SHOOTOUT: CTS XHP vs CPM S30V on 5/8" rope with coarse edge.

[Ankerson]

Been waiting to do this one until I got more rope in and for things to calm down some.

This is the same method as I use in my Edge retention thread, but with coarse edges so the smaller differences will show up, it's good for head to head comparisons. I cut until I reached 20 LBS of down force on 5/8" Manila rope, both knives are Military's and 15 DPS, edge finish was 400 grit silicone carbide mold master stone.

Both knives have been hardness tested:

CTS XHP - 60 HRC

CPM S30V - 60 HRC

Steel information:

CPM S30V

Carbon 1.45%
Chromium 14.00 %
Vanadium 4.0%
Molybdenum 2.0%

CTS XHP

Carbon 1.65%
Chromium 16.00%
Molybdenum 0.80%
Silicon 0.40%
Manganese 0.50%
Vanadium 0.45%
Nickel 0.35%


First up was CTS XHP

Next was CPM S30V

And the knives together.

Test results and conclusions:

CTS XHP did very well and cut very aggressively on the rope with the edge tested and suffered very little edge damage with a few small shiny spots on the edge. The edge would still slice printer paper easy after the testing.

CPM S30V also did very well and was aggressive with the edge tested and had very slight edge damage with a shiny spot. The knife would cut printer paper easy after testing.


Results:

CTS XHP - 240 cuts

CPM S30V - 300 cuts

The Vanadium in the S30V took over and and caused it to perform better than XHP in this test.

Other numbers using the same method, edge finish and edge geometry also using the same model knives, the Military, for comparison only to show higher wear resistant steels.

M390 (61 HRC) - 380 Cuts

CPM S90V (60 HRC) - 460 Cuts

 

[JayGoliath]

Thank you Ankerson! May i ask why do you use the weight?

 

[JNewell]

Great dope as always, Jim - thank you. I was surprised by the difference between S90V and M390.

 

[jstn]

Interesting results, thanks for sharing. BTW Ankerson, you are sitting at 13,666 posts. That has to be unlucky so you better post again soon!

 

[Ankerson]

Thank you Ankerson! May i ask why do you use the weight?

It's a good stopping point.....

To get a feel for how much pressure that really is take one of your knives and go to a bathroom scale and while holding the knife in hand edge down put pressure on the scale until you reach 20 LBS a few times...

Then you will get the idea, then do it again at 25 LBS a few times because that's how much pressure I am really putting on them during cutting as in just cutting, then the 20 LBS is the test stop weight, cutting with the least possible pressure.

 

[Maddogg774]

Great test. Keep 'em coming.

 

[jwolf90]

Great test Jim, I figured the Vanadium would come into play on this one and you confirmed it. Thanks for all your time and effort doing these tests:thumbup:. I've always had a fondness for s30v, especially when it has a nice toothy edge.

 

[Ankerson]

Great test Jim, I figured the Vanadium would come into play on this one and you confirmed it. Thanks for all your time and effort doing these tests:thumbup:. I've always had a fondness for s30v, especially when it has a nice toothy edge.

Yes the Vanadium will make a difference defiantly in straight edge retention with an optimal edge finish.

 

[dflores]

Just what I have experienced what those two steels! XHP has held a polished edge much better than s30 but s30 just holds that working edge very well.

 

[Ankerson]

More info based on my data:

Example of how big the difference can be between 15 DPS and 20 DPS is the following:

This was XHP...

20 DPS - 160 cuts
15 DPS - 240 cuts

At 100 cuts:

20 DPS - 17 LBS
15 DPS - 15 LBS

So from the data at 15 DPS the knife made 100 cuts and was at the same pressure as the starting point of the 20 DPS edge at 15 LBS.

Starting pressure:

15 DPS - 10 LBS
20 DPS - 15 LBS

And that's the same knife with the same edge finish and level of sharpness, the only difference was the edge geometry change from 20 DPS to 15 DPS.

These are the things that I look at and test for, same goes for difference in edge finish, most of this information isn't posted, but I do reference it from time to time when it's important.

I do a lot more testing and get into much more detail than I usually post in the testing threads, most of it's behind the scenes and with custom knives.


Another Example is Polished vs Non Polished edge, same knife at 15 DPS.

Starting Pressure:

Polished - 15 LBS
Coarse - 10 LBS

100 Cuts:

Polished - 17 LBS
Coarse - 15 LBS


Same thing here as above comparing 15 DPS vs 20 DPS

So in effect looking at the data cutting with a polished edge at 15 DPS is the same as cutting with a coarse edge at 20 DPS from my testing.

 

[Jastab]

Great test!, I like that you used the same knife for both tests. So blade geometry had no factor on the outcome. Great work as always.

 

[hardheart]

if you have some more comparative data for edge angles, that would be great. From the CATRA test we ran, I am figuring close to ~5.5% increased total cut per one degree drop in included edge angle, and your numbers are close to that as well (50% more cut for a 10 degree drop) I still have to control for edge thickness among the test blades, but angle blew thickness out of the water as the dominant variable to begin with.

I do prefer a polished blade, as it primarily allows me to push cut, which is my favored method. But I also like how degradation is not as pronounced,which is cool that your testing also supported. Yes, the coarse edge slices with much lower initial force, and this can be extremely helpful in many tasks, but for me the way the polished edge only required 13% more force at 100 cuts 'feels' less intrusive to my task as the coarse edge requiring 50% more force, even though that only gets it to the starting level of the polished edge after quite a lot of cutting. But I believe that is because my coarse cutting in in such short duration, so the higher starting force is not so apparent because it isn't all that different from the final force... and I mostly push cut whenever possible. It appears it is because the coarse finish undergoes a greater amount of alteration to the edge apex as the steel is abraded smooth,while the polished edge is already very near that. Then it becomes more dependent on edge angle to influence the amount of force needed to wedge the blade into the media being cut after the shape of the edges normalize to each other.

I'm more tortoise than hare, I suppose.

 

[chiral.grolim]

...Example of how big the difference can be between 15 DPS and 20 DPS... the same knife with the same edge finish and level of sharpness, the only difference was the edge geometry change from 20 DPS to 15 DPS.

These are the things that I look at and test for, same goes for difference in edge finish, most of this information isn't posted, but I do reference it from time to time when it's important.

I do a lot more testing and get into much more detail than I usually post in the testing threads, most of it's behind the scenes and with custom knives.

Another Example is Polished vs Non Polished edge... ...cutting with a polished edge at 15 DPS is the same as cutting with a coarse edge at 20 DPS from my testing.

:thumbup:
Excellent submission with dramatic ramifications. Thank you, Jim!
What I get out of this is the following:
View attachment 339254
The trend line for the 15-dps coarse edge is toward a long-lasting working edge for this type of cutting, while the 20-dps coarse edge trends toward rapid edge-loss with continued cutting... which is odd, as I would expect a similar trend toward an established 'working-edge'... HOWEVER, 3 data points is not enough for a definitive statement on the matter, much less 2 data points for the 15-dps polished edge which might trend either way. I am curious to know how each blade is cutting at more data points.

 

[chiral.grolim]

I still have to control for edge thickness among the test blades, but angle blew thickness out of the water as the dominant variable to begin with...

Not to derail the thread, but I always get confused by statements like this as the entire reason that angle has any impact on cutting performance is because it informs thickness behind the apex. Thickness (i.e. cross-sectional geometry) is THE determining factor in the force required to complete a cut. Thus, i must assume that you mean thickness behind the bevel rather than thickness within the bevel at set distance behind the apex...

 

[Ankerson]

if you have some more comparative data for edge angles, that would be great. From the CATRA test we ran, I am figuring close to ~5.5% increased total cut per one degree drop in included edge angle, and your numbers are close to that as well (50% more cut for a 10 degree drop) I still have to control for edge thickness among the test blades, but angle blew thickness out of the water as the dominant variable to begin with.

I do prefer a polished blade, as it primarily allows me to push cut, which is my favored method. But I also like how degradation is not as pronounced,which is cool that your testing also supported. Yes, the coarse edge slices with much lower initial force, and this can be extremely helpful in many tasks, but for me the way the polished edge only required 13% more force at 100 cuts 'feels' less intrusive to my task as the coarse edge requiring 50% more force, even though that only gets it to the starting level of the polished edge after quite a lot of cutting. But I believe that is because my coarse cutting in in such short duration, so the higher starting force is not so apparent because it isn't all that different from the final force... and I mostly push cut whenever possible. It appears it is because the coarse finish undergoes a greater amount of alteration to the edge apex as the steel is abraded smooth,while the polished edge is already very near that. Then it becomes more dependent on edge angle to influence the amount of force needed to wedge the blade into the media being cut after the shape of the edges normalize to each other.

I'm more tortoise than hare, I suppose.

I have a lot more data with different blades and steels that basically say the exact same thing as was posted above.

The only reason I posted it was because it was relevant to this test and I was asked about it on another forum.

I tested 20 DPS, 15 DPS and 10 DPS in customs with different steels and the pattern holds so your CATRA data is dead on as you already know.

Also the reason why I never posted anything meaningful in your CATRA thread because I already knew what the results were going to be.

 

[Ankerson]

Not to derail the thread, but I always get confused by statements like this as the entire reason that angle has any impact on cutting performance is because it informs thickness behind the apex. Thickness (i.e. cross-sectional geometry) is THE determining factor in the force required to complete a cut. Thus, i must assume that you mean thickness behind the bevel rather than thickness within the bevel at set distance behind the apex...

He is correct, from my testing edge geometry will effect cutting efficiency by HUGE percentages.

He is talking about thickness behind the edge....

 

[Ankerson]

:thumbup:
Excellent submission with dramatic ramifications. Thank you, Jim!
What I get out of this is the following:
View attachment 339254
The trend line for the 15-dps coarse edge is toward a long-lasting working edge for this type of cutting, while the 20-dps coarse edge trends toward rapid edge-loss with continued cutting... which is odd, as I would expect a similar trend toward an established 'working-edge'... HOWEVER, 3 data points is not enough for a definitive statement on the matter, much less 2 data points for the 15-dps polished edge which might trend either way. I am curious to know how each blade is cutting at more data points.

I only posted enough to make the point, but the data I have supports the pattern with different knives and steels across the board.

 

[hardheart]

Not to derail the thread, but I always get confused by statements like this as the entire reason that angle has any impact on cutting performance is because it informs thickness behind the apex. Thickness (i.e. cross-sectional geometry) is THE determining factor in the force required to complete a cut. Thus, i must assume that you mean thickness behind the bevel rather than thickness within the bevel at set distance behind the apex...

Yes, thickness after the primary grinding and before final sharpening. The range was pretty small, as you quickly stop having a decent knife edge and I didn't want to get into anything outside what a person is normally going to purchase - it still only came to about a 20% difference at the extreme ends. OTOH, edge angle varies quite a lot, and the impact is really large - up to ~1000% while still representing very common factory edge angles.

 

[hardheart]

I have a lot more data with different blades and steels that basically say the exact same thing as was posted above.

The only reason I posted it was because it was relevant to this test and I was asked about it on another forum.

I tested 20 DPS, 15 DPS and 10 DPS in customs with different steels and the pattern holds so your CATRA data is dead on as you already know.

Also the reason why I never posted anything meaningful in your CATRA thread because I already knew what the results were going to be.

I think once good controls are set up in testing, people find that there just isn't any magic to it and it is all very repeatable. I'm fairly certain that before you posted these results some people would argue that XHP would have come ahead just because it is 'stainless D2' and D2 is awesome-er than other stuff.

 

[chiral.grolim]

He is correct, from my testing edge geometry will effect cutting efficiency by HUGE percentages.

He is talking about thickness behind the edge....

I am sure that this is stuff that you both are already very well aware of and certainly more informed regarding the repercussions thereof, but i keep running into confusion about knife performance and what aspects matter when, even in regards to geometry (not getting into the 'aura' of steels Hardheart mentioned ), so forgive me as I run through this.

Edge geometry includes both edge angle and edge thickness. "Thickness behind the edge" = thickness as measured at the bevel shoulder regardless of how far back from the actual apex. Such measurement tells us more about the primary bevel and blade profile than the secondary bevel and edge apex itself.
Knives with the same sharpened edge angle but different stock thickness perform quite differently because of what happens beyond the shorter secondary bevel distance from the edge, i.e. thickness at a set distance behind the edge. This is the case because, beyond that set distance, the cross-section thickness of the blades diverge and the thicker blade offers more material for the medium to resist.
For knives of identical stock thickness sharpened to different apex angles, the cross-sectional area of a blade sharpened to 10-dps is less than50% that of the blade sharpened to 20-dps if both are measured at 20-dps shoulder distance. This is so because, at that set distance, the thickness of the 10-dps blade is less than half that of the 20-dps blade. It is key to note that, while the apex angle dropped by exactly 50%, the thickness behind the edge outpaces it! It is NOT a linear relationship, not quite: From 20-dps to 10-dps is a 52% reduction in thickness, 30 to 15 is 54%, 30 to 10 is 69.5%


For every % reduction in angle there is a greater reduction in thickness. Edge-angle's role in the physics of cutting is limited to its import in regard to thickness.

Any disagreement? Am I the one confused?

Now given all that, I am fascinated by the notion that a 50% reduction in thickness could improve cutting efficiency by ~1000% Do you have a link to a graph of this data, Hardheart?