Steel Edge Retention testing

Vassili, I'm curious about that Boker Leo III Damascus. One of the steels used is also used in barrels of tank cannons, right? Please let me know how that thing holds an edge.
- Thanks.
 
Troop said:
Vassili, I'm curious about that Boker Leo III Damascus. One of the steels used is also used in barrels of tank cannons, right? Please let me know how that thing holds an edge.
- Thanks.
Click to expand...

This one I do not have so far.

Thanks, Vassili.
 
nozh2002 said:
Last cuts for Friction Forged D2 from 180 to 220 is really all around 85. Actual tests looks like this:

190

070 ++
080 ++++++++X+
090 +++++++
100 +
110 +

200

070 +
080 ++++++++
090 +X+++++
100 +++
110 +
120 +

- all more or less like this. So median in or almost in between 80 and 90. And one or two tests in that or this faivor may swing median on other side. So in general it is border value and this is why it is jumping from 80 to 90 and back. I think sharpness real is 85 and did not change too much.

Thanks, Vassili.
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Question. Why such variation in sharpness at such low number count??
 
Yes! And it is stable as ATS-34 in results.

This is really nice surprise for me because I used this blades 4 years ago as cheap blades for my own experiments in knife making. Turn out that it is not only cheap but excellent performers. 3 years ago I forgot about this blades and pay attention only to new well promoted steels.

After I tested FFD2 I start thinking about other carbon steels and this reminds me about my old Laury Progressive Tempered blades which used while ago as an exercise blade for beginners in handle making. With 63HRC on the edge and 53HRC on the spine it looks like good comparison to FFD2.

Turns out that it performs same (so far) or bit better!

And this is for 13.50eur blade, so you just need to make your handle.

Unfortunately, the biggest blade available so far with PT - 9 cm (3 1/2"), they have Leukus and Lapplanders but without progressive tempering.

What a good example of real value versus values created by sophisticated PR.

Thanks, Vassili.
 
nozh2002 said:
Cut INFI 420 ATS FF LAU
000 040 030 040 020 020
001 060 050 060 030 020
002 070 050 070 040 030
003 070 060 070 040 030
004 080 050 070 040 040
005 080 060 070 040 040
006 080 060 070 040 050
007 --- 070 080 040 050
008 080 080 080 040 050
009 --- 070 080 050 050
010 070 070 080 040 050
012 080 070 080 050 050
015 080 080 090 050 050
020 080 070 090 050 050
025 080 080 090 050 050
030 090 080 090 050 060
035 090 080 090 050 060
040 090 090 090 060 060
045 090 070 090 060 060
050 080 080 090 060 060
060 090 070 090 060 060
070 --- 080 090 060 060
080 100 080 090 070 070
090 110 080 --- 070 070
100 110 080 090 070 070
110 110 080 090 070 070
120 110 090 090 080 070
130 110 090 090 070 070
140 100 080 090 080 070
150 110 090 100 090 070
160 110 100 100 100 080
170 120 110 100 090 080
180 120 110 100 080 080
190 120 110 100 080 080
200 130 100 100 090 080
210 120 110 100 090 080
220 130 110 110 080 080
230 110 --- 110 090
240 110 130 110 090
250 110 130 110 100
260 110 130 110 100
270 110 140 110 100
280 110 130 110 100
300 110 140 110 090
320 110 140 120 100
340 120 150 120 100
360 120 140 120 110
380 120 140 120 110
400 120 140 130 110
420 110 140 130 110
440 110 140 130 110
460 110 150 130 110
480 110 160 130 110
500 110 170 130 110
520 120 170 130 110
540 120 170 130 110
560 120 180 140 110
580 120 190 140 110
600 120 200 140 110
650 130 230 140 110
700 130 260 140 120
750 130 --- 150 120
800 130 --- 150 120


Knives used:
Busse Game Warden - INFI 58-60HRC
Cold Steel ODA (Taiwan) - 420HC sub zero quenched 57HRC
Buck Strider Solution - ATS-34 by Paul Bos 59-60HRC
DiamondBlade The Summit - Friction Forged D2 (factory edge) 65-68HRC
Nozh2002 The Shrimp - blade from Laury (Finland) Progressive tempered ThyssenKrupp made UHB17VA 63HRC

Thanks, Vassili.
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How long do you plan on taking this test out to? ?:D
 
Next I decide to test three steels simultaneously. I have three Spyderco Military with CPM S60V, CPM S30V and BG-42. Knives and blades identical so it will be only steel what differs them from each other and so it will be pure side-by-side test to compare steel performance (well for manila rope cutting and for given blade geometry).

At first all three blades get exceptional sharpness without any troubles - I heart before that vanadium carbides will not allow to have it sharpened to the same extent as carbon steel. Now it is clear that it is not true and carbide grains can be sharpened as well as surrounding steel. All blades whittle hairs and shows 20g results on thread test.

Next I think I need to repeat INFI test - it was first so I was learning while testing it, so I think I am more skilled, more accurate now and so I think I need to repeat that exercise to be absolutely fair.

I thought someone else will try to do same testing... It is really necessary! It is part of scientific methodology - results should be backed up by independent researchers.

Thanks, Vassili.
 
nozh2002 said:
Now it is clear that it is not true and carbide grains can be sharpened as well as surrounding steel. All blades whittle hairs and shows 20g results on thread test.
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Yes, they can. That is something that remains all too often unmentioned. There are some people though that will point out that even when sharpened the carbides will quickly break out as they are insufficiently supported, and the blade will dull quickly. Your test will show whether that is right or wrong. However, for that argument it is absolutely paramount to mention at what angle you are sharpening, as this argument might be valid below a certain critical angle but may not hold above that angle.
 
You don't necessarily have to be sharpening the carbides to get maximum sharpness. It's not about how sharp you are getting it though, it's how it holds it afterwards. The military has a thick enough geometry that we may not notice a difference, we'll see.
 
nozh2002 said:
Next I decide to test three steels simultaneously. I have three Spyderco Military with CPM S60V, CPM S30V and BG-42. Thanks, Vassili.
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This should be your best test so far all three knives will have same edge profile, which is necessary for comparisons sake. That should be interesting. I wonder in your past tests why you did not sharpen all the knives to have the same edge. I know it is hard to do but it would get rid of some factors. Great tests by the way. I admire your ability to do so much. I would have given up at 200 cuts on one knife. I am wondering if adding a VG10 spyderco would work, I would like to see how it does against other spyderco steels.
 
Does anyone know the hardness values for those three Spyderco knives?
 
Larrin said:
Does anyone know the hardness values for those three Spyderco knives?
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My two Spydercos (Native and Manix) in S30V were Rockwell tested to 58 RC. I was just given an S30V Military for testing, which I plan on having Rockwell tested along with my CPM D2 Military in the coming months. I'm not sure what hardness Spyderco ran the other steels at.

Mike
 
NuclearBossHog said:
This should be your best test so far all three knives will have same edge profile, which is necessary for comparisons sake. That should be interesting. I wonder in your past tests why you did not sharpen all the knives to have the same edge. I know it is hard to do but it would get rid of some factors. Great tests by the way. I admire your ability to do so much. I would have given up at 200 cuts on one knife. I am wondering if adding a VG10 spyderco would work, I would like to see how it does against other spyderco steels.
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No same edge profile is not necessary for this test. This argument may instantly exclude anything but identical knives from steel edge retention testing on manila rope, which is way too picky. How length of the blade, for example, can affect edge stability?

As I explained already blade geometry does not matter for this tests - only angle is what may be important and it is same for all blade. I do cut manila rope and it made from fibers which does not stick to each other too much, so once edge cut fiber - it is as thick as a thread, it just fall out. So it does not matter is it fine edge Spyderco puts on their knives of super thick edge from Busse, the only part being affected by cut - the first fractions of millimeter of the edge. It is really easy to check for yourself (and someone checked already).

Now even if I cut something solid, like wood it will not matter too much because thickness of the edge will to my understanding only affect how much force I need to apply to make blade penetrate the target, but for few fractions of the millimeter which I test with thread later does not matter how hard for me it was to make a cut. So again in this case it will not be any difference is it Spyderco Military or Busse Game Warden.

If you have different argument - I like to hear them.

Thanks, Vassili.
 
NuclearBossHog said:
I admire your ability to do so much. I would have given up at 200 cuts on one knife.
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Jerry did more then 2700 cuts several times!
Initially I did 400 cuts, but decide that it does not expose INFI ability to hold working edge for long time, so I increase test to 800. It is all in this thread.

Thanks, Vassili.
 
nozh2002 said:
Now even if I cut something solid, like wood it will not matter too much because thickness of the edge will to my understanding only affect how much force I need to apply to make blade penetrate the target, but for few fractions of the millimeter which I test with thread later does not matter how hard for me it was to make a cut.
Click to expand...

I would think just by virtue of the fact that you have to use more force to make the blade penetrate the material you are stressing the edge in a different fashion thereby altering the results.
 
nozh2002 said:
Now even if I cut something solid, like wood it will not matter too much because thickness of the edge will to my understanding only affect how much force I need to apply to make blade penetrate the target, but for few fractions of the millimeter which I test with thread later does not matter how hard for me it was to make a cut. So again in this case it will not be any difference is it Spyderco Military or Busse Game Warden.
Click to expand...

Well, I have a pdf of a paper where tests were done on cross-grain cutting, and it was found that increased edge angles and decreased blade thickness lowered cutting forces. The possible effect I could see form this is that having to use more force to cut through wood, if done by hand, would decrease the ability to maintain the angle, and lateral forces on the edge could increase. "Sloppier" cutting from the outset because of differing geometry might skew the results. Also, moisture content in the wood was found to be the most important variable, so consistency in the test media would be important. If you were to test by cutting through 3/8" dowel instead of 3/8" rope, these may or may not actually be factors, I'm just speculating.

Now I wanna run to Home Depot and get some doweling. But not on the day after Christmas, I value my sanity.;)
 
Thicker edge need more pressure because area of contact with target is bigger, but pressure per square inch very well may be the same. So pressure and stress put on the very edge may be same for thin and for thick edge. May be lateral forces on the edge will be different but this lateral stress most likely insignificant - during cut there is not too much angle variation.

Anyway - I am cutting manila rope not wood.

Thanks, Vassili.
 
nozh2002 said:
Thicker edge need more pressure because area of contact with target is bigger, but pressure per square inch very well may be the same. So pressure and stress put on the very edge may be same for thin and for thick edge.
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That might be the case if the pressure was being evenly distributed across the area of contact, but I would think that the edge itself as it forces its way through the material would be taking a greater share of the force.
 
theonew said:
That might be the case if the pressure was being evenly distributed across the area of contact, but I would think that the edge itself as it forces its way through the material would be taking a greater share of the force.
Click to expand...

Well, it should be easy to test... Run side by side thin vs thick edge with same steel. May be I'll do this sometime.

Thanks, Vassili.
 
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