Wooden Bowls Chainsaws Stackable Potato Chips Jet Compressor Blades
Today on "how it's made"... Wooden bowls... Chain saws... Stackable potato chips... And jet compressor blades. There was a time when bowl making was a cherished trade passed down through generations of woodworkers. But today, with so much mass-produced tableware, handcrafted wooden bowls have become a specialty item, and this centuries-old traditional craft is practically a lost art. Each of these exquisite bowls is made from a solid piece of hardwood-- beech, maple, walnut, or cherry. Logs arrive at the bowl mill fresh from the forest, so they're still very damp, and that's an advantage because the moisture lubricates the cutting tools. The first step is to divide the log into blocks with a chain-saw operator measuring and inspecting as he goes. Defects such as knots or scarring dictate the length of each block. Any cracks or other flaws are marked with a red crayon. Next, a rip-saw operator uses different-size bowl patterns to determine the best way to cut the block. The goal is to get the biggest bowl-size pieces possible without including any defective wood. Each bowl-sized piece is called a bowl blank. This block is large enough to yield three blanks, each of which will produce a 17-inch bowl and a series of progressively smaller bowls that nest inside it. The blank is mounted onto a woodworking lathe. From this point on, production is entirely dependent on the lathe operator's skill. As the block spins, he carves out the bowls using a series of specialized knives designed and forged at this very mill. First he uses this curved knife to shear off the outer portion of wood. It takes great expertise to know exactly how to angle the tool and when to pull it out and release the wood shavings and prevent a jam. After two or three minutes, the exterior bark shell has been sheared off. The bare wood that's left represents the outside of the largest bowl that he'll mill from this blank. With a finer blade, he sculpts the wood to just the right thickness and smoothes the surface. Now he switches to a smaller curved knife and cuts into the wood. This forms the inside of the largest bowl and the outside of the next smaller one. The lathe worker repeats the smoothing and cutting process with progressively smaller knives, making bowl after bowl at a rate of about one a minute. This one bowl blank produces four nested bowls, the smallest measuring about nine inches in diameter. The bowls are steamed for about four hours to draw out the sap and hydrate the pores of the wood uniformly. Once a bowl is dry--  about a month later-- workers even out the top rim on a sanding table. Then, using a belt sander, they smooth the outside and inside surfaces. A motorized saw shaves off the bottom of the bowl, giving it a flat base on which to sit and a place to inscribe the company name. Businesses can order custom-made bowls featuring their company logo. Artists burn the design into the wood or paint it on. The bowls now go for a bath in food-safe mineral oil. This nourishes the wood, preventing dryness and cracks. Oiling also brings out the natural beauty of the wood grain, and because all raw wood is unique, no two bowls are ever alike. Up next... High-tech production at a chain-saw factory. It's loud, it's powerful, and it rules the forest. The chain saw has revolutionized the logging industry by replacing simple muscle power with mechanical might. The chain saw can fell a tree and quickly turn logs into lumber. Production begins with the plastic housing. Three aluminum inserts must be molded into the housing to provide solid anchors for other parts. A robot picks up the inserts one at a time and delivers them to an injection molding machine. Then it places the inserts into a mold at the front of the machine. The machine injects melted plastic into the mold to make the chain saw's engine cover. During the molding process, the metal inserts become integrated into the housing. It takes just seconds to transform these plastic pellets into a chain-saw engine cover. The robot carries each engine cover to an automated cutter that removes any unwanted bits of plastic. The scraps drop into a bin below. The hot covers cool for about 10 minutes. Then the robot moves them to the next station. There's one more piece of plastic housing-- the fuel tank. The sonic welder melts and fuses it to the engine cover using high-frequency vibration. Now it's time to move on to the engine and install a spring system for the starter cord. The two-stroke engine slides into the plastic casing. And a spark plug is popped into place. After the crankshaft is lubricated, the chain saw's automatic oiling system is installed. The carburetor is attached, along with a pull-cord starter system. This saw gets an air filter. Then the chain bar's stud bolts are dipped in adhesive and screwed into the inserts molded into the plastic housing. The rear handle goes on... Along with a safety-release trigger. The front handle is screwed into place. And the oil line gets a filter attachment that lubricates the bar and chain. That will strain out any impurities. Next, workers install bearings and the crankshaft clutch system. The clutch is the link between the engine and chain. When it's engaged, the chain will move around the cutting bar. The engine is now ready for a test run at typical speed-- 8,000 rpm. Technicians adjust the carburetor so that it mixes the right amount of gas and air and check the exhaust to make sure it doesn't exceed pollution standards. Workers attach the company's logo and other operational information. Then the brake system goes into place. Finally, the metal bar and chain blade are packed in a protective sleeve. Once the saw's chain blade is installed, the owner has a power tool with teeth for almost any job. When we return... Get the skinny on stackable chips. It's a snack that's made to stack. Unlike other chips that come in irregular shapes and sizes, these chips have a uniform concave shape that allows them to tightly interlock and fit neatly in a tubular container. The process for making these tubes starts with big rolls of plain brown paper and foil-backed paper that help keep the chips fresh. The streams of paper travel across rollers that apply a coat of glue. The paper layers then twist around the mandrel that's turned by a big belt. The belt also presses the glued layers together. Next, the label paper gets a coat of glue. This helps it stick to the paper on the mandrel. A camera photographs the white edging on the label paper, then relays its location to a set of circular knives. They make a precise cut just below the white edging. Cued by the camera, the carriage then moves the knives into position for the next cut. You the tubes then head into a turning station... A box with a pathway inside that flips the tubes right side up. Hot metal heads curl the tops to accommodate lids. A roller pulls foil-backed paper into a cutter that punches out the lid shapes. Little vacuums take the lids to the tubes and heat-seal them on. Plastic lids go over the paper ones. The lidded tubes are now turned upside down, ready to be stacked with chips. The chip recipe is 1/3 water to 2/3 potato flakes with a little cornstarch mixed in. A conveyor delivers the mix to an auger, which disperses it. Then it sets out on the production line. Using four tons of pressure, the mix is rolled into one long potato sheet. A rotary cutter then punches out oval shapes. A device pulls away the scrap dough, leaving flat, uncooked chips. This scrap dough goes back into the chip-making process, while the potato chips head for the fryer. As they travel through the fryer, rolling molds give the chips their uniformly concave shape, making them more easily stackable. The chips spend 11 seconds in hot oil, crisping. Then they travel under blowers to get rid of excess oil. The chips get a coat of seasoning, then do a backflip off one conveyor and onto another, falling into neat piles. A worker inspects the rows of chips. Then it's onto another conveyor that shakes them up to loosen the stack. They travel over scales to be portioned out for packaging. Automated spoons shove the chips into the open ends of the tubes. Guides tap the tops of the tubes to nudge the chips into position. Grippers then lower the stacks of tubes to a station, where spinning heads force metal bottoms onto them. Now they're ready for shipping. It takes about 20 minutes to make a tube of stackable chips, but it takes less time to polish them off. Up next, jet compressor blades that really make the cut. Compressor blades are key components in a jet's engine. Thousands of them whirl inside the engine, rotating 400 times per second and whipping air into small hurricanes. Large compressor blades made of titanium compress the air in front of an engine's turbo chamber. In the back of the chamber, smaller blades made of nickel alloy compress it even more. The air heats up to more than 1,000 degrees, then combines with jet fuel, creating a powerful mix that explodes out the back of the engine. The blades start off as metal pellets called slugs. A ceramic layer prevents their surfaces from oxidizing when exposed to intense heat. The slugs are heated for 15 minutes in an 1,800-degree oven. Meanwhile, a robot sprays lubricant on two dies inside a press. The robot retrieves the slugs and loads them in the first die. The press applies over 1,000 tons of pressure to preform the metal. The robot then transfers the slugs to the second die, where they take the initial shape of the blade. The blades are dipped in water to cool. Another robot cleans the metal burrs off the edges. The blade is now an airfoil. Robots will shape the rounded base of the blade, called the dovetail, later. The airfoil has gone from this to this. After a new ceramic layer is applied, the blade is heated again. Each heating and cooling cycle tempers the metal, making it more resilient. Almost 1,800 tons of pressure gives the airfoil its final shape. A trimmer shaves off the excess metal. The searing heat has turned the protective ceramic layer into glass. That will come off later. It's taken an hour to shape the blade's airfoil. The dovetail, that nub on the right, is next. But first, this measuring machine inspects the airfoil. If any measurement is off by just half the thickness of a human hair, the blade doesn't make the cut. This casting machine will encase the airfoil in a matrix, a coating that protects the airfoil during work on the dovetail. The matrix is molded from liquid tin and bismuth. It solidifies into a metal cast around the airfoil. The future dovetail sticks out at the end. The cast is then loaded into what is called a broach machine. Its series of teeth carve the dovetail into its final shape. Now the cast can come off. A worker loads it onto the removal machine, and a hydraulic cylinder hits the cast at its weakest point, breaking it in half. The finished airfoil emerges unscathed. A dot-matrix machine punches identification numbers onto the blade. Next, the blades are submerged in a fluid that penetrates any flaws in the metal. This inspection is critical because even the tiniest nick can spell disaster when a jet's engines are working at full speed. Inspectors examine the blades under a black light. This one's perfect, but spots of fluorescence on this one indicate microscopic cracks and weaknesses. This one gets rejected. The dovetail gets two strips of rubber silicone that ensure an airtight seal when the dovetail slides into the slot on the compressor drum. A final check, and the blades are now ready for takeoff.