Тесты ножей. ENG Sub

Uploaded by RuslanKiyasov on 28.09.2012

Hi youtube, hi community.
Today I want to talk about knife tests,
About steel tests and all other knife related tests
The video is made a bit like improvisation,
Because I didn't want to film it.
But now I design methodology
for a new testing that will be on my channel.
I don't want to reveal my hand,
but soon we will see the first series of this test.
And developing this methodology I investigated tons of forums,
russian speaking, non-russian speaking,
about any means of testing control.
And what surprised me a lot
is what people think about one or another tests,
one or another examination
in terms of it's performing
control methods and so on.
But now I want to start from afar.
I think we will talk about folders
and their testing,
because fixed blades differ to much,
and testing that is appliable to Strider DBS
or to Zero Tolerance 100,
Will not be apropriate for a thin
custom skinner or something like that.
These knives are to different in their purpose.
And if we will design tests for one of them
the second will definitelly fail.
Folders are also different,
but thay still have more common properties
although at first sight this phrase seems stupid.
So, theoretically, what are the knife tests?
On my opinion it's possible to divide them into 2 big groups.
These are direct functional tests
and construction stability tests.
Functional tests are cut tests, piercing test,
penetration tests and more, and more, and more.
Point durability test more or less.
Stability tests are lock tests,
And more, and more, and more.
In fact, if we will test a knife in general
and consider it not only as a knife which cuts sausages,
but as a tool in general,
without thinking that it is a knife,
than stability tests have sense.
But we will talk about them later.
So, what are the basic criteria in any tests?
Basic criterion is repitability.
Basic criterion is methodology identity.
Basic criterion is understanding simplicity.
For example is we will clean the blade with sand blower,
tear of the coat and make scratches with certain depth,
put this blade into lemon juice
and watch which steel will corrode faster
this will be interesting of course,
but it says nothing practically important.
So, which materials can we use in first group of tests?
These are rope, wood, or any other material
that is, lets say, medium abrasive.
What does it mean?
Imagine that we have very different knives
in their performance, their cutting ability
Recent examples: SOG NW Ranger
factory sharpened, which cuts the rope 15 times
And Shirogorov 111 with S90V steel and 30 degree angle
which cuts it over 500 times.
We need to choose a material,
which will be abrasive,
but won't destroy cutting edge immediately.
Decyphering this leads us
to two simple examples.
If we will test knives on bread,
on a sausage,
we can do it forever.
On the other side,
if we will cut tin plates,
or coarse sand paper,
there will be a big chance
to see no difference in a cheap steel group,
as well as in supersteel group, between different steels.
So in first case
the material is not abrasive enough,
in second case it's too abrasive.
Rope, cardboard, thick felt maybe, wood
are in that certain category of materials,
that are suitable for testing.
What can I tell about wood.
My experience tells that in general
wood tests knife geometry instead of sharpness.
I mean how the knife goes into wood,
how convenient is that.
And thinking logically we can conclude that thin kitchen knife
which cuts sausages much better
than thick sabre grind knife
will loose in wood test.
So I think that wood as a testing material...
if it's soft wood, it will not give much information.
If it's hard, dry wood,
difficult for a knife,
than we can perform hack test
on a cutting edge stability.
Also it's possible to use bones
in hack test.
Bone can imitate, for example,
wild fowl or beast butchering,
and, well, when we hit bone
cutting edge will suffer. So, if we hit bone advisedly
it can show us something.
But most of all I want to talk about rope.
I am familiar with rope testing
and it's good presented on my channel.
Lots of information that I read about rope tests
told how to perform tests, how to cut,
which steps to do,
cover with tape, do not cover with tape...
Actually, situation, at least documented,
is the following.
For real, really correct and the only possible rope test
absolutelly objective,
we will need the following things.
First of all, hardness meter.
And it's accuracy should be at least 0.5 HRC.
And even better 0.2 HRC.
I can't tell you exactly how much does it cost,
but last time I have checked the price, it was about 200-300 thousand rouble.
Than we need a mechanical cutter
that will use defined pressure to cut the rope.
this pressure should be calculated using
reference sample. At the moment it's 440C steel.
440C heat treated to 59 HRC, with a certain blade form,
certain geometry and certain cutting edge thickness.
Which is sharpened to a certain degree on a certain grinder.
And I emphasize that, with a grinder but not by hand.
Of course, cutting adge should be precisely controlled,
to make sure that it's not changing from one knife to another,
to keep scratch and furrow direction constant.
And this mechanical cutter with a certain
exact pressure in several kPa
or may be several tenth of kPa, it doesn't matter.
cuts the rope
that is placed on a mechanism
that excludes
or at least makes as slight as possible
knife contact with base.
Of course, the blade should have certain form,
certain geometry and size,
equal for all knives.
And only in this case we will test steel correctly.
This test methodology is used by CATRA.
Unfortunatelly some manufacturers,
by hearsay e.g. Kershaw,
do not work with CATRA, do not test their steels
for cut-resistance, for cutting performance
on a rope for example.
Of course the rope should be
in a huge coil.
because the rope may be different in different coils.
Its abrasiveness may differ.
Of couse we cannot compare ropes only by thickness.
Rope may be hard or soft,
one is good for rough spine,
another is bad for it.
And in this case we will get the real testing
in terms of rope cutting.
In all other cases
e.g. when we perform hand cutting with 10 cm steps,
it only reduces subjectivity,
but does not remove it. Even more.
That subjectivity that exists
is so huge that in fact
all the efforts to reduce it can be leveled.
I'll try to explain it.
My own example. I have been investigating sharpening for a long time.
I have tried to understand how different sharpness can be.
And this investigation leaded me to a thought that knife,
and it was shown with Zero Tolerance,
when I've done 4 and 80 cuts.
In both cases knife have sliced paper easily.
Before the test. Easily.
So it just slices. Why?
It's not important. So, sharpness level
is a very interesting term.
It can be checked using microscope.
Unfortunatelly I has no one
and I cannot document it,
But once I'll do it.
So paper as a sharpness check
is a very, very, very questionable thing.
You can always cast discredit on it
In my tests as well as in any other.
It's not important. So, if paper
is not a good sharpness checker, than what is it?
And here we start to talk about some interesting things.
It's all easy in CATRA testing. We have defined pressure,
very rought, 3 kPa, on the blade.
And our mechanical cutter just cuts the rope.
For example we can define this pressure based on 100 cuts for 440C,
to lower the error, widen results range.
And with this pressure CTS-XHP have done 250 cuts.
It will just not cut the 260th, it will require more pressure.
You see, CATRA has objective result, clean and understandable.
But what can we do at home?
At home we can cut on scales.
Actually, cutting on scales is a very interesting thing.
but on my opinion it's more objective
when cutting is done by some mechanism.
But when cutting is done by man, applied pressure
may be different.
While cutting on scales is a very interesting thing,
it still has some specifics.
Different steels have different cutting.
Some cut aggressively, some not aggressively, soapy.
I don't know how to classify this, but you can just feel it
when you cut viscous material.
Such viscous, unpleasant
like rope or tyre.
So you just feel that knife goues through it like through butter, aggressively.
But sometimes you feel that it cuts, but a bit wrong.
It cuts, but cuts wrong. And you can not explain this.
It's like a piece of soap.
And different steels gain their working sharpness in a different way.
For example we test
these two knives I've placed here.
For example it's Buck with S30V and
very figuratively but still
Civilian with VG-10. Of course I understand
that rope cutting with Civilian is stupid,
but it's just an example.
Lets imagine that
Buck and Civilian become dull.
VG-10 is a bit fragile of course
but it's still not a powder-made steel.
At the same time S30V inclined to microshearing,
when it becomes a microsaw and that's its working sharpness
(the best example for this is ZDP-189)
and with this sharpness it will cut for a very long time.
So lets imagine that we have a threshhold pressure
for example 10 kg on scales.
VG-10 may cut 50 times, become dull and exceed these 10 kg.
At the same time S30V may cut 20 times and exceed the same 10 kg.
Can we conclude that S30V is worse? No.
In fact, VG-10 may cut some times
50, 100 - it's not important, exceed 10 kg and become completely dull.
Steel have got a huge wreck
on the most part of cutting edge and it will cut nothing more.
While S30V have ganed it's working sharpnes,
it's not razor sharp, but working sharp, and it can work for a very long time.
May be 100 cut, may be 200,
it depends on initial sharpening, on heat treatment
and many other factors.
And scales will not show this to us.
But scales, however, can be used as a control tool
to make a control cut before the test and after it.
To check how tested steel has changed it's properties.
For example we cut the rope 200 times.
and perform a scale cutting before and after it.
And we see the difference.
And different steels will have
different value.
But again this different dulling type
will affect the results much.
Also it's possible to check sharpness by hair shaving and so on
but it also depends on blade direction and many other things.
So there are not much really objective control methods
except good microscope.
And even microscope will show as
overall picture of cutting edge wrack
or some shearing,
but how do we know that this is bluntness itself?
And one more thing about scales.
We'll need very precise scales
with certain workload.
And it's very desirable for result undestanding and clearness
to have a workload cutoff.
Lets suppose that we have taken a knife and cut the rope
we have cut it completely
and workload will disappear,
at this moment we will start to cut surface where the rope is placed.
And between these two moments,
may be in parts of a second
scales should cut off the workload.
I mean they should show us peak value,
but do not show knife pressure on wood,
which is redundant.
So that's all about rope tests.
I can tell you something concerning all other tests,
but the matter will be the same.
Anyway the most important thing is control,
the most important thing is repeatability.
Why repeatability is that important?
In my test I try to use
as a default option
factory sharpening.
Most people that argued me
that don't like this option
told me the same: it's sharpening of uncle John.
Damn unknown who, damn unknown where. It tells nothing.
I think it's only one half of truth.
I'll explain.
It's impossible to sharpen all knives in one way.
For example if I can sharpen 111th with 25 degree angle
without making bevel too wide,
I'll try to show you,
Here I have started
to form bevels.
So it's not a finished edge.
It's pretty sharp, but not finished.
I think you can see it, right?
Here is width with 36 degree.
I mean I can easily make 25 degree here
without any problems.
On the other side if I'll try to sharpen Sebenza
or Buch with s30V to 25 degree,
I'll get approximatelly 15 mm wide bevel near the point.
May be just a bit less.
You'll tell me
"OK, lets sharpen all the knives with 50 degree".
any knife can hold it.
May be. But 50 degree may level the difference
between 0.2 mm and 0.4 mm thick cutting edges.
Because the angle is like on axe.
It's not a secret, that 111th sharpening,
as well as factory sharpening of any Shirogorov
is not very good, to say the least.
This 111th initially sliced paper easily,
but didn't cut the rope at all.
So I have concluded that the angle is about 60 degree.
So it's impossible to sharpen all the knife in the same way
in my main rope test.
That is why I try to test factory sharpening at first
to check the angle
it may be checked in sharpening videos or in some other way,
Which was chosen by the manufacturer.
Benchmade has its own policy, Spyderco has its own.
At the second time, since my test is comparative,
we have 40 episodes at the moment, and it will be more,
I'm not going to stop,
so we can compare for example M390
it's a perfect live example
of sharpening quality.
Spyderco Military with M390 have done 330 cuts in rope test.
In main rope test. With factory edge.
And almost the same result
in cutting edge test.
Cutting edge test (I told about it in a special video
which you can see in description to any other)
is a bit different test, I'll continue it
but it's possible not with any knife.
Benchmade Ares with M390 had
moderate result for M390 in rope test.
it was about 180 with factory edge.
But after manual sharpening,
when the angle was changed to 30 degree,
it became a leader of cutting edge test.
It has shown that M390 heat treatment is done by Benchmade
not worse than by Spyderco. There is no big advantage
but there is a little.
Finally I think that factory edge
in comparison of different knives,
lets us understand,
what can we expect from a knife.
Of course it will be great
to test factory edge first and then
test manually sharpened knife.
But there is no ideal things in our lifes,
as well as infinite time and money.
That's why I test knives as I test,
and this methodology is not randomly chosen.
To summarize info about all tests
I want to tell, that on my opinion
using my investigation of test materials and methodics,
the most important thing is testing identity for all the knives.
I mean if we will take a knife
and make some WOW-things with it,
We will tell nothing about the knife. Absolutely nothing.
Because we need to compare it with other knives.
With it's competitor, preferably with several competitors.
And in this case, in comparison with another knife
this one may play the game, while the third one will loose.
Without such comparison
without testing identity from one to another,
results may look too bad
or too good.
So this is the problem.
That is why repeatability and methodicalness of repeating of one test
is one of the main foundations of testing methodology
Which, on my opinion, may be any.
Thanks for watching, bye-bye, so long.