28x07 - Nail Files, Birch Bark Canoes, Cruiser Boat Hardtops, High Voltage Circuit Breakers

[bunniefuu]

Narrator:
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


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


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.

Narrator: 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.

Narrator: a hardtop encloses
the c*ck 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 sh**t shredded
fiberglass strands into the mold

Along with a stream of resin
which saturates the fibers.

When the fiberglass is about


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 c*ck

Into a weather-protected lounge.

Narrator: 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.