwrights. The carriage's turning mechanism is a fifth wheel that is positioned horizontally above the two front wheels. Workers weld the fifth wheel to the carriage's steel frame then weld the boarding steps to the frame. Until now the frame has been positioned upside down. Now they turn it right side up to install the driver's seat. First they measure carefully to ensure it's perfectly centered. Then they weld it in place. Once the frame is complete, it goes through an acid wash to remove any residue. Then they buff the welded joints to smooth out their surface. The carriage has drum brakes. Workers install them onto the axle then assemble the steel springs that make up the suspension and bolt them onto the axle as well. Next, they connect the brake line. Then they install the whole assembly under the carriage's frame. Like in the olden days, they make the wheels out of wood. Metal isn't flexible enough to withstand bumps in the road. They use ash because it's a very hard wood that doesn't rot easily. Workers position 16 spokes around a steel hub. They clamp the spokes in place, compressing them against the hub. Then they secure them with nuts and bolts. Next, they mark the spokes in two places. The first line shows how long to cut each spoke, the second line how far to dowel the end. To form the dowel, they first shape the end into a cone. Then the cone into a dowel. Those doweled spokes will fit into corresponding holes they now drill into two semicircular strips of wood. The strips form what's called the fellow, the round part of the wheel. Workers tighten the hub then press a steel band called a channel against the fellow. They cut the channel to size. Then weld the ends together. Finally, they buff the joint smooth. Next, they drill eight holes through the channel then, using a tapering tool, thread the holes to fit the bolts that bind the channel to the fellow. Finally, they tighten the bolts with a special gun. The tires are made of rubber. They contain two steel wires to hold them in place over the wheel. Workers grease the channel of the now-painted wheel so that the tire will slip on easily. Then they mount the wheel on the automated tire-installation machine, which pulls on the wires, installing the tire tightly over the wheel. They solder the wire ends together using bronze solder for a stronger joint. Then-- here comes the high-tech part-- they bang the wheel on the ground four or five times until the distance between the tire ends closes, covering the soldered wires inside. A tap of the hammer followed by a final bang ensures the tire joint is secure. Now they can mount the wheels onto the axles and install the axles under the body of the carriage. After testing the fifth wheel and the brakes... It's time to apply the finishing artistic touches. All they need now is a little horsepower. The ancient romans and egyptians fashioned artificial eyes out of painted clay. By the 1500s, europeans started making them out of enameled gold and soon out of glass, which remained the norm for hundreds of years. Today most artificial eyes are made of acrylic. If you've lost an eye in an accident or to a disease, a specialist known as an ocularist can fit you with an artificial eye. You can get a ready-made model or a custom-made prosthesis, like the one for which this patient is being fitted. No two people's eye sockets are the same, so the first step is to take an impression. After inserting an impression tray, they inject a material called alginate, filling the entire socket cavity. After 90 seconds, the alginate sets, and they can remove the hardened impression. They place the impression in a mold. And pour in a type of plaster. When the plaster has hardened, they remove the impression tray and then the impression itself. What's left in the mold is a plaster replica of the socket. Now they put a wad of acrylic plastic dough into the mold... Lock the mold into a press, and submerge it in a high-pressure curing unit for 25 minutes. Then they cool the mold in cold water. Here's the original impression compared to the acrylic model they've just cast. This model is called the fitting shape because they use it to fit and mark the positioning of the fake iris. They accentuate the markings, then attach a peg with a drop of wax. The peg indicates the natural angle of the iris when the patient is looking forward. Next, they add wax around the perimeter to enlarge the fitting shape. This excess will give the ocularist some room to work with for the final sizing. Now they take this marked and enlarged fitting shape and make a plaster mold. They will later use that mold to cast the actual artificial eye. But first they have to make the iris. They take a curved, black acrylic disc and paint it as realistically as possible with high-quality artist oils. The patient has to be present so they can match the real eye. Next, they glue an acrylic cornea with an appropriate-sized pupil onto the painted iris. At this point, the artificial iris is half an inch in diameter. If the patient's real iris is smaller, they trim down the replica to match. The iris then goes into the plaster mold covered with white acrylic dough. After the same high-pressure curing process as before, out comes the artificial eye covered with excess white acrylic. They trim off that excess and the peg using a grinding tool and a cutter. This refines the shape and exposes the iris buried underneath. They smooth the surface against a grinding stone and verify the measurements. Then, using hard coloring pencils, they add finishing touches to the iris and draw blood vessels. They label the eye with the patient's initials and then apply an acrylic coating to seal the pencil marks. To create veins with some dimension, they use the same acrylic coating to stick on some delicate silk threads. Once they're satisfied the artificial eye is a perfect match, they seal the artwork with another acrylic coating. Once that cures, they polish the eye to a shine with a cotton wheel. The shapes and colors of artificial eyes are endless because patients' eye sockets and irises vary greatly, as do their scleras, the white of the eye. This artificial eye, or ocular prosthesis, is ready. The final step is to ensure that the fit is perfect. The patient's ocular muscles attach to the implant, enabling his artificial eye to move in unison with his real eye. So much for feeding fido scraps from the table. Today's pet food is the stuff of sophisticated nutritional science. It's about protein, carbohydrates, vitamins, minerals--  a well-balanced diet. Want to bet some dogs and cats eat healthier than their owners? The formulas for dog and cat food differ because dogs and cats have different nutritional requirements. Cats, for instance, need more fat and protein in their diet than dogs do. But the basic ingredients that factories grind up to make dog and cat food are similar. First, corn kernels. Then cereals, such as barley... Wheat... And rice. Workers weigh the ingredients, grind them in a mill, then combine everything in a mixer until they have an even and well-blended powder. A machine called the extruder transforms that powder into bite-sized pieces of pet food. It steam-coats the mixture, then forces it through dies at high pressure. The dies shape it, the way the tip of a pastry bag shapes icing into swirls or roses. Check out this dog-bone die. As the continuous stream of shaped mixture exits the die, a spinning knife cuts it into pieces. The company has different dies to produce different shapes. This is a batch of round pieces. Next stop, a hot-air dryer for 25 minutes. It heats the pieces to 300 degrees fahrenheit to draw out the moisture, then cools them at room temperature. Once the pieces exit the dryer, they enter a revolving drum, where they're sprayed with fat and flavoring. The fat is designed to add food energy while the flavoring gives the bland pieces an appetizing odor and taste-- appetizing for pets, that is. The rotation ensures the pieces get coated evenly. From here, the pieces go into storage silos. When they leave the silos for bagging, the machinery screens out any crumbs. The pet-food industry has made some interesting observations about the likes and dislikes of its four-legged clientele. Apparently, cats and dogs aren't crazy about food that's too dry, too hard to chew, or too mushy. If the pieces are too small, they'll swallow them whole without chewing and not digest them properly. But if the pieces are too big, they'll gag and get turned off to the food altogether. In the packaging department, automated scales weigh the exact quantity per package. This batch is destined for bags weighing about 6 1/2 pounds. The package sizes range from just under one pound all the way up to 44 pounds. Shelf life is from 12 to 16 months, depending on the formula. Pet-food experts say dogs and cats prefer food with a fattier content and a combined meat-and-cereal formula over just cereal alone, but too much meat flavoring can turn them off. Cats, as a rule, are more particular. They favor more acidic food, while dogs tend to have a sweeter tooth. And you thought kids were fussy eaters. No bathroom is complete without one. And any parent will tell you that no teenager can survive without one. Mirror, mirror on the wall, how do they make you, after all? Well, "how it's made" is about to show you. But first, let's reflect on the history of mirrors. The earliest mirrors were curved pieces of highly polished metal, such as brass or bronze. They're even mentioned in the bible. Then, in the 14th century, the venetians invented very crude glass mirrors that reflected off a metallic backing. They later perfected this technique using an amalgam of tin and mercury. Eventually, the secret of mirror-making spread to other cities. By 1835, a german chemist developed the silver-backed mirror that we know today. A mirror starts out as clear glass. A robot lays each panel horizontally on a conveyor belt, which transports it to the washing station. There, sprayers blast the glass with water and cerium oxide, a powder derived from a type of soil. Rotating brushes scrub and polish both the top and bottom surfaces, removing oils and other contaminants. This washing process takes about a minute per panel. Next, sprayers rinse the glass with piping-hot demineralized water, demineralized because the minerals in plain tap water would damage the metals they apply next. The first metal is liquefied tin, which goes on what will be the back of the mirror. It allows the second metal, silver, to adhere because silver won't stick directly to glass. The silver is also in liquid form mixed with a chemical activator. Within seconds of interacting with the tin, it hardens. And as it does, you begin to see a reflection. It's this silver backing that transforms clear glass into a mirror. Sprayers rinse off the excess silver, which gets recycled back into the system. The factory will seal the silver backing with two coats of paint. Paint by itself, however, isn't enough to protect the silver in the long term. So they first spray on a layer of copper. Sprayers rinse off the excess copper. Then the panel passes through a dryer at almost 160 degrees fahrenheit. This evaporates the moisture on the surface in just 75 seconds. Now the panel passes, copper side up, through what is called the curtain coater, a machine that runs a continuous curtain of paint across the conveyor belt. With its fresh coat of paint, the mirror then passes through an oven heated to 210 degrees fahrenheit. After a minute and 45 seconds, the paint is cured. Now the second coat of paint. There's no reason for the different color other than to differentiate the coats. This time, the curing period is twice as long and at a higher temperature, close to 245 degrees fahrenheit. After an acid wash to remove any metal residues, they stand the panel upright to inspect it. If they find a fault, such as a bubble in the glass, they cut that portion out. The factory now cuts these large panels into whatever size and shape the customer has ordered using a special mirror-cutting machine that's precision-guided by computer software. It scores the mirror using a carbide wheel. Carbide is a strong metal. To make round mirrors, the machine first scores the panel into squares. Then, in each square, it scores a circle. Using special tools, workers separate the squares, then the circles. To make beveled mirrors, they use what's called the shape-bevel machine. First, it carves out the edge. Then polishes it to a shine using concentrated cerium oxide, a stronger version of what they used earlier to clean the glass surface before plating it with metals. Mirror factories also ship whole panels to shops that do the cutting themselves, a fragile feat that's certainly not for the superstitious.