K390 IS "The M4 Killer"

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Albatross
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Re: K390 IS "The M4 Killer"

Postby Albatross » Fri Sep 11, 2020 1:15 am

GarageBoy wrote:
Thu Sep 10, 2020 7:16 pm
Does k390 do that sticky sharp edge that m4 is renown for? (Guessing due to its high carbide percentage)
Short answer is yes.
sal wrote:
Fri Nov 09, 2018 3:01 pm

...But in general, I'm all about high performance, Ergos, safety. That's why I've been accused of "deigning in the dark"...

sal

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Albatross
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Re: K390 IS "The M4 Killer"

Postby Albatross » Fri Sep 11, 2020 1:42 am

JohnDoe99 wrote:
Thu Sep 10, 2020 7:51 pm
GarageBoy wrote:
Thu Sep 10, 2020 7:16 pm
Does k390 do that sticky sharp edge that m4 is renown for? (Guessing due to its high carbide percentage)
If by "sticky sharp" you mean keenness, then a higher carbide percentage can only negatively affect the keenness of a blade as the carbide "clogs up" the edge because of the radical difference between the carbide and the surrounding alloy. K390 would not have an inherently sharper or keener edge than M4 as both are extremely wear resistant, and beyond that the skill of the sharpener and the abrasive used would be at least as relevant.
It's possible to have a more keen edge, that does not feel sticky, so I don't think it's the only factor. I would assume it's a combination of keenness and carbide content, but can't say for sure. Maybe Larrin could enlighten us?

Ive found that the 3 finger test gives an excellent preview of what to expect from the edge, such as how mild or aggressive the steel itself is (how it responded to sharpening determines the feel), and also keenness. Not very scientific, but it works for my purposes. I really enjoy a "sticky" edge because it seems to cut more efficiently.
sal wrote:
Fri Nov 09, 2018 3:01 pm

...But in general, I'm all about high performance, Ergos, safety. That's why I've been accused of "deigning in the dark"...

sal

JohnDoe99
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Posts: 94
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Re: K390 IS "The M4 Killer"

Postby JohnDoe99 » Fri Sep 11, 2020 8:08 pm

Albatross wrote:
Fri Sep 11, 2020 1:42 am
JohnDoe99 wrote:
Thu Sep 10, 2020 7:51 pm
GarageBoy wrote:
Thu Sep 10, 2020 7:16 pm
Does k390 do that sticky sharp edge that m4 is renown for? (Guessing due to its high carbide percentage)
If by "sticky sharp" you mean keenness, then a higher carbide percentage can only negatively affect the keenness of a blade as the carbide "clogs up" the edge because of the radical difference between the carbide and the surrounding alloy. K390 would not have an inherently sharper or keener edge than M4 as both are extremely wear resistant, and beyond that the skill of the sharpener and the abrasive used would be at least as relevant.
It's possible to have a more keen edge, that does not feel sticky, so I don't think it's the only factor. I would assume it's a combination of keenness and carbide content, but can't say for sure. Maybe Larrin could enlighten us?

Ive found that the 3 finger test gives an excellent preview of what to expect from the edge, such as how mild or aggressive the steel itself is (how it responded to sharpening determines the feel), and also keenness. Not very scientific, but it works for my purposes. I really enjoy a "sticky" edge because it seems to cut more efficiently.
There's at least a few ways to gauge sharpness. I've found edges to stick when they are very sharp coming off a fine non-diamond abrasive, like ceramic. Diamond on the other hand "grabs" the skin because of the serrated effect of the diamond gouging on the edge. That's why I kind of hate diamond. Fortunately when you break-in the very fine DMT, which takes some time, this effect is diminished.

Carbide is harder than the surrounding steel by a wide margin, particularly vanadium and the newer ones, as we all know. That is why I said it "clogs up" the edge; you're trying to sharpen the steel, but you have this exotic carbide constantly getting in the way and slowing down the process. ZDP-189 exists because of the trade off between the exotic carbide steels and grindability. The more vanadium, the slower going the sharpening, the harder it is to get the steel at a "keen" edge. This is why people resort to a whole gradation of diamond micron pastes to whittle hair with these things.

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Albatross
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Re: K390 IS "The M4 Killer"

Postby Albatross » Sat Sep 12, 2020 4:21 am

JohnDoe99 wrote:
Fri Sep 11, 2020 8:08 pm
Albatross wrote:
Fri Sep 11, 2020 1:42 am
JohnDoe99 wrote:
Thu Sep 10, 2020 7:51 pm
GarageBoy wrote:
Thu Sep 10, 2020 7:16 pm
Does k390 do that sticky sharp edge that m4 is renown for? (Guessing due to its high carbide percentage)
If by "sticky sharp" you mean keenness, then a higher carbide percentage can only negatively affect the keenness of a blade as the carbide "clogs up" the edge because of the radical difference between the carbide and the surrounding alloy. K390 would not have an inherently sharper or keener edge than M4 as both are extremely wear resistant, and beyond that the skill of the sharpener and the abrasive used would be at least as relevant.
It's possible to have a more keen edge, that does not feel sticky, so I don't think it's the only factor. I would assume it's a combination of keenness and carbide content, but can't say for sure. Maybe Larrin could enlighten us?

Ive found that the 3 finger test gives an excellent preview of what to expect from the edge, such as how mild or aggressive the steel itself is (how it responded to sharpening determines the feel), and also keenness. Not very scientific, but it works for my purposes. I really enjoy a "sticky" edge because it seems to cut more efficiently.
There's at least a few ways to gauge sharpness. I've found edges to stick when they are very sharp coming off a fine non-diamond abrasive, like ceramic. Diamond on the other hand "grabs" the skin because of the serrated effect of the diamond gouging on the edge. That's why I kind of hate diamond. Fortunately when you break-in the very fine DMT, which takes some time, this effect is diminished.

Carbide is harder than the surrounding steel by a wide margin, particularly vanadium and the newer ones, as we all know. That is why I said it "clogs up" the edge; you're trying to sharpen the steel, but you have this exotic carbide constantly getting in the way and slowing down the process. ZDP-189 exists because of the trade off between the exotic carbide steels and grindability. The more vanadium, the slower going the sharpening, the harder it is to get the steel at a "keen" edge. This is why people resort to a whole gradation of diamond micron pastes to whittle hair with these things.
If you compare the feel of XHP vs K390, you'll find K390 to be much more "sticky", even though XHP takes a more keen edge, with much less effort. My original point was that keenness isn't the only contributing factor for a sticky edge.
sal wrote:
Fri Nov 09, 2018 3:01 pm

...But in general, I'm all about high performance, Ergos, safety. That's why I've been accused of "deigning in the dark"...

sal


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