All language subtitles for S14E12 - Air Boats; Onions; 3D Metal Printing; Curved Cabinet Doors (1080p AMZN WEB-DL x265 Garshasp)_track3_[eng]

Narrator: an airboat
Is a flat-bottomed vessel

With a huge propeller
At the back.

All of the boat's mechanics
Are above the water line,

And just a bit of the hull
Rests below.

This makes the airboat
The preferred mode of transport

Through shallow water,
Particularly marshes and swamps.

[ engine turns over ]

To steer an airboat,

Large vertical rudders
Direct the propellers' airflow.

At full speed, an airboat
Can hit 62 miles per hour.

The boat's hull
Is made of aluminum

That's about
2/10 of an inch thick.

Workers stiffen
The hull's bottom plate

With aluminum "T" bars
Positioned 7 inches apart.

After they clamp the "T" bars,

A jig descends
To hold everything steady

As workers weld on the strips.

Next, they weld on
Aluminum sheets

To form the sides of the hull.

At the front, they push
The bottom up for welding,

Giving the boat a curved bow.

They complete the hull

By welding on a sheet across
The back to form the transom.

To that,
They weld a splash plate

That prevents water
From coming over the edge

Into the back of the boat.

Next, they weld various parts
To the front of the boat

To reinforce it structurally

And to create
A covered storage area.

Once that's done,

They screw a thick sheet
Of high-resistance polymer

To the bottom of the hull.

Should the boat scrape
Against a rock,

This layer will shield the hull
From damage.

Once that's secured,

They paint
The inside of the boat

With a blend of epoxy and paint.

This forms a layer
Of what they call "Webbing."

On the outside of the boat,

They apply a coat of primer

Followed by two coats
Of durable marine paint.

Meanwhile,
Others have constructed

And painted the boat's
Above-water structure

Out of steel or aluminum tubes.

The rigging,
As the structure's called,

Supports the mechanics,
Two fiberglass seats,

And the instrument panel.

They mount
A belt-driven reduction unit

To the boat's gasoline engine.

This unit
Reduces the propeller speed

In conjunction with
A preassembled set of gears.

Without it,
The propeller would turn

At the same rate as the engine.

This would exceed
The propeller's operating limits

And destroy it.

The engine is now ready

To take its place
At the rear of the rigging.

Heavy-duty bolts secure it.

Under the engine goes
A 50-gallon fuel tank --

At the very back,
An aluminum radiator.

Then they bolt the rigging
To the hull's "T" bars.

Next comes a floor panel
And a 3-passenger bench seat

With a storage compartment
Underneath.

The boat's exhaust system

Consists
Of stainless-steel pipe,

Which attaches with band clamps

To a header
Coming off the engine.

The other end leads
To a stainless-steel muffler.

From that, an exhaust pipe
Runs out the rear of the boat.

Next, they mount
The propeller guard,

A stainless-steel safety cage

That surrounds
The engine and propeller.

The three propeller blades
Are made of carbon fiber.

Aluminum rudders steer the boat

By directing
The propellers' airflow.

Cables or rods connect
The rudders to a control stick.

Smaller airboats, like this one,

Are ideal
For hunting and fishing.

There are also much larger
Pleasure models

That can carry 18 or more
Passengers on excursions.

Narrator:
Historians believe

Consumption
Of this common vegetable

Dates back to prehistoric times,
When it grew in the wild.

Man eventually learned
To cultivate onions,

And this strong-tasting
Plant bulb

Became a food staple
Of many ancient civilizations

Throughout the world.

In ancient egypt, the onion
Was an object of worship,

The inner structure
Of concentric rings

Symbolizing
The eternal circle of life.

Today mechanical harvesters
Pull the bulbs out of the ground

And lay them out in rows.

After drying for a day or two,

A tractor collects them
Into large baskets for storage.

To prevent spoilage,

The onions are stored at between
34 and 36 degrees fahrenheit.

When they arrive from the field,

Their first stop
Is a cooling tunnel

From which powerful fans
Remove the heat.

The vegetables
Take about five hours

To cool down
To the storage temperature.

The grower separates the onions
According to variety and size,

Then either bags them
For sale whole

Or sells them
To a processing plant.

At the processing plant,

Workers load the onions
On a conveyer

That leads to the peeling
And cutting stations.

A cutter chops off each bulb's
Top and tail simultaneously.

It also scores the skin
To prep it for peeling.

The onions then move into a
Custom-designed peeling machine.

It uses a combination
Of air and water pressure

To blow off the skin.

The onions then roll off
The peeler

And pass before quality-control
Workers

Who swiftly cut away bruises
And any other imperfections

As well as anything the cutter
And peeler might have missed.

The next machine
Rinses the onions

With cold, ozonated water
That kills bacteria.

Then the onions pass through
A metal detector,

Just as a precautionary measure.

At this point, there's a fork
In the processing road.

One direction leads to slicing,
The other to dicing.

On the slicing line,

Workers load the onions
Into tubes

That feed slicing blades.

These blades are adjustable
To output slices

Anywhere from 1 1/2
To 25 millimeters thick.

Workers gather up
The complete slices

And fill 5-pound plastic trays.

A conveyer moves the trays
Through a machine

That seals them
With plastic film.

The film
Has microperforations

Designed to allow in
Just the right amount of oxygen

To keep the onions fresh.

On the dicing line, meanwhile,

The onions collide head-on
With a rotary blade

That chops them to bits

Ranging from 3 to 25 millimeters
In diameter.

The diced onions then go
For a bath in cold water.

Chopping an onion
Releases juice from its tissue,

Paving the way
For bacteria to grow.

This cold-water treatment
Reverses the damage,

Restoring shelf life.

Next, an escalator
Transports them

From a spin dryer
To the packaging department.

There an automatic scale

Portions out the specific weight
They're packaging

In this production run.

When the target weight
Is reached,

A trapdoor swings open,

Dropping the portion
Into the waiting package.

Restaurants buy their diced
Onions in jumbo-sized bags.

The filling machine

Automatically
Forms plastic into a bag,

Adds a zipper closure,
Then seals the bag.

For grocery stores,

The factory packages
Smaller quantities

Of both diced and sliced onions
In plastic containers.

Kept in the fridge,
They remain fresh

For at least a couple of weeks.

For busy cooks, it's a
Convenient, no-tears time-saver.

Narrator: building complex
Shapes out of metal

Typically requires weeks
Of manufacturing,

Using tailor-made casts
Or precise machining techniques.

But 3-d metal printers
Are faster and cheaper.

They build objects

From successive layers
Of metal powder,

Which are then fused together
At high temperatures.

3-d metal printing makes it easy

To manufacture
Complex metal shapes

Using a fully automated process.

Every item starts with
A computer model of the object.

This is the build box in which
The object will be created.

A technician plugs in
Electric heaters

And pours superfine
Stainless-steel powder

Into the box.

The heat will keep
The metal powder from clumping.

He pushes the box
Into the machine,

Then fills the feed box with
More stainless-steel powder,

Which will be needed later
In the process.

The machine
Spreads the first layer

Of stainless-steel powder
In the build box.

Tubes carry a binding substance
To the machine's printhead.

This binder
Acts like a weak glue

And is injected in very narrow
Jets by the printhead.

As the printhead
Moves back and forth

Over the stainless-steel
Powder bed,

It deposits binder
At the exact locations

Specified by the computer.

As soon as the printhead

Has finished printing
A full slice of the object,

Powerful overhead heaters ensure
The layer is completely dry.

A roller applies
A new layer of powder

A fraction
Of a millimeter thick.

Then the printhead
Adds a new layer of binder.

This builds the object
From the bottom up.

The printing process
Takes several hours.

Once the layering is done,

They put the build box
In a curing oven

Heated to 350 degrees fahrenheit
For 24 hours.

This will evaporate all the
Moisture and harden the binder.

They vacuum out
The loose powder,

And the piece emerges,

Its stainless-steel particles

Lightly held together
By the binder.

They gently blow air
To dislodge any excess powder.

At this point,
The object is very porous

And contains about 40% air.

It is so fragile

That it can easily be crushed
With bare hands.

Using more
Stainless-steel powder,

They prepare another box

In which the piece
Will be infused with bronze.

They're making
A support structure

On which to rest the pieces

During the next phase
Of the process.

They carefully fill the box
With alumina oxide grit,

Which will support the pieces
During the infusion process.

This dam prevents the grit
From leaking out.

Now they pour in bronze powder.

The piece is then heated
In a furnace

At more than 2,000 degrees
Fahrenheit for 24 hours.

This melts the bronze,

Which then gets sucked up
Into the piece

Like water by a sponge.

Infused with bronze,
The piece is now solid metal.

They knock off the base
With a hammer.

It's taken just a few days

To build this intricately
Designed piece of hardware.

It can now be polished,
Gold-plated,

Or painted to match any decor.

Whether they build
Sophisticated door handles

Or fancy sculptures,

3-d metal printers work faster
Than conventional methods

At just a fraction of the cost.

Narrator: to create
Classic, elegant style

In a kitchen or bathroom,

Decorators typically use
Traditional materials

Such as wood and marble.

Curved cabinets
Can heighten that effect.

But their unique style
Comes at a higher price

Because, for the most part,
These elegant doors

Must be custom-ordered
And handmade.

Most cabinet doors produced
By this factory are custom-made.

They typically start out
As a sketch,

Which the factory transforms
Into a technical drawing.

They then use that drawing

To program the automated
Woodworking machines.

After cutting all the pieces
Of wood they'll need,

They run each one
Through a planer.

It simultaneously smoothes both
The top and bottom surfaces.

A cabinet door consists
Of a center panel

Surrounded by a frame.

This machine, called a molder,

Carves the frame's
Two vertical pieces

And cuts a groove on one edge

Into which
The center panel will fit.

To construct that center panel,

A worker feeds planks
Through a wood shaper

That bevels their edges.

The angle of the bevel is such

That when the pieces line up
Side by side,

They'll form a curve.

After trimming the pieces to
The length of the center panel,

Another worker runs them
Through a glue applicator,

Which coats the beveled edges
In adhesive.

Then she lines up the pieces
In an assembly fixture

That's been adjusted to the
Center panel's width and radius.

Once everything's positioned,

She applies clamps which force
The pieces tightly together.

The glue sets in 20 minutes.

Once the glue cures
To full strength,

The piece goes onto
A computer-guided router.

It rounds both sides
Of the panel

For a smooth, seamless look.

This particular door
Has a concave curve.

Others can have a convex curve
Or a crossbow curve,

Which is "S"-shaped.

The same router
Now automatically switches

To a different type of tool
And profiles the panel's edges.

It also carves a tongue

That fits into the groove
In the frame pieces.

The same machine
Can then load another tool

To engrave a custom motif

Or monogram
If the customer desires.

Next, a computer-guided sander
Smoothes out the panel,

Preparing the wood
For stain or paint later on.

Making the frame's
Horizontal pieces

Is more complex than making
The vertical ones

Because the top and bottom

Have to curve
Just like the center panel.

Workers coat thin slices of wood
With heat-activated glue,

Then stack them over
A curved form in a press.

The press squeezes the slices
Tightly together.

Then a high-frequency electrical
Current generates intense heat,

Triggering the adhesive.

The bonded slices exit the press

Looking like a solid,
Curved piece of wood.

Once the glue has set,

A computer-guided router carves
It to the same decorative style

As the vertical pieces.

It also miters the corners

So the horizontal
And vertical frame pieces

Will fit together seamlessly.

All that's left to do
Is glue the frame to the panel.

The tongue running along
The panel's perimeter

Fits neatly into the groove
Of each frame piece.

Workers now clamp
Everything together

And let the glue set
For a half-hour.

Then the cabinet door goes off
For painting or staining.

This factory produces
Curved cabinets

In 10 different types of wood

And dozens
Of colors and finishes,

Opening the door to endless
Design possibilities.

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

Captions paid for by
Discovery communications

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