Why CPM 3V

[vivi]

Well, in that case, I think I know of the perfect knife for you. It's super tough steel too!




The last sentence is kind of what in pointing out though. When we're talking about CATRA, we're already dealing with cutting forces that are high enough to drive a butter knife through a carrot. I dunno anyone that would call that sharp. Except maybe vivi but I'm still waiting to see how he'll respond

I don't understand the point you are trying to make. Could you clarify?

That 12 lbs of cutting force is more than enough to cut a carrot with a butter knife.

I'm not sure what tasks you're doing that requires that much cutting force, particularly in the kitchen--and no, chopping doesn't count. If you were doing that all day, every day I couldn't imagine how sore you'd get. Imagine dicing carrots at 10 lbs per slice. Who'd need a gym membership.

Maybe you haven't actually measured the forces you're cutting at. I figured cutting a carrot with a butter knife would be a good demonstration of how 12 lbs is a lot more than it seems. If it's still not made an impression, maybe you should actually go try it for yourself and see how many cutting tasks you do reach or exceed that force. If you're still going to insist that twelve pounds isn't much after that then it speaks volumes more than I could.

I don't understand why you think 12lbs of force applied to a knife is such an extreme amount.

I do that often, despite using thin stock knives with thin edges that cleanly shave.

It seems to me you are looking down your nose at me for having a different set of cutting tasks in my day to day life than you?

That doesn't seem conducive towards good conversation.

Why wouldn't chopping count? I chop with machetes often, those are just long knives.

The other day I took my Winkler Belt knife and hammered it through some scrap wood with a rubber mallet to flatten out a section. I was building a bench for my kids fort out of it. Definitely applied more than 12lbw of force with the mallet.

Cutting double and triple wall cardboard often requires more than 12lbs of force.

12lbs of force is such a low number, I'm confused why you're hung up on it.

It takes more than 12lbs of force to cube a pound of butter. Something I do every day I work.



Cutting taro roots requires more than 12lbs of force too. Lots of foods do.

I still don't understand what point you are driving at.

[Mushroom]

I'm surprised by how much fuss there is over this subject.

[vivi]

Well the direction this thread has gone has me curious about two things.

1. Who makes a cpm3V machete.

Looks like the only one that popped up on a quick 2 minute search was a $450 cold steel kukri machete. Maybe I'll finally pull the trigger on a 3V trail master instead since those are $250 and big enough to use like a short machete.

2. What other completely mundane every day things we cut that take over 12lbs of force.

Add halving pineapple to the list



13.5# using straight downward pressure with a 2mm stock 9dps shaving sharp gyuto.

[Synov]

Like Cedric and Ada's rope cutting tests where he determines the stopping point by how well it still cuts paper? That's itself a measure of the cut-initiation force, and how much rope it's able to cut before it falls through a threshold of force able to cleanly cut paper, but again at any point the force being used to cut the rope might be quite high compared to the force someone might want to use to cut a piece of cardboard or a package or something right?

The point of the test is not to see how sharp the knife is after cutting rope, it's to see how much rope is cut before it dulls, so yes the entire test is a cutting ability test, not a sharpness test. And that's why it correlates.

The arbitrary criteria of the test makes the specific number it results in inapplicable to other tasks but the results relative to each other should be applicable to other tasks, and they are.

The last sentence is kind of what in pointing out though. When we're talking about CATRA, we're already dealing with cutting forces that are high enough to drive a butter knife through a carrot. I dunno anyone that would call that sharp. Except maybe vivi but I'm still waiting to see how he'll respond

OK, but again the specific criteria of the test don't matter as long as they're constant.

Now if I were gonna go put that butter knife in the video to a stone and put a super obtuse edge on it, let's say 40-45 degrees per side, but just make sure the apex was very crisp, do you think the force to cut would have been significantly lower, higher or unchanged? Obviously it would have been lower than the rounded edge on it now. Sharpness is still an integral part of cutting ability, even if cutting ability can still remain long after some threshold for sharpness has been exceeded.

Agreed, but since we're testing and comparing blades that start at the same sharpness, I don't see how this is relevant.

Anyway, this conversation seems to headed into circular territory. If your preference is truly to cut with really dull and thin knives then who am I to say that's wrong.

It's not my preference. Just because I say a dull knife with high cutting ability is better than a sharp knife with low cutting ability doesn't mean I prefer either to a sharp knife with high cutting ability.

[vivi]

I hope we see a 3V Spyderco sometime this year or next.

[VashHash]

Darn Dao flash batch in 3V.

[vivi]

Darn Dao flash batch in 3V.

now that would be fun to swing around.

[civilian_g10]

A Respect and/or Providence in 3v would be nice.

[VashHash]

Darn Dao flash batch in 3V.

now that would be fun to swing around.

I'd buy 2 more. Just maybe canvas micarta for a better grip.

[salimoneus]

I think BBB may have just gotten lucky in that 15V had some room to be improved by additional fine tuning of the steel treatment, where as this isn't necessarily the case for all steels. Not taking any credit away, but just pointing out that the potential may not be there with most other steels. He's not a magician, he just happened to stumble upon something with ONE particular steel. Just my opinion of course.

[tomhosangoutdoors]

I think BBB may have just gotten lucky in that 15V had some room to be improved by additional fine tuning of the steel treatment, where as this isn't necessarily the case for all steels. Not taking any credit away, but just pointing out that the potential may not be there with most other steels. He's not a magician, he just happened to stumble upon something with ONE particular steel. Just my opinion of course.

There's no luck involved there. That's all research and knowledge of metallurgy and the processes in heat treating that elevate certain properties and fine tuning those to get what you desire. He knew exactly what variables to manipulate, and that takes hundreds (if not thousands) of hours of research. I think there is room for improvement on almost every steel's heat treatment. But that isn't necessarily attainable in a production setting. A lot of times it takes extreme care over temperatures (down to the degree) and minimal handling time between steps. That's achievable when making 1 or 2 blades at a time, but not necessarily when heat treating hundreds in one go. What Shawn did with 15V is incredible. And for Spyderco to be able to work with him and get it translated to a production setting is unheard of.

[salimoneus]

A lot of times it takes extreme care over temperatures (down to the degree) and minimal handling time between steps. That's achievable when making 1 or 2 blades at a time, but not necessarily when heat treating hundreds in one go. What Shawn did with 15V is incredible. And for Spyderco to be able to work with him and get it translated to a production setting is unheard of.

Like I said, not taking anything away from what Shawn accomplished by improving 15V, it's undeniable. I was mainly responding to those who suggest that we could take practically any existing steel and "work some magic" on it, which is entirely not true. In fact most steels that are currently being produced are not able to be improved by a very noticeable margin by simply changing the heat treatment as was done with 15V. The "standard 15V" just happened to fall into that category of having some room for improvement, most all other existing steels do not.

[VandymanG]

Hmm 3V thread please. That said yes please to a BBB AKA @Deadboxhero heat treated 3V. No pressure big guy just some more magic heat treats please.

[srivats]

I think BBB may have just gotten lucky in that 15V had some room to be improved by additional fine tuning of the steel treatment, where as this isn't necessarily the case for all steels. Not taking any credit away, but just pointing out that the potential may not be there with most other steels. He's not a magician, he just happened to stumble upon something with ONE particular steel. Just my opinion of course.

BBB's 15V work and results was not "luck". Lots of knowledge, lots of trial and error and very hard work. To call it being lucky is severely underestimating the amount of work that was put in.

[Bolster]

OK OK -- remove the word "luck" since that's obviously giving people gas pains. What I understand salimoneus as saying, is that there may not be as large a payoff for tweaking the heat treats of other steels, as there was for 15V.

[srivats]

Like I said, not taking anything away from what Shawn accomplished by improving 15V, it's undeniable.

You did take something away by calling it "luck".

In fact most steels that are currently being produced are not able to be improved by a very noticeable margin by simply changing the heat treatment as was done with 15V. The "standard 15V" just happened to fall into that category of having some room for improvement, most all other existing steels do not.

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[Bolster]

I don't think it matters in order to show which blade requires more force to cut. The test result should be applicable beyond the criteria of the test, and I think this has been proven by correlation of CATRA results to other tests like rope-cutting.

Do you by chance know what the correlations are, between CATRA and some of the other cutting tests?

EDIT: I should have researched before asking. https://knifesteelnerds.com/2019/02/11/ ... rformance/

[cabfrank]

You could call it kismet.
But if luck is the intersection of hard work and opportunity, why not?
Either way, lots of skill is included.
Looking forward to getting my first piece of 15V.

[Bolster]

On CATRA's correlation with other tests, a summary taken from Larrin:

CATRA and Ankerson, r-squared is .68.
CATRA and Cedric & Ada, r-squared is .66
CATRA and Sandor, r-squared is .50, or .65 with one outlier removed.

For human data, those would be very high correlations. For physical data, they're decent, but not really what I'd call large. It opens the possibility that the other tests (they're all rope cut tests) are, in part, measuring something other than what is measured by CATRA. Of course, there's inherent error in home-shop-human-arm data, as was shown by the intercorrelations between the different raters (two of which were .50 and .77 -- for some reason Larrin didn't calculate the intercorrelation between Ankerson and Sandor -- unless I missed it.)

I was unable to find a correlation between feet of cardboard cut, and CATRA. That strikes me as a test that could be done, if someone had the inclination.

I tend to be a fan of lab tests myself; I look askance at "real world data" when it's uncontrolled or just a collection of anecdotes. But the size of the correlations reported above, against careful and controlled home-shop (I assume) tests, makes me open my mind somewhat more to the idea that CATRA may measure a good proportion of what steels & treats best resist edge degradation, but not necessarily capture all of it.

That said, I'm not aware of a better single measure of edge retention than CATRA. Are you?

[VandymanG]

Please redirect back to 3V discussion.