K390 vs Maxamet

[Fireman]

Spyderco is leading the charge in these two steels, thing is, why would I want K390 over Maxamet? They seem to have some overlap and unique qualities as well.
If you have both, why would you chose one over another and why?
Toothy vs polished edge performance?
Which is easiest to sharpen and with what tools and techniques?
What do’s and don’ts of both?
If you had to chose only one?
What model is best for each steel? (what model brings out the best or maximizes the strengths of the steels qualities and porpose?)
Is the answer a different steel?

[aaronkb]

I can’t compare it to maxamet but I’d say call my sharpening abilities intermediate and k390 doesn’t give me any trouble. I use diamond stones and strop with cbn compound.

From my understanding, maxamet will hold an edge way longer but k390 is a lot tougher. And given that it’s miles ahead of everything else in edge retention, k390 is good enough for me. Easily my favorite steel.

I have a pm2 and a para 3. My understanding is that people like the heat treat even better on the seki city models.

[Deadboxhero]

Maxamet will cut longer if the method of dulling is blunting from cutting.

K390 is more durable so will cut longer if the method of dulling is not just blunting from cutting but also some chipping and chowdering on the edge from not being aware or caring what the edge is making contact with.


Maxamet makes a more aggressive edge that is quite noticable and very exciting.

K390 still has more aggression than most other steels on the market but Maxamet is more extreme.

Neither should be sharpened with ceramic if the best results are desired, Maxamet is hard enough and with enough carbide volume to cause problems if sharpened on ceramic from a dull used edge.

Can't choose, gotta have both.

[aaronkb]

Neither should be sharpened with ceramic if the best results are desired, Maxamet is hard enough and with enough carbide volume to cause problems if sharpened on ceramic from a dull used edge.

I struggle with burr removal on the diamonds (in general, not with any specific steel) so I recently picked up a Spyderco UF for that. Haven’t done a full sharpening on k390 since I got it but I’m curious to hear your thoughts on a few passes at the end for burr removal. I trust your opinion more than most.

[Deadboxhero]

Neither should be sharpened with ceramic if the best results are desired, Maxamet is hard enough and with enough carbide volume to cause problems if sharpened on ceramic from a dull used edge.

I struggle with burr removal on the diamonds (in general, not with any specific steel) so I recently picked up a Spyderco UF for that. Haven’t done a full sharpening on k390 since I got it but I’m curious to hear your thoughts on a few passes at the end for burr removal. I trust your opinion more than most.

It's a difficult point to get across since it's not like it doesn't work at all or that the knife explodes if it touches ceramic stones.

So you'll get a "SEE! I told you so!" from some folks.

Here's the deal though, if you're a discerning sharpener you'll notice when using both abrasives the diamond/CBN clearly cuts cleaner and makes a crisper edge without burnishing the apex to death.


I can sharpen with anything but I'd be remiss if I didn't see what was clearly working better.


Deburring is a skill in itself for any abrasive.

[aaronkb]

Deburring is a skill in itself for any abrasive.

I appreciate the reply! If you’ve got the time I’d love any tips on deburring in general. I can do it but it takes far more time, energy and frustration than it should.

[kobold]

So far, Maxamet is available in models that I prefer to those available in K390.. I like Maxamet for the way it sharpens, cuts, holds an edge, and patinas.
I am mainly waiting for a Military and Chief in PE Maxamet. And almost any steel in a SE, but K390 would be nice.

[kobold]

Deburring is a skill in itself for any abrasive.

I appreciate the reply! If you’ve got the time I’d love any tips on deburring in general. I can do it but it takes far more time, energy and frustration than it should.

Light, edge trailing motion on the Spyderco UF and a diamond loaded leather strop should do it.

[aaronkb]

Deburring is a skill in itself for any abrasive.

I appreciate the reply! If you’ve got the time I’d love any tips on deburring in general. I can do it but it takes far more time, energy and frustration than it should.

Light, edge trailing motion on the Spyderco UF and a diamond loaded leather strop should do it.

Yep, that’s what I do (I load my strops with cbn but that’s equivalent)

I will say I’ve had less trouble deburring on the Spyderco UF, but it sounds like BBB is saying it’d be better not to use that at all with certain steels.

[kobold]

Deburring is a skill in itself for any abrasive.

I appreciate the reply! If you’ve got the time I’d love any tips on deburring in general. I can do it but it takes far more time, energy and frustration than it should.

Light, edge trailing motion on the Spyderco UF and a diamond loaded leather strop should do it.

Yep, that’s what I do (I load my strops with cbn but that’s equivalent)

I will say I’ve had less trouble deburring on the Spyderco UF, but it sounds like BBB is saying it’d be better not to use that at all with certain steels.

I think it is okay to do the work with diamonds and only clean up the edge with a fine ceramic at the end, in my experience, but also according to this:

https://scienceofsharp.com/2019/11/03/c ... n-maxamet/

[Matt Deaner]

I don't like using ceramic with any high vanadium steel. The edge I get with ceramic just doesn't last and it kills the aggression. Maxamet is not high vanadium... It does ok with ceramic for touch up in my experience but I still prefer diamonds with it. This is just my experience.

Between the two steels, k390 and Maxamet, it is hard for me to pick a favorite. They are so different from one another. I do think k390 is more broadly useful given it's better sharpening response and toughness. But I love the edge maxamet takes.

[aaronkb]

I think it is okay to do the work with diamonds and only clean up the edge with a fine ceramic at the end, in my experience, but also according to this:

https://scienceofsharp.com/2019/11/03/c ... n-maxamet/

Interesting read, thanks!

[tomhosangoutdoors]

I appreciate the reply! If you’ve got the time I’d love any tips on deburring in general. I can do it but it takes far more time, energy and frustration than it should.

Light, edge trailing motion on the Spyderco UF and a diamond loaded leather strop should do it.

Yep, that’s what I do (I load my strops with cbn but that’s equivalent)

I will say I’ve had less trouble deburring on the Spyderco UF, but it sounds like BBB is saying it’d be better not to use that at all with certain steels.

I think it is okay to do the work with diamonds and only clean up the edge with a fine ceramic at the end, in my experience, but also according to this:

https://scienceofsharp.com/2019/11/03/c ... n-maxamet/

You definitely can, but then you're missing out on the capability of diamond/CBN to properly cut/abrade the carbides. Ceramic leaves those carbides fully intact at the apex which makes it kinda chunky and coarse. An apex with a full diamond/CBN progression is much more crisp and will last longer.

[prndltech]

I’m a basic guy so in layman’s terms… diamonds/cbn vs. ceramics is like Toyota vs. Lexus. Both will get you where you want to go (for the most part) but you will really enjoy the outcome of the edge off diamonds/cbn . In these high end steels you get what you’re paying for out of the steels by using diamond/cbn to sharpen over cermamic. Same is true for s30v, s90v, s110v etc.

Just my experience… as always your mileage may and probably will, vary.

[Evil D]

I’m a basic guy so in layman’s terms… diamonds/cbn vs. ceramics is like Toyota vs. Lexus. Both will get you where you want to go (for the most part) but you will really enjoy the outcome of the edge off diamonds/cbn . In these high end steels you get what you’re paying for out of the steels by using diamond/cbn to sharpen over cermamic. Same is true for s30v, s90v, s110v etc.

Just my experience… as always your mileage may and probably will, vary.

More like trying to plow a field with a tractor (diamond/CBN) vs with a mobility scooter (ceramics).


It's not a quality vs quality issue, the ceramic rods are very nice, and they technically will cut any steel because they're harder than the steel is, but you'll get significantly better results with the diamond/CBN because of how much more aggressively they cut.

What we really need are some more coarse and more fine versions of the diamond and CBN rods, if that's even possible.

[FRNFanboy]

The biggest difference in performance you will notice is in terms of toughness. Both offer extreme edge retention, although Maxamet is somewhat better. You would really have to punish either of them to actually dull the edge. Both are fairly lackluster in their rust resistance as well, although in my experience K390 doesn't as stain as readily as Maxamet. But whereas K390 is respectably tough, say, in the VG10 or S35vn realm... Maxamet is very brittle, arguably moreso than any commonly used knife steel. With that in mind, I would want a Maxamet blade to shorter and stouter, a Para 3 or Sage 5 instead of a PM2 or Manix.

[kobold]

Light, edge trailing motion on the Spyderco UF and a diamond loaded leather strop should do it.

Yep, that’s what I do (I load my strops with cbn but that’s equivalent)

I will say I’ve had less trouble deburring on the Spyderco UF, but it sounds like BBB is saying it’d be better not to use that at all with certain steels.

I think it is okay to do the work with diamonds and only clean up the edge with a fine ceramic at the end, in my experience, but also according to this:

https://scienceofsharp.com/2019/11/03/c ... n-maxamet/

You definitely can, but then you're missing out on the capability of diamond/CBN to properly cut/abrade the carbides. Ceramic leaves those carbides fully intact at the apex which makes it kinda chunky and coarse. An apex with a full diamond/CBN progression is much more crisp and will last longer.

I think, since the majority of the work is already done (eg with diamond plates) at that point, the idea is to remove/clean the residual matrix steel from the surface and make the carbides exposed and ready for a diamond strop.


Here is a practical take:
https://youtu.be/a6ibhLbDH1c

[RustyIron]

If you have both, why would you chose one over another and why?

I have both, in vastly different platforms, but they're both fun to use. If I was buying a general purpose knife right now, and all the other variables were equal, I would choose K390 for its toughness. It's not that Maxamet is bad, in fact I enjoy using and sharpening it. In the beginning, it frustrated me, but that has helped me learn. It can hold a keen edge for a long time, no doubt. But my knives get used for a multitude of purposes: shaving down some plastic parts, cutting through or stripping copper wire, pruning bushes and hacking twigs, and even banging into hidden staples when I open shipping boxes containing new knives. Hitting hard stuff and lateral forces tend to chip Maxamet more than other steels I've used. As long as you understand it, it's not all bad. I'm intrigued how some microscopic chipping changes the way the knife cuts. It's not necessarily dull, it just cuts differently, and it's fun to experiment with it. My K390 is on a lighter-duty knife. It keeps an edge nicely, to the point where I'd like to try the steel in a heavier duty knife.

Toothy vs polished edge performance?

Whatever. It's not like it's a permanent decision. I change my edge style like young ladies change their hair color. However, most of my work gets finished in the 650 to 2200 range--it's whatever entertains me at that moment. Last week I was carrying a knife that I finished to 4.4k, then stropped with 1 micron diamonds. I was on a trail that had a lot of yucca plants. Getting stabbed by yuccas kinda sucks. If you're an outdoorsman here, you're familiar with getting get stabbed, but you don't like it. Folks who do trailwork will manage the encroaching yuccas, and I thought I would be a Good Samaritan and cut some tips off the yuccas. They're very fiberous, so I didn't have high expectations for a polished blade, but my knife cut through the yucca leaves like butter. I guess it's all about how much effort you put into the edge. Much of the "grit controversy" is akin to arguing the number of angels can dance on the edge of your blade.

Which is easiest to sharpen and with what tools and techniques?

Easiest? Everything is easy once you take the time to figure it out. And really, figuring out problems is the fun part for me. As for tools, I use an EdgePro Professional, and I use their diamond matrix stones for most high-end steel. These stones are made by Columbia Gorge Stoneworks. If you're a bench stone sort of guy, then order from them directly. Trust me, these are the greatest thing since bread sliced with Spyderco's polypropylene bread knife. If it helps, I find it much easier to put a nice edge on high end tool steels than more plebeian stainless.

What do’s and don’ts of both?

Don't fall into the pit of indecision. You'll like whatever you get, and you'll aways want to try whatever you didn't get.

What model is best for each steel? (what model brings out the best or maximizes the strengths of the steels qualities and porpose?)

Hmmm... overthinking you are. Go with whatever model of knife most appeals to you, either in functionality or aesthetics. There is no crossover between knife models and these two steels, so your decision might be easier. Hint: Manix 2.

[tomhosangoutdoors]

Yep, that’s what I do (I load my strops with cbn but that’s equivalent)

I will say I’ve had less trouble deburring on the Spyderco UF, but it sounds like BBB is saying it’d be better not to use that at all with certain steels.

I think it is okay to do the work with diamonds and only clean up the edge with a fine ceramic at the end, in my experience, but also according to this:

https://scienceofsharp.com/2019/11/03/c ... n-maxamet/

You definitely can, but then you're missing out on the capability of diamond/CBN to properly cut/abrade the carbides. Ceramic leaves those carbides fully intact at the apex which makes it kinda chunky and coarse. An apex with a full diamond/CBN progression is much more crisp and will last longer.

I think, since the majority of the work is already done (eg with diamond plates) at that point, the idea is to remove/clean the residual matrix steel from the surface and make the carbides exposed and ready for a diamond strop.


Here is a practical take:
https://youtu.be/a6ibhLbDH1c

Even just that little amount can make a difference in performance. I've seen it first hand with Maxamet and S90V as explained in the video below.

https://youtu.be/9IkGs8Irpkk

[Deadboxhero]

I’m a basic guy so in layman’s terms… diamonds/cbn vs. ceramics is like Toyota vs. Lexus. Both will get you where you want to go (for the most part) but you will really enjoy the outcome of the edge off diamonds/cbn . In these high end steels you get what you’re paying for out of the steels by using diamond/cbn to sharpen over cermamic. Same is true for s30v, s90v, s110v etc.

Just my experience… as always your mileage may and probably will, vary.

More like trying to plow a field with a tractor (diamond/CBN) vs with a mobility scooter (ceramics).


It's not a quality vs quality issue, the ceramic rods are very nice, and they technically will cut any steel because they're harder than the steel is, but you'll get significantly better results with the diamond/CBN because of how much more aggressively they cut.

What we really need are some more coarse and more fine versions of the diamond and CBN rods, if that's even possible.

The ceramic stones cut "some" of the steel but the steel isn't all pure "steel", there are harder phases in the steel that are more ceramic like called carbides with vanadium carbides being the hardest, even harder than tungsten carbides. (~2500hv)

The Vanadium carbides in the steel are harder than the ceramic stones, 17% of the matrix in k390 is vanadium carbide, AlOx ~2000hv VC ~2800hv (hardness will vary depending on type, element richness and orientation)

So if you're pushing a submicron apex with carbides at 1-3um in the apex you'll have to use something harder than the carbides to shape them flush with the apex.

So it's technically not about the cutting aggression as much as it's about cutting everything down to shape in the steel.