Some edge testing (CPM-10V, D2, VG-10, AUS-8)

Pretty much what I expected. Thanks for doing the tests Mr. Stamp--always vauable info.

thanks and take care
collin
 
Another nice job Cliff.

Maybe you should 'normalize' your results by dividing by the blade lengths. This assumes that your wear is distributed along the full lengths of the blades, giving the long blades a disproportionate advantage.
 
I have added more detail to clearify the method used and expand on the results. Nice idea there Jeff, I had intended to compare the cutting performance of a few blades and will keep that in mind.

I will repeat this cutting later on as I have a couple of knives from Fällkniven coming and I am interested in how their VG-10 compares to Spyderco.

I will probably include more abrasive materials in the cutting like AL cans, and carbon rods, cleaning pads and such, as the better edge holders like D2 and CPM-10V require an awful amount of work to blunt on cardboard and rope. The harder materials will also give me some insight into the edge durability so I can determine the limits before chipping or excessive indenting will occur.

Anyone who knows the RC of the Calypso Jr. and Bill Moran, please post so I can include them.

-Cliff

[This message has been edited by Cliff Stamp (edited 18 August 1999).]
 
Very interesting reading Cliff. Thanks.

It looks like AUS-8 was added as a baseline of sorts. I would've liked to have seen figures for a comparable ATS-34 blade.

Echoing Jeff's note on blade length differences, I wonder how the differences in blade geometry affected the results. I noticed that your Mel Sorg has a recurve.. might that not have given it added slicing ability (albeit modest) over a comparably worn straight edge (such as the Calypso Jr)?
 
Longden :

It looks like AUS-8 was added as a baseline of sorts
Click to expand...

Exactly right. It is a very common steel and probably bottom of the barrel in terms of soft material edge retention so I figured it would be interesting to see just how much of an improvement is made going to the better blade materials.

I would've liked to have seen figures for a comparable ATS-34 blade.
Click to expand...

Would you believe I don't have one. I have had Benchmade ATS-34 blades in the past but the durability was not there and I quickly gave them away.

I noticed that your Mel Sorg has a recurve.. might that not have given it added
slicing ability
Click to expand...

I would hope so since that is why I asked Mel to put it there
smile.gif


There are other differences in blade geometry which are important as well. For example the Bill Moran has a convex edge which makes a smoother cut. Mel's knife had a convex edge as well until I v-ground it to see what difference it made (it was not a positive one).

-Cliff
 
Cliff, I posted RCs you asked for on the Spyderco forum... but for the sake of thread continuity:

Spyderco mini-catalog (1998) shows Calypso Jr (C52) at RC=58-59 and for the Moran (FB01) it shows RC=60-62.

 
Okay, AUS-8A seems to stink. I have come to the same conclusion from owning a Cold Steel Gunsite. It gets extreemly sharp with little effort, but dulls like plastic. I thought I had a poor heat treat or poor grind angle, but thanks to this test I have been enlightened. Cold Steel, which is starting to use AUS-10A in some new knives, claims that this steel holds an edge 20% longer than their AUS-8A, giving it better characteristics than ATS-34 or 440V. If AUS-10A is only 20% better than 8A, I highly doubt that it is going to beat ATS-34, never mind 440V. I have little experience with ATS-34, and none with 440V, so could someone knowledgeable give his opinion on Cold Steel's claim? Maybe AUS-10A could be tested in a similar manner to the above (along with ATS-34 and 440V...sorry, you probably have better things to do). If this claim turns out to be a farse, then how can knife companies make such claims without being held responsible? It seems like they can just print whatever makes them look good without careing about their reputation or customer relations. Or is it that the companies figure the vast majority of consumers to be too stupid to know the difference when a lie is sold? I realize most companies aren't like this, but some are. Why can't a company just say, "We probably don't make the absolute best knife in the world, but we think you will be pleased to invest in our quality products." I know Randal has a similar, humble attitude, and it hasn't hurt them any, has it? (see their little brochure) Sorry I got off the topic.

PS: I won't be around for the weekend, so I can't respond for a while.

[This message has been edited by bigtim (edited 20 August 1999).]
 
Bigtim, one of the reasons that AUS-8 did so poorly was that it easily suffered the most amount of wear. Note that it had to make 14 times more slices on the fabric than the CPM-10V blade in round one alone. One of the reasons it dulled so bad was that it sliced so poorly.

If you look at the results you will note a very strong correlation between cutting ability and edge retention. Basically the better a knife cuts then the less work it has to do in cutting a material. This means it wears less and thus will hold its edge longer.

The AUS-8 blade had a really hard time on slicing because at a high polish it has no bite at all left. It is a fine grained steel and you can with little effort achive a very fine push cutting edge. The other blades, particularly the D2 and CPM-10V one retain a high amount of bite even when finished on an 800 grit ceramic rod.

Next time I do this I will leave the edge on the Calypso down to 600 grit dmt, this drastically increases slicing performance. I didn't do it this time as I wanted the finishes to be similar. But it is important to note that for most steels you do not want to do this, different steels perform better at different finishes.

In regard to Cold Steel's claim, Drew brought this up before. And I'll repeat what I said then. AUS-8 (and probably AUS-10) are fairly durable steels meaning that they don't tend to chip easily or suffer from broken tips. Both of which have plagued Benchmades ATS-34. In comparasion to 440V, well, 440V is less than half as tough as 440C so again on harder work AUS-8 might fare better.

One of the reasons people can make strong claims without having to worry about feedback is that they tend to keep them really vague which makes it easier to lawyer out of. This is one of the reasons I like to see things like Busse stating the properties of the BM so clearly .

-Cliff
 
The other disadvantage the Calypso Jr. had is short blade length. The wear is distributed over a smaller length so that it should wear faster. It has a shorter blade length so that the strokes across cloth used to measure sharpness at the end of each pass are half as long as the strokes on the larger knives. The Calypso is doubly penalyzed this way.

Another thing that would be very interesting would be a "round 0" reading on how well the knives cut before being abraded. This would give you an idea of "length handicap" in simple cutting measurement. It would also let you see if certain steel is sharper for light duty application, but is less durable.
 
The 10V blade was about 0.6x longer than the AUS8 blade but the 10V was about 15x to 23x better in performance.

Looking at the Crucible site they mentioned that 10V was a good replacement for D2 where wear was an issue but not where breakage was the problem, so one gets the impression that 10V is about as tough or maybe only slightly tougher than D2. The 9V looks attractive as wear resistance and toughness are both significantly improved over D2 but the lower hardness could be a problem, it'd be interesting to see if it'd still make a good knife steel, and M4 also looks attractive as wear resistance and toughness are also significantly improved over D2 but the hardness is still good.
 
Thanks, Cliff and others. It's nice to here from those who sound like they actually know what they are talking about. Very rare these days.
 
Jeff :

Another thing that would be very interesting would be a "round 0" reading on how well the knives cut before being abraded.
Click to expand...

An excellent point Jeff and one I realized just as soon as I finished the first round. I had no baseline of zero-wear performance. Live and learn, I will do this next time.

John :

one gets the impression that 10V is about as tough or maybe only slightly tougher than D2
Click to expand...

The spec sheets say much the same, rating 10V as being slightly tougher than D2 . You can see them at the bottom of the following page :

http://www.physics.mun.ca:80/~sstamp/knives/index.html


-Cliff


 
My compliments on your thoroughness and the clarity of your report.
You acknowledge the variables, and this gives us a lot to think about.
I look forward to your Falkniven/Spyderco VG-10 report.
 
Ken :

You acknowledge the variables, and this gives us a lot to think about.
Click to expand...

This is one of the most important aspects, that and knowning the confidence limits or uncertainties in the results. Without these two conclusions cannot be meaningful.

I look forward to your Falkniven/Spyderco VG-10 report.
Click to expand...

As an update I now have the S1, F1, and WM in VG-10. I have done some work on rope, card stock, wood, cardboard, cables, and wire and all perform soundly. And as a very pleasant surprise an old F1 in ATS-34 is on the way. Comparing it to the F1 in VG-10 should be very interesting.

I have also done some mild lateral stress testing on the above knives. Even the WM can twist split a 1/4" board without excessive flexing (this is driving the blade in and twisting the handle to split the board). While it is convex ground to form a nice thin cutting edge, it is fairly thick and should be decently strong.

The Moran should compare well in cutting ability and edge retention but I am guessing from some initial comparasions that it does not have near the strength / toughness of the
Fallkniven blades. I'll know more about this after I have worked them out a little.

-Cliff
 
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