Anyone ever try doing edge retention testing on their own?

[marrenmiller]

Spine? If you're going test your behind the edge theory than your flange has to be at the shoulder of the edge bevel not the spine.

Sure, I'm only using that location as an example to make it clear it's separated from the apex. Just an extreme example.

The only testing I've seen on this indicates there's no difference. I'd welcome proof that an apex wears more if the edge thickness behind it is *greater.

 

[David Richardson]

A lot of info (and opinion) here. I've done 100s of cut tests and am hoping to publish them. The big issue for me is controlling the variables. I'm doing it manually, so that's a big one. But I also can't get rope that is consistent. Even from the same manufacturer it varies so widely by spool that it makes my testing irrelevant. I'm on hold until I can get this figured out. I've probably tested ~40 steels, including all the Spyderco Mules, except S35 and the damascas. (The mules are not identical, but they're close enough for this level of testing.)

Geometry will change everything. You can't really test the same steel on one knife that's got geometry like an ax and other like a thin kitchen knife and expect similar results. Whenever possible you want to test with the same geometry. One variable controlled.

After testing a lot of steels my conclusion is that they're all good (almost), but different. I don't have a need for K390 in a pocket knife, but I still like carrying it.

Big mistake. I heard this tiny “tick” sound and after pulling the blade from the can I discovered about an 1/8 of an inch of tip was missing. It had snapped off under the twisting motion. I know you’re not supposed to use a knife in that manner but it was something I had done several times before with Bucks and Swiss Army knives with no damage.

Different steels for different uses. If you want something tough, S90 isn't it.

You could basically pick any point to stop at in any of these tests I've done and not be wrong. It's entirely subjective, it seems. I think a lot of the value in the cut testers that have been doing this a long time is that they've gotten good at identifying the point at which that they feel a knife is done with a test. It might be subjective but they seem to be able to determine that point for them consistently, at least.

I could go on and on about this. If I'm testing an edge and I stop at 400 rope cuts and it won't cleanly cut paper, was it sharp until 400? Or 350? Or 300? How do I know? I don't. My process is to test the edge more often as cuts increase and to adjust my result to 50% of the way between my last two sharpness tests. For example, if my edge would cut paper cleanly at 350 and then not at 400, the best result I can claim is 375, and even that may be high. (I should probably be claiming 376.) You could ask "why not just check the edge more often?" Too much hassle to check every 20 cuts if you're getting 600 rope cuts.

Finally I tested a S110V blade against a CTS BD1 blade during a garage clean up. Side by side, dividing each task between the 2 blades, edges sharpened to the same angle and grit finish and the thickness behind the edge within a few thousandths of an inch. The next weekend I repeated it. No discernable difference between the 2. I sold the S110V blade and use the BD1 blade as an EDC knife.

Not the same geometry, right? Geometry is king. (I read Knife Steel Nerds and watch BBB. My own testing has confirmed this, but the info comes from them and others.)

I buy knives based on design and features now, not steel. If steel is an option I get the steel I think can take the shallowest edge angle and is the easiest to sharpen. My current EDC knife is a reground Delica with VG10 steel.

Agree, but only up to a point. I won't carry Victorinox steel. Every time I need to cut something it's dull. VG-10 is ok. 154 CM/CPM 154 are more than adequate for me in a pocket knife. 8Cr will work. 14C28N or so is about my minimum. (Currently carrying Cru-wear in a small fixed blade.)

 

[me2]

Both full flat ground with similar blade widths, edge angles, edge thickness and grit. Without buying the same knife in different steels, it's close. Even then as you found with the miles, they are exactly the same.

 

[Razor]

A Dozier knife in D2 was the only steel I found that would cut bear hide real good. Would this count? Lol

 

[David Richardson]

Both full flat ground with similar blade widths, edge angles, edge thickness and grit. Without buying the same knife in different steels, it's close. Even then as you found with the miles, they are exactly the same.

This is the reason I test every steel at least twice. 3 times is better. 5 times is even better. Then I can check the deviation between those tests and start looking for variables. Not seeing any difference between BD1 and S110V is more than a little curious. S110Vs edge retention is pretty clearly established. Many things could have happened, but I'd guess the stones you used weren't hard enough to cut S110V.

 

[Natlek]

M42 steel , 67 HRC . 2mm on spine , 0.17mm BTE and 16 degree edge , total 32 degree ..... This is what i have in hand from cardboard.....i don t believe that i will ever done this Exactly 30 meters or 100 feet , right ? Tomorrow i will find some more and thicker cardboard , fun job...but i must be careful nobody to see me doing that .....This is Macedonia ..............

Last I remember that i cut with this shop knife is this .......i did not sharpen it before cutting this cardboard box..........

NOTE ...............blade don t want to cut that yellow page paper or shave after cutting cardboard .After I clean it with nitro thinner .....
Edit .........edge is sharpened on 800 grit DMT diamonds and several pass from both side on clean leather .

 

[marrenmiller]

This is the reason I test every steel at least twice. 3 times is better. 5 times is even better. Then I can check the deviation between those tests and start looking for variables. Not seeing any difference between BD1 and S110V is more than a little curious. S110Vs edge retention is pretty clearly established. Many things could have happened, but I'd guess the stones you used weren't hard enough to cut S110V.

Or the differences are just really hard to see. At this point I've done a good dozen trials of some of my knives and the differences are so slight between any steel used that you may not even notice them. Test for yourself and see if S110v holds up as well as you think.

 

[David Richardson]

Test for yourself and see if S110v holds up as well as you think.

As I wrote earlier, I've tested all a Spyderco Mule steels (-2) and several others (~40 or so in total). These includes S110V and BD1. Pete of Cedric & Ada also tested these Mules and you can see his results below. He used the same edge for all these tests (17 degrees polished). FYI, the difference I saw between S110V and BD1 are similar to Pete's.

Given this, I hope you can see why I'm asking about the results you got. I'm not doubting them, I'm just wondering why they're so different.

(Maybe interesting to some of you, you can see there's low correlation between hardness and edge retention across these knives. You can read Knife Steel Nerds and watch some BBB videos to see why this is.)

 

[me2]

S110V was shaped with SiC water stone and finished on diamonds for that reason. I suspect if I'd repeated it enough I would have seen a difference. I also think some work is particularly rough on an edge. Even if the steel has 5x the edge holding, that's 5 cuts vs 25 or 10 vs 50 in a task requiring hundreds or even thousands of cuts. It won't be noticable in qualitative comparison, which this was.

 

[DangerZone98]

I’d love to, but I don’t have the skills or equipment yet.

As a knife user, I think the important thing is that your knife performs according to your needs. If it works just fine for your EDC tasks and performance is more or less comparable to what other reliable sources report (e.g. Larrin, Pete from Cedric and Ada, Outdoors55), then you should be golden. It’s not scientific, but I think most users out there will be fine.

Anyway, cool thread! It’s always great to learn something new every day.

 

[David Richardson]

S110V was shaped with SiC water stone and finished on diamonds for that reason. I suspect if I'd repeated it enough I would have seen a difference. I also think some work is particularly rough on an edge. Even if the steel has 5x the edge holding, that's 5 cuts vs 25 or 10 vs 50 in a task requiring hundreds or even thousands of cuts. It won't be noticable in qualitative comparison, which this was.

Good point about qualitative vs. quantitative.

 

[OrangeBlueOrangeBlue]

Well just like the videos that show M390 vastly outperforming S30V etc., this is also a case of my experiences differing from people's testing.

I think it depends how you define a cut, right? Are we talking about a clean laceration or just separating matter? If so I'll take a dull Delica over a dull 0562. I find when a knife is very thin BTE I'm cutting with the whole blade (or at least more of it) rather than just the secondary bevel, which is how I felt cutting with a lot of ZT offering's and some of the chubbier Hinderer's.

Take a Spyderco Smock. Dumb thin behind the edge. Give me that in AUS-8 over a 0562 in 20CV any day of the week if I have a stack of cutting to do. I believe after the same amount of material cut the Smock is going to do a better job cleanly separating matter.

Maybe I'm sharpening wrong or judging sharpness in a different way, but geometry has always been the biggest variable in how long my blades stay at the level of sharpness I like them to be.

In my experience the Smock is absurdly sharp, but isn't great at stuff like cleanly slicing an apple. The excellent hollow grind makes it sharp, but relatively thick blade stock with the grind starting around half-way down a relatively short blade means you get a "shoulder" pretty close to the cutting edge. The rapid transition from thin to thick tends to crack apples rather than slice. It's not a Medford or anything, but it's not as eager to slice as Spydercos with more conventional grinds.