All language subtitles for Modern.Marvels.S23E06.Super.Sharp.Saws.1080p.WEB-DL.DDP2.0.H264-BTN_track3_[eng]

- [Narrator] Table,
circular, chain or jig,

it's one of the most
essential tools in the world.

A truly cutting edge technology

worth over billions of dollars.

- We've a lot of mills

all over the United States.

- [Narrator] From humble,
prehistoric origins,

through medical discoveries
and industrial revolutions.

This tool's ability to
both create and destroy.

Have made it a cornerstone
of human achievement.

Better stay sharp because
you'll never hack through wood

the same way again.

With saws on Modern Marvels.

[saw blade purring]

[upbeat music]

[metal clinking]
[water bubbling]

[saw machine purring]

It's an 800 pound behemoth

and it's loose in the
Washington state forest.

Spinning at a blinding
200 miles per hour.

It's taking down
everything in its path.

[saw blade purring]

It's the circular saw blade
on the John Deere 959J

and it means business.

This blade, which at close range

sounds more like a
jet engine than a saw.

Takes one second to blow through
an 18 inch diameter tree.

It's carbide teeth are bolted
to a huge circular blade.

That dishes out punishment
for up to 10,000 hours.

Cutting down as many
as 2 million trees

before workers have
to swap it out.

- It's a hardened steel blade

that is balanced during
the manufacturing process,

much like the flywheel on an
engine or the tires on your car

so that it spins freely
and spins and balanced.

- [Narrator] The Circular
Saw is recognized

as the most useful,
popular and versatile

of all the power saws.

Spinning at 1200 RPM,
this huge saw blade

severs a tree completely before
the grab arms grabs them.

- If you actually clamp
onto a tree and cut it,

you can induce some
stress into the tree

and actually cause some
damage to the tree.

And as a result, you're
never clamping onto the tree

until after it's cut.

- As soon as you see
the first chip flying,

you have to be
closing your grab arms

instantly otherwise
you are dropping trees

where you don't want them.

- [Narrator] Forest harvesting

the process of cutting
and clearing a forest

employs the use of various
heavy duty machinery.

The 959J rig is one of
these massive machines,

commonly called
a Feller Buncher.

And a Feller is someone
who cuts down these trees.

The Feller Buncher is
used to cut and gather

several trees at once.

The Feller Buncher specs;
90,000 pounds, 294 horsepower,

hydraulics that tilt the cab
and an 8,700 pound cutting head

that rotates 310 degrees.

Its power is used to
service one thing.

Finding a way to
level that blade

into fresh wood
cleanly every time.

A skilled Feller
Buncher operator

like Dale Stoken
is a multitasker.

Maneuvering and
stabilizing his machine

on steeps slippery grounds
as he chops down trees.

Threads them through the
canopies obstacle course

and piles them like
so many matchsticks.

With this $600,000
Feller Buncher,

Dale can cut down anywhere from
a 100 to 200 trees an hour.

But how do you stay safe
while you're harvesting trees

as tall as a 20 story building.

- These polycarbonate windows
are literally bulletproof.

And so they're meant to
withstand the impact from debris

and trees that that may come
down out here in the woods.

- Well, I haven't had any
trees fall on this machine yet

tops, rotten pieces,
snakes, a lot of dead wood

in the stand of timber.

They bang on it, but it's
built pretty heavy duty.

- [Narrator] Ultimately
the key to Dale's safety

is knowing his limits.

- A lot of times we have timber

that's too big for the
Buncher, can't handle it.

And the steeper ground
like, on the backside here,

he's not gonna be able to get
in here with that machine.

He slides around too much.

- Dale leaves the job
to the crew on foot

to cut down the trees

with an entirely
different kind of saw.

A steel MS 460 chainsaw.

This chainsaw's motor
engages a Sprocket

that drives the cutting chain.

The saw chain is comprised

of alternating left
and right cutters.

Each tooth is capable of
cleanly slicing off a chip.

But if the cut is incomplete,

the opposing cutter
will finish the job.

Severed chips are carried
away through the chip channel

to be ejected at
the end of the cut.

[saw blade purring]

With chainsaw in hand,
a skilled logger,

will take down a tree
like this Western hemlock

in about 30 seconds.

- You start as what's
called, your top cut

and you start your saw here.

When you're finished
with your top cut,

you get behind your saw

and you look down
the site of your saw

out there, 50 to 60 feet

and sight in on
something out there.

And that will determine
where your tree's gonna lay.

Then as your slope cut,

you can come up underneath
and you gotta match up

your slope cut with
your top cut perfectly.

- [Narrator] The last
cut, the back cut,

actually fells the tree.

- You want to be an
inch to two inches

above your original undercut.

And with an even hinge wood.

Hinge wood is what's considered
the wood that's left,

which actually steers
the tree in the direction

you're falling in.

If you're falling
this tree this way

and it brushes another tree
or an object out there,

the force of that tree
springing can spring back

and actually push that
tree back on the stump.

I've seen him come back,
20 to 30 feet back up

through the timber before.

If it hits something, it'll
come up against that step

that you're gonna
have back here.

And that step of wood will
hold that tree upon the stump.

- [Narrator] Everything
about this job

from falling timber to
the saws is dangerous.

- We had a guy get
hurt a few years ago.

He didn't get cut with the saw,

but he got smashed by a
top came out of a tree

and smashed him
and broke his back.

- [Narrator] With all the
sound and furry of power saws,

it's easy to miss
some of the subtleties

of what makes a saw a saw.

For that it helps to take
a look at a simpler saw.

The panel saw, also
known as a hand saw.

Of course the defining
feature of a saw is its teeth.

- It's got separately
formed teeth

that cut into the material
and sliced the fibers away

so that it cuts very, very
quickly through the material.

- [Narrator] Saw teeth are
only sharp on the forward edge,

the cutting edge.

They're also raked, inclined
in the direction of the cut.

- On all western hand saws,

the teeth all basically point

in the same direction, forward.

That's because these saws

are de designed to cut
on the push stroke.

And when you pull the blade
back, the saws isn't cutting.

- [Narrator] And for every
tooth, there is a gullet.

- The gullets are the
spaces between the teeth

and these spaces are
allowed to fill up

with the material
that's being cut away.

It's called swarf.

The swarf builds up in
these little gullet.

And then soon as the blade exits
at the bottom of the board,

the swarf just falls out
of the Gus and falls away.

- [Narrator] The last
key feature is the kerf.

The width of any saw
cut is known as the kerf

and it's worth knowing
this measurement

to get the most accurate cut.

- The actual cutting
edge creates a wider kerf

than the thickness of the blade.

So the blade has clearance
and doesn't stick in the kerf.

- [Narrator] Despite all
these design features,

there's still plenty
of skill involved

in making a clean
cut with a hand saw.

[gentle upbeat music]

- Now the whole trick to
getting a nice clean cut

is starting off with
a nick on the edge.

But I'm gonna use my thumb

to keep the saw from
moving sideways.

And I'm just gonna pull
backwards a little bit

to create a starting
groove for the saw blade.

Now I'm gonna bring the angle,
my saw to about 45 degrees.

[handsaw chittering]

I'm gonna start sawing.

I lift the saw slightly as
I go on the reverse stroke,

so the teeth aren't dragging,

keep sawing until I
get right near the end.

I gonna get this close.

What I'm gonna do is I'm
gonna hold this piece.

I'm gonna slow down.

I'm gonna saw very
gently at the very end

to avoid tearing out the corner.

There's my cut.

- [Narrator] But not all saws
has cut on the push stroke.

- Japanese saws, all
cut on the pull stroke.

Japanese saws are
very, very thin.

When you have a thinner saw,

that means you have to remove
less wood to make the cut

so they faster.

- [Narrator] Western
saws have thicker blades,

so they won't buckle on the
more powerful push stroke.

Japanese pulls saw are
designed to cut softer woods.

- The reason we
wanna work this low,

we want to be able
to use our foot

to hold the work piece down

and then use both
our arms on the saw

to get lots of power to the cut.

Now, at the end of the cut,

I slow down a little tiny
bit, that comes right off.

[handsaw chittering]

- [Narrator] East or west,
modern saws are efficient.

But they're most
ancient ancestors,

prehistoric flint
saws, Circa 8,000 BC.

Were thick and jammed
in the cutting groove.

Around 4,900 BC, Egyptians
and Mesopotamians

fashion the first metal saw

with relatively soft
metals, like copper.

- And naturally they could
only cut very, very soft woods.

Then we basically
progress to a point

where we use harder
and harder materials.

Bronze and bronze alloys
that have the ability

to hold a little bit
of a better edge,

right up until we get to iron.

And of course, iron is
where we make a major leap

into tools that
were really capable

of doing some
pretty serious work,

felling trees and cutting
up very thick logs.

- [Narrator] The
saw of the Iron Age,

roughly 700 BC to 50 AD.

Incorporated two breakthroughs;

teeth that were raked in
the direction of the cut

likely in Egyptian innovation

and from the Romans, set teeth
bend to the left and right

that created a kerf.

The 19th Century brought
widespread use of steel.

Giant crosscut saws
soon replaced axes

for the job of cutting down
the old growth forests.

[tree thuds]

Ah saws, they're
used to cut down trees

and to slice and chop wood.

The modern chain
saw packs the power,

but is still popular
choice today.

It's lighter and more
flexible and commonly called,

the saw that sings.

Is a crosscut saw.

They become much scarcer
than they were in 1939.

With their large teeth designed
to cut in both directions,

These saws are still considered

the most efficient cutting
tool in the forest.

- It's called a misery whip.

They nicknamed that
because listening to it,

whip back and forth
through the trees

and pulling it like a whip.

And by the end of the
day, it was miserable.

So they would take an
axe, chopping undercut

in the front of the tree,

whichever direction
they wanted it to go.

And then they would start
with the crosscut saw.

If you had a tree that
was 15 feet in reality,

you had to have a 20 foot
or larger Misery whip saw.

You were pulling a lot
of steel through there.

- Just hold that.

- Lot of work.
[Calvin laughs]

Now that ain't bad.

Just a lot of pulling.

- You ready Hoss?
- Yeah.

- Timber!

- [Calvin] This saw right here

is the reason they always said

would never be
able to cut it all.

You never would
to what this saw.

[Calvin laughing]

- [Narrator]
Luckily for loggers,

if not for the
forest environment,

the two man crosscut
saws day has passed.

But for timber sports
competitors like David Moses

and his wife, Annette from
Snoqualmie Washington,

this old school saw
presents an opportunity

for them to show their skills.

David's father trains them.

- Timer's ready,
contestants ready!

One, two, go!

[saw blade chittering]

- This is a modified
peg and raker.

And the way these cutters are,

they'll make two cuts on
either side

of the wood,
which will make a line.

And then this ranker come
through and push underneath that

and it'll pull out a noodle.

And the longer the noodle,
generally the faster the cut is.

- [Narrator] But these teeth
that make the saw sharp

also make it dangerous.

Annette had a painful
reminder of this

while competing in July, 2006.

- We were coming back.

We were coming off
towards the bottom

and we went right
across my knee.

And somehow it moved,
just came right across,

ended up with 22 stitches.

- [Narrator] But it wasn't the
end of Annette's competitive.

- In fact, we kept going
and then when we were done,

I went to the hospital.

Came back and single bucked.

We're a different breed.

- [Narrator] And this chainsaw
is also a breed apart.

Few saws are as fast and as
dangerous as David's hot saw.

A stock chain saw that has been
modified for maximum power.

- This is a hot saw.

And it's a Rotax hot saw,

which is half a snowmobile,

twin cylinder snowmobile engine.

- [Narrator] You heard right?

He said snowmobile.

This $5,000, 35 horsepower
hot saw, runs on racing fuel.

Has a motorcycle exhaust pipe,

weighs in at 50 pounds and feels

nothing like a stock chain saw

that would've just
1/6 the power.

- There's just a
tremendous amount of force.

So it takes some
getting used to.

So the first year I was a
little bit scared of it.

You don't wanna stand at
the front end of the saw

because there's possibilities
of any of the teeth

breaking off and shooting out at
the end,

which can come
off like a bullet.

- [Narrator] In action,
the saw lives up

to its powerful billing.

Do not try this at home.

- Timer's ready!

Contestants ready!

One, two go!

[power saw revving]

- 8.53 that's with three cuts.

So that's with his
practice chain, not bad.

The modern lumber mill.

Its basic components haven't
changed in a hundred years,

but the heart and
soul of the mill,

the saws are thinner,
sharper, stronger and faster.

Dahlstrom Lumber Mill
in Hoquiam Washington

is a big log mill.

It handles, well, big logs.

- Generally that means a log,

maybe over 20 inches
on the small end.

We can run up to five foot
from the log through our mill.

- [Narrator] As these
large Western hemlocks

roll into the mill.

The first saw they
face is a deck saw.

- The deck saw we have
here is a chainsaw.

Basically like every chain saw.

This one has a
bigger teeth on it.

It's got an eight
foot bar on it.

It's capable of cutting
logs up to over five feet.

- [Narrator] The
chainsaw bucks the logs

or in layman's terms,
cuts them to length.

Then the operator runs
them through the debarker,

which preps them
for the head rig.

A steel bandsaw that
does most of the job

of sawing logs into lumber.

- And the band is actually
35 feet in length.

The rim speed or the
speed of the blade

is about 8,800 feet a minute
or a hundred miles an hour.

- [Narrator] This large
bandsaw turning on

six foot diameter wheels is
the workhorse of the mill.

It's large enough
to cut the big logs.

It's more energy efficient
than a circular saw.

And it slices a thinner
curve than a circular saw.

Cutting back on wood waste.

As the log approaches,

the head Sawyer attempts to
slice the most high grade

or appearance grade lumber
out of the outside of the log.

A laser helps the Sawyer
to place the bandsaw.

The cants sliced boards
that have not been edged

rule down the conveyor
belt towards the edger.

- Every saw in the
edger is identified

on that table with
a laser light.

So the operator knows if
he sends that piece of wood

in there exactly
where it would be cut.

- [Narrator] A 250
horsepower motor

drives a bank of six circular
saws, spinning at 1,750 RPM.

The blades are expensive and
require constant maintenance.

- Friction builds heat

and heat is like the enemy
of the saw blades or steel.

It warps and distorts it.

So you gotta keep
your saw blades cool.

Our band mills and our
edge are water cooled.

As you saw, waters is
sprayed on the blades

to help keep it cool.

- [Narrator] In addition,
carbide cutting teeth,

which are wider than the plate,

curve out kerf for
the saw is spin.

Friction is also the
enemy of the bandsaw.

- When you get a bandsaw hot,

it can possibly leave the wheel.

It distorts it so bad and
it can walk off the wheel.

[upbeat music]

- [Narrator] To
maintain the bandsaws,

a saw pier sharpens
and widens the teeth,

so that they'll cut
a broad enough cut

for the blade to run cleaning.

- This is called wedging.

It's how we make
the saw teeth wider

than the plate of the saw.

This turns and it
forces the metal up

to the point of the tooth,

which makes it spread out
and wider than the plate.

And then we shape it back
and then grind it sharp.

And it's ready to go.

- [Narrator] With the
help of their dog, Marius

John and Laurel Robarge run
the blade maintenance shop

at Dahlstrom lumber.

As they sharpen the blades
over several months,

they will grind the
width of each blade down

by a couple of inches.

This process extends
the life of the blades,

but eventually makes
them too narrow to use.

Heat also causes blades to warp.

- You'll get these hot
spots and it'll expand.

And then your saw starts
wobbling in there.

[metal clinking]

And then we get 'em after that

and you just sit and you bench
'em until the lumps are out

and the teeth are sharp.

Benching is basically what
I'm doing on this anvil.

Making sure that if
you got high spots

that you gotta pound
them back down.

- [Narrator] As the
lumber leaves the mill,

it's on its way to
becoming an essential part

of some kind of structure.

But one day that structure
may face remodeling.

When that time comes an
entirely different saw

the Milwaukee Sawzall
will be there.

The Sawzall is a
reciprocating saw.

A power saw with a blade

that moves back and
forth during cutting.

The Sawzall aim is to
live up to its name.

- What can't you
use Sawzall for,

from cutting birthday
cake, to lumber,

to demolition, to
fire and rescue to...

I even knew a guy
he talked about,

he wanted to get rid of a stump.

So he actually used it
to cut down in the ground

to cut the roots of the stump
so he could pull it out.

- [Narrator] The Super Sawzall

is the top of the
Milwaukee line.

And includes orbital
cutting action.

- Normally a
reciprocating action

is straight back and forth.

Orbital cutting is
more of a circular cut,

it's a much more aggressive cut.

Now have a unique
feature to Milwaukee.

It's a 360 degree
rotating handle.

This is nice 'cause it
allows the contractor

to adjust the handle to the
most comfortable position.

Generates zero to 3000
strokes per minute.

So it's literally the fastest

reciprocating saw on the market.

- [Narrator] The
Sawzall has no problem

cutting through wood
screws and nails.

Even the steel
hinges on this door.

- The Sawzall was
introduced in 1951

and originally developed for
plumbers and electricians.

And actually what
they were looking for

was compact, durable,
lightweight solution

to cut basically anything
that they ran into.

- [Narrator] The
original Sawzall

was a heavy all metal tool.

Today's version, incorporates
plastics and nylons

for lighter weight and
vibration dampening.

This Super Sawzall in its blades

are made at a Milwaukee
Electric Tool Plant.

Which is not in Milwaukee.

- And Greenwood, Mississippi,

the heart of the Mississippi
Delta, catfish and cotton.

The building itself is
150,000 square feet.

It may send a thousand
Sawzall a year.

- [Narrator] The key
to making a machine

that's always just
about anything,

is manufacturing blades
for all types of materials.

- The blade we're looking
at now is for metal cutting.

And the reason we know that,
because the teeth are finer.

There's more TPI
or Teeth Per Inch.

Because you don't wanna have

it's aggressive bite when
you're cutting metal.

Comparing it to wood, you
can take a heavier cut,

a larger chip because
the wood is softer.

Then on metal you have
to have a finer tooth.

As you see on this blade,

the tooth is much different
from the previous one.

It's much larger.

The angles are different.

The depth of the
gullet is different.

And this one is designed
for a very aggressive

sheetrock and plaster cutting.

- [Narrator] There were no saws

involved in the
manufacture of saw blades.

The teeth are ground in.

- The blade process
begins with the uncoiler

with a coil of steel.

The encoiler, encoils it
into the straightener.

The blade material
is straightened

prior to going into the press.

Once it gets into the press,

the blades are stamped
out to the configuration

of the blade itself.

Once they are loaded
off of the press,

the blades are accumulated
into handfuls sort of robots.

The robot swings over,

picks it up and loads
into the grinder.

- [Narrator] A
ceramic grinding wheel

grinds the saws tooth pattern
into a pack of 90 blades.

The grinding wheel forms
and sharpens the teeth

as a mixture of
water and lubricant

washes metal filings away.

Workers then load the
blades into furnaces

to temper the metal in
order to retain its hardness

and its flexibility.

The National Cathedral,

the Empire State
Building, the Pentagon.

They all have one thing in
common, Indiana limestone.

- What's unique about
Indiana limestone

is its ability to be worked.

It's a soft stone
relative to limestone.

It's very consistent in color.

For that reason it's been
chosen as a building stone.

- [Narrator] The stone
projects, an aura of permanence

stateless, calm.

But today the process of
cutting it into blocks

is anything but calm.

[machine trilling]

At the quarry, the first
cut is the deepest.

In this case, 15 feet down
into the limestone bed.

The saw for the job, a WF
Meyers, Diamond Belt Saw.

Though designed specifically

for the task of quarrying stone,

it resembles
another popular saw.

[power saw machine revving]

- Just picture a
chainsaw for example.

And we put a belt around a bar

that is in geometry very
similar to handheld chainsaw.

Instead of using a chain,

we use a belt that has
the diamond segments

and the plastic around it.

- [Narrator] The belt saw
is Diamond studded teeth,

will slice out almost 30,000
square feet of limestone

before needing replacement
after 375 hours of operation.

Cutting with diamonds
is a simple principle.

To cut something hard, it
takes something harder.

And diamonds are one of the
hardest materials known to man.

- Diamonds of cells
are the cutting tool.

They're just like
the teeth on a saw.

Powder itself, what
holds the diamonds in

but the diamonds do the cutting.

- [Narrator] The
powder in this case,

20% carbide and 80% cobalt
is mixed with the diamonds.

Cold pressed into shape

and then hot pressed to
form a hardened segment.

As these diamond infused
segments cut stone,

the cobalt carbide
alloy slowly wears away.

Continually exposing fresh
diamonds at the cutting surface.

- The diamonds sit in
through the segment

and as this segment wears,

the diamonds stay sharp on
the surface of the segment

all the way through.

- [Narrator] The diamond
segments are then braized

or soldered at high
temperatures to steel mounts.

Heated to 1200 degrees, the
molten silver solder fuses

the segment to the steel mount.

- It gets cherry red.

It has to melt the silver
and you gotta work it around

and make sure that you have
a good surface on each one

so that it holds good.

'Cause as you
probably can figure it

takes a pretty good hold
because that stone...

Whenever it hits that stone

that's what does the
cutting of the stone.

- [Narrator] The segments
will cut everything

from limestone, to granite,
to marble, to slate.

The segments are sharp,

but they wouldn't stay that
way without lots of water.

The belt saw guzzles
50 gallons a minute.

It pressurizes the water
in a labyrinth theme system

inside the hollow guide bar

and shoots it out
beneath the belt

at 50 pounds per square inch.

The belt hydroplanes on the
pressurized water reducing wear.

- [Eddie] It also allows the
cuttings that we've created

to be flushed out so
that we're not constantly

re-cutting the same old stone

and prematurely
wearing out the belts.

- [Narrator] The
computer controlled saw

will cut a 15 foot deep 70 foot
long channel in eight hours.

- It's an auto saw.

You program it right
there in that cut

and it'll go down all on
its own, automatically.

Never you have to fool with it.

- [Narrator] After the saw has
completed the vertical cut,

workers drill horizontal holes

and hydraulically split
the rock along the bottom.

Removing the limestone
and 50 foot long,

five foot wide, 15
foot deep sections.

Though the Meyers quarry
saw his cutting edge,

it's merely the most
modern application

of stone cutting techniques,

first practiced
thousands of years ago.

The most prolific
ancient stone cutters

were the Egyptians who worked
extensively with limestone.

Metal saws, fashion of copper,
bronze and sometimes iron

were used with sand or emery,

a cutting grit like
modern day diamonds

to fashion blocks of limestone
over 6,000 years ago.

- In order to get the
abrasive particles

to stick to the edge that
use a resinous substance

of some kind, you
know, plant resins

to get those particles
against the stone

or the material that
they were trying to cut.

[cutting machines trilling]

- [Narrator] In stone mills,

a modern version of this
abrasive fed cutting technique

was widespread before
the advent of diamond studded

cutting teeth in the 1960s.

100 years ago, gang
saws like these

at B.J. Hoadley Quarries,
would've been fed with

an abrasive slurry
of sand or silica

to enable them to grind
through limestone.

Today, these old fashioned
saws are still at work,

but they've been updated
with diamond teeth.

- This is a rocking gang,

what they call lift gang.

And it lifts and
hits lifts and hits.

And the slurry gets trapped

in between the segments
and in the middle.

'Cause when it's cut and
the first one will cut,

then the slurry will get
trapped in between the segments.

And then the second one
has cleaner spot to cut.

And it just carries it all out

to the end of the
blade with water.

- [Narrator] At Indiana
Limestone Company,

fully modern mill.

The job of slabbing stone
block from their quarry

is accomplished by
gigantic diamond belt saws.

- The blocks come
directly from the quarry

looking just like this.

And the first wheel operation
of fabrication that we do

is to slab them.

We use these narrow belt saws.

- [Narrator] Cutting
14 inches per minute,

this saw slices a block into
seven slabs in one hour.

It works much like
the quarry belt saw.

But uses a narrower
cutting belt.

- The belt travels
around in a circle

through the two big wheels
hydroplaning across it.

It's about washing
the slurry out,

allowing the diamond to
dig next and dig next

and if the slurry is
there, it can't do that.

- [Narrator] Once
blocks have been slabbed,

they're run through an
assembly line

of 40, 48 and 64
inch circular saws.

Tipped with diamond
cutting teeth

and running at a surface speed
of 10,000 feet per minute.

The stone is cut to last.

Phil Beyers and Eddie Brooking

have been brazing
diamond teeth to saws

for more than 80 combined years.

- While we have a lot
of mills in this area,

but we ship all over
the United States.

Not only here, it's
everywhere, Canada everywhere.

But this is what they call
the home of the limestone.

- Limestone capital of the world

is what they bill it as.

- [Narrator] Rightly
so, Indiana's limestone

is of the highest quality and
most plentiful in the world.

The mill and quarry saws get
down and dirty every day.

When you look at a saw,

what it's designed to cut
is not always a obvious.

The basic wood saws, most
of us recognize them.

Stone saw is a little less
common and harder to place.

But this saw, for the surprising
amount of power and speed.

It must be for something
fairly serious and it is.

This is the MPower
6,300 oscillating saw

designed to cut bone.

A surgeon turns to the saw
for large bone surgeries

like total hip and
knee replacement

or for more delicate procedures

like anterior cruciate
ligament or ACL repair.

- In several
sporting activities,

the anterior cruciate
or the front ligament

tends to be torn
and can get torn.

What we need to do
surgically speaking

is to replace that ligament
with a separate tendon

that we harvest
from the patient.

- [Narrator] The
replacement tendon

will be anchored by two 10
by 25 millimeter bone grafts

harvested from the knee
by the MPower 6,300.

This cordless $17,000
steel aluminum plastic saw

can accommodate over a hundred
different types of blades,

tipped with serrated teeth

and covered in a
hardened chrome coating

to reduce friction
when cutting bone.

The saw's variable speed blade
oscillating from a dead start

to 14,000 cycles per minute,

offers the surgeon
increased control.

- That could start it up
slowly just to score the bone

without much vibration or
jump until I get it started.

[power saw revving]

And then I can go
ahead and go for broke.

- [Narrator] The combination
of a thin profile

yet stiff blade
allows the surgeon

to plunge the saws tip
directly into bone.

- The saw blade has
depth marks on it.

And I can watch my
depth marks as I cut.

- [Narrator] In
an actual surgery,

these bone were grafts
would be screwed in place

to anchor the new
tendon replacement

for the torn anterior
cruciate ligament.

Ultimately, the
greatest challenge

for surgical saws
comes after surgery.

When they're cleaned and then
run through an autoclave,

a device that uses steam
to sterilize equipment.

- The autoclaves run at
about 272 degrees Fahrenheit.

So looking at that, you have
to have electronic components

that can withstand
that type of heat.

Go through their
hundreds of cycles a year

for each handpiece.

And then still focusing on
getting it to work each time.

- [Narrator] For all but
the most recent history

of medical saws
germs were unknown

and sterilization
was not practiced.

- The early physicians knew
that cutting off a limb

was really the only way
to save a patient's life.

There were no antibiotics.

There was no nothing else
you can do to avoid sepsis.

So even going back to
Greek and Roman times

amputation was an operation
that was carried out.

- [Narrator] A surgeon
would've given this 1730s,

German amputation saw
only a cursory cleaning.

- Sterilization came in at
the end of the 19 century.

So essentially they
would take this saw

from patient to patient
without cleaning it.

And that was one of the
reasons why infection

killed far more people
than the surgery itself.

The friend of the surgeon
in those days was speed.

The faster you could get
the limb off the better

because patient didn't
tolerate it very well.

And it would be used
to saw back and forth

on a patient's arm or
leg while two assistance

or more were holding
the patient down.

- [Narrator] Though, this
practice must have been brutal,

it's even harder
to imagine the use

of the earliest medical saws,
prehistoric stone instruments.

- The earliest civilizations,
thousands of years ago,

used saw like instruments
made from flint stones

actually to cut into bones

and even do potentially
brain surgery in the skull.

- [Narrator] Trepanation, sawing

or boring holes in the skull
is one of the oldest surgeries,

dating back as far
as 6,500 years.

The practice was widespread
among the Inca and Maya.

And was accomplished
by abrasion,

cutting and drilling techniques.

It speculated that these
cultures performed Trepanation

to treat head trauma suffered
in battle or accidents,

to relieve headaches
for ritualistic reasons

And even perhaps to
release evil spirits.

Today, trephination is still
used

in some neurosurgical
procedures.

This trephine set was
handcrafted

in Philadelphia in the 1840s.

And would've been used
to treat hematomas

or bleeding on the brain.

By cutting a hole in the skull,

the surgeon allowed
blood to exit

thus relieving pressure
on the patient's brain.

- The way that the
trephine find would work

is there was a central pin

and the pin would
slide in and out

to direct exactly
where the cuts will go.

The trephine would be turned

and the cut made
would be circular

to whatever depth was indicated.

And then the skull flap was
then lifted with an elevator,

which is this
instrument right here.

- [Narrator] Sawbones carpenter,

though it's unclear when
these slang terms for doctors

enter the lexicon.

They derived from
a surgical practice

that though ancient
came into its own

as a result of modern warfare.

- Most civil war amputation
sets have multiple thin blades

because they had to be
traded out quite frequently.

There were over
30,000 amputations

in union forces alone.

Everything from fingers,

which the survival
rate was quite good for

up to mid thigh amputations

where the survival
rate was less than 50%.

Both from bleeding
and trauma of surgery

and also infection
which obviously set in

very commonly prior to
the age of antibiotics.

- [Narrator] This early saw
was called an osteotome.

It was made in the 1830s

by an orthopedist
named Bernhard Heine.

- It is the first
mechanical chainsaw.

And as you can see, is
a bit unwieldy to use.

It's quite heavy.

It has to be directed
to a very specific point

for the very small teeth.

And it was so expensive
to make and to maintain

that I just don't think
it survived very well.

- [Narrator] Medical
saws come in a variety

of shapes and sizes, but
they're not the only ones

whose purpose is to save lives.

[siren wailing]

When it comes to life and death,

you need a chainsaw that can
cut through walls and roofs

in any rescue situation.

An earthquake,

hurricane

or fire.

[upbeat music]

Smoke is pouring from
a burning building.

A firefighter is trapped inside.

- [Narrator] Each passing moment

cuts into his
chances of survival.

- So we're making entry.

[glass crackling]
[power saw revving]

- [Narrator] Though, this
is just a training exercise,

it highlights the importance
of one piece of equipment,

the Stihl Magnum Rescue Saw.

- That's all when it encounters
something behind here

conduit, nails, two
by four, four by four,

it cuts right through that
with no problem at all.

We went in there with
a quick extraction

and got him out here to safety.

All is good.

- [Narrator] Designed
exclusively for rescues.

This saw can make repeated
cuts through wood and metal.

This durability is
what makes it special.

Now firefighters have used
chainsaw since the 1950s.

This specialized type of
power saw evolved slowly.

Chainsaw chains were
prone to breaking

when they encountered
extreme heat

and metals embedded
in walls and roofs.

So for decades, firefighters
relied mostly on axes

to chop out access
and ventilation holes.

But this process could
eat up valuable time

during a rescue effort.

In 1992 faced with
these obstacles,

the Virginia Beach Fire
Department sought the help

of the world's largest
chainsaw manufacturer, Stilhl.

Stilhl's engineers designed
a more durable saw

that could withstand the
extreme heat firefighters face

when cutting ventilation holes.

The best standard chains

may have only a portion of
the cutter dipped in carbide.

Whereas the cutting
edge on the RDR

or Rapid Dural Rescue chain

is entirely covered in carbide

which gives the teeth
greater impact resistance.

At the firefighters request,

saws designers also
made modifications

to the body of the chainsaw.

- Our structural
firefighting gloves

are big and they're thick.

So it's very difficult to
grip the old starter handle,

so they develop this
for us right here.

It's very easy to grab
with your gloved hand.

Another thing that they did

was this wrap
around handle right here,

this gives us ability
to use it right or left.

Most chainsaws are
right-handed saws.

So we needed that flexibility
up on a roof or in a house

or somewhere where we need
it right or left operation.

Another thing that you see
right here is this front guard.

Basically what happens
is when you're cutting

asphalt shingles, roofs
that have tar in there,

the tar will strike the
exhaust system and stick.

So they developed this guard
that you see right here.

It's easy to clean up, protects
us all and works very well.

[power saw revving]

- [Narrator] They are sharp,
powerful and can be dangerous.

And when they're
doing their thing,

it's often best to
keep our distance.

But they do or bidding

helping us to shape
our environment,

to build, to destroy
and even to save lives.

And when push comes to shove,
they can even make music.

[gentle lifting music]