Laminated knife steels

[hardheart]

Unless he states edge angles and types, like you did, those charts don't have pretty much any meaningful interpretation from the comparison standpoint.

Do you mean Vassili? He sharpens at 15 degrees per side using DMT diasharps followed by chromium oxide loaded leather. He's posted videos of the process. Honestly, too many imo, making a pass against a DMT XX coarse is the same as making one against a DMT X fine.

 

[Josh K]

Do you mean Vassili? He sharpens at 15 degrees per side using DMT diasharps followed by chromium oxide loaded leather. He's posted videos of the process. Honestly, too many imo, making a pass against a DMT XX coarse is the same as making one against a DMT X fine.

Chromium oxide is softer then the carbides in S90V right?

 

[hardheart]

yes, the matrix around the carbides can be abraded by the CrO, but the vanadium carbide is harder. I believe Vassili mentioned he has some 50,000 mesh diamond, he'll have to comment on his use of it. I added 100,000 mesh diamond powder to my strop to help with more carbide rich steels. Works well on my 110V shallot, though really wasn't needed for zdp-189.

 

[MJF]

Steel comparison tests are really just conjecture unless you are using blades with the exact same Geometry and angles. Geometry can be more important in cutting power than any other factor. Something to keep in mind.

 

[Gator97]

Do you mean Vassili? He sharpens at 15 degrees per side using DMT diasharps followed by chromium oxide loaded leather.

Yup. Although the chart never states angles, so I dunno if he does the same for all of the knives. Shallot didn't look like it was sharpened on sharpmaker, and the other 710 edge from the pic posted elsewhere, looked higher than 15 per side. That can be because of reprofiling, but I I have 710 with 15 per side (using edge-pro) and the edge "road" is much wider.
And then there is the whole blade thickness, grind thing to consider.

Honestly, too many imo, making a pass against a DMT XX coarse is the same as making one against a DMT X fine.

Agreed. On the other hand, DMT X fine is 1200 grit, or 6-7 mic. particle size. CrO is 0.5mic, or 50K-60K grit.
It's a really big jump from one to another and it'd require very long stropping to get truly 0.5 mic edge, I am not sure it's really possible. Plus you could add free hand variations during such a long stropping, resulting to edge rolling, not sharpening.
I don't disregard effects of stropping on CrO loaded strop, but, IMHO when making such a big jump in sharpening abrasive grit the final results will vary significantly.

To get more or less consistent results I have to use 5mic, 2 mic, 1mic(optional, mainly for very hard steels), then 0.5 and then 0.25 mic.

I've skipped grits in between few times, for experimenting and went straight to 0.5 or 0.25 mic. Can't get that edge as usual. As Dave Martell says, 0.25mic diamond spray or even 0.5mic CrO isn't for sharpening, the edge has to be "there" before you get the real benefits. If you skimped on previous steps then those fine abrasives won't make the fine edge you want.

Alternatively, the fine edge may not be the goal, but then the whole hair whittling criteria doesn't make much sense. I can get my knives to that sharpness using 2K Japanese natural whetstone, which during sharpening gets to ~4K as I understand, because the particles break down to finer grit, but that's still way far from 50K or 100K.

Shrpness test itself is cutting a thread, then the measurements are in grams, and tenth of a gram, so the variation can be quite significant because of all the above, during the sharpening process.

 

[Squeezymo]

Why 5 why not 100? Is it magical number making it scientific.

Not at all. He has same procedure for every knife and with certain probability it show what to expect from this or that manufacturer.

For example if he get knife made out of wood and it fail. I guess nobody will ask to test 5 of this knives before make conclusion. Science deals with all kind of information and sometimes with fenomens which happened very rare. So it is not required to have 5 observation to be scientific. What are you talking about is how representative this tests are. But we deal with this all the time - and results from one knife also valuable, until he use same procedure for all of them.

People who attack Noss4 does not realise that only valid way to prove that it is not representative is to increase number of observation - do more tests. But so far nobody like to do real work, just talk and get angry.

Thanks, Vassili.

P.S. You may talk a lot about inaccurate tests - but you do not even bother to chack my tests - I did not test VG10 yet.
Do your own tests and then I will listen to you on how inaccurate my tests are.

No, my point is that the number 1 is a magical number in a respect making something unscientific. If you drop a pane of glass on the ground and it doesn't break, then you wouldn't stop there. You've done 1 inconclusive test and it'd be silly to draw the conclusion that if you drop a pane of glass on the ground it won't break. Do it 5 times you'll have a better idea. do it 15 times you'll get an even better idea. Do it 1000 times you have some more evidence. Some procedure doesn't mean crap either. He does the same procedure but he has very wide variables. He might hit a knife harder than he did another knife with a mallet, the humidity could cause the wood he's batoning with to be softer, he could hit a rock in the concrete block that shouldn't of been there, chipping the edge, etc. You can't simply do one test and call that scientific evidence. Back to the pane of glass example. All you "prove" when you did that is that you can drop a pane of glass on the ground without it breaking. You don't assess anything else unless you do more tests.

I didn't attack Noss4 at all. I like his tests. But I don't think they are scientific. That's all I said.

P.S. Once again I admit I don't agree with your tests. I think you use innaccurate methods, and I don't even own half the steels on your list and the ones I do do "pretty well." I already told you that if you want people to believe your tests are accurate you need to do the same test on the same knife several times, then get the same model of the knife and test it again and again. Until then you're just cutting string.

 

[hardheart]

And then there is the whole blade thickness, grind thing to consider.

The nice thing with using string and rope is that the strands are smaller in diameter than the edge bevel, so the thickness is the same when the material parts. A 30 degree edge is the exact same no matter the stock thickness, at least for that fraction of a millimeter of steel that cuts the string.

It's a really big jump from one to another and it'd require very long stropping to get truly 0.5 mic edge, I am not sure it's really possible. Plus you could add free hand variations during such a long stropping, resulting to edge rolling, not sharpening.
I don't disregard effects of stropping on CrO loaded strop, but, IMHO when making such a big jump in sharpening abrasive grit the final results will vary significantly.

To get more or less consistent results I have to use 5mic, 2 mic, 1mic(optional, mainly for very hard steels), then 0.5 and then 0.25 mic.

I've skipped grits in between few times, for experimenting and went straight to 0.5 or 0.25 mic. Can't get that edge as usual. As Dave Martell says, 0.25mic diamond spray or even 0.5mic CrO isn't for sharpening, the edge has to be "there" before you get the real benefits. If you skimped on previous steps then those fine abrasives won't make the fine edge you want.

Honestly, I find it doesn't matter if you put in enough time. If he's still doing it the same, Vassili uses 50 strokes per side on the strop. I myself have noticed improvements in edge performance at a tenth that number, and have played with large jumps, like stropping after coarse crystolon. CrO is not fast, but it is an abrasive, and will sharpen an edge. I've taken edges that won't shave at coarse grit (greater than 50 micron abrasive), and worked them with the strop, 13,000 grit waterstone, or Spyderco ultra-fine,and gotten them to whittle hair.

Alternatively, the fine edge may not be the goal, but then the whole hair whittling criteria doesn't make much sense. I can get my knives to that sharpness using 2K Japanese natural whetstone, which during sharpening gets to ~4K as I understand, because the particles break down to finer grit, but that's still way far from 50K or 100K.

The coarsest edge I have split a hair with so far was sharpened on coarse crystolon (100 grit, 141 micron size) It was tricky to do, but I have done it at a few other levels of finish and find that it can be done without extreme difficulty if some patience is used. I still don't know how to separate sharp from polished, as I have done some tricks with edges that wouldn't be expected to pull it off.

 

[Gator97]

The nice thing with using string and rope is that the strands are smaller in diameter than the edge bevel, so the thickness is the same when the material parts.

Agree about the string, but that's just a control/measurement cut. Rope, which consists of multiple, intertwined(?) strands is still not the same as single strand. When pushing through it thickness matters.

Honestly, I find it doesn't matter if you put in enough time.

Unless the final edges are of the same thickness, otherwise it sure matters.

Let's do some very simple math/physics ok? I'll use SI system for simplicity.
P = F/A. Where P is pressure, F is force and A is the surface area. For the sake of example, let's consider that edge tip, or contact surface, is rectangle( it's a wedge after all), constantly 1micron long, width will be variable, depending on the abrasive used.
For the case when 100g force was needed to cut the string, with the blade sharpened on 1200 grit sharpened, edge width would be ~7mic.
Using the formula we have: 0.1kg/0.000007m ~= 14285.75p.
Now, we can safely assume that 14285.75p is the pressure that is required to break that strand.
Using that pressure, we can find the force necessary to break the same strand at 5mic for example, F = 14285.75p x 0.000005m ~= 0.0715kg, or ~71g.
If you look at his sharpening test tables, on 100th or even 200th cut the differences rarely exceed 30g, more often it's considerably less.
So... To me, that looks pretty imprecise, or inconsistent to judge metal wear resistance by those results.
Now, depending on what type of steel you're stropping with CrO and how you do it you can easily get quite distorted picture. ZDP-189 won't wear at the same rate as S30V or AUS-8.
The simple fact that in his own table, the force required to cut the string 1st time, varies by as much as 100%(10g and 20g) does tell me that sharpening results are quite inconsistent.
I personally think that is the result of going to strop from 1200 grit. Yes, it does improve sharpness, I am not arguing neither the usefulness of stropping, nor the apparent improvements in sharpness.
I do argue however, difference in initial sharpness will provide incorrect picture for steel comparison in terms of wear resistance.

I don't believe that every knife can be brought to hair whittling sharpness(which seems to be Vassili's sharpness criteria) using 50 strokes per side on CrO loaded leather right after ex fine DMT. Especially, when those DMTs are those narrow diafolds and it's not that easy to keep consistent angle on handheld sharpeners.
I don't even know what's the starting point, after 50 strokes on the CrO strop or when it is hair whittling?

The coarsest edge I have split a hair with so far was sharpened on coarse crystolon (100 grit, 141 micron size)

No, I am not there yet, haven't even tried that. Although, considering that the human hair is 50mic thick it's a pretty hard feat May be the hair got stuck on exceptionally large carbide

 

[hardheart]

If the end of the rope is not restricted, then the individual strands are cut and move away from the blade, so there is not an accumulation of material impinging the blade. Or, if the rope is under tension, so it kinda depends on how the rope is held as to how much affect the bundle of strands is versus single ones.

As for the calculations, it is hard to tell what is going on because it is hard to say what the edge condition is, no matter what the final finishing stone. I split a hair with an edge finished at 100 grit because I treated the stone like a fine strop (and tried many times before I got it ). Same way I get a hair shaving edge with a bastard file. In my hands, with what I call light pressure, I have a pretty good idea of what the edge can do. I don't know exactly what condition his edges are at after the DMT (diasharp, btw, not diafold, pretty sure all his plates are 3 inches wide) or the strop. From what I've managed to do, I would say the edge could/should be whittling hair before the CrO. Without the appropriate viewing equipment, I don't know what the edges actually look like, and I don't really know how the hairs are being split. The hair is layered in scales, and the knife edge is a ragged bit of metal possibly with various sizes of carbide exposed from the matrix, which can be at varying levels of hardness depending on the composition.

 

[Gator97]

As for the calculations, it is hard to tell what is going on because it is hard to say what the edge condition is, no matter what the final finishing stone.

Partly true. But, skip all that math and sharpening complications. Right there, in those tables, one knife starts twice as dull as the other. and based on that fact alone, I wouldn't be comparing two steels for edge holding...
Even with identical edges it's still bunch of variables, because it's a free hand cutting anyway. 100% difference in initial sharpness is way too much to make any serious conclusion.

 

[Squeezymo]

If the end of the rope is not restricted, then the individual strands are cut and move away from the blade, so there is not an accumulation of material impinging the blade. Or, if the rope is under tension, so it kinda depends on how the rope is held as to how much affect the bundle of strands is versus single ones.

As for the calculations, it is hard to tell what is going on because it is hard to say what the edge condition is, no matter what the final finishing stone. I split a hair with an edge finished at 100 grit because I treated the stone like a fine strop (and tried many times before I got it ). Same way I get a hair shaving edge with a bastard file. In my hands, with what I call light pressure, I have a pretty good idea of what the edge can do. I don't know exactly what condition his edges are at after the DMT (diasharp, btw, not diafold, pretty sure all his plates are 3 inches wide) or the strop. From what I've managed to do, I would say the edge could/should be whittling hair before the CrO. Without the appropriate viewing equipment, I don't know what the edges actually look like, and I don't really know how the hairs are being split. The hair is layered in scales, and the knife edge is a ragged bit of metal possibly with various sizes of carbide exposed from the matrix, which can be at varying levels of hardness depending on the composition.

He cuts the rope about an inch at a time off the end of the rope, free hanging. This would force the rope to close on the blade making thickness an important variable.

 

[nozh2002]

I am cutting rope about ~1/4" from the end (it is on video I provided).

But there is testing thread in testing subforum. It will be better place to discuss this there and also it will be better if people who talk a lot about this test first learn what it is - there is quite a bit of disclosures there. Otherwise it is hard to discuss real test vs imaginary test (which to my knowledge happened all the time - people do not bother even look at something they jump to discuss, I am not even talking about doing real testing).

Thanks, Vassili.

 

[Gator97]

That is exactly what he said. That end is free hanging. If your rope was "hanging" then nothing would close.
Besides, initial force variation of 100% is your own data, posted on your site, so you don't have to complain about that.