Bohler K390 v M390

Well everyone has their own opinions and experiences.
My experience having been at a military camp working long days and having one bag and working 30 days straight, was that a soft blade like a SAK was easy to get resharpen when dull and work out edge deformation with a simple stone not a portable gizmo. it's not about not knowing how its about ease ...

There are people who don't look at knives as a hobby but tools.
If you want to keep discussing and use smilies let's start a new thread and not hijack this one. ;)
 
It is always nice to clarify if one is removing steel to eliminate chips and heavy blunting, or if one is just honing to restore sharpness. Softer steels with less carbide are cut faster than harder steels or higher alloyed, it's the reason they both exist. What matters at the edge is how much has to be removed. The difference in effort to remove an amount measured in micron thickness from a couple of slightly dulled blades is barely noticeable. The need to bring the edge back half a millimeter because you had to cut something right on top of metal or rock and got a chip is going to give results in line with why industry chooses high wear steels in the first place.
 
Superdave1 said:
Well everyone has their own opinions and experiences.
My experience having been at a military camp working long days and having one bag and working 30 days straight, was that a soft blade like a SAK was easy to get resharpen when dull and work out edge deformation with a simple stone not a portable gizmo. it's not about not knowing how its about ease ...

There are people who don't look at knives as a hobby but tools.
If you want to keep discussing and use smilies let's start a new thread and not hijack this one. ;)
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Silicone Carbide sharpening stones are as simple as they get...... Will sharpen ANY knife steel including the high alloy ones..... I know because that's what I use.... And they have been around for longer than I can remember, I have one that is about 40 years old...

And they are CHEAP, can be had for around $5 to $20 depending on size, grit and brand... And there are lots of choices from very small rods to large bench stones...

Not exactly a gizmo......

And I am one of those who uses their knives as tools also... At work....
 
hardheart said:
It is always nice to clarify if one is removing steel to eliminate chips and heavy blunting, or if one is just honing to restore sharpness. Softer steels with less carbide are cut faster than harder steels or higher alloyed, it's the reason they both exist. What matters at the edge is how much has to be removed. The difference in effort to remove an amount measured in micron thickness from a couple of slightly dulled blades is barely noticeable. The need to bring the edge back half a millimeter because you had to cut something right on top of metal or rock and got a chip is going to give results in line with why industry chooses high wear steels in the first place.
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The reason why I mentioned reprofiling. :D
 
I'm just saying there are many users with experience who prefer an easier to maintain steel such as 1095 than harder high alloy "super steels" that prefer them in the field ...
I also like hard modern steels, they all have their place.
Let's not derail the thread, because I don't accept your opinion over my own experience and preference. Take it to another thread.

I also have a few different types of stones natural, synthetic, diamonds and strops... ;)
 
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ridnovir said:
Ok

fixed blade
slicer type utility blade about 3 to 4 inches long
flat grind
convex edge
to be sharpened on compound loaded leather strop

intended use: light camping chores, food prep etc.
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For that, I would take a K390 knife if it is as similar to CPM-M4 as it seems. Hard choice really, but i really like M4.
 
Sonnydaze said:
IMO, the M390 with the much greater chromium content will be much more stain resistant. The K390, higher carbon content and hardness, will be more brittle, more likely to chip than roll the edge, not as tough, harder to sharpen but will hold an edge longer.
Ankerson can correct me as necessary. :)
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I though chromium carbides made steel harder to sharpen and more brittle? Granted, the hardness would play a large role in the toughness, but you are comparing carbon and stainless steels.
 
dkb45 said:
I though chromium carbides made steel harder to sharpen and more brittle? Granted, the hardness would play a large role in the toughness, but you are comparing carbon and stainless steels.
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yes, but tungsten, molybdenum, and vanadium carbide are all much harder, with vanadium the hardest. K390 probably has about 18-20% carbide volume. It is no closer to carbon steel than any stainless, and has a much higher carbide volume than many. It has around 5% more carbide than S30V, for example. Toughness between M & K 390 are about the same, in the low 30s measured in lbs on charpy impact.
 
Sonnydaze said:
IMO, the M390 with the much greater chromium content will be much more stain resistant. The K390, higher carbon content and hardness, will be more brittle, more likely to chip than roll the edge, not as tough, harder to sharpen but will hold an edge longer.
Ankerson can correct me as necessary. :)
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Well that depends on how K390 is tempered and the finial hardness, like K294 it has a very high compression strength, that's something that is not talked about very much in favor of impact testing which measures something completely different. Ideally when a blade is heat treated and tempered the maker shoots for the edge to roll before chipping and that's a very fine line to hit and in that hardness range of 63-65 RC it takes a maker that really knows the steel and has the experience to deal with it. What I am saying is the answer would be no, K390 wouldn't be more likely to chip than roll even at optimal hardness, but all blades will fail at a certain point or should I say snap, chip out etc if pushed beyond their limits.

I own a K294 blade that's at 64 RC and .010" behind the edge with a 12 DPS edge geometry and have pushed it straight through knots in wood with no issues whatsoever.



dkb45 said:
I though chromium carbides made steel harder to sharpen and more brittle? Granted, the hardness would play a large role in the toughness, but you are comparing carbon and stainless steels.
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Brittleness is result of a blown heat treatment..... If a blade is brittle then there are much bigger issues at hand and the blade needs to go back to the maker.

Yes carbides will make a steel harder to sharpen because they aid in wear resistance and that in itself is the result in general.
 
I have done some naughty things with my K390 blades (63-64rc) and I have not had any chipping at all. As for M390 I did have some chipping when my wife used my M390 (61rc) santoku to chop frozen chocolate haha
 
capid1 said:
I have done some naughty things with my K390 blades (63-64rc) and I have not had any chipping at all. As for M390 I did have some chipping when my wife used my M390 (61rc) santoku to chop frozen chocolate haha
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That's not surprising at all. :D

K390 and K294/10V aren't nearly as fragile as some would have people believe, even at optimal hardness of 63-64 and ground thin.

The urban legend is that because of the high alloy content they are automatically chip monsters.......

They aren't at all......

If one needs a knife they can pound on with a hammer there are other steels for that.....

If one wants a knife to cut with that will hold an edge for almost forever then these are the ones to look at. :)
 
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Superdave1 said:
I'm just saying there are many users with experience who prefer an easier to maintain steel such as 1095 than harder high alloy "super steels" that prefer them in the field ...
I also like hard modern steels, they all have their place.
Let's not derail the thread, because I don't accept your opinion over my own experience and preference. Take it to another thread.

I also have a few different types of stones natural, synthetic, diamonds and strops... ;)
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You were the one who derailed it here with this post.........

Superdave1 said:
I disagree, harder to sharpen issues are not taken out of the equation ...
Ease of sharpening on non powered equipment, or common whet stones can be desireable when one is away from civilization and is limited to a rucksack for example and one may only have a pocket stone.
Seems like all these backyard testers and Internet experts hype the hardest stainless super steels, but there are many who have experience who prefer toughness and ease of sharpening that contradicts the thread/rope/card board cutting whizzes.
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Hereby taking it into a different direction........ Trolling against the higher alloy steels again..... No surprise there though.

And taking a shot at those who do the testing along with it........ :grumpy:

I for one take offense to that because I do the testing at my own expense for the most part only to provide useful information to the community and others like knife makers and some Companies who ask me about about steels based on my testing results.... Most of which isn't on the internet or on YT, but done privately behind the scenes for various reasons and it's one heck of a lot of work on my end and time spent developing a proven testing method that is accurate so I can provide good data.

This also includes long term real world use and testing under various conditions so my posts aren't based on opinions, they are based on testing results of testing a large variety of steels.

Do I think I am an expert?

No I don't.....

I am a student and the steels are the teachers....
 
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K390 is more tougher and edge holding than M390, I have all of them
K390 is hard to sharping and machining, but M390 is easy.
 
If you need stainless or if stainless would be desirable, I'd go with M390 over K390.

If super edge holding is the key, I'd go with the harder, vanadium-rich K390.

If chopping is critical, I'd give the edge to M390.

But personally, I'd be more worried about blade/edge geometry. And I'd be more worried about the maker's ability to heat treat that particular steel. And I'd really, really want the edge to come already profiled to my needs, rather than have to reprofile a 65 HRc steel stuffed with 9 percent vanadium.

Even with diamond stones, a steel like 1095 with a thick blade is no picnic to reprofile. I recently got a custom in 1095 that came with a 60 degree (30 dps) inclusive edge. The blade was so poorly ground, with a thin spot in the spine at the base of the blade, that I suspected the heat treat was going to be awful, as well. It was. I held the handle and pointed the blade into my wood-plank floor at 45 degrees and gave the side of the blade a kick with my boot. An inch of the tip immediately broke off. A second kick broke the blade at the thin spot. I gave the same test to a cheap skinner that I found in the road. It had a much thinner blade made out of some kind of carbon steel. Its tip also broke off, but I could not break the blade.

I know that many people don't like abusive testing, but I've come to embrace it. In another test, a 1095 blade took lateral abuse that ruined a heavier 3V bowie blade. If you asked which is tougher, 3V or 1095, almost everyone would say 3V. But the heat treat is really important, and 1095 with a good heat treat can easily outperform 3V with a poor heat treat.

We keep getting threads about which steel makes a better knife, but there are way too many variables to give a simple answer.
 
Ankerson said:
You were the one who derailed it here with this post.........




Hereby taking it into a different direction........ Trolling against the higher alloy steels again..... No surprise there though.

And taking a shot at those who do the testing along with it........ :grumpy:

I for one take offense to that because I do the testing at my own expense for the most part only to provide useful information to the community and others like knife makers and some Companies who ask me about about steels based on my testing results.... Most of which isn't on the internet or on YT, but done privately behind the scenes for various reasons and it's one heck of a lot of work on my end and time spent developing a proven testing method that is accurate so I can provide good data.

This also includes long term real world use and testing under various conditions so my posts aren't based on opinions, they are based on testing results of testing a large variety of steels.

Do I think I am an expert?

No I don't.....

I am a student and the steels are the teachers....
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All true, except you are an expert to many around here interested in learning what you have learned yourself. I for one will keep reading about your silly tests, and look to try out new steels based upon them. You can call me a super steel fanboy:cool:
 
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