All language subtitles for S07E01 - Footballs; Electric Guitar Amplifiers; Marbles; Airplane Propellers (576p AMZN WEB-DL x265 Garshasp)_track4_[eng]

Narrator:
Today, on "How it's made"...

Footballs...

...Electric-guitar amplifiers...

...Marbles...

...And airplane propellers.

In 1869, players in the first
Football game used a round ball,

Like in soccer.

It was tough to carry
And awkward to throw,

So they changed it
To look more like a watermelon.

The current shape
Enables a better grip

And passing on an arc
That's unique to football.

A lot of people
Handle a football

Before it ever gets
To the field.

They start with cowhide.

Footballs are traditionally
Made of this leather

Because it wears well over time.

With a die, a worker cuts out
The four sections

That make up the ball's skin.

A stamping machine then brands
The skin with the company logo.

They may put other markings
Elsewhere on the ball,

Depending on the design
Of the model they're making.

Each of the sections
Goes into a machine

That trims the pieces'
Combined weight down to spec.

To strengthen the skin,

A seamstress
Sews cotton and vinyl linings

Onto all four sections.

Then she places them in a die

That positions them
For another set of markings.

These four white lines
Will form two stripes

When the sections come together.

This is purely aesthetic

And varies according
To the football model.

Now it's time to sew
The top sections together

And then the bottom ones
To each other.

Exactly how many stitches
This takes

Is this company's
Closely guarded secret.

This press makes a hole
In one of the top sections

For the air valve.

They make eight holes
In the top sections

For laces that will hold
The skin tightly

Around an inflated bag
Called a bladder.

To join the ball's
Top and bottom sections,

The seamstress first cups them

And then joins
The edges together.

She sews the leather inside out

To make the stitches
Less visible.

Later, workers will turn
The skin right-side out

By reaching through the opening
Between the lace holes.

This is also where
They'll insert the bladder.

It's important
To flatten the four seams.

To do this, a worker places
Each one on a wheel,

As a roller
Passes over the top.

This keeps the ball
From being bumpy

When they stretch the skin
Over the bladder.

A 15-second steam
Softens the leather

And makes it easier
To manipulate.

A concave press
Flattens the seams at the tips.

This will also keep the ball
Smooth when they inflate it.

Time to turn the skin
Right-side out.

The worker places it
On a metal bar,

Then, reaching through the
Opening between the lace holes,

He grabs the other side of
The skin and pulls it through.

Then he runs the bar
Along the inside

To reshape the skin.

The bladder is made of
Polyurethane, a type of plastic,

With a vinyl patch
Reinforcing the lacing area.

After squeezing the bladder
Inside the skin,

A worker snips off
The end of the air valve

To keep it out of the way.

Then she inflates
The bladder a bit

To make it rigid enough
For lacing.

After steadying the ball
With clamps,

She uses an awl to thread
The lace through the holes --

Just one vinyl lace,
Measuring four feet.

It worms through both sides
And then down the center

And through all the holes
Once again.

The lacing is spaced
About a half inch apart --

Wide enough to comfortably grip

For that magic pass
You've got in mind.

Next, workers temporarily
Overinflate the balls.

Steel molds surround them

To ensure they'll assume
The correct shape.

After 90 seconds,
The extra air seeps out.

Finally,
The factory inspects the balls

To ensure
They're up to standard.

Fully inflated, a ball must
Weigh no more than 15 ounces.

It should measure 21 1/2 inches
Through the middle

And 28 inches around both ends.

After a five-day
Manufacturing process,

These balls are ready
For the field.

Narrator:
You have to plug an electrical
Guitar into an amplifier

If you want it to be more
Than barely audible.

A guitar amplifier
Is typically a boxed unit,

Containing an amp
To boost the electronic signal

And a loudspeaker.

Some amplifiers

Use state-of-the-art
Silicon-chip circuitry,

While others
Use traditional vacuum tubes.

The amp's electronics are housed
Inside a metal chassis.

This model's chassis is made
From a sheet of metal

That's less than
.04 inches thick.

A computer-guided machine
Called a turret punch

Cuts the contour

And pierces a series
Of holes and slots

For the controls.

A worker then uses
A computer-guided bender

To shape the chassis cutout.

Elsewhere in the factory,

The amp's circuit board
Takes shape.

It'll go inside the chassis.

A computer-guided drill
Makes tiny holes

In a laminate board
That's coated with copper.

The holes are for the board's
Various electronic components.

An automated silk-screen printer

Now applies a diagram
Of the electrical circuitry

In ammonia-resistant ink.

Then the board goes
Into a machine called an etcher,

Which uses ammonia
To dissolve the copper coating.

Copper shielded
By the ink diagram stays intact.

The machine
Then rinses the board

With sodium hydroxide
To dissolve the ink,

Leaving behind just the
Circuitry diagram and copper.

This copper configuration
Will conduct electricity

To the circuit-board components.

Automated machines
Insert the smaller components.

Here's what that looks like
In slow motion...

...And at actual speed.

As a worker provides
Counterpressure,

A machine folds over the leaves
Of some larger components

To secure them to the board
Until they're soldered.

Workers then install large,
Irregular parts by hand,

Among them --
The sockets that hold the tubes

Which power the amp...

...The ribbon connecters

That join different areas
Of the circuit board...

...And the wires
That connect external components

To the board.

The factory permanently affixes
Everything in one shot,

Using a process
Called wave soldering.

The circuit board runs through
A bath of molten tin and lead.

In just a couple of seconds,
The liquefied metal hardens,

Bonding the components securely.

Back to that steel chassis

We saw them bend
Into shape earlier.

Since then,
They've painted it black.

With a silk screen printer,

They apply the control markings,
Logos, and other information.

They begin the final assembly.

First, they screw the
Circuit board into the chassis.

Then they plug the preamp tube

Into the appropriate socket
On the board.

This tube boosts the electrical
Signal coming from the guitar

And feeds it
To the output tubes,

Which up the voltage level,

Making the signal
Stronger and louder.

After installing control knobs

And covering the bottom
Of the chassis,

Workers insert
And clamp the output tubes,

The number of which
Usually varies

According to
How many watts of power

The amp is designed to produce.

The chassis housing
The electronics goes into a box.

This factory builds its boxes

From high-grade
Baltic birch plywood,

But other companies
Often use domestic plywood, mdf,

Or even plastic.

After covering the box
In leatherette

And adding
Corner reinforcements,

They install
The two remaining components --

The spring reverb...

...And the speaker.

As the guitar's electrical
Signals run through the amp,

Part of the electrical signal

Diverts to one end
Of the spring, vibrating it.

The spring's other end
Picks up this vibration

And sends it back through
The amp as a delayed signal.

That reverberation combines
With the original signal

To produce a bigger sound.

Narrator:
People have been playing

With small balls
Of stone, clay, or marble

Since ancient egyptian
And roman times.

Today's marbles
Are actually made of glass

And used for industrial tasks
As well as games.

Glass is not only
Inexpensive and durable,

But also quite beautiful.

To make marbles,

This company melts recycled
Glass with marbles made earlier

But rejected
For being the wrong size.

All this goes into a kiln

Heated to 2,200 degrees
Fahrenheit.

After 16 hours, they open a door
At the bottom of the kiln,

And the molten glass flows out.

A shearing device cuts
The stream every half a second,

Forming segments called slugs
That become marbles.

To make different-sized marbles,

They adjust the device to cut
At shorter or longer intervals.

The slugs slide down chutes,

Landing between grooves
On spinning cast-iron rolls.

The spinning keeps the slugs
From sticking.

They'll need 72 hours
To cool completely,

But their final appearance
Is already set.

That was determined
Back in the kiln,

When the airflow
Drove the heat

To melt the glass
And mix the colors.

These channels separate
The good from the bad.

Openings along the way

Weed out the ones
That are too big or too small

And collect the ones
That are just right.

More intricate marbles
Are handmade.

This craftsman first preheats
Some clear glass

In a small oven.

Then he breaks off a piece
Of colored glass.

After the clear glass has melted
In the furnace overnight,

He gathers some on a steel rod

Then picks up a chunk of
Preheated colored glass with it.

He forms a knob and works
The mass into a long string

That's up to 16 1/2 feet long
And thin as a noodle.

He'll use them in various colors

To decorate the clear glass
Cores of the marbles.

He gathers a clump
Of melted clear glass on the rod

And shapes it
With wet newspaper,

Which won't stick to hot glass.

After shaping the end,

He rolls the clump on several
Preheated colored glass strings.

Then it's back in the furnace.

He repeats these steps
Up to three times

And rolls the clump
On a metal table

To even out the surface between
Each trip to the furnace.

Then he adds a layer
Of clear glass on top.

With another tool now,

He stretches the clump
To about 1 1/2 feet long.

He'll use this
To make several cores.

To make the second layer
Of the core,

He rolls a 2-inch-long segment

Onto colored glass slivers
Called ribbons.

After rolling them
In the furnace to melt them,

He flattens the ribbons
With pliers

And snips off the excess
At the ends.

He wraps the core
And the ribbons

In a layer of clear glass,
Then hand-shapes it.

Now he rolls the core
On more glass strings.

Then it's back in the furnace
To meld them.

He adds one more
Clear glass layer,

And the inside is finished.

That's a total of six layers
For this marble.

Other models have fewer or more.

The craftsman shapes the glass

With several metal
And wooden tools.

He measures the diameter
With metal calipers

And gradually sculpts a sphere.

He'll make up to five marbles
From this segment,

Ranging up to the size
Of a golf ball.

After scoring the glass
With a knife,

He places it in the open end
Of a pipe to hold it.

Then he gently taps the rod,

Which breaks the glass
And releases the sphere.

He melts away the bump left at
The spot where the glass broke.

Next, the marble goes
Into an oven

At 986 degrees fahrenheit.

The oven slowly cools overnight
To strengthen the glass.

Clearly a cut above,

This eye-catching,
Handcrafted marble

Is already an object of art.

Narrator:
An airplane propeller usually
Has two, three, or four blades,

The angles of which
The pilot can adjust

In response to airspeed
And flight conditions.

A propeller's main parts
Are made of aluminum

Because it's critical to keep it
As lightweight as possible.

The blades and hub are made
Of aerospace-grade aluminum

That resist corrosion
And metal fatigue.

The propeller's blades
Attach to a hub.

This piece of aluminum is
On its way to becoming that hub.

Like the starting pieces
For all parts,

It was forged beforehand

Into a rough version
Of the final shape.

This sophisticated,
Computer-guided mill

Now machines the piece.

40 minutes later,

The hub is finished and ready
For assembly to the engine.

This roughly shaped piece

Is about to become
One of the propeller's blades.

A computer-guided lathe
Machines it to the final shape.

Liquid lubricant washes away
The metal shavings

And cools
The friction-generated heat.

The lathe first forms
The shank --

The end of the blade
That fits into the hub.

The next milling machine
Cuts the blade's shape.

Now the finishing steps --

Done manually
Because they require a keen eye.

Workers use a rotary sander,

Then a belt sander
To grind away the marks

The machining process
Left behind.

They buff the metal
With a polishing wheel...

...Then clean the blades

By dipping them
In a strong detergent.

This acidic solution eats away
Any dirt, oil, or grease

On the surface of the metal.

After that, they dip the blades

In a bath of water
And chromic acid.

This seals the pores
In the metal,

Fending off corrosion.

The factory tests all critical
Parts for surface defects

By dipping them
In a fluorescent solution

That leaches
Into any imperfections.

After rinsing,
An inspection under black light.

A blue glow means
The parts are a-okay.

Any imperfections show up
As bright, fluorescent green.

The defective part
Is either repaired

Or rejected
From the production line.

Blades that make the cut
Move onto the paint shop --

A coat of black on the back side

To prevent sun reflection
Into the pilot's eyes

And stripes for safety,

To make
The spinning blades visible.

Next comes a de-icing boot --

A rubber-encased
Electric heating element

That prevents ice buildup.

The rubber is highly durable,

Yet flexible enough to mold
To the curve of the blade.

Next, they lubricate a part
Of the blade shank with grease,

Then install a strong
Steel-ball-bearing system.

This will hold the blade
Securely in the hub,

Yet still enable it to pivot
To change its angle.

The shanks of the three blades

Fit right into this steel part
Called the fork.

It keeps all the blades
At the same angle.

Now for what's called
The pitch change rod.

The term "Pitch" refers
To the angle of the blades.

Engine oil will exert
Hydraulic pressure

On a piston that moves
The pitch rod,

Which advances the fork,

Rotating the blades
To the required angle.

After removing the
Pitch change rod temporarily,

They apply sealant
To the top half of the hub

And place it
Over the bottom half

That contains
The ball-bearing set.

A rubber o-ring seal,

Then a sturdy spring to provide
The required counterpressure.

Workers thread and torque the
Piston and pitch change rod --

Now attached to each other --
To the fork.

Another rubber o-ring --

This one to prevent leaks
Out of the top of the cylinder

That will contain
The engine oil.

They use a special tool

To tightly torque the cylinder
Down against the hub.

With assembly complete,

This propeller is ready to be
Installed on today's airplanes.

--captions by vitac--
Www.Vitac.Com

Captions paid for by
Discovery communications, inc.

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