M390 VS ZDP-189 Rope Cutting - Informal testing

[Tripton]

bevel width means nothing without knowing primary grind angle, as the two together determine the width of the edge bevel for any given sharpening angle. He sharpens on a 15 degree block, so the inconsistencies would be from an inability to hold the knife parallel to the ground. So that may be the case, but he is attempting a known and represented angle created by the jig. It also means his thumbstuds are sharpened at 15 degrees

This American Lawman is an example of looks being baseless. Factory edge, equal bevel width comparing side to side. Actually measured 30 degrees on one side, 12 on the other.


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This is true, but what about the bottom 710, where the edge appears wide, then thin, then wide, then thin, then wide.

Its wavy. They only way that you could get that, aside from a poor sharpening job, is with a poor blade grind, which I kind of doubt is the case.

 

[hardheart]

The blade grind would not have to be poor, it could be following a recurve. This removal of the recurve shape is not the best way for aesthetics and consistency, which would be to regrind the profile then reset a new primary grind. It is resetting the edge profile purely by sharpening with no consideration of the recurve, treating it like a straight grind until it becomes one.

Starting with the stock 710 shape, you can see the recurve portion is narrow on the regrind, that is because that is essentially the stopping point. The edge is wide ahead of and behind that, because that is where the metal needed to be removed to straighten out the edge until it lined up with the narrowest point. Now that the edge grind ignores the primary grind, the edge bevel width changes along the length. It is narrow again at the belly because that is the other end of the straight line before the turn up to the tip. With the tip above the centerline and no distal taper, that is seemingly why it widens as well.

I really don't think the edge bevel width is one of the main concerns with his testing results. There are others unaddressed.

The CATRA tester can be rented, ie they will test blades for you. If Vassili wants, I can email Roger Hamby about it, or maybe Sal would let us rent some time on Spyderco's. Then we could compare Vassili's results to the CATRA's on his knives/edges, and some of us could send in our own as well for more data points. These would be ELU applied edges, not factory comparisons that I think Sal wouldn't want to appear to be poo-pooing on competitiors. I would like to have each edge measured on a laser goniometer, width above the edge bevel mic'd out, before/after high magnification pics of the edges, and hardness tests.

 

[nozh2002]

little bit more "math gibberish".

This is negative curve of the blade. if we take straight line "a" and check thickness of the blade at ther beginning - point A, at the center - point B and at the end - point C. We will have at point B less thickness then at points A and C.

It is obvious but mathematically speaking at A and C we ill be at base of cross section triangular while at point B almost in th middle of same cross section triangular.

Same also seen if wee look at straignt line "b" for points D, E and F. Thickness at the point E obviously zero while at the ends of that negative curve section it is not.

Now once I straighten edge I have edge shoulders wider at the ends of this negative curve and thinner at the center. This happened because edge angle is same as well as edge line is straight.

Hope this will help.

Thanks, Vassili.

 

[oromoto]

That's a 950 cuts man! good exercise!

 

[wongKI]

Thanks Vassili and Hardheart. I had assumed the same thing.

Vassili, in your photo the edges of the three knives seem to vary in thickness-is this just the photo/angle?

Oh, and Ankerson, don't know where you got your rope, but you may want to look around fishing wholesalers and places like that, where I've seen 500m and 200m bales. Should be cheaper, and saves you the trouble of having to re-order so often. For our scout troop we usually get 150-200m bales.

Thanks for doing all these tests. It's been really interesting.

 

[nozh2002]

Vassili, in your photo the edges of the three knives seem to vary in thickness-is this just the photo/angle?

This is what I just explained. Because thickness of the blade (T) among straight edge line is different, so width of edge shoulders (S) vary as well, because it directly related and reflect blade thickness this way:

S = T/sin(PI/12)

Thanks, Vassili.

 

[wongKI]

I'm not actually referring to variation between edge thickness at different parts of the same knife, but edge thickness from knife to knife. The top blade seems to have a higher-bevel than the bottom one, for example. I am assuming all the blade stock is of same thickness and grind depth? If so it is either the camera, or my eyes are fooling me, or the bevels of the three knives are indeed different.

Thanks for the explanation on the individual blade variation, by the way. I had suspected that to be the case.

 

[nozh2002]

I'm not actually referring to variation between edge thickness at different parts of the same knife, but edge thickness from knife to knife. The top blade seems to have a higher-bevel than the bottom one, for example. I am assuming all the blade stock is of same thickness and grind depth? If so it is either the camera, or my eyes are fooling me, or the bevels of the three knives are indeed different.

Thanks for the explanation on the individual blade variation, by the way. I had suspected that to be the case.

Those three knives I bought different time. One is 7 years old, another over one and last one - this week. Older were sharpened many times on different tools (Sharpmaker, waterstones, but not machine tools). I do not understand why this is a big deal? Why all edge shoulders should be same. Edge angle all same, to the point you can achieve this by hands.

I also at the end of sharpening usually lower angle to remove edge shoulder edges - like bevel it, convex it a bit, to have less friction during cut. So width of edge shoulders is not good indicator of edge angle.

But why it is in discussion here - I tested only M390 knife today and M2 while ago?

Thanks, Vassili.

 

[xtestifyx]

But why it is in discussion here - I tested only M390 knife today and M2 while ago?

Because it matters more than so your problem with Ankerson using Wood as the backboard.


Look at your pictures, then Jim's pictures. The pictures you demonstrated your skill in sharpening in bringing uneven surfaces, from tip to choil, it is a difference and your testing has been compromised.


Comparing each knives to themselves, and according to your math, the conclusion is: If the edge has the consist angle from tip to end, the place where the grind is taller is where there is more steel at the shoulder/thicker grind.

You have broken your own math and falsely tried to confuse us, or at least those of us who aren't as bright as others in this department.

Jim's pictures, and some of mine of how angles are means to look like. Consistency is key, all the way through.

Even grinds on two different knives:

Even Grind

Even grind with low-lighting:

 

[DennisStrickland]

xtestifyx you are great at your edges & your critiques. thanks for the great pics & the update.as they say-- you talk the talk & walk the talk.
dennis

 

[nozh2002]

Because it matters more than so your problem with Ankerson using Wood as the backboard.


Look at your pictures, then Jim's pictures. The pictures you demonstrated your skill in sharpening in bringing uneven surfaces, from tip to choil, it is a difference and your testing has been compromised.


Comparing each knives to themselves, and according to your math, the conclusion is: If the edge has the consist angle from tip to end, the place where the grind is taller is where there is more steel at the shoulder/thicker grind.

You have broken your own math and falsely tried to confuse us, or at least those of us who aren't as bright as others in this department.

Jim's pictures, and some of mine of how angles are means to look like. Consistency is key, all the way through.

Even grinds on two different knives:

Even Grind

Even grind with low-lighting:

Really, I can not help you here... Really, sorry.

Thanks, Vassili.

 

[Premiumsteel]

I wish there were more models of BM available in M390 than the 710 and 755. I don't really like the recurve on the 710. Might wind up getting an MPR though.

Is there anyone else doing M390? I think I saw a Kershaw composite in it, but I think the cutting edge was in something else.


I'd be interested in seeing them being compared in the resistance of the metal to deform under impact. I've heard some interesting stories about ZDP in that regard, and I'd probably go for edge-holding in this aspect over wear resistance.

You can purchase M390 knife bars in short lengths from ALPHA KNIFE SUPPLY and make your own knife. Bohler-Uddeholm sells single sheets of the material from stock in Seattle WA. Specs, online brochures and heat treat info are at bucorp.com under knives. Suggested heat treat range is 60-62 Rc.

 

[hardheart]

Because it matters more than so your problem with Ankerson using Wood as the backboard.


Look at your pictures, then Jim's pictures. The pictures you demonstrated your skill in sharpening in bringing uneven surfaces, from tip to choil, it is a difference and your testing has been compromised.


Comparing each knives to themselves, and according to your math, the conclusion is: If the edge has the consist angle from tip to end, the place where the grind is taller is where there is more steel at the shoulder/thicker grind.

You have broken your own math and falsely tried to confuse us, or at least those of us who aren't as bright as others in this department.

There are many things we have brought up about his testing. The lack of repetition of testing on multiple knives of the same steel, the lack of a control knife retested on each run, the lack of retests after measuring equipment was changed and test method was altered. What you are talking about is no more important, and no better handled by Ankerson. Fact is, it is uncontrolled in both Vassili and Ankerson's cases. A pretty bevel does not mean anything. What angles are Ankerson's edges, what is the bevel thickness, how old and how often was the ZDP Endura sharpened? Without any of this recorded, without any of it compared to other parameters, in other knives, other profiles, or with other heat treats, you can't say anything about the steels alone.

That is probably the biggest hole in Vassili's testing. What is his worst rated steel? D2. What is his best rated steel? D2. The difference? Probably who made it. Well then, how well do any of Vassili's other rankings/results hold? They don't. Neither do Ankerson's, or unit's, or So-Lo's, or mine, or sodak's, or Thom's, or anybody's. It takes what Sal talked about in testing variations with controls in place.

Does the edge striking the wood matter? If it happens to all tested edges, and you do enough runs, then probably not. Does the change in edge thickness matter on one knife? No more than the change in edge thickness from one knife to another. That does matter in force required to cut, in how that can influence loading on the edge, twisting and harder impacts into the wood from fatigue or sloppiness. But we are too inconsistent from the outset to measure this alone.

The title of this thread is spot on, this stuff is informal and inconclusive. Once you get into the classes we group steels into, like the specific examples given by Phil, the differences require hundreds of cuts into abrasive media, with consistent test media, cut method, and measuring criteria. What is 10 or 20% longer edge life on manila rope without measurement on cardboard, or measurement in corrosion resistance, or differences in impact resistance on multiple axes, or ability to handle prying & torquing? And what does any of that mean if we don't know what angle the edges were formed at, what angle the primary is set at, how thin the blade was ground before sharpening, or what finish was applied to the edge? What steel is better? For what knife? For what task? From which company?

The CATRA test is consistent, the submitted blades are not. I have seen two test results that showed one blade out cut the other by nearly two to one. If I didn't tell you what steel each one was, we would possibly assume one alloy was clearly better. But, it's the same alloy. A proprietary one only produced at one foundry. Same people made the same steel, so obviously there is a lot more to performance than that. Here we have random people making random cuts with random knives in random test media and measuring degradation against random thread, random paper, and random scales. What is the test winner? Impossible to say.

Does any of this testing tell us if we want M390, ZDP-189, S110V, 8Cr13MoV, etc? Or does it tell us if we want Benchmade, Spyderco, Kershaw, etc? Or does it tell us if we want a Military, and Endura, a Police, a Stretch, etc? It doesn't tell us anything because it is talking about everything all at once.

 

[DennisStrickland]

i believe that all the tests give information. no tests give us absolute parameters addressing all varibles. the important scenario is with enough people doing these various cutting sequences we do gain some knowledge, to totally dismiss this cutting of sisal, cardboard, & auto tires is just as an erroneous conclusion as the fact the tests give no truisms.keep on cutting gang.
dennis

 

[MORIMOTOM]

hardheart,

i think the point is that vasilli's are no better than ankerson's tests, regardless of what vasilli says, and way less practical and meaningful to the average knife carrier, like me.

cutting a bunch of strings and creating a spreadsheet with a bunch of numbers and equations means nothing to me. while he may be intelligent, he lives in a vacuum.

videos of a guy cutting various media and giving me an actual opinion i can relate to has meaning and usefulness.

 

[Ankerson]

There are many things we have brought up about his testing. The lack of repetition of testing on multiple knives of the same steel, the lack of a control knife retested on each run, the lack of retests after measuring equipment was changed and test method was altered. What you are talking about is no more important, and no better handled by Ankerson. Fact is, it is uncontrolled in both Vassili and Ankerson's cases. A pretty bevel does not mean anything. What angles are Ankerson's edges, what is the bevel thickness, how old and how often was the ZDP Endura sharpened? Without any of this recorded, without any of it compared to other parameters, in other knives, other profiles, or with other heat treats, you can't say anything about the steels alone.

That is probably the biggest hole in Vassili's testing. What is his worst rated steel? D2. What is his best rated steel? D2. The difference? Probably who made it. Well then, how well do any of Vassili's other rankings/results hold? They don't. Neither do Ankerson's, or unit's, or So-Lo's, or mine, or sodak's, or Thom's, or anybody's. It takes what Sal talked about in testing variations with controls in place.

Does the edge striking the wood matter? If it happens to all tested edges, and you do enough runs, then probably not. Does the change in edge thickness matter on one knife? No more than the change in edge thickness from one knife to another. That does matter in force required to cut, in how that can influence loading on the edge, twisting and harder impacts into the wood from fatigue or sloppiness. But we are too inconsistent from the outset to measure this alone.

The title of this thread is spot on, this stuff is informal and inconclusive. Once you get into the classes we group steels into, like the specific examples given by Phil, the differences require hundreds of cuts into abrasive media, with consistent test media, cut method, and measuring criteria. What is 10 or 20% longer edge life on manila rope without measurement on cardboard, or measurement in corrosion resistance, or differences in impact resistance on multiple axes, or ability to handle prying & torquing? And what does any of that mean if we don't know what angle the edges were formed at, what angle the primary is set at, how thin the blade was ground before sharpening, or what finish was applied to the edge? What steel is better? For what knife? For what task? From which company?

The CATRA test is consistent, the submitted blades are not. I have seen two test results that showed one blade out cut the other by nearly two to one. If I didn't tell you what steel each one was, we would possibly assume one alloy was clearly better. But, it's the same alloy. A proprietary one only produced at one foundry. Same people made the same steel, so obviously there is a lot more to performance than that. Here we have random people making random cuts with random knives in random test media and measuring degradation against random thread, random paper, and random scales. What is the test winner? Impossible to say.

Does any of this testing tell us if we want M390, ZDP-189, S110V, 8Cr13MoV, etc? Or does it tell us if we want Benchmade, Spyderco, Kershaw, etc? Or does it tell us if we want a Military, and Endura, a Police, a Stretch, etc? It doesn't tell us anything because it is talking about everything all at once.

I never said mine were conclusive, nor will I.

I am not done either, I still have to post results once the last Endura gets here and I do the cutting.

It will be 4 knives in Part 2 of this, 2 Endura 4's and 2 BM 710-1's on 5/8" rope, all sharpened to 30 degrees inclusive and polished to 6000 grit Polishing tapes on the Edge Pro. All knives are sharpened until they will slice though TP clean like in my video.

Even after all of this nothing is set in stone.

Total once I am done will be 3 Endura 4 ZDP-189's and 2 BM 710's tested between part one and two.

Sofar in my testing I have made 2430 cuts and I am not done yet.

 

[hardheart]

i believe that all the tests give information. no tests give us absolute parameters addressing all varibles. the important scenario is with enough people doing these various cutting sequences we do gain some knowledge, to totally dismiss this cutting of sisal, cardboard, & auto tires is just as an erroneous conclusion as the fact the tests give no truisms.keep on cutting gang.
dennis

The question is exactly what is the information. Why are some blades coming ahead of others. Why are some steels, Why are some edge angles or levels of edge polish. What are the successful combinations? We don't know, the controls aren't in place

hardheart,

i think the point is that vasilli's are no better than ankerson's tests, regardless of what vasilli says, and way less practical and meaningful to the average knife carrier, like me.

cutting a bunch of strings and creating a spreadsheet with a bunch of numbers and equations means nothing to me. while he may be intelligent, he lives in a vacuum.

videos of a guy cutting various media and giving me an actual opinion i can relate to has meaning and usefulness.

I both agree and disagree. I know that hardness affects cutting performance. I know that edge geometry affects it. I know that carbide volume does. So spreadsheets and numbers are very important to us if we are going to care about steel. Vassili's numbers aren't representative for anything other than this is what happened when Vassili used Vassili's knives to cut Vassili's rope. But even the industry metrics don't matter if I won't bother to own the knife utilizing the steel & heat treatment due to other factors in cost, design, etc.

As well, after a few hundred knives, I know what I like more or less. I also can and will change edge geometry at the drop of a hat, so out of the box performance is not such a big deal. And a lot of us order customs. I am waiting on one now where I specified the steel and target Rc to the maker.

So tabletops and cutting demos only go so far, as do numbers and documents with no real world examples. I can watch someone cut cardboard in a 15 minute youtube video, and it would take a couple years of my recent history to match that length of time slicing boxes. In the three years I worked offshore I didn't cut as much rope as any of these guys do in one clip. I had cut a lot of electrical tape, but no one cuts that on video, and it doesn't really matter what steel you use for it anyway, imo. I also cut up some roofing shingles. That doesn't get used because that wrecks an edge in short order.

Sofar in my testing I have made 2430 cuts and I am not done yet.

That is an impressive amount of cutting, as is Vassili's amount. I don't know what I can do with that. Even the CATRA results I posted from the magazine article are pretty abstract. And the tests vary so much. A calibrated machine on 20% silica cardstock with a constant load. Human hands doing a set number of cuts and measuring string cutting force intermittently. Or hands cutting rope and then slicing paper. Or shaving arm hair. Or cutting on a scale until it reads 20 pounds. Then we start slicing tires. With edges polished on leather with chromium oxide. Or diamond pastes. or polishing tapes. or lapping film. Or only finished at fine India. 40, 30, 24, 20, etc degrees included.

Just sometimes it feels like we're trying to determine the best engine by comparing Fords, Dodges, and Chevys, but some going offroad, or pulling a trailer, or running the quarter mile, or pulling the drain plug while running... yet no one has stopped and said that the tests are actually different and providing different results.

 

[Ankerson]

That is an impressive amount of cutting, as is Vassili's amount. I don't know what I can do with that. Even the CATRA results I posted from the magazine article are pretty abstract. And the tests vary so much. A calibrated machine on 20% silica cardstock with a constant load. Human hands doing a set number of cuts and measuring string cutting force intermittently. Or hands cutting rope and then slicing paper. Or shaving arm hair. Or cutting on a scale until it reads 20 pounds. Then we start slicing tires. With edges polished on leather with chromium oxide. Or diamond pastes. or polishing tapes. or lapping film. Or only finished at fine India. 40, 30, 24, 20, etc degrees included.

I have plenty of impressions sofar, but I will wait until it's all done to lay it all out along with my findings and photos.

One thing I can say is that Manila rope really tears up edges and it's extremely harsh on them especially when making the amount of cuts per knife that I am. It's something you won't see in just a few cuts, but make a lot and it will start to really tear them up.

One can really start to feel the difference in sharpness after 100+ cuts from these 2 steels what I have noticed.

I could stop testing around 150~200 cuts if I was just doing force needed, pressure etc, but I am not testing for that, I am going until the edges start to really break down and really start to dull bigtime by tearing paper. There is a purpose for my madness as in to see what will still be sharp enough to use and how long they will last before they really break down. I can't test until completely dull because both of these steels will cut rope for a very long time after I stopped. I would have to buy a lot of rope, and I mean one heck of a lot of rope to test to completely dull.

I have said enough.

 

[nozh2002]

Well, it sounds like - lets just give up and trust Sal that he will chose best for us. I heard something similar in different country in different era and have kind of bit negative experience with that.

Sorry, now I am not buying it. For example CPM S30V turns out to be not such a good replacement then CPM S60V. I wish to know that CATRA results 7 years ago. But it was pushed very hard the time that switch happen. After all Sal is selling his knives and as he mentioned himself

...Salesmen aren't always the best source of information on their produts...

Sal tell a lot about his intensive testing of this way and that way - but did not provide any results. Only some half truth, some foggy hints. Like H1 work hardening - in result I bought Salt, but after tested it myself was bit disappointed. I also was disappointed with CPM S35V, CTS-BD1, CPM M4...

I am not sure about others, but I need the way to have independent test results and without other options, I developed mine. Actually for my own use.

So of course I do not have enough numbers of tests, but did you join my effort? No I can not do 100 of tests myself alone. I described my method with full detales in hope that there is enough enthusiasts here who will do same. But not no one help.

But I rather hear from you - "You did not done enough!" - Thanks a lot!

As I mentioned before - this is only what you have, There is no Sal's test results available, as well as same for Phil. I really hope Ankerson will refine his tests and have some numbers to analyze.

I also hope to have statistically better results, but Sal is not giving it away, and nobody want to do testing using my method, let's wait for Ankerson.

Until you want to do some hard work yourself?

Thanks, Vassili.

 

[Noctis3880]

It would be nice if we could get a nice picture of the edges after the torture test and an opinion on what ultimately dulled the edge(abrasion, edge rolling, micro chipping). But this is all getting a little TOO scientific for my tastes:barf:.