K390 and S110V Discussion Thread

[fanglekai]

Did some googling about AEB-L and it seems it would be a good slicer, razor blade or kitchen knife steel which is what it seems to be primarily used for. Would be a good indoor knife.

Its also 20 years or more old..hard for me to believe it would be better than K390..

5 DPS? Such an edge is only marginally useful in normal knife use at best..

IIRC S90V is 20 years or more old...

[Ankerson]

IIRC S90V is 20 years or more old...

A lot of those steels are pretty old...

CPM 10V (A11) has been around almost 40 years now....

[Philo Beddoe]

A lot of those steels are pretty old...

CPM 10V (A11) has been around almost 40 years now....

I found this thread on BF: http://www.bladeforums.com/forums/showt ... 0-Military

and some on that thread were saying K390 and S110V would be nearly impossible to do in a production setting due to how hard those steels are to work with. Wearing out belts, machines, etc.

Somebody at Spyderco must have seen read thread..less than 2 years later and K390 and S110V knives made in a production setting are shipping.

Good job Spyderco.

[Ankerson]

I found this thread on BF: http://www.bladeforums.com/forums/showt ... 0-Military

and some on that thread were saying K390 and S110V would be nearly impossible to do in a production setting due to how hard those steels are to work with. Wearing out belts, machines, etc.

Somebody at Spyderco must have seen read thread..less than 2 years later and K390 and S110V knives made in a production setting are shipping.

Good job Spyderco.

Methods of production have improved over the years in dealing with the high wear resistant steels like S90V, 10V, S110V etc....

It could always have been done, it's just the cost to actually make the knives blades is high compared to the more normal steels, that's equipment wear.....

[chuck_roxas45]

Yeah on a blade that thin going from 5 DPS to 10 DPS won't make any noticeable difference in cutting ability....

Or you could have just used a very small micro bevel.......

But then the edge wouldn't have been that weak now would it?

All you did was weaken the edge to the point of guaranteed early failure... Yes I have done the testing too so it's not a surprise to me at all.

It's like punching a brick wall with your bare hand... WOW I broke my hand....

In contrast doing the same with a boxing glove on.....

I haven't any experience with customs but on my production knives, I have mostly a 26/36 bevel and it cuts anything I need it to cut. Not prone to edge damage too. How much sharper do I need my EDC knives to be? At the cost of a fragile edge? No, thanks.

[Ankerson]

I haven't any experience with customs but on my production knives, I have mostly a 26/36 bevel and it cuts anything I need it to cut. Not prone to edge damage too. How much sharper do I need my EDC knives to be? At the cost of a fragile edge? No, thanks.

I usually stay around 15 DPS on production blades personally.

[chuck_roxas45]

I usually stay around 15 DPS on production blades personally.

Do you microbevel Jim?

[Ankerson]

Do you microbevel Jim?

Yeah, when I do quick touch ups using my ceramics I put a very small microbevel on.

[chuck_roxas45]

Yeah, when I do quick touch ups using my ceramics I put a very small microbevel on.

That's about how I roll too. When the micro starts getting to be a macro, I refresh the back bevel and start anew. :)

[Ankerson]

That's about how I roll too. When the micro starts getting to be a macro, I refresh the back bevel and start anew. :)

Yeah you can go for a VERY long time with light touch ups before having to refresh the edge. :)

[chuck_roxas45]

Yeah you can go for a VERY long time with light touch ups before having to refresh the edge. :)

Yes sir. :)

[senorsquare]

I usually stay around 15 DPS on production blades personally.

I have been doing 15dps based on the various discussions around here and I have no complaints with performance. I have a stop-collar on my edgepro set to 15 degrees and now I just leave it there so I can grab any knife and put what is pretty close to a 15dps edge on it without futzing around with angle cubes and what-not. This is perhaps a lazy man's approach but it at least keeps me somewhat consistent.

I plan to put a new edge on the MT17 and forum knife this weekend if I can find a few hours to spare sitting at the sharpening table. I do not expect these steels to give up their bounty without a fight.

[Ankerson]

I have been doing 15dps based on the various discussions around here and I have no complaints with performance. I have a stop-collar on my edgepro set to 15 degrees and now I just leave it there so I can grab any knife and put what is pretty close to a 15dps edge on it without futzing around with angle cubes and what-not. This is perhaps a lazy man's approach but it at least keeps me somewhat consistent.

I plan to put a new edge on the MT17 and forum knife this weekend if I can find a few hours to spare sitting at the sharpening table. I do not expect these steels to give up their bounty without a fight.

It won't be that bad even with the Stock EP stones. :)

[Cliff Stamp]

Or you could have just used a very small micro bevel.......

A micro-bevel would not have resolved the problem because it is fracturing at a larger scale. Yes the bevel angle could have been increased to stabilize the steel, that is exactly what edge stability measures and thus steels which have higher edge stability are stable at lower edge angles. Yes you can stabilize any steel at some angle, it is no different than you could make a knife tougher by simply increasing the stock thickness, but you would not claim that the steel itself was not brittle simply because you were able to overcome that through cross section. Again the work on edge stability quantifies the angles required to stabilize steels as a function of carbide volume. It even goes beyond that and discusses the same on ceramic/carbide edges.

There are also of course downsides to even applying micro-bevels to knives because of lack of edge stability which include effects such as the fact that the apex angle itself sets the slicing aggression at a given grit finish and thus a higher micro-bevel will thus significantly reduce the slicing aggression at a given sharpness level (apex width). It also adds to complexity of sharpening and maintenance and has many other drawbacks when you are doing it simply to compensate for lack of ability of the steel.

All you did was weaken the edge to the point of guaranteed early failure.

That wasn't an attempt to set the edge failure point specifically, it was just from a recent stock run. It also wasn't a 5 DPS bevel, you can run those on that type of steel for rope/cardboard and get better results but you have to utilize the fact that you know it is going to fracture and sharpen accordingly.

But in general, that is obviously how you determine the optimal geometry for cutting ability, it is that which is just above the durability requirements. As AEB-L has a higher edge stability it will hold a lower angle in the same cutting without fracture. This not only has the effect of the immediate cutting ability being higher the cutting lifetime itself is higher. And you sharpen faster, and it takes less damage in extremes, etc. .

Its also 20 years or more old..hard for me to believe it would be better than K390.

K390 isn't a knife steel, K390 is simply an attempt to increase the secondary hardening response of A11 which in general is a cycle which should be avoided in knives entirely because it sacrifices all other properties to gain heat resistance. This is why you will rarely see hot work tool steels used for cold work as they don't have an advantage there.

If you want to look at modern metallurgy applied to knife steels then look at Nitrobe 77. This is an attempt to achieve the edge stability of AEB-L but offer increased strength, toughness and corrosion resistance through modern advancements in alloying and PM processing. It is of course much more expensive.

5 DPS? Such an edge is only marginally useful in normal knife use at best..

That isn't a 5 DPS edge in the pictures, however I do run such bevels and they are perfectly functional if the steel has high edge stability. I can guarantee you have more limits on what you will do with your knives than I do with mine.

The problem with modern angles is the influx of steels with very poor edge stability leading to modern pocket knives having edge angles which exceed what are on felling axes. This isn't even hyperbole though it sounds like it, 15 dps is in range of apex angles for felling axes.

By the way, I hope Clyde is still doing well.

[Ankerson]

A micro-bevel would not have resolved the problem because it is fracturing at a larger scale. Yes the bevel angle could have been increased to stabilize the steel, that is what edge stability measures. It is no different than you could make a knife tougher by simply increasing the stock thickness, but you would not claim that the steel itself was not brittle simply because you were able to overcome that through cross section.

Wouldn't really want it thicker really because of the loss in cutting efficiency... Really thin with a decent edge angle to balance things out is best usually. That will vary depending on the knives and or steels used to get optimal performance.

On Phil's knives I normally go down to 10 DPS and that seems to be optimal for his work as I haven't experienced any major issues other than normal wear and tear.

There are also downsides to even applying micro-bevels to knives because of lack of edge stability which include effects such as the fact that the apex angle itself sets the slicing aggression at a given grit finish and thus a higher micro-bevel will thus significantly reduce the slicing aggression at a given sharpness level (apex width). It also adds to complexity of sharpening and maintenance and has many other drawbacks when you are doing it to compensate for lack of ability of the steel.

Not really that big of a deal, I was talking about a very small micro bevel, could be done freehand in a few passes usually. So small one would have to really look to see it. But yeah it would normally need to be the same grit range to keep cutting aggression.

That wasn't an attempt to set the edge failure point specifically, it was just from a recent stock run. It also wasn't a 5 DPS bevel, you can run those on that type of steel for rope/cardboard and get better results but you have to utilize the fact that you know it is going to fracture and sharpen accordingly.

But in general, that is obviously how you determine the optimal geometry for cutting ability, it is that which is just above the durability requirements. As AEB-L has a higher edge stability it will hold a lower angle in the same cutting without fracture. This not only has the effect of the immediate cutting ability being higher the cutting lifetime itself is higher. And you sharpen faster, and it takes less damage in extremes, etc. .

Well yes, in testing we take things down to the point of failure and back off until they stabilize and develop what we call the optimal standard.

[Invective]

Man I love these threads with both Ankerson and Cliff. I learn so much more than I ever thought I would about these topics and at the end I still am confused. Regardless of your guys' feelings towards each other, I quite enjoy reading your posts about steels!

Well yes, in testing we take things down to the point of failure and back off until they stabilize and develop what we call the optimal standard.

So basically this right :D

[DougC-3]

Man I love these threads with both Ankerson and Cliff. I learn so much more than I ever thought I would about these topics and at the end I still am confused. Regardless of your guys' feelings towards each other, I quite enjoy reading your posts about steels!



So basically this right :D

haha, we could do a little more lateral thinking and apply this to all walks of life :D

[chuck_roxas45]

Wouldn't really want it thicker really because of the loss in cutting efficiency... Really thin with a decent edge angle to balance things out is best usually. That will vary depending on the knives and or steels used to get optimal performance.

On Phil's knives I normally go down to 10 DPS and that seems to be optimal for his work as I haven't experienced any major issues other than normal wear and tear.



Not really that big of a deal, I was talking about a very small micro bevel, could be done freehand in a few passes usually. So small one would have to really look to see it. But yeah it would normally need to be the same grit range to keep cutting aggression.



Well yes, in testing we take things down to the point of failure and back off until they stabilize and develop what we call the optimal standard.

Thinking points I take away from this discussion.

*Steel choice comes down to what bevel angles we use on on our knives.

*How much performance difference is there between a 15 dps or 10 dps bevel and 5 dps?

*Is there anything to be gained by normal EDC uses in such thin angles over slightly thicker ones?

*Do the advantages of such a thin bevel outweigh the probability for edge damage?

*How long does the high sharpness on extremely thin angles really last?

[DunninLA]

Man I love these threads with both Ankerson and Cliff.

me too.

[xceptnl]

Man I love these threads with both Ankerson and Cliff. I learn so much more than I ever thought I would about these topics and at the end I still am confused. Regardless of your guys' feelings towards each other, I quite enjoy reading your posts about steels!

+2 this is how I feel.