How It's Made (2001–…): Season 6, Episode 2 - Springs/Pavers/Pianos #1/Pianos #2 - full transcript
Narrator:
TODAY ON "HOW IT'S MADE"...
SPRINGS...
...PAVERS...
...AND PIANOS.
A SPRING
IS A FLEXIBLE METAL DEVICE
THAT RETURNS TO
ITS ORIGINAL SHAPE OR POSITION
AFTER IT'S STRETCHED,
SQUEEZED, OR TWISTED.
SPRINGS WERE FIRST USED IN
CLOCKS DURING THE 16th CENTURY
AND, STARTING IN THE LATE 1800s,
IN CHAIR SEATS AND BEDDING.
TODAY SPRINGS POP UP ALL OVER.
THEY'RE CRUCIAL COMPONENTS
OF MODERN TECHNOLOGY.
DIFFERENT TYPES OF SPRINGS
INCLUDE COMPRESSION,
ON THE RIGHT,
AND EXTENSION, ON THE LEFT.
DURING USE,
THESE TORSION SPRINGS
WILL TWIST AT ONE OR BOTH ENDS.
WORKERS START
WITH ROLLS OF STEEL CORD.
THE CORD DIAMETERS RANGE IN SIZE
DEPENDING ON THE TYPE OF SPRINGS
BEING MADE.
A MACHINE CALLED A DEREELER
UNWINDS THE ROLL,
FEEDING IT TO A COMPUTER-GUIDED
FORMING MACHINE.
THIS FORMING MACHINE FORCES
THE CORD THROUGH A CHANNEL,
SHAPES IT INTO A COIL,
AND THEN CUTS IT INTO SEGMENTS.
SMALL WHEELS AND A METAL SHAFT
GUIDE THE CORD INTO SHAPE.
THESE ARE TORSION SPRINGS FOR
USE IN THE AUTOMOTIVE INDUSTRY,
WHICH RELIES HEAVILY
ON A VARIETY OF SPRINGS.
THE AVERAGE CAR, FOR EXAMPLE,
HAS ABOUT 350 OF THEM.
A CONE-SHAPED YELLOW SENSOR
DETECTS THE CORRECT ANGLE
OF EACH SPRING.
A GOOD READING IS REQUIRED
SO THE MACHINE CAN MOVE
THE NEXT SPRING FORWARD
THROUGH THE CHANNEL
TO BE FORMED.
THIS MACHINE CAN PRODUCE
UP TO 2,000 SPRINGS PER HOUR,
DEPENDING ON THEIR SIZE.
HERE ANOTHER LARGER
FORMING MACHINE
CREATES EXTENSION SPRINGS
THAT ARE OVER 6 INCHES LONG.
A MECHANICAL ARM GRABS THE COIL
AND CHOPS IT INTO SEGMENTS
AFTER IT'S FORMED IN A CHANNEL.
AS THE COIL EMERGES,
ANOTHER MECHANICAL ARM STEADIES
IT TO PREVENT IT FROM VIBRATING.
THIS KEEPS
THE SPRING TENSION CONSTANT,
ENABLING THE MACHINE
TO PRODUCE AT TOP SPEED.
IN SLOW MOTION,
YOU CAN SEE HOW THE MACHINE
GRABS THE COIL'S FIRST RING
AND BENDS IT TO FORM A HOOK.
THIS ALL TAKES PLACE AS THE COIL
EMERGES FROM THE CHANNEL.
A VISE THEN SECURES THE LAST
RING ON THE END OF THE COIL,
WHILE ANOTHER ARM TWISTS IT
TO MAKE THE SPRING'S OTHER HOOK.
SLOWED DOWN,
YOU SEE HOW TWO ARMS
SURROUND THE COIL
BEING HELD IN THE VISE.
ONE ARM THEN GRABS THE LAST RING
WHILE THE OTHER ARM
TWISTS IT UPWARD.
THIS MACHINE
MAKES COMPRESSION SPRINGS --
A MODEL WITH TAPERED ENDS
THAT'S OFTEN USED IN SEAT BELTS.
A METAL PROBE DETECTS THE
CORRECT LENGTH OF THE SPRINGS
AFTER THEY'RE FORMED.
THE MACHINE HAS FOUR
ROTARY SHAFTS CALLED CAMS.
A COMPUTER ENSURES EACH SPRING
HAS THE DESIRED SPECS.
THE SPRINGS ARE ALSO HEATED
TO RELAX THE METAL.
THIS GIVES THEM THE ABILITY
TO RETAIN THEIR SHAPE
AFTER FLEXING.
ANOTHER MACHINE CREATES LONGER,
THICKER TORSION SPRINGS.
IT SHAPES THE CORD INTO A COIL
WITH A SHAFT
AND THEN PASSES IT OVER A TUBE
TO STEADY IT.
THIS ENSURES THE SPRING
WILL HAVE THE REQUIRED TENSION.
SPRINGS CAN BE AS THIN
AS A HUMAN HAIR
OR AS THICK AS A BROOM HANDLE.
TRAIN WHEELS, FOR INSTANCE,
INCLUDE SOME OF THE INDUSTRY'S
THICKEST COMPRESSION SPRINGS.
THIS MACHINE
MAKES ANOTHER TYPE OF SPRING,
OFTEN CALLED WIRE FORMS.
THEY'RE FLEXIBLE STEEL CORDS
CURVED OR BENT AT AN ANGLE.
THESE ONES, SHAPED LIKE A "W,"
ARE USED IN OVENS.
HERE, A WORKER PLACES A SPRING
INTO A MACHINE
THAT MAKES ITS HOOKS.
HE USES AN ADAPTOR
TO AVOID HURTING HIS FINGERS.
HE PLACES EACH ONE INDIVIDUALLY
BECAUSE SPECS FOR SPRINGS
CAN VARY BY MINUTE AMOUNTS.
THIS COMPANY MAKES SOME SPRINGS
WITH HOOKS MADE OF TWO RINGS
INSTEAD OF ONE.
CLIENTS ORDER THEM THIS WAY
BECAUSE THE HOOKS
ARE MORE DURABLE.
CUSTOM ORDERS FOR SPRINGS
CAN RANGE FROM JUST A FEW
TO MANY THOUSAND.
THIS IS ANOTHER TYPE
OF WIRE FORM.
IT'LL BE USED IN A FIREARM.
A WORKER ASSEMBLES IT BY HAND
BECAUSE IT'S SO INTRICATE.
AFTER JOINING TWO BASE PIECES,
HE PLACES THEM INTO A SMALL DIE.
USING A FOOT PEDAL,
HE CONTROLS THE DIE
TO BEND THE SEGMENTS
AND COMPLETE THE ASSEMBLY.
TO CHECK THE
COMPRESSION SPRING'S TENSION,
A WORKER TESTS IT
WITH A WEIGHT GAUGE.
THE CORRECT TENSION VARIES
DEPENDING ON WHAT
THE CLIENT WANTS.
A 1 1/2-INCH LONG SPRING,
FOR EXAMPLE,
MIGHT NEED TO WITHSTAND
5 POUNDS OF TENSION
WHEN COMPRESSED TO 1 INCH.
TO TEST AN EXTENSION SPRING,
WORKERS JUST ADD HOOKS
TO THE WEIGHT GAUGE.
WHETHER THEY'RE EXTENSION,
COMPRESSION,
TORSION, OR WIRE FORM,
AND WHETHER THEY'RE INSIDE PENS
OR SATELLITES,
SPRINGS PROVE THAT SOME
OLD IDEAS DEFINITELY STILL WORK.
Narrator: YOU COULD SAY THAT
INTERLOCKING CONCRETE PAVERS
CAME OUT OF THE RUBBLE
OF WORLD WAR II.
IN POST-WAR HOLLAND,
THERE WEREN'T ENOUGH CLAY PAVERS
TO REBUILD CITY STREETS,
SO THE DUTCH
BEGAN MAKING CONCRETE PAVERS.
THE GERMANS
REFINED THE TECHNOLOGY
AND EXPORTED IT
TO NORTH AMERICA,
AND THEY FOUND
A QUICK ROAD TO SUCCESS.
THESE PAVERS ARE SOLID,
AND THE INTERLOCKING DESIGN
DISPERSES WEIGHT,
EASING THE LOAD ON THE ROAD.
TO MAKE THESE PAVERS,
A CONVEYOR BELT DELIVERS
CONCRETE SAND TO A WEIGH BELT
THAT WEIGHS THE COARSE SAND
AS IT FALLS ONTO IT.
THE WEIGH BELT
CARRIES THE SAND FORWARD,
WHILE ANOTHER CONVEYOR BELT
UNLOADS STONE CHIPS
TO BE WEIGHED.
THESE CHIPS ARE NO LONGER
THAN AN 1/8 INCH.
THE RATIO OF SAND
TO STONE CHIPS VARIES
DEPENDING ON THE TYPE
OF PAVER BEING MADE.
THE WEIGH BELT TRANSPORTS
THE STONE CHIPS FORWARD
ALONG WITH THE COARSE SAND.
BOTH ARE EN ROUTE
TO THE SKIP HOIST.
THEY SPILL OFF THE CONVEYOR
INTO THE SKIP HOIST,
WHICH IS ESSENTIALLY
A BUCKET ON RAILS.
CABLES PULL
THE LOADED BUCKET UPWARDS.
IT STOPS ABOUT 30 FEET UP,
JUST ABOVE A BIG CONCRETE MIXER.
A TRAP DOOR OPENS AND DUMPS
THE SAND AND STONE CHIPS
INTO THE MIXER.
SIX GIANT STEEL PADDLES MIX
AND THEN ROTATE AND MIX AGAIN,
WHILE CEMENT
IS ADDED AUTOMATICALLY
THROUGH SEVERAL NOZZLES
ON THE SIDE
OF THIS ENORMOUS MIXING BOWL.
MAKING PAVERS
IS A BIT LIKE BAKING COOKIES.
TOO MUCH OR TOO LITTLE LIQUID
IN THE BATTER,
AND IT WON'T BAKE PROPERLY.
WATER IS ADDED UNTIL
THE CONSISTENCY IS JUST RIGHT.
NOZZLES ALSO SHOOT A PIGMENT
INTO THE MIX TO TINT IT.
THE MIXTURE
LOOKS DRY AND CRUMBLY,
BUT THE RECIPE GIVES IT
JUST ENOUGH MOISTURE
TO FORM THE CONCRETE.
NOW A FILLING WAGON
SPREADS THE MIX
OVER A STEEL MOLD CONTAINING
UP TO 50 PAVER-SHAPED CAVITIES.
THE MOLD PRESSHEAD APPLIES
11 TONS OF VIBRATING PRESSURE.
THIS PULSATING FORCE COMPACTS
THE MIXTURE IN THE PAVER MOLD
AND REMOVES ANY AIR POCKETS,
WHICH COULD WEAKEN THE PAVERS.
HYDRAULIC CYLINDERS
LIFT THE MOLD,
LEAVING THE PAVERS
ON THE PRESS BOARD.
THE PRESS BOARD SLIDES OUT,
AND THE MOLD ONCE AGAIN
GETS FILLED IN
AND MAKES ANOTHER
50 PAVER STONES.
IT ONLY TAKES ABOUT 10 SECONDS
TO MOLD, COMPACT,
AND RELEASE A BATCH OF PAVERS.
THE PRESS BOARDS FILLED
WITH PAVERS SLIDE INTO A RACK.
A HYDRAULIC CHAIN HOIST
LIFTS EACH BOARD
INTO A LARGE HOLDING RACK.
THERE, A SPECIAL MOVING WAGON,
CALLED A FINGER WAGON,
PICKS UP ALL THE BOARDS
FROM THE RACK
IN JUST ONE MOVE.
THE ELECTRICAL WAGON MOVES
ALONG A RAIL TO A CURING KILN,
WHERE IT'S ALMOST
100 DEGREES FAHRENHEIT.
THE PAVERS
ACTUALLY GENERATE THE HEAT,
DUE TO A CHEMICAL REACTION
FROM THE COMBINATION
OF CEMENT AND WATER.
ABOUT 12 HOURS LATER,
THE FINGER WAGON CARTS
THE PAVERS OUT OF THE KILN.
THEY ARE NOW 70% CURED AS
A RESULT OF THE CHEMICAL PROCESS
THAT BINDS THE CEMENT,
SAND, AND GRAVEL,
CAUSING THE PAVERS TO HARDEN.
THE REST OF THE CURING WILL
HAPPEN OVER THE NEXT 28 DAYS.
THE PAVERS
ARE NOW STURDY ENOUGH TO HANDLE,
SO FOUR STEEL ARMS
WITH RUBBER PADS MOVE IN
AND STRAIGHTEN THE STONES
ON THE BOARD.
THESE ALIGNMENT ARMS
ARE HYDRAULICALLY DRIVEN.
THEY ARRANGE THE CONCRETE PAVERS
SO THEY INTERLOCK SNUGLY.
NOW HYDRAULIC CLAMP ARMS
LIFT THE PAVERS OFF THE BOARD
AND BEGIN TO PILE THEM UP.
THEY'RE MAKING A CUBE OF STONE.
THIS STACKING MACHINE
IS CALLED A CUBER.
IT PACKS 9 OR 10 LAYERS
OF PAVERS ON TOP OF ONE ANOTHER
TO MAKE THIS CUBE.
THE CUBE
IS ACTUALLY CALLED A BUNDLE.
IT WILL BE STRAPPED
AND SHIPPED OUT TO THE JOBSITE.
THESE CONCRETE PAVERS
WILL BE ON THE ROAD SOON
BUILDING AND REBUILDING
OUR STREETS.
Narrator: PIANO KEYS
WERE ONCE MADE OUT OF IVORY.
THIS SOUGHT-AFTER MATERIAL
ISN'T USED ANYMORE
BECAUSE IT'S BANNED TO PROTECT
ELEPHANTS WHO WERE KILLED
FOR THEIR IVORY TUSKS.
PIANISTS NOW PLAY PLASTIC KEYS,
BUT THE TECHNIQUES INVOLVED
IN MANUFACTURING A PIANO
HAVEN'T CHANGED MUCH AND STILL
RELY ON HANDCRAFTSMANSHIP,
JUST LIKE A CENTURY AGO.
[ UP-TEMPO MUSIC PLAYS ]
BEAUTIFUL MUSIC IS A TRIUMPH,
BUT SO IS THE PIANO ITSELF...
...MADE OF INNER AND OUTER RIMS,
A SOUNDBOARD,
TREBLE AND BASS BRIDGES OVER
WHICH THE STRINGS ARE STRETCHED,
AND A HEAVY CAST-IRON PLATE.
TO MAKE A PIANO RIM,
AUTOMATED ROLLERS SPREAD GLUE
ONTO SHEETS OF HARD ROCK MAPLE,
COATING BOTH SIDES.
THEN THEY LAYER THE GLUE-SOAKED
SHEETS 5 TO 8 DEEP,
DEPENDING ON THE MODEL OF PIANO.
WORKERS FEED THE WET LAYERS
OF WOOD TO A RIM PRESS.
AN IMPACT WRENCH,
POWERED BY COMPRESSED AIR,
TURNS THE CLAMP SCREWS.
THE SCREWS BEND THE WOOD
INTO A PIANO RIM FORM.
THEY MEASURE THE PRESSURE
ON THE LAYERS
WITH A TORQUE WRENCH.
STEEL ARMS
REACH ACROSS THE WOOD,
HOLDING THE SHAPE
WHILE THE GLUE DRIES.
AFTER 24 HOURS, WORKERS LOOSEN
THE MACHINE'S GRIP,
AND THE RIM
NOW HOLDS ITS CONTOUR.
NOW IT'S INTO WHAT'S CALLED
THE CONDITIONING ROOM
FOR MORE DRYING OUT.
THE PIANO RIMS STAY IN THIS
WARM, ARID ROOM FOR 30 DAYS.
IT'S TIME TO MAKE
THE BRACING STRUCTURE.
THEY PLACE GLUED STRUTS
INSIDE THE RIM,
THEN APPLY PRESSURE
WITH A CLAMP.
THE FRAMEWORK REMAINS
IN THIS EMBRACE FOR AN HOUR
WHILE THE GLUE DRIES.
THIS PIANO WILL HAVE A TENSION
RESONATOR FOR EXTRA SUPPORT.
STEEL TURNBUCKLES
ATTACH TO A CENTER HUB.
A WORKER TIGHTENS
THE TURNBUCKLES WITH A WRENCH.
THEN HE THUMPS IT TO MAKE SURE
IT'S TIGHT AND WON'T RATTLE.
NEXT, THEY'LL INSTALL
THE SOUNDBOARD MADE OF SPRUCE
AND THE TWO BRIDGES.
STRINGS WILL STRADDLE
THE BRIDGES
AND TRANSMIT VIBRATIONS
TO THE SOUNDBOARD,
WHICH IS THE AMPLIFIER
OF THE PIANO.
A WORKER GLUES RIBS
ONTO THE SOUNDBOARD.
HE LOWERS WOODEN CLAMPS
OVER EACH RIB
TO APPLY PRESSURE
WHILE THE GLUE DRIES.
THAT TAKES ABOUT AN HOUR.
NEXT, HE THINS THE RIBS
AROUND THE EDGES
WITH AN AUTOMATED
STAGGER-TOOTH SHAPER CUTTER.
THIS WILL ALLOW THE SOUNDBOARD
TO RESONATE FREELY
WHEN THE PIANO IS PLAYED.
NOW THEY POSITION THE SOUNDBOARD
IN A BRIDGE PRESS.
THEN THEY PLACE
A BRIDGE-LOCATING FIXTURE
ON TOP OF THE SOUNDBOARD.
THIS DEVICE HOLDS THE BRIDGE
IN PLACE
WHILE IT'S GLUED
TO THE SOUNDBOARD.
AFTER THE TWO BRIDGES
ARE GLUED DOWN,
THEY LOWER THE SOUNDBOARD
ONTO THE PIANO RIM.
THEN THEY HOIST
A CAST-IRON PLATE ONTO IT.
IT'S A CRITICAL FITTING.
IF THEY DON'T GET IT RIGHT,
THE PIANO
WILL NEVER FUNCTION PROPERLY.
THEN THE PLATE IS REMOVED
FOR FINISHING.
A WORKER CUTS NOTCHES
IN THE BRIDGES,
WHICH ARE NOW TOPPED
WITH A LUBRICANT.
THIS VERY SHARP CHISEL
CUTS THROUGH THE HARD MAPLE
LIKE BUTTER.
EACH NOTCH WILL CRADLE
THREE PIANO STRINGS,
GIVING THEM THE FREEDOM
TO VIBRATE.
NOW THEY ROLL GLUE ONTO
THE OUTSIDE CASE OF THE PIANO,
WHICH IS MADE
OF ROSEWOOD VENEER ON MAPLE.
THEY FIT IT SNUGGLY
OVER THE RIM STRUCTURE.
A MECHANICAL CLAMP
HOLDS IT IN PLACE FOR AN HOUR
WHILE IT DRIES.
THEN THEY STAND THE ENTIRE PIANO
ON ITS SIDE.
SPINNING CUTTERS SHAPE THE ARMS
THAT SIT NEXT TO THE KEYBOARD
INTO AN ELEGANT CURVE.
THIS IS CALLED
A VERTICAL STROKE SANDER.
A WORKER RUNS IT
ALONG THE SIDE OF THE PIANO
TO SMOOTH OUT THE WOOD.
AFTER A BLACK POLYESTER PAINT
IS APPLIED,
THEY BUFF IT UP WITH
THIS ELECTRICAL CLOTH POLISHER.
THEN THEY HAND-RUB
A MIRROR GLAZE CREAM INTO IT
UNTIL YOU CAN
REALLY SEE YOURSELF
IN THIS HALF-FINISHED PIANO.
Narrator: TO PLAY A PIANO,
YOU NEED TIME TO PRACTICE
AND LOTS OF MONEY
BECAUSE A GRAND PIANO CAN COST
ABOUT THE SAME AS A LUXURY CAR.
AND LIKE A LUXURY CAR, WHEN YOU
LIFT THE TOP OF A GRAND PIANO,
YOU'LL SEE THAT A LOT
HAS GONE INTO ITS CONSTRUCTION.
[ UP-TEMPO MUSIC PLAYS ]
THE BASS AND TREBLE BRIDGES
ARE NOW FIXED TO THE SOUNDBOARD
OF THIS HALF-FINISHED PIANO.
THEN TO ADD GLAMOUR,
THEY SPRAY GOLD PAINT
ON THE CAST-IRON PLATE.
THE NEXT STEP
INVOLVES THE PIN BLOCK,
WHICH HOLDS ALL THE STRESS.
IT BEARS 45,000 POUNDS
OF TENSION FROM THE STRINGS
AND TRANSFERS IT
TO THE IRON PLATE.
HE DRILLS
INTO THE MAPLE PIN BLOCK,
THROUGH HOLES
IN THE IRON PLATE OVER IT.
THE HOLES
ARE FOR THE TUNING PINS,
HENCE THE NAME -- PIN BLOCK.
THEY UNFURL PIECES
OF STEEL WIRE FROM BIG COILS.
USING A VISE GRIP,
THE WORKER TWISTS THE END
OF THE WIRE INTO A NEAT LOOP.
THEN HE HOOKS IT
ONTO A HITCH PIN
ON THE BACK SIDE
OF ONE OF THE BRIDGES,
MAKING SURE IT RUNS BETWEEN
THE GUIDE POSTS OVER THE BRIDGE.
NOW HE THREADS THE WIRES THROUGH
ANOTHER GUIDE CALLED AN AGRAFE.
USING WIRE CUTTERS,
HE SNIPS THE WIRE TO
THE EXACT LENGTH THAT HE NEEDS.
THEN HE WRAPS THE WIRE
ON THE TUNING PIN
USING A DEVICE
CALLED A STRINGING CRANK.
HE TAPS IT INTO A HOLE
IN THE PIN BLOCK.
THEN, USING A PNEUMATIC HAMMER,
HE DRIVES THE TUNING PINS
INTO THE PIN BLOCK.
NOW THE STRING STRETCHES
FROM ABOVE THE BRIDGE
TO THE PIN BLOCK.
EACH STRING IS UNDER A TENSION
OF UP TO 425 POUNDS,
AGAIN, A FORCE
THAT WILL BE KEPT IN CHECK
BY THE HEAVY CAST-IRON PLATE.
NOW HE PLACES
LITTLE FELT-COVERED BLOCKS
CALLED DAMPERS
ABOVE THE STRINGS
TO STOP THEM FROM VIBRATING
WHEN A NOTE IS PLAYED.
USING PLIERS, HE MAKES PARALLEL
BENDS IN THE DAMPER WIRES,
SO THEY'RE ALIGNED.
HE POUNDS THE KEY FRAME,
CHECKING FOR GAPS
THAT COULD CAUSE KNOCKS
UNDER A PIANIST'S
VIGOROUS BLOWS.
HE SMOOTHES OUT THE GAPS,
SHAVING OFF BITS OF WOOD
WITH A STRIP OF SANDPAPER
ATTACHED TO A HANDLE.
NOW ANOTHER WORKER
PRESSES THE PIANO KEYS
IN BETWEEN STEEL GUIDE PINS
THAT HAVE BEEN INSTALLED
IN ROWS ON THE KEY FRAME.
SHE USES AN AIR CYLINDER
TO PUSH THE BACKCHECK
INTO THE END OF A PIANO KEY.
THE BACKCHECK IS A PIECE OF WOOD
COVERED WITH FELT AND BUCKSKIN
THAT WILL CATCH
THE PIANO'S HAMMER
AFTER IT STRIKES A STRING.
IT'S TIME TO MAKE THOSE HAMMERS.
SHE GLUES THE FELT-COVERED TOP
ONTO A THIN PIECE OF HORNBEAM,
A SPECIES OF VERY STRONG WOOD.
WHEN A PIANIST HITS A KEY,
IT WILL CATAPULT THE HAMMER
INTO THE STRING,
AND THAT PRODUCES A NOTE.
NOW SHE ALIGNS THE HAMMERS
TO BE PERFECTLY PARALLEL,
USING A PLASTIC SQUARE
AS A GUIDE.
THIS IS CALLED "SQUARING IT UP."
NEXT, SHE SANDS THE TAIL
OF EACH HAMMER WITH A FILE
SO THERE'LL BE NO SHARP EDGES
TO DAMAGE THE BACKCHECK.
THEN SHE ATTACHES THE HAMMERS
TO THE TOP OF THE KEYBOARD
WITH SCREWS.
NOW SHE PLACES WEIGHTS
ON EACH KEY
AND THEN GENTLY TAPS THE RAIL
TO GET THE HAMMERS MOVING.
SHE'S TESTING THE AMOUNT
OF EFFORT IT WOULD TAKE
FOR A PIANIST
TO PUSH EACH KEY DOWN.
THIS IS CALLED "THE WEIGH OFF."
AFTER SHE DETERMINES
HOW MUCH WEIGHT IS NEEDED,
SHE MARKS A PLACE
ON THE SIDE OF THE KEY
AND DRILLS ONE OR TWO HOLES.
SHE PLUGS EACH HOLE
WITH A PIECE OF LEAD.
IN A PROCESS CALLED SWEDGING,
SHE PUSHES A DIVOT INTO THE LEAD
SO IT EXPANDS
AND FITS SNUGLY INTO THE KEY.
THE LEAD WILL COUNTERBALANCE
THE WEIGHT OF THE HAMMERS
AND GIVE THE KEY
THE REQUIRED AMOUNT OF WEIGHT.
NEXT, THIS TECHNICIAN
CHECKS EACH HAMMER AND EACH KEY,
MAKING SUBTLE
MECHANICAL ADJUSTMENTS
SO THEY MOVE SMOOTHLY
AND FLUIDLY.
IT'S THE PIANO'S
FIRST BIG TUNE-UP.
HE FINE-TUNES THE HAMMER ACTION
BY USING A LET-OFF TOOL
TO ADJUST THE DRIVING MECHANISM.
THE PIANO IS NOW READY FOR
THE HANDS OF A SKILLED PIANIST
AND THE EARS
OF AN APPRECIATIVE AUDIENCE.
[ UP-TEMPO MUSIC PLAYS ]
CAPTIONS PAID FOR BY
DISCOVERY COMMUNICATIONS, INC.
IF YOU HAVE ANY COMMENTS
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OR IF YOU'D LIKE TO SUGGEST
TOPICS FOR FUTURE SHOWS,
DROP US A LINE AT...
TODAY ON "HOW IT'S MADE"...
SPRINGS...
...PAVERS...
...AND PIANOS.
A SPRING
IS A FLEXIBLE METAL DEVICE
THAT RETURNS TO
ITS ORIGINAL SHAPE OR POSITION
AFTER IT'S STRETCHED,
SQUEEZED, OR TWISTED.
SPRINGS WERE FIRST USED IN
CLOCKS DURING THE 16th CENTURY
AND, STARTING IN THE LATE 1800s,
IN CHAIR SEATS AND BEDDING.
TODAY SPRINGS POP UP ALL OVER.
THEY'RE CRUCIAL COMPONENTS
OF MODERN TECHNOLOGY.
DIFFERENT TYPES OF SPRINGS
INCLUDE COMPRESSION,
ON THE RIGHT,
AND EXTENSION, ON THE LEFT.
DURING USE,
THESE TORSION SPRINGS
WILL TWIST AT ONE OR BOTH ENDS.
WORKERS START
WITH ROLLS OF STEEL CORD.
THE CORD DIAMETERS RANGE IN SIZE
DEPENDING ON THE TYPE OF SPRINGS
BEING MADE.
A MACHINE CALLED A DEREELER
UNWINDS THE ROLL,
FEEDING IT TO A COMPUTER-GUIDED
FORMING MACHINE.
THIS FORMING MACHINE FORCES
THE CORD THROUGH A CHANNEL,
SHAPES IT INTO A COIL,
AND THEN CUTS IT INTO SEGMENTS.
SMALL WHEELS AND A METAL SHAFT
GUIDE THE CORD INTO SHAPE.
THESE ARE TORSION SPRINGS FOR
USE IN THE AUTOMOTIVE INDUSTRY,
WHICH RELIES HEAVILY
ON A VARIETY OF SPRINGS.
THE AVERAGE CAR, FOR EXAMPLE,
HAS ABOUT 350 OF THEM.
A CONE-SHAPED YELLOW SENSOR
DETECTS THE CORRECT ANGLE
OF EACH SPRING.
A GOOD READING IS REQUIRED
SO THE MACHINE CAN MOVE
THE NEXT SPRING FORWARD
THROUGH THE CHANNEL
TO BE FORMED.
THIS MACHINE CAN PRODUCE
UP TO 2,000 SPRINGS PER HOUR,
DEPENDING ON THEIR SIZE.
HERE ANOTHER LARGER
FORMING MACHINE
CREATES EXTENSION SPRINGS
THAT ARE OVER 6 INCHES LONG.
A MECHANICAL ARM GRABS THE COIL
AND CHOPS IT INTO SEGMENTS
AFTER IT'S FORMED IN A CHANNEL.
AS THE COIL EMERGES,
ANOTHER MECHANICAL ARM STEADIES
IT TO PREVENT IT FROM VIBRATING.
THIS KEEPS
THE SPRING TENSION CONSTANT,
ENABLING THE MACHINE
TO PRODUCE AT TOP SPEED.
IN SLOW MOTION,
YOU CAN SEE HOW THE MACHINE
GRABS THE COIL'S FIRST RING
AND BENDS IT TO FORM A HOOK.
THIS ALL TAKES PLACE AS THE COIL
EMERGES FROM THE CHANNEL.
A VISE THEN SECURES THE LAST
RING ON THE END OF THE COIL,
WHILE ANOTHER ARM TWISTS IT
TO MAKE THE SPRING'S OTHER HOOK.
SLOWED DOWN,
YOU SEE HOW TWO ARMS
SURROUND THE COIL
BEING HELD IN THE VISE.
ONE ARM THEN GRABS THE LAST RING
WHILE THE OTHER ARM
TWISTS IT UPWARD.
THIS MACHINE
MAKES COMPRESSION SPRINGS --
A MODEL WITH TAPERED ENDS
THAT'S OFTEN USED IN SEAT BELTS.
A METAL PROBE DETECTS THE
CORRECT LENGTH OF THE SPRINGS
AFTER THEY'RE FORMED.
THE MACHINE HAS FOUR
ROTARY SHAFTS CALLED CAMS.
A COMPUTER ENSURES EACH SPRING
HAS THE DESIRED SPECS.
THE SPRINGS ARE ALSO HEATED
TO RELAX THE METAL.
THIS GIVES THEM THE ABILITY
TO RETAIN THEIR SHAPE
AFTER FLEXING.
ANOTHER MACHINE CREATES LONGER,
THICKER TORSION SPRINGS.
IT SHAPES THE CORD INTO A COIL
WITH A SHAFT
AND THEN PASSES IT OVER A TUBE
TO STEADY IT.
THIS ENSURES THE SPRING
WILL HAVE THE REQUIRED TENSION.
SPRINGS CAN BE AS THIN
AS A HUMAN HAIR
OR AS THICK AS A BROOM HANDLE.
TRAIN WHEELS, FOR INSTANCE,
INCLUDE SOME OF THE INDUSTRY'S
THICKEST COMPRESSION SPRINGS.
THIS MACHINE
MAKES ANOTHER TYPE OF SPRING,
OFTEN CALLED WIRE FORMS.
THEY'RE FLEXIBLE STEEL CORDS
CURVED OR BENT AT AN ANGLE.
THESE ONES, SHAPED LIKE A "W,"
ARE USED IN OVENS.
HERE, A WORKER PLACES A SPRING
INTO A MACHINE
THAT MAKES ITS HOOKS.
HE USES AN ADAPTOR
TO AVOID HURTING HIS FINGERS.
HE PLACES EACH ONE INDIVIDUALLY
BECAUSE SPECS FOR SPRINGS
CAN VARY BY MINUTE AMOUNTS.
THIS COMPANY MAKES SOME SPRINGS
WITH HOOKS MADE OF TWO RINGS
INSTEAD OF ONE.
CLIENTS ORDER THEM THIS WAY
BECAUSE THE HOOKS
ARE MORE DURABLE.
CUSTOM ORDERS FOR SPRINGS
CAN RANGE FROM JUST A FEW
TO MANY THOUSAND.
THIS IS ANOTHER TYPE
OF WIRE FORM.
IT'LL BE USED IN A FIREARM.
A WORKER ASSEMBLES IT BY HAND
BECAUSE IT'S SO INTRICATE.
AFTER JOINING TWO BASE PIECES,
HE PLACES THEM INTO A SMALL DIE.
USING A FOOT PEDAL,
HE CONTROLS THE DIE
TO BEND THE SEGMENTS
AND COMPLETE THE ASSEMBLY.
TO CHECK THE
COMPRESSION SPRING'S TENSION,
A WORKER TESTS IT
WITH A WEIGHT GAUGE.
THE CORRECT TENSION VARIES
DEPENDING ON WHAT
THE CLIENT WANTS.
A 1 1/2-INCH LONG SPRING,
FOR EXAMPLE,
MIGHT NEED TO WITHSTAND
5 POUNDS OF TENSION
WHEN COMPRESSED TO 1 INCH.
TO TEST AN EXTENSION SPRING,
WORKERS JUST ADD HOOKS
TO THE WEIGHT GAUGE.
WHETHER THEY'RE EXTENSION,
COMPRESSION,
TORSION, OR WIRE FORM,
AND WHETHER THEY'RE INSIDE PENS
OR SATELLITES,
SPRINGS PROVE THAT SOME
OLD IDEAS DEFINITELY STILL WORK.
Narrator: YOU COULD SAY THAT
INTERLOCKING CONCRETE PAVERS
CAME OUT OF THE RUBBLE
OF WORLD WAR II.
IN POST-WAR HOLLAND,
THERE WEREN'T ENOUGH CLAY PAVERS
TO REBUILD CITY STREETS,
SO THE DUTCH
BEGAN MAKING CONCRETE PAVERS.
THE GERMANS
REFINED THE TECHNOLOGY
AND EXPORTED IT
TO NORTH AMERICA,
AND THEY FOUND
A QUICK ROAD TO SUCCESS.
THESE PAVERS ARE SOLID,
AND THE INTERLOCKING DESIGN
DISPERSES WEIGHT,
EASING THE LOAD ON THE ROAD.
TO MAKE THESE PAVERS,
A CONVEYOR BELT DELIVERS
CONCRETE SAND TO A WEIGH BELT
THAT WEIGHS THE COARSE SAND
AS IT FALLS ONTO IT.
THE WEIGH BELT
CARRIES THE SAND FORWARD,
WHILE ANOTHER CONVEYOR BELT
UNLOADS STONE CHIPS
TO BE WEIGHED.
THESE CHIPS ARE NO LONGER
THAN AN 1/8 INCH.
THE RATIO OF SAND
TO STONE CHIPS VARIES
DEPENDING ON THE TYPE
OF PAVER BEING MADE.
THE WEIGH BELT TRANSPORTS
THE STONE CHIPS FORWARD
ALONG WITH THE COARSE SAND.
BOTH ARE EN ROUTE
TO THE SKIP HOIST.
THEY SPILL OFF THE CONVEYOR
INTO THE SKIP HOIST,
WHICH IS ESSENTIALLY
A BUCKET ON RAILS.
CABLES PULL
THE LOADED BUCKET UPWARDS.
IT STOPS ABOUT 30 FEET UP,
JUST ABOVE A BIG CONCRETE MIXER.
A TRAP DOOR OPENS AND DUMPS
THE SAND AND STONE CHIPS
INTO THE MIXER.
SIX GIANT STEEL PADDLES MIX
AND THEN ROTATE AND MIX AGAIN,
WHILE CEMENT
IS ADDED AUTOMATICALLY
THROUGH SEVERAL NOZZLES
ON THE SIDE
OF THIS ENORMOUS MIXING BOWL.
MAKING PAVERS
IS A BIT LIKE BAKING COOKIES.
TOO MUCH OR TOO LITTLE LIQUID
IN THE BATTER,
AND IT WON'T BAKE PROPERLY.
WATER IS ADDED UNTIL
THE CONSISTENCY IS JUST RIGHT.
NOZZLES ALSO SHOOT A PIGMENT
INTO THE MIX TO TINT IT.
THE MIXTURE
LOOKS DRY AND CRUMBLY,
BUT THE RECIPE GIVES IT
JUST ENOUGH MOISTURE
TO FORM THE CONCRETE.
NOW A FILLING WAGON
SPREADS THE MIX
OVER A STEEL MOLD CONTAINING
UP TO 50 PAVER-SHAPED CAVITIES.
THE MOLD PRESSHEAD APPLIES
11 TONS OF VIBRATING PRESSURE.
THIS PULSATING FORCE COMPACTS
THE MIXTURE IN THE PAVER MOLD
AND REMOVES ANY AIR POCKETS,
WHICH COULD WEAKEN THE PAVERS.
HYDRAULIC CYLINDERS
LIFT THE MOLD,
LEAVING THE PAVERS
ON THE PRESS BOARD.
THE PRESS BOARD SLIDES OUT,
AND THE MOLD ONCE AGAIN
GETS FILLED IN
AND MAKES ANOTHER
50 PAVER STONES.
IT ONLY TAKES ABOUT 10 SECONDS
TO MOLD, COMPACT,
AND RELEASE A BATCH OF PAVERS.
THE PRESS BOARDS FILLED
WITH PAVERS SLIDE INTO A RACK.
A HYDRAULIC CHAIN HOIST
LIFTS EACH BOARD
INTO A LARGE HOLDING RACK.
THERE, A SPECIAL MOVING WAGON,
CALLED A FINGER WAGON,
PICKS UP ALL THE BOARDS
FROM THE RACK
IN JUST ONE MOVE.
THE ELECTRICAL WAGON MOVES
ALONG A RAIL TO A CURING KILN,
WHERE IT'S ALMOST
100 DEGREES FAHRENHEIT.
THE PAVERS
ACTUALLY GENERATE THE HEAT,
DUE TO A CHEMICAL REACTION
FROM THE COMBINATION
OF CEMENT AND WATER.
ABOUT 12 HOURS LATER,
THE FINGER WAGON CARTS
THE PAVERS OUT OF THE KILN.
THEY ARE NOW 70% CURED AS
A RESULT OF THE CHEMICAL PROCESS
THAT BINDS THE CEMENT,
SAND, AND GRAVEL,
CAUSING THE PAVERS TO HARDEN.
THE REST OF THE CURING WILL
HAPPEN OVER THE NEXT 28 DAYS.
THE PAVERS
ARE NOW STURDY ENOUGH TO HANDLE,
SO FOUR STEEL ARMS
WITH RUBBER PADS MOVE IN
AND STRAIGHTEN THE STONES
ON THE BOARD.
THESE ALIGNMENT ARMS
ARE HYDRAULICALLY DRIVEN.
THEY ARRANGE THE CONCRETE PAVERS
SO THEY INTERLOCK SNUGLY.
NOW HYDRAULIC CLAMP ARMS
LIFT THE PAVERS OFF THE BOARD
AND BEGIN TO PILE THEM UP.
THEY'RE MAKING A CUBE OF STONE.
THIS STACKING MACHINE
IS CALLED A CUBER.
IT PACKS 9 OR 10 LAYERS
OF PAVERS ON TOP OF ONE ANOTHER
TO MAKE THIS CUBE.
THE CUBE
IS ACTUALLY CALLED A BUNDLE.
IT WILL BE STRAPPED
AND SHIPPED OUT TO THE JOBSITE.
THESE CONCRETE PAVERS
WILL BE ON THE ROAD SOON
BUILDING AND REBUILDING
OUR STREETS.
Narrator: PIANO KEYS
WERE ONCE MADE OUT OF IVORY.
THIS SOUGHT-AFTER MATERIAL
ISN'T USED ANYMORE
BECAUSE IT'S BANNED TO PROTECT
ELEPHANTS WHO WERE KILLED
FOR THEIR IVORY TUSKS.
PIANISTS NOW PLAY PLASTIC KEYS,
BUT THE TECHNIQUES INVOLVED
IN MANUFACTURING A PIANO
HAVEN'T CHANGED MUCH AND STILL
RELY ON HANDCRAFTSMANSHIP,
JUST LIKE A CENTURY AGO.
[ UP-TEMPO MUSIC PLAYS ]
BEAUTIFUL MUSIC IS A TRIUMPH,
BUT SO IS THE PIANO ITSELF...
...MADE OF INNER AND OUTER RIMS,
A SOUNDBOARD,
TREBLE AND BASS BRIDGES OVER
WHICH THE STRINGS ARE STRETCHED,
AND A HEAVY CAST-IRON PLATE.
TO MAKE A PIANO RIM,
AUTOMATED ROLLERS SPREAD GLUE
ONTO SHEETS OF HARD ROCK MAPLE,
COATING BOTH SIDES.
THEN THEY LAYER THE GLUE-SOAKED
SHEETS 5 TO 8 DEEP,
DEPENDING ON THE MODEL OF PIANO.
WORKERS FEED THE WET LAYERS
OF WOOD TO A RIM PRESS.
AN IMPACT WRENCH,
POWERED BY COMPRESSED AIR,
TURNS THE CLAMP SCREWS.
THE SCREWS BEND THE WOOD
INTO A PIANO RIM FORM.
THEY MEASURE THE PRESSURE
ON THE LAYERS
WITH A TORQUE WRENCH.
STEEL ARMS
REACH ACROSS THE WOOD,
HOLDING THE SHAPE
WHILE THE GLUE DRIES.
AFTER 24 HOURS, WORKERS LOOSEN
THE MACHINE'S GRIP,
AND THE RIM
NOW HOLDS ITS CONTOUR.
NOW IT'S INTO WHAT'S CALLED
THE CONDITIONING ROOM
FOR MORE DRYING OUT.
THE PIANO RIMS STAY IN THIS
WARM, ARID ROOM FOR 30 DAYS.
IT'S TIME TO MAKE
THE BRACING STRUCTURE.
THEY PLACE GLUED STRUTS
INSIDE THE RIM,
THEN APPLY PRESSURE
WITH A CLAMP.
THE FRAMEWORK REMAINS
IN THIS EMBRACE FOR AN HOUR
WHILE THE GLUE DRIES.
THIS PIANO WILL HAVE A TENSION
RESONATOR FOR EXTRA SUPPORT.
STEEL TURNBUCKLES
ATTACH TO A CENTER HUB.
A WORKER TIGHTENS
THE TURNBUCKLES WITH A WRENCH.
THEN HE THUMPS IT TO MAKE SURE
IT'S TIGHT AND WON'T RATTLE.
NEXT, THEY'LL INSTALL
THE SOUNDBOARD MADE OF SPRUCE
AND THE TWO BRIDGES.
STRINGS WILL STRADDLE
THE BRIDGES
AND TRANSMIT VIBRATIONS
TO THE SOUNDBOARD,
WHICH IS THE AMPLIFIER
OF THE PIANO.
A WORKER GLUES RIBS
ONTO THE SOUNDBOARD.
HE LOWERS WOODEN CLAMPS
OVER EACH RIB
TO APPLY PRESSURE
WHILE THE GLUE DRIES.
THAT TAKES ABOUT AN HOUR.
NEXT, HE THINS THE RIBS
AROUND THE EDGES
WITH AN AUTOMATED
STAGGER-TOOTH SHAPER CUTTER.
THIS WILL ALLOW THE SOUNDBOARD
TO RESONATE FREELY
WHEN THE PIANO IS PLAYED.
NOW THEY POSITION THE SOUNDBOARD
IN A BRIDGE PRESS.
THEN THEY PLACE
A BRIDGE-LOCATING FIXTURE
ON TOP OF THE SOUNDBOARD.
THIS DEVICE HOLDS THE BRIDGE
IN PLACE
WHILE IT'S GLUED
TO THE SOUNDBOARD.
AFTER THE TWO BRIDGES
ARE GLUED DOWN,
THEY LOWER THE SOUNDBOARD
ONTO THE PIANO RIM.
THEN THEY HOIST
A CAST-IRON PLATE ONTO IT.
IT'S A CRITICAL FITTING.
IF THEY DON'T GET IT RIGHT,
THE PIANO
WILL NEVER FUNCTION PROPERLY.
THEN THE PLATE IS REMOVED
FOR FINISHING.
A WORKER CUTS NOTCHES
IN THE BRIDGES,
WHICH ARE NOW TOPPED
WITH A LUBRICANT.
THIS VERY SHARP CHISEL
CUTS THROUGH THE HARD MAPLE
LIKE BUTTER.
EACH NOTCH WILL CRADLE
THREE PIANO STRINGS,
GIVING THEM THE FREEDOM
TO VIBRATE.
NOW THEY ROLL GLUE ONTO
THE OUTSIDE CASE OF THE PIANO,
WHICH IS MADE
OF ROSEWOOD VENEER ON MAPLE.
THEY FIT IT SNUGGLY
OVER THE RIM STRUCTURE.
A MECHANICAL CLAMP
HOLDS IT IN PLACE FOR AN HOUR
WHILE IT DRIES.
THEN THEY STAND THE ENTIRE PIANO
ON ITS SIDE.
SPINNING CUTTERS SHAPE THE ARMS
THAT SIT NEXT TO THE KEYBOARD
INTO AN ELEGANT CURVE.
THIS IS CALLED
A VERTICAL STROKE SANDER.
A WORKER RUNS IT
ALONG THE SIDE OF THE PIANO
TO SMOOTH OUT THE WOOD.
AFTER A BLACK POLYESTER PAINT
IS APPLIED,
THEY BUFF IT UP WITH
THIS ELECTRICAL CLOTH POLISHER.
THEN THEY HAND-RUB
A MIRROR GLAZE CREAM INTO IT
UNTIL YOU CAN
REALLY SEE YOURSELF
IN THIS HALF-FINISHED PIANO.
Narrator: TO PLAY A PIANO,
YOU NEED TIME TO PRACTICE
AND LOTS OF MONEY
BECAUSE A GRAND PIANO CAN COST
ABOUT THE SAME AS A LUXURY CAR.
AND LIKE A LUXURY CAR, WHEN YOU
LIFT THE TOP OF A GRAND PIANO,
YOU'LL SEE THAT A LOT
HAS GONE INTO ITS CONSTRUCTION.
[ UP-TEMPO MUSIC PLAYS ]
THE BASS AND TREBLE BRIDGES
ARE NOW FIXED TO THE SOUNDBOARD
OF THIS HALF-FINISHED PIANO.
THEN TO ADD GLAMOUR,
THEY SPRAY GOLD PAINT
ON THE CAST-IRON PLATE.
THE NEXT STEP
INVOLVES THE PIN BLOCK,
WHICH HOLDS ALL THE STRESS.
IT BEARS 45,000 POUNDS
OF TENSION FROM THE STRINGS
AND TRANSFERS IT
TO THE IRON PLATE.
HE DRILLS
INTO THE MAPLE PIN BLOCK,
THROUGH HOLES
IN THE IRON PLATE OVER IT.
THE HOLES
ARE FOR THE TUNING PINS,
HENCE THE NAME -- PIN BLOCK.
THEY UNFURL PIECES
OF STEEL WIRE FROM BIG COILS.
USING A VISE GRIP,
THE WORKER TWISTS THE END
OF THE WIRE INTO A NEAT LOOP.
THEN HE HOOKS IT
ONTO A HITCH PIN
ON THE BACK SIDE
OF ONE OF THE BRIDGES,
MAKING SURE IT RUNS BETWEEN
THE GUIDE POSTS OVER THE BRIDGE.
NOW HE THREADS THE WIRES THROUGH
ANOTHER GUIDE CALLED AN AGRAFE.
USING WIRE CUTTERS,
HE SNIPS THE WIRE TO
THE EXACT LENGTH THAT HE NEEDS.
THEN HE WRAPS THE WIRE
ON THE TUNING PIN
USING A DEVICE
CALLED A STRINGING CRANK.
HE TAPS IT INTO A HOLE
IN THE PIN BLOCK.
THEN, USING A PNEUMATIC HAMMER,
HE DRIVES THE TUNING PINS
INTO THE PIN BLOCK.
NOW THE STRING STRETCHES
FROM ABOVE THE BRIDGE
TO THE PIN BLOCK.
EACH STRING IS UNDER A TENSION
OF UP TO 425 POUNDS,
AGAIN, A FORCE
THAT WILL BE KEPT IN CHECK
BY THE HEAVY CAST-IRON PLATE.
NOW HE PLACES
LITTLE FELT-COVERED BLOCKS
CALLED DAMPERS
ABOVE THE STRINGS
TO STOP THEM FROM VIBRATING
WHEN A NOTE IS PLAYED.
USING PLIERS, HE MAKES PARALLEL
BENDS IN THE DAMPER WIRES,
SO THEY'RE ALIGNED.
HE POUNDS THE KEY FRAME,
CHECKING FOR GAPS
THAT COULD CAUSE KNOCKS
UNDER A PIANIST'S
VIGOROUS BLOWS.
HE SMOOTHES OUT THE GAPS,
SHAVING OFF BITS OF WOOD
WITH A STRIP OF SANDPAPER
ATTACHED TO A HANDLE.
NOW ANOTHER WORKER
PRESSES THE PIANO KEYS
IN BETWEEN STEEL GUIDE PINS
THAT HAVE BEEN INSTALLED
IN ROWS ON THE KEY FRAME.
SHE USES AN AIR CYLINDER
TO PUSH THE BACKCHECK
INTO THE END OF A PIANO KEY.
THE BACKCHECK IS A PIECE OF WOOD
COVERED WITH FELT AND BUCKSKIN
THAT WILL CATCH
THE PIANO'S HAMMER
AFTER IT STRIKES A STRING.
IT'S TIME TO MAKE THOSE HAMMERS.
SHE GLUES THE FELT-COVERED TOP
ONTO A THIN PIECE OF HORNBEAM,
A SPECIES OF VERY STRONG WOOD.
WHEN A PIANIST HITS A KEY,
IT WILL CATAPULT THE HAMMER
INTO THE STRING,
AND THAT PRODUCES A NOTE.
NOW SHE ALIGNS THE HAMMERS
TO BE PERFECTLY PARALLEL,
USING A PLASTIC SQUARE
AS A GUIDE.
THIS IS CALLED "SQUARING IT UP."
NEXT, SHE SANDS THE TAIL
OF EACH HAMMER WITH A FILE
SO THERE'LL BE NO SHARP EDGES
TO DAMAGE THE BACKCHECK.
THEN SHE ATTACHES THE HAMMERS
TO THE TOP OF THE KEYBOARD
WITH SCREWS.
NOW SHE PLACES WEIGHTS
ON EACH KEY
AND THEN GENTLY TAPS THE RAIL
TO GET THE HAMMERS MOVING.
SHE'S TESTING THE AMOUNT
OF EFFORT IT WOULD TAKE
FOR A PIANIST
TO PUSH EACH KEY DOWN.
THIS IS CALLED "THE WEIGH OFF."
AFTER SHE DETERMINES
HOW MUCH WEIGHT IS NEEDED,
SHE MARKS A PLACE
ON THE SIDE OF THE KEY
AND DRILLS ONE OR TWO HOLES.
SHE PLUGS EACH HOLE
WITH A PIECE OF LEAD.
IN A PROCESS CALLED SWEDGING,
SHE PUSHES A DIVOT INTO THE LEAD
SO IT EXPANDS
AND FITS SNUGLY INTO THE KEY.
THE LEAD WILL COUNTERBALANCE
THE WEIGHT OF THE HAMMERS
AND GIVE THE KEY
THE REQUIRED AMOUNT OF WEIGHT.
NEXT, THIS TECHNICIAN
CHECKS EACH HAMMER AND EACH KEY,
MAKING SUBTLE
MECHANICAL ADJUSTMENTS
SO THEY MOVE SMOOTHLY
AND FLUIDLY.
IT'S THE PIANO'S
FIRST BIG TUNE-UP.
HE FINE-TUNES THE HAMMER ACTION
BY USING A LET-OFF TOOL
TO ADJUST THE DRIVING MECHANISM.
THE PIANO IS NOW READY FOR
THE HANDS OF A SKILLED PIANIST
AND THE EARS
OF AN APPRECIATIVE AUDIENCE.
[ UP-TEMPO MUSIC PLAYS ]
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DISCOVERY COMMUNICATIONS, INC.
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