Steel Edge Retention testing

on_the_edge said:
I happen to think that Cobalt's thread interpreting your numbers is the single-most enlightening post in this thread.

I wonder if the disparaging remarks about Cobalt's positive contribution to this thread would have (could have) been made had the same thing been said by someone other than a well-known Busse fan. Moreover, I don't recall anyone saying that Cobalt is a fan of Busse knives only.

So much for no hidden agenda!
Click to expand...

OK we have conspiracy theory here. This is not about INFI, I choose INFI first as a top steel to set top of the range. I like INFI (for the reason you may find in this results!), I have some collection of Busse knives and do not have any intention to get rid of it.

I had some experience with Cobalt before - this is why he is in my ignore list. So I do not want this thread to be trashed by steel fan wars, because I think this tests are important.

If this offend you in any way - I can simple remove INFI from that table - just let me know! One steel more one steel less does not matter. However I am not sure Jerry Busse will support you.

It is ATS34 I am testing now - next will be bulat and probably CPM S30V, as widely used steel now, and I plan to test some exotic steel then regular then exotic and regular again... I think I will keep them coming on regular bases.

Thanks, Vassili.

P.S.

If you do not trust me for some reason , if you think I have hidden agenda - do it yourself!

I disclose everything, how I am doing this - I have it on video etc. So you may do same rope cutting and measure thread on the scales - this does not require special equipment or anything, no complicated math involved eather - just do the same and post results!
 
By the way sometimes imageshack does an annoying thing where you can't seem to enlarge the image. Refreshing usually fixes that.
 
Still new to this forum, but I'm finding this real interesting.

Is it possible to express the percentage of increase in pressure when comparing cut number X to the original? I mean if steel #1 took 20 grams of force to make the initial cut and 40 grams at cut 200 while steel #2 took 10 grams for the initial cut and 30 grams for cut 200, someone looking just at the final number may assume that steel #2 holds the edge better because it uses less force. The reality is steel 1 took a 100% increase while steel 2 used a 200% increase in force to make the cut.

I'm just making up my examples above, but I think you get the idea of what I'm trying to say.
 
I agree that for analysis it would be more valuable to compare ratios vs. real numbers since the steels did not start at the same sharpness.
 
No you can not reference the sharpness decay to the original sharpness, because it represents no absolute value in any sense. As you can see in the Excel chart, the initial really high sharpness is gone very quickly anyways. If you want to present it as a relative number, you would have to do it relative to a completely blunt edge.

And for those critics, AFAIK, Nozh is a Busse fan, too.
 
Taking my own suggestion in the last post I made, here's the table:
__________________________________________________________________

% Increase Over Cut 0
Cut INFI 420 ATS INFI 420 ATS
0 40 30 40
1 60 50 60
2 70 50 70
3 70 60 70
4 80 50 70
5 80 60 70
6 80 60 70
7 --- 70 80
8 80 80 80
9 --- 70 80
10 70 70 80 75.00% 133.33% 100.00%
12 80 70 80
15 80 80 90
20 80 70 90 100.00% 133.33% 125.00%
25 80 80 90 100.00% 166.67% 125.00%
30 90 80 90
35 90 80 90
40 90 90 90
45 90 70 90
50 80 80 90 100.00% 166.67% 125.00%
60 90 70 90
70 --- 80 90 166.67% 125.00%
80 100 80 90 150.00% 166.67% 125.00%
90 110 80 ---
100 110 80 90 175.00% 166.67% 125.00%
110 110 80 90
120 110 90 90
130 110 90
140 100 80
150 110 90 175.00% 200.00%
160 110 100
170 120 110
180 120 110
190 120 110
200 130 100 225.00% 233.33%
210 120 110
220 130 110
230 110 ---
240 110 130
250 110 130 175.00% 333.33%
260 110 130
270 110 140
280 110 130
300 110 140 175.00% 366.67%
320 110 140
340 120 150 200.00% 400.00%
360 120 140 200.00% 366.67%
380 120 140
400 120 140 200.00% 366.67%
_____________________________________________________________________

I did not bother with comparing all the cut data, but I think this shows the trends well enough.
 
wow, some real creative math at work here. Vassili, you should post the actual measurements for each run instead of just the median value. I wonder how much importance the infiholics will place on a 10 gram difference in initial sharpness when they see it comes from 21 cuts with a, what, 50 gram spread?
 
hardheart said:
wow, some real creative math at work here. Vassili, you should post the actual measurements for each run instead of just the median value. I wonder how much importance the infiholics will place on a 10 gram difference in initial sharpness when they see it comes from 21 cuts with a, what, 50 gram spread?
Click to expand...
I did post everything on this page:

http://playground.sun.com/~vasya/Manila-Rope-Testing.html

Every single test, including control tests between sessions, tests after I wash blade with warm water and soap - just every single digit I have in my study journal. It did not updated from last friday - need to came to the office, but I have some cold now? so I stay in home and cut ropes instead...

This is initial sharpness and it is not so spreaded:

INFI
30 ++++
40 ++++++X++
50 ++++++++

420HC
20 ++++
30 ++++++X+++
40 ++++
50 +++

ATS-34
20 +++
30 ++
40 +++++X+++
50 +++++
60 ++

INFI has excellent Gauss curve, and 420 and ATS is pretty good also.

Actually, difference in 10 is pretty clear - 30 gives long nice shave out of hair, easy. 40 split the hair but tends to cut it - it is not shave - too thick - but more like long diagonal cut. 50 may cut hair by touch but not whittle it. All have 10 g difference came from 50 spread. Spread is result of tools precision not quality of edge (which I purify using statistic - median).

Thanks, Vassili.
 
nozh2002 said:
Spread is result of tools precision not quality of edge (which I purify using statistic - median).
Click to expand...

kinda my point, you've reduced the error, and there is a difference, but going from raw measurements, to the median, choosing arbitrary points to start averaging the medians, or generate some ratios, there's a reason a lot of people don't like stats. The numbers don't lie, but they can be interpreted in a myriad of ways. To me, what it boils down to is pretty much what you said, for a specific test, you have these particular results, and they don't alone make any absolute statement about steel superiority. Trying to make one steel look better than another through additional steps that the test wasn't designed to accommodate doesn't help.

How would you classify the cutting ability after the 400 cuts? I had a knife shaving arm hair, albeit with some irritation, at 190g. Perhaps some don't also realize how crazy sharp 30-40g really is.
 
Well, this is what is this raw data for - for people to interpret, try to understand. This is second step of scientific practice:

1. Collect data during experiments
2. Analize and interpret
3. Came up with theory
4. Predict someting new with this theory.
5. Prove that prediction by another experiment.

I think it is great what PghMitchS02 did. This is some point of view. I respect it. He may be wrong, may be not - we may discuss it.

May be this % need to be defined better because I do not think that it is correct to say that 50g edge "twice sharper" then 100g edge.

But I like this to be like community project and welcome any ideas. May be some body even join my effort and start doing same tests too...

Thanks, Vassili.
 
HH: Perhaps some don't also realize how crazy sharp 30-40g really is.

Nozh: I do not think that it is correct to say that 50g edge "twice sharper" then 100g edge.

I think these two statements really show the heart of the issue here. I tried to address this in my previous post. In order to give percentages you need an absolute point of reference and the initial sharpness is not one. It is the same mistake to say that 50g is twice as sharp as 100g as it is to say that the temperature increased by 100% when the temperature was raised from 50F to 100F. Let's examine this a bit more Cobalt's argument would be that you take a pot of water at 40F and heat it to 120F and a second at 50F and heat it to 100F. You then proceed to claim that the first pot is 300% hotter than it was before and the second is 200% hotter, a difference of 100%. Without wanting to step on anybodies toes but the truth is that this line of argument is complete and utter nonsense as the Fahrenheit scale happens to be about as arbitrary a scale as one could envision. In truth, the first pot was raised from 278K (K stands for Kelvin which is measured to the absolute 0 temperature) to 320K, a mere 15%, and the second from 283K to 310K, by 10%. Hence the difference of the temperature increase between the two pots is a mere 5%.

For sharpness, value of absolute sharpness is practically not really possible to define, as towards 0g the scale would get hopelessly nonlinear, but in principle, it would be possible to use 0g as point of reference. Far more practical is it to use absolute bluntness as reference. My guess is that the thread, that Vassili is using, breaks at about 1.5kg (this corresponds to the strength of the polythread that I started testing on) on a completely unsharpened edge. So 30g is actually 2% bluntness while 40g represents 2.7% bluntness. This is a much more illustrative number, as shows, that both are bloody damn sharp with little difference between them. Now, after so-and-so many cuts the 30g blade dulls to 120g while the 40g blade dulls to 100g, or 8% and 6.7% of complete bluntness. So the first dulled by 6% while the second dulled by 4%....a difference of wopping 2%!!!!!

These numbers represent much more closely how the dulling is experienced in practice. They also explain why this test has changed Nozh's steel-snob attitude....(I still have my doubts.....about this change of attitude, I mean, not about his numbers; I would bet a good deal of money that he will continue to lust after the latest and greatest steel :D....but then, who doesn't :D).
 
Larrin said:
You can't interpret results that way. You can say that this test is not completely accurate because they didn't start out at the same level of sharpness, but only through statistical nonsense can you say that INFI performed "83% better than 420HC," unldess you're just making sarcasic comments, in which case I don't think you're adding anything to the discussion.
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Larrin as usuall you are incorrect. The results have to be interpreted as a matter of difference from start to finish if yu want to discount the initial sharpness, if you could get away from your hidden agenda you would realize that. The way I interpreted the results is correct and the only logical way.


Noz, I resent your statement of my turning this into a fan boy club issue. I correctly interpreted results. IF you can't see that, that is your problem, but the numbers speak VOLUMES!!!! LOOK AT INFI FROM CUT 100 TO CUT 400, IT DOES NOT CHANGE. If you have trouble giving kudos where they are do then maybe you need to look at your partiality in this and your real reason for doing this. The results are quite clear to anyone with a logical mtrl's/me engineering background or even analysis theory background.
 
Noz,

I know how hard this work is, and how long it takes. I'm doing a similar test with D2 and CPM D2, and it's *much* more work than I thought it would be. I aggrevated an old elbow injury, so had to take a break for a while.

I'll be posting the raw data also, so people can draw whatever conclusions they like, but the results will be posted on Cliff's site. I'll let you know when I'm done if you are interested.
 
Cobalt said:
Larrin as usuall you are incorrect. The results have to be interpreted as a matter of difference from start to finish if yu want to discount the initial sharpness, if you could get away from your hidden agenda you would realize that. The way I interpreted the results is correct and the only logical way.
Click to expand...
I am not discounting the original sharpness, I am telling you that you cannot interpret based on percentages from initial sharpness. HoB gave a nice lengthy post about why.

I haven't said anything about INFI being better or worse than 420HC, and I haven't discounted any maker's work or choice in steel. The only one with an agenda here is you. You're trying to show by your interpretation of data that INFI is the better steel. Regardless of whether the data shows what you are saying it does, doesn't say that it is better anyway. INFI is a good steel. It is a good choice for Busse's designs, purpose, and customer base. I have no problem with it.

I don't necessarily think 420HC or INFI are "better" than the other. Different steels for different applications.
 
sodak said:
Noz,

I know how hard this work is, and how long it takes. I'm doing a similar test with D2 and CPM D2, and it's *much* more work than I thought it would be. I aggrevated an old elbow injury, so had to take a break for a while.

I'll be posting the raw data also, so people can draw whatever conclusions they like, but the results will be posted on Cliff's site. I'll let you know when I'm done if you are interested.
Click to expand...

Yes be carefull - I think I developed corns on my fingertips now and it is not as painfull as it was before. Still cutting rope 20 times with short handled Game Warden kind of hurt my wrist... Be careful!

It is more painful to hear from people that I have some hidden agenda here or something.

I think you should post your results here too.

Thanks, Vassili.
 
I hear you. The raw data is the raw data, if people don't want to believe that, they can always duplicate it themselves. You've been pretty open about your methods, I wouldn't think it would be too hard for someone to duplicate your methods.

Actually doing the work, though, would be very difficult.
 
HoB said:
I think these two statements really show the heart of the issue here. I tried to address this in my previous post. In order to give percentages you need an absolute point of reference and the initial sharpness is not one. It is the same mistake to say that 50g is twice as sharp as 100g as it is to say that the temperature increased by 100% when the temperature was raised from 50F to 100F. Let's examine this a bit more Cobalt's argument would be that you take a pot of water at 40F and heat it to 120F and a second at 50F and heat it to 100F. You then proceed to claim that the first pot is 300% hotter than it was before and the second is 200% hotter, a difference of 100%. Without wanting to step on anybodies toes but the truth is that this line of argument is complete and utter nonsense as the Fahrenheit scale happens to be about as arbitrary a scale as one could envision. In truth, the first pot was raised from 278K (K stands for Kelvin which is measured to the absolute 0 temperature) to 320K, a mere 15%, and the second from 283K to 310K, by 10%. Hence the difference of the temperature increase between the two pots is a mere 5%.
Click to expand...

An excellent argument illustrating the importance of working from the proper frame of reference in order to draw conclusions from raw data.

HoB said:
For sharpness, value of absolute sharpness is practically not really possible to define, as towards 0g the scale would get hopelessly nonlinear, but in principle, it would be possible to use 0g as point of reference. Far more practical is it to use absolute bluntness as reference. My guess is that the thread, that Vassili is using, breaks at about 1.5kg (this corresponds to the strength of the polythread that I started testing on) on a completely unsharpened edge. So 30g is actually 2% bluntness while 40g represents 2.7% bluntness. This is a much more illustrative number, as shows, that both are bloody damn sharp with little difference between them. Now, after so-and-so many cuts the 30g blade dulls to 120g while the 40g blade dulls to 100g, or 8% and 6.7% of complete bluntness. So the first dulled by 6% while the second dulled by 4%....a difference of wopping 2%!!!!!

These numbers represent much more closely how the dulling is experienced in practice. They also explain why this test has changed Nozh's steel-snob attitude....(I still have my doubts.....about this change of attitude, I mean, not about his numbers; I would bet a good deal of money that he will continue to lust after the latest and greatest steel :D....but then, who doesn't :D).
Click to expand...

Working backwards, a great approach IMO. I don't think I've seen it proposed before. Nice work HoB.
 
Larrin said:
I am not discounting the original sharpness, I am telling you that you cannot interpret based on percentages from initial sharpness. HoB gave a nice lengthy post about why.

I haven't said anything about INFI being better or worse than 420HC, and I haven't discounted any maker's work or choice in steel. The only one with an agenda here is you. You're trying to show by your interpretation of data that INFI is the better steel. Regardless of whether the data shows what you are saying it does, doesn't say that it is better anyway. INFI is a good steel. It is a good choice for Busse's designs, purpose, and customer base. I have no problem with it.

I don't necessarily think 420HC or INFI are "better" than the other. Different steels for different applications.
Click to expand...


yes, and I would agree that the percentage between the two steels is not relevant. However, it is quite evident from the data that the INFI started out duller and ended up remaining sharper than the 420HC at the end. What's more it did not degrade hardly at all from cut 100 to 400. Something that cannot be said for 420HC. Tell me you don't see the obvious from the results and we have nothing more to talk about.

I have knives of 420HC from buck. The edge is very sharp from factory. I have never found it to be durable in long term edge wear and this confirms what I have done. I have had 2 Buck Nighthawks and 2 Intrepids, one of which I still own.

Noz, part of doing these tests, which are impressive by the way, is to know how to study and analyze your results. To do all this work and just say "oh, INFI did not perform that much better than 420 HC" is to do yourself a disservice. IF you don't like being accused of "an agenda" then maybe you shuld refrain from accusations as well. That "fan Boy" comment was accusational and IMO showed your bias.

you want to do a fair? test have both edges sharpenned to the exact same profile, then the starting number will be identical and your end result will show exactly what you saw today that the percent degradation for infi was much less than for 420, 50% versus 133%, and these numbers are straight from your results.
 
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