Metal Nail Files Birch Bark Canoes Cruiser Boat Hardtops High Voltage Circuit Breakers
Today on "how it's made"... Metal nail files. Birch bark canoes. Cruiser boat hardtops. And high-voltage circuit breakers. Throughout history, people have wanted nice nails. And they used whatever they could get their hands on to make them look good. Marie antoinette is said to have used a pumice stone file to shape her fingernails. By the end of the 19th century, metal nail files became the norm. Metal nail files can be used to grind and shape fingernails with a few strokes. Their abrasiveness is the secret to their popularity. Making metal nail files starts with a thick spool of stainless steel. The steel unwinds at a steady pace. A punch press wields 88 tons of hydraulic pressure to cut out nail file blanks. The blanks spill into a bin and accumulate. The blanks bounce around with ceramic stones and a mix of water and polishing solution. This smoothes the rough bits on the blanks and also cleans them. The nail file blanks then slide down a chute into a dryer. This dryer doesn't use hot air to do the job. Instead, a pulsating mass of hot corn grain soaks up the lingering liquid on the blanks. As the blanks exit, some of the corn falls through a perforated conveyor to be reused. The blanks continue on and land in a bin, ready for the next phase of production. It involves the cutting of an abrasive grid on both sides. It's a three-stage process. First, a worker places the blank under a sharp tool that's angled at 52 degrees. The tool pounds the blank repeatedly to cut angled grooves into it. Here is the blank before and after the first cut. He switches the cutting tool, and it carves over the first cuts on the opposite angle. The third cut goes straight across the other two. The ridges and valleys created by the cross cuts make the surface of the blank sharp. The grid cutting has bent the still-pliable steel out of shape, so the worker now bends the nail files in the opposite direction, using a round form as a guide. This restores their linear profile. The carving process has also caused steel to bulge on the edges of the nail files, so he grinds them against a fine abrasive sanding belt to make the edges smooth again. Next, he places the metal nail files in perfect alignment in a tray. He transfers the tray of files to an oven. The files bake for an hour at a temperature of 1,832 degrees fahrenheit. The intense heat begins to alter the physical properties of the steel and is the first phase of a hardening process. When the hour is up, he takes the red-hot tray of nail files out of the oven using tongs and then immerses them in a vat of cold saltwater. This is called quenching. The shock of the quench completes the hardening process. Shielded by an enclosure, he sandblasts each nail file to remove stains left by the hardening process and to make the steel around the triple-cut grid shinier. He places the handle into the nail file beneath a plastic stencil. A stamp applies acid to the open areas of the stencil to etch brand information onto it. Some nail files have plastic handles. To make the handles, this machine melts plastic and injects it into molds. The handles are stuck together by hardened flow lines or runners. A few tumbles in this revolving drum knocks off the runners, separating the handles from them. The worker places each handle under an automated printing head that soaks up ink from a pad and then stamps brand information onto the plastic. Another worker heats the end of each metal nail file using copper elements. She inserts the hot metal into the plastic sleeve, and the plastic melts a little to bond to the metal. These metal nail files are ready for the grind. For centuries, the canoe was indispensable to the indigenous people of north america. Essential for hunting, fishing, transportation, and commerce, indigenous people often crafted their canoes from birch bark, which is lightweight, strong, waterproof, and rot-resistant. Historically, different indigenous tribes constructed different styles of birch bark canoes. This one is the type crafted by both the algonquian and eastern ojibwe. Even today, the canoe builder crafts every component from water- and rot-resistant plant materials found in the forest, such as the exceptionally strong roots of black spruce trees. After scraping off the bark with a tool crafted from a moose rib, this craftswoman cuts a slit in the top and pulls, splitting the long root into two strips. She coils up each strip and puts it aside to dry out. The canoe builder uses spruce root to bind structural components and lace together sections of birch bark. To build the canoe's cedar structure, the builder connects end frames at the front and back with long strips of cedar called gunwales, then he lashes crossbars called thwarts to the gunwales with spruce root. To make each end frame, he splits a piece of cedar many times to let it bend, soaks it in boiling water to soften the wood fibers, and binds the shape with spruce root. Then the builder checks this curved part, called the stem, against the straight part, called the headboard. If the proportions are right, he notches the bottom of the headboard to fit over the base of the stem, then lashes the parts to each other with spruce root. He laces together several pieces of birch bark to make a sheet large enough for the canoe. The builder saturates the bark sheet with boiling water and bends it up around a wooden template. Then, on each side of the canoe, he sandwiches the top edge of the bark in between the two cedar strips that form the gunwale. The builder shaves pieces of cedar to make straight, vertically laid planks and u-shaped horizontally laid ribs that line the inside of the canoe. He uses a gauge to make sure each piece is the required thickness. He lays each rib piece across the structure and makes a mark on each side in line with the bottom edge of the floor. That's where he'll bend the piece. Just as he did to bend the stem portion of the end frame, the builder ladles boiling water onto the wood to soften the fibers. He positions his knees on the charcoal marks and pulls up the ends. He bends two ribs at a time, as this reduces the chances of them cracking. After checking that he cut and bent all the ribs correctly, the builder begins the process of securing the birch bark. He drills holes in the gunwales at nearly six-inch intervals. Then he takes pegs carved from hardwood such as ash or maple and hammers one through each hole. Then he pierces holes through the bark with a traditional awl made from deer antler. He threads spruce root through the holes to lash the bark to the gunwale. With an assistant's help, he fully lines the canoe with straight cedar planks and installs the remaining ribs. The tight fit presses the planks against the bark, stretching it taught, which strengthens it. The final step is known as pitching the seams. He melts down dried resin gathered from scars on spruce trees and mixes in two ingredients-- ground charcoal and oil rendered from bear fat. He applies this hot mixture to all the lacing holes in the birch bark, making the canoe water-tight. The canoeist carries a small supply of dried pitch and lights a stick to remelt and apply it. The repair dries quickly, so in about five minutes, the canoeist can be back in the paddle. A hardtop encloses the cockpit of a cruiser boat. It provides shelter from water spray, wind, and sun, and a roof on which to mount antenna for marine and satellite radio and gps. On the inside, it provides walls and a ceiling for recessed lighting and other features. This cruiser hardtop has windows that wrap around the front and sides. The tall one in the middle is retractable so you can walk through to the front deck. Workers use two molds to make the inner and outer parts that form the hardtop. First, they spray white gelcoat to a thickness of just . 6 millimeters. Next, workers shoot shredded fiberglass strands into the mold along with a stream of resin which saturates the fibers. When the fiberglass is about 3/4 of an inch thick, they let the resin cure for an hour or so. Then workers apply bonding putty to the fiberglass in the outer mold. They mate the inner and outer molds and let the putty set, which takes about an hour. Finally, it's time to extract the fiberglass from the molds. It comes off relatively easily because prior to spraying the gelcoat layer, workers have applied a release agent on the mold's surface. The inner and outer parts are built in the mold upside-down so the gelcoat gives the coarse fiberglass a smooth and shiny surface finish. Then they cut openings for the windows and for the various components to be installed into the hardtop. They install the retractable front window. Workers then position the window and mark the screw holes, then remove it in order to apply adhesive, which also functions as a sealant to prevent water infiltration. They reset the window and screw it to the hardtop. Workers install a non-opening window on each side of the retractable one. After taping off the area, a worker applies primer. Once the primer dries, they remove the tape and apply an adhesive-backed foam gasket that's about 1/4-inch high. A worker applies a 1/4-inch high bead of adhesive sealant next to the gasket and sets the window. The primer gasket and adhesive sealant are all black to match the window frame. On the roof of the hardtop, workers install a thin molded fiberglass cover. The retractable window, when opened, slides under it. Workers fill the gap between the cover and hardtop with sealant. This adheres the cover and makes it watertight. At the rear, workers install the radar arch. This, too, is made of molded fiberglass but with a black gelcoat finish. They mount various components on it, such as the horn, navigation light, and antenna. Inside the hardtop, after passing wires for lighting, workers connect the wiring to the retractable window. The window comes as a self-contained unit with an incorporated motor and intricate pulley system. The hardtop is now ready to be mounted to the cruiser's deck. Workers install a windshield wiper on each non-opening front window. The last step is to install a large window on both sides of the hardtop. Its middle section opens. Like a giant windshield, the hardtop transforms the cruiser boat's otherwise open cockpit into a weather-protected lounge. Electrical substations play a critical role in the grid as they distribute electricity to entire communities. The circuit breakers at these stations routinely interrupt short circuits to prevent damage to the system. They perform the same function as the ones in a home electrical panel, but on a much larger scale. The size of a car or even a large truck, these circuit breakers troubleshoot high-current situations at electrical substations. This protects the grid and prevents power outages. Making one starts with a cast-aluminum tank that has receptacles for bushings. A worker inspects the tank for dirt or flaws and then places protective covers on the bushing receptacles. He installs bases for current transformers on these receptacles. The worker applies adhesive to the outside of these metal bases. He presses squares of plastic insulation to the glued areas. With the help of an overhead lift, the worker installs the two current transformers on the insulated bases. These current transformers will act as sensors, enabling the circuit breaker to detect short circuits in an electrical system in mere milliseconds. Another worker brushes lubricant on the moving part of the interrupter that will break the electrical current when needed. He inserts the exhaust tube that helps direct the flow of gas used to break the current. He sets the interrupter module in an upright position on the floor and returns to the workbench. The worker dabs thread lock liquid in the mounting holes of the stationary contact assembly and installs a resin ring in the base. He inserts the stationary part into the moving one, leaving the end protruding. The worker applies thread lock to the assembly holes of a large tube that will shield the entire interrupter once it's installed in the tank. It will also direct the flow of interrupting gas. After assembling it to the interrupter, he inserts a synthetic insulating tube. Then with the help of a lift, he flips the module over in order to work on the other end. He installs another insulating tube in this end. He then sets the module to a stand to steady it as he inserts the contact assembly that opens to interrupt the electrical current. He caps one end of the interrupter with the unit that houses the bell crank. He slides the bell crank into the housing. This crank will convert the rotary motion from the operating mechanism to a linear motion. He turns the crank to confirm that it rotates freely. He now clamps leads to test probes inserted in the interrupter and applies 100 amps of current. The testing device measures the interrupter's resistance to the current to confirm that it's within an acceptable range. With a lift bearing the load, the other member of the team guides the interrupter module into the cast-aluminum tank. He bolts the bell crank's housing to the tank opening and places cylindrical electrical shields in each of the bushing receptacles. He then encases the transformers at the base with aluminum covers. They'll protect the transformer wiring from rain, snow, or dirt. Lifts now hoist the silicone-rubber-wrapped bushings into the receptacles. The worker bolts them in place... And caps the rear of the tank. This interrupter is now ready to be mounted to the steel support structure. Each high-voltage circuit breaker will be equipped with three interrupters. The team connects the bell cranks to the operating system in the control cabinet. And workers equip each bell crank with a pressure gauge. A worker grounds the circuit breaker to the support structure with copper cables. This will prevent shocks to anyone who touches it. In one last test, towering transformers apply high voltages to the circuit breakers. These high-voltage circuit breakers are ready to interrupt situations before they become problems.