K390 and S110V Discussion Thread

[CarbonFiberNut]

the most likely cause of that is what is referred to as an example of "lies told to children". When you are introducing a subject it is often simplified to the point that some of the information is no longer strictly true (there is no Santa Claus Charlie Brown).

(been on the road for a few days, so this comment is pretty delayed)

Coming from a similar background to you, these "lies told to children" have been one of the most infuriating things I've ever dealt with. When you are teaching early college-level physics classes, sometimes the hardest part is convincing the students to "unlearn" the half truths they learned in high school. I've gotten some serious headaches after dealing with students who absolutely insisted that friction could NEVER EVER depend on surface area, because the first approximation they learned in class said so, and they "proved" it with wooden blocks sliding on an aluminum ramp. And then you start discussing centrifugal force, and things go to ****...

You always wish you could just jump to D'Alembert's Principle, and build to the Lagrangian and Hamiltonian formulations, but unfortunately the math background usually isn't there at that point. Instead, you have to deal with students who, like the original comment that spawned this discussion, end up going in all the wrong directions due to a teacher who could have been a lot clearer and more careful with his words in the first place.

This discussion is reminding me how happy I am to have left academia. Living in a world where fewer and fewer have respect for scientists and the scientific method, I left a lot of stress behind when I moved away from that world.

I stand by my "terrible professor" statement, though, if this really was a case of "lies told to children." Whenever I've had to teach these simplified concepts, I've always tried to go out of my way to be extremely clear that these are simplifications and don't show the whole picture. You sometimes deal with some pushback and disdain from the students, but I'd rather do that than feel like I was misleading them. If they cared that much, they could take some more math classes and come see me in a few years

[DougC-3]

Iwould love to compare the two steels but I got a Calyx3.5 ZDP instead of the ordered and confirmed Forum Native Opening the pack that arrived today was a shock!!! :eek:

Sent a message to Spyderco to get a solution for the mishap, they might have a suggestion to correct it.
Sad to have a fine knife I didn´t order instead of the long awaited S110V blade.

Meanwhile, if another person received your order, there's the chance they may return it. And another long shot: a forum member may have ordered a second one in case another member missed out for some reason, might see your post, and possibly be willing to pass it on to you for cost. (I considered buying two for this reason myself but decided not to because, of course, it would also the lessen the total number in stock by one and prevent the "last" orderer from getting one -- and that person might be a "deserving forum member" rather than someone who just wanted to resell it.)

Good luck!!

[Commendatore]

So there might be someone who ordered a ZDP 3.5 that got a surprise.

Hopefully they will get you straightened out even if it takes giving you one of the more expensive CF models when it comes out later. Good luck Commendatore.

Joe

Thanks for your kind words Joe, let´s hope if it was sent to someone else it gets appreciated. At least the Mule arrived so I have all the Bohler steel Mules to compair.
I am sure the folks in Golden take care though it is a difficult situation all papers stating Forum Native but the mail box contained the Caly instead.
I would have a hard time trying to believe an online customer when all order papers tell a different story ...

Back to topic (or rather where the discussion went): I did my Diploma thesis (graduation paper at an Austrian University) right at the border to the detecting limit of the optical instrument I used. It was an awful lot of try and err until the experiment was refined to a point I could get conclusions from. Then I collected massive amounts of data to get results indicating a direction.
Statistics and a lot of samples was the only way to do this work.

Same should apply to evaluating quantitative material characteristics of our blades.
I enjoy seeing one-time tests of this-or-that cutting task, rather like pictures than numbers I guess but systematical work on the steels requires a test with minimized error sources as Cliff states.
On the other hand Jim´s rope tests convinced me to get some of the knives I own as my cutting jobs are rather pulling cuts through abrasive material.

So I might try to get a S110V blade as the one I wanted didn´t make it to my home and try a qualitative and subjective comparison to the K390 and M390 Mules. That´s because I am too lazy to keep quantitative track of my cutting and way too lazy to think about a mechanical device to ensure valuable data +too goofy to build it :)

Josef

[Commendatore]

Meanwhile, if another person received your order, there's the chance they may return it. And another long shot: a forum member may have ordered a second one in case another member missed out for some reason, might see your post, and possibly be willing to pass it on to you for cost. (I considered buying two for this reason myself but decided not to because, of course, it would also the lessen the total number in stock by one and prevent the "last" orderer from getting one -- and that person might be a "deserving forum member" rather than someone who just wanted to resell it.)

Good luck!!

Well, I am not extremely upset because of not having this knife I was looking forward to try. The Caly is a fine and classy piece too, always wanted to buy one, just couldn´t convince myself to pull the trigger because of cost. S110V on the other hand did sound as good as to spend that sum.
I guess as it took three weeks for the mail to arrive all the forumites who bought spares to help might have already done so.
Now I will wait for Spyderco to answer my message and keep track of this post to see how people evaluate those two super steels.

[shunsui]

Trying to get this thread back on topic, I seem to recall an article by Cliff suggesting that corrosion of the knife edge at the apex in non stainless steels caused a loss of sharpness and cutting ability when cutting wet materials such as vegetation. (Please correct me if I'm wrong here.)

I was wondering if the rope tests were repeated using rope soaked in water, if we would see a dramatic difference in the ratio of the number of cuts for S90V and K390.

[Cliff Stamp]

I seem to recall an article by Cliff suggesting that corrosion of the knife edge at the apex in non stainless steels caused a loss of sharpness and cutting ability when cutting wet materials such as vegetation.

Yes, I have seen that in a number of media, it also gets worse when the cutting is paused or interrupted which is normally how it is done when you are working. Someone on the docks/boats may cut a number of ropes in a day but it is very rarely that they sit down at one time and cut all the rope they need that day and it is the time between the cutting where the knife rusts.



That knife was perfectly fine working outside in the rain, but as soon as I stopped working with it you could almost see the corrosion form. That is after about an hour on a plain carbon steel.

Whenever I've had to teach these simplified concepts, I've always tried to go out of my way to be extremely clear that these are simplifications and don't show the whole picture.

Yes, I would argue that when presenting science it should always be done from the perspective of "least wrong". It needs to be very clear that everything we are talking about is simply what we know to be least wrong. This is further complicated because we don't even know what we don't know.

It is easy to demonstrate this because all you do is take something very complicated to describe and have a bunch of students describe it. They will all describe it differently. Now reveal that you only showed them a part of a larger object and that not everyone even saw the same part.

From this very simple demonstration which you can do even on an elementary level you can introduce the concepts of observation, conclusions, and even such things as bias. You can then show them how much better (less wrong) they become if they share the parts they had with each other so they each see more.

It is easy then to relate this to the general way science is groping to understand the world around us when we can't really see it directly and it is just a bunch of different people looking at a bunch of different things in a bunch of different ways all trying to come up with some uniform description.

Another really nice quote is this one :

That is not only not right, it is not even wrong! - Pauli

Most people will not understand what that means, as it reads like jibberish in lay english. However it is at the heart of the modern scientific method and if you really understand it then you really understand the core methodology of science.

In regards to angles and edge stability :



That knife has an edge of 12.5 dps, there is a true-micro bevel (beyond the visible) of about 15 dps. That kind of chopping has no visible effect on the edge. This knife has of course to be stable at that profile if an axe can be stable at 15-17 dps as the knife has only a fraction of the impact energy of a felling axe.

[Ankerson]

(been on the road for a few days, so this comment is pretty delayed)

When you are teaching early college-level physics classes, sometimes the hardest part is convincing the students to "unlearn" the half truths they learned in high school.

That's not all that different than what I used to tell the people I used to train years ago in the computer industry.

The 1st thing I would tell them is forget everything you learned in school and College because it's of no use here. Then we would start them over from the beginning and teach them how things really work in the real world so they could function in their job.

Sometimes I thought I would rather have middle school students instead of HS and College graduates because they haven't been corrupted and feed all of that BS they feed them in school.

I am glad I don't have to do that anymore......

[Zenith]

In regards to angles and edge stability :



That knife has an edge of 12.5 dps, there is a true-micro bevel (beyond the visible) of about 15 dps. That kind of chopping has no visible effect on the edge. This knife has of course to be stable at that profile if an axe can be stable at 15-17 dps as the knife has only a fraction of the impact energy of a felling axe.

Kind of makes one wonder why you receive knives with 22 + degree per side on some knives. Even when looking into professional tree loggers, they tend to go thin at the edge and let the primary do the main work.

As a side note I was interested in the affects of Vanadium and found this in US Patent 5344477 That belongs to Crucible Industries.



I know this is not S110V's patent or K390 but I found it interesting that one can easily find the affects of alloying elements, both the negative and the positive in patent information and in quite some detail.

[Cliff Stamp]

Kind of makes one wonder why you receive knives with 22 + degree per side on some knives.

Right now there is a requirement to use very high edge angles because steels used in knives have a very low edge stability. However it is a chicken/egg thing as to which one is actually causing the other.

Even when looking into professional tree loggers, they tend to go thin at the edge and let the primary do the main work.

When you are working then the efficiency is very important, the more work you do the more it matters. The more a knife is used the more likely it will thus be optimized :



Note the very low grinds on these blades, they are all sharpened flat to the stone and then the edge is put on and maintained with a butchers steel (this is why they all have recurves). If you are just peeling a couple of potatoes then anything will do, but if you literally are doing pots of it, and buckets of fish, then improving cutting ability gets important very fast.

... one can easily find the affects of alloying elements, both the negative and the positive in patent information and in quite some detail.

In a patent you have to explain not only the thing but the components this is very critical to both getting and defending the patent. If you look at the patents for actual knife steels you can not only get all of that information you will get the raw data on the steel itself. Here is the patent for S110V : https://www.google.com/patents/EP1721999A1 .

If you ignore the marketing sheets and look at the patent data it usually prevents many of the misconceptions. Marketing data is made to sell, patent data openly site direct materials test with full details on multiple reference steels.

How they are hardening the steels is very critical, in regards to S110V for example just look at how they compare S110V to Elmax/m390 in regards to pin-abrasion. This fact is left out of the marketing data/sheets and causes the erroneous conclusion that a couple of points of hardness is causing a huge difference when in fact what they are doing is intentionally comparing one steel with low retained austenite vs another with high retained austenite.

[Ankerson]

If you ignore the marketing sheets and look at the patent data it usually prevents many of the misconceptions. Marketing data is made to sell, patent data openly site direct materials test with full details on multiple reference steels.

How they are hardening the steels is very critical, in regards to S110V for example just look at how they compare S110V to Elmax/m390 in regards to pin-abrasion. This fact is left out of the marketing data/sheets and causes the erroneous conclusion that a couple of points of hardness is causing a huge difference when in fact what they are doing is intentionally comparing one steel with low retained austenite vs another with high retained austenite.

CPM S110V wasn't developed to be a knife steel, it was developed to be used in the Plastics industry where high wear and corrosion resistance are necessary. That's due to the extremely abrasive and corrosive nature of the elements the steels come in contact with. The same goes for CPM S90V, M390 and ELMAX.

Making knives out of it was an after thought as some of the Custom makers thought it might be a good steel for knife blades so that process started after a lot of research and testing to see how it would work and what HT would be be best for that type of use. Due the high alloy content there was problems rolling it out in sheets so the makers could make knife blades out of it, a lot of material loss percentage wise during the process rolling it out that thin. That's also one the reasons for the high cost of the steel. So working with Crucible the process began to see if it would be a good steel for knife blades and or if it could even be used at all.

The steel is very wear resistant so it really puts a lot of wear on equipment during the process of making knife blades out of it and that along with the availability, cost and other issues it wasn't readily available in sizes the makers could use so special runs had to be ordered.

[Cliff Stamp]

CPM S110V wasn't developed to be a knife steel ...

Yes, the information is in the patent listed on what it was developed for.

"The alloy is characterized by very high wear and corrosion resistance, making it particularly useful for use in the manufacture of components for advanced bearing designs as well as machinery parts exposed to severe abrasive wear and corrosion conditions ..."

This steel is just a modification of the S90V series of steels which covers steels which have never even been released such as S150V but are all under the same patent.

The main differences of S110V vs the S90V family of steels are

-niobium partially replaces vanadium
-cobalt is added

The niobium produces a higher free chromium and increases the MC carbide percentage as niobium has a higher affinity for carbon than chromium, and is even stronger than vanadium. The cobalt keeps the ferrite out of the final as-quenched form at reduced soak temperatures as it is an austenite stabilizer.

This allows the steel to retain the high level of abrasion resistance of the previous steels but with a higher corrosion resistance and a easier and more consistent response to hardening.

In regards to machining, rolling, etc. it is no different than the previous series of steels (the S90V) family which all have the same and very high difficulty of processing due to the extreme carbide volume.

[Ankerson]

Yes, the information is in the patent listed on what it was developed for.

"The alloy is characterized by very high wear and corrosion resistance, making it particularly useful for use in the manufacture of components for advanced bearing designs as well as machinery parts exposed to severe abrasive wear and corrosion conditions ..."

This steel is just a modification of the S90V series of steels which covers steels which have never even been released such as S150V but are all under the same patent.

The main differences of S110V vs the S90V family of steels are

-niobium partially replaces vanadium
-cobalt is added

The niobium produces a higher free chromium and increases the MC carbide percentage as niobium has a higher affinity for carbon than chromium, and is even stronger than vanadium. The cobalt keeps the ferrite out of the final as-quenched form at reduced soak temperatures as it is an austenite stabilizer.

This allows the steel to retain the high level of abrasion resistance of the previous steels but with a higher corrosion resistance and a easier and more consistent response to hardening.

In regards to machining, rolling, etc. it is no different than the previous series of steels (the S90V) family which all have the same and very high difficulty of processing due to the extreme carbide volume.

It's the element content as a whole of S110V, the combination of those elements that cause the problems in the rolling process over other steels like S90V, some other steels have had some of the same types of problems (I have a knife in one that was in the development stages that was even worse) over the years and worse also when they are being rolled out. It's the combination of the elements and the percentages that cause the issues, Crucible stopped making S110V for awhile due to the problems they had rolling it out. It was in VERY limited supply for YEARS and what was available was usually gone before long.

There is a huge difference between producing the materials and sizes needed to make machine parts and molds and rolling it out into thin flat sheets for making knife blades, kinda difficult to get a sheet when it comes out in pieces and is so rough they have to grind away 50% of it just to get to smooth material.

But then that information isn't in the data sheets or any other literature anyplace to analyze so I am just saying.......

It's more like good luck rolling that steel out.......

[Cliff Stamp]

But then that information isn't in the data sheets or any other literature anyplace to analyze....

The actual methods of processing the steels themselves is patented and the methods used in thermal processing are well known and actively researched and published. There is considerable active research in the thermal processing of steels, especially the high carbide ones as it is very critical to the performance post-HT. This isn't magic, it is science so it is all well documented. However of course what is in the literature and presented for peer review is not what is presented in marketing information.

[Ankerson]

The actual methods of processing the steels themselves is patented and the methods used in thermal processing are well known and actively researched and published. There is considerable active research in the thermal processing of steels, especially the high carbide ones as it is very critical to the performance post-HT. This isn't magic, it is science so it is all well documented. However of course what is in the literature and presented for peer review is not what is presented in marketing information.

That's what I was getting at in general....

It was just one of the better known small examples of why some things are the way they are.

And that was ment to be vague and I can't go into it all any deeper. :)

[Ankerson]

K390 Mule after cutting up 5 large boxes, and it would still shave hair and slice phone book paper. :eek:

[chuck_roxas45]

That can't be, material properties of K390 should just make the edge crumble.

[Ankerson]

And last but not least the wood cutting, and we can see the edge didn't fall apart.

[Zenith]

And last but not least the wood cutting, and we can see the edge didn't fall apart.

I would love to see you drop the edge down to 5 degrees per side and redo the testing.

[Ankerson]

That can't be, material properties of K390 should just make the edge crumble.

Yeah I know Spyderco must have mislabeled the Mule, must have been AEB-L and not K390 because there is just no way it would have survived..... ROFL :D

[Ankerson]

I would love to see you drop the edge down to 5 degrees per side and redo the testing.

The blade would have to be reground before that happened, to around .010" or under behind the edge from the current .025" and I don't go below 10 DPS as I don't see the need to.

Already did it at 10 DPS on Customs in S110V, K294, 10V, M390 and a development steel, all at or under .010" behind the edge in past reviews as it's part of my normal format.