"Difficult To Sharpen" Steels?

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Vivi

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Why are steels with high wear resistance properties given the label difficult to sharpen? I've never understood this.

I find most of them (S30V, D2, ZDP189, S60V, CPMD2) to be easy to sharpen. They take more time to reprofile, but that is time consuming, it is not difficult. This part is trivial with proper sharpening equipment.

When actually sharpening, not shaping the back bevel, they are a pleasure to work with compared to softer steels with a tendancy to burr heavily. I spend less time sharpening ZDP189, S30V, D2 etc. because of this. When I sharpen a lot of my AUS8 blades or SAKs I often feel like I'm fighting the burr. I've never once had a persistent burr with a CPM steel.

Here is hair whittling with D2, ZDP189 and S30V blades (The S30V video is poorly done and will be re-shot, it was my first time trying to capture this on video).

http://youtube.com/watch?v=SrknF_Uwo8w
http://youtube.com/watch?v=t9-oHZ_rqZw
http://youtube.com/watch?v=3kT5zIAptbc

Why are these steels considered difficult to sharpen?
 
I agree.

"Time consuming" is not the equivalent of "difficult".

That is why I find M2 to be easy to sharpen. The initial shaping of the edge may take time, but there is no requirement to play the "knock the stubborn burr off" game and such.
 
i think its all about the time spent too. when i used to sharpen knives by hand i hated the "time consuming" part of it. i enjoyed putting a shaving sharp edge on a knife, i just didnt like the fact that some knives took a lot longer to get sharp.
when i bought the ez sharp system, that cut down on the time spent working up a burr but it was still time consuming. the system i use now gives me the same results only faster.
my knives for instance rockwell between 63-65rc and even though the initial edge for a 6" long blade can take up to 1/2 an hour to do with my belt sander it beats doing it by hand ( i set my sander to run slow). once i have an edge it only takes a few minutes to resharpen or touch it up. other than a ceramic knife, i havent found any knife that i cant sharpen and do it fast plus do a good job.
 
I think "difficult to sharpen" is often used to describe knives with thick and obtuse edge bevels. Maintaining stock bevels still leaves the user with thick and obtuse edges. This can apply to steels cheap or expensive. Both s30v and 420j2 are much easier to sharpen when the reprofiled so the primary grinds are near zero edge, and a microbevel honed for the actual cutting edge.
 
time consuming is difficult. if it's going to take twice as many strokes to begin with, you then also have twice as many chances to do it wrong, and more than twice as many corrections, which may themselves lead to more mistakes, which leads to way more than twice as many strokes.

if minimizing the time and effort requires a greater degree of control, that that makes it more difficult. once you get consistent, then the difficulty decreases or is eliminated.
 
I don't really have any experience, but I would imagine these things:

1. The longer it takes, the less steady the hand will hold, making it harder to keep a consistent angle.

2. Less wear resistance = faster grinding. The faster you can get a flat bevel, the better it'll turn out I would think. I guess this is pretty much just the converse of #1.
 
I feel plain carbon steel is the most easily sharpened. Other complex alloys are more difficult. The difference is I think how easily and cleanly burr can be removed.
 
Use diamond hones for sharpening...you won't notice much of a difference. For the simple carbon steels, just use the medium diamond hone instead of a coarse one.

Works great for me!

Dan
 
All I now is right now I'm having a helluva long time getting my right side of the VG10 to match the angle on the left - ground different from the factory.

I put a small level across the spine of the blade, and rubberbanded it on with the end of the handle. Lets me know if I've got the knife canted one way or the other.

Would be nice to have the diamond stones...but not for that kind of money. Sandpaper and a binder clip if it's not done tomorrow.
 
After some more time with the medium stones I got somewhere - WOW is all I've got to say. I'd been using a clamp system with stropping afterwards, and thought it was sharp. No comparison.

I honestly never thought I'd be able to whittle hair - I tried it for the heck of it, and with the basic Sharpmaker kit and stropping afterwards I'm whittling hair.

Amazing product.
 
The most difficult to sharpen steels that I have dealt with are all burr prone steels, like CRKT AUS-8 & AUS-6. My higher hardness, higher carbide steel knives are all very easy to sharpen. A big part of that is that I thin out the back bavel a lot on my knives, so there is an acute angle to work microbevels off of. It only takes a minute or two to take my CPM D2 Military from dead dull (I cut the edge off by cutting straight into the stone) to hair whittling sharp by doing a few passes per side on Spyderco ceramics. If I want to spend north of 5 minutes I can bring out the most sharpness my skills will allow by going up to .05 micron lapping film on glass. Since I never really have to fight the burr on that knife it is extremely easy to sharpen for me. A huge part of that is the narrow angle and use of a microbevel. Anyone with a Krein grind can probably concur on how much easier it is to sharpen a very thin knife, no matter what the steel.

Mike
 
I'll concur if it's M2 or ZDP-189 because those are the only Krein-ground steels I have right now.

Oh, and Takeda-ground, too, if you're a sinner and microbevel (and I do!).
 
gunmike1 said:
The most difficult to sharpen steels that I have dealt with are all burr prone steels, like CRKT AUS-8 & AUS-6. My higher hardness, higher carbide steel knives are all very easy to sharpen. A big part of that is that I thin out the back bavel a lot on my knives, so there is an acute angle to work microbevels off of. It only takes a minute or two to take my CPM D2 Military from dead dull (I cut the edge off by cutting straight into the stone) to hair whittling sharp by doing a few passes per side on Spyderco ceramics. If I want to spend north of 5 minutes I can bring out the most sharpness my skills will allow by going up to .05 micron lapping film on glass. Since I never really have to fight the burr on that knife it is extremely easy to sharpen for me. A huge part of that is the narrow angle and use of a microbevel. Anyone with a Krein grind can probably concur on how much easier it is to sharpen a very thin knife, no matter what the steel.

Mike
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Good to see you back Mike!

I agree. The "harder to sharpen" steels are actually much easier to sharpen when the geometry is right. And for me, dmt stones will bring ANY knife to it's knees in very short order. The ceramics are the icing on the cake!

But given all that, I'll still take well heat treated 52100 and O1. They are just a dream to sharpen, and I don't know why. But there you go.
 
sodak said:
Good to see you back Mike!

I agree. The "harder to sharpen" steels are actually much easier to sharpen when the geometry is right. And for me, dmt stones will bring ANY knife to it's knees in very short order. The ceramics are the icing on the cake!

But given all that, I'll still take well heat treated 52100 and O1. They are just a dream to sharpen, and I don't know why. But there you go.
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Thanks for the welcome back. Long time no talk. I'll have to shoot you an e mail.

52100 as done in my Spyderco Mule gets really sharp, easily tree topping at DMT Coarse for me. My Krein Ultimate Caper in CPM M4 gets really sharp as well. Nothing like good old tool steel, I guess.

And yes, DMT's bring out a nice edge real quick. I like to start out a lot of my bevels (most, actually) with the DMT coarse, and then progress to the ceramics on steels other than ZDP 189 or Super Blue, which don't much like the ceramic stones and need water stones for the finer grits. Most pocket knife friendly steels are very happy on the ceramics, though.

Mike
 
Vivi said:
Why are steels with high wear resistance properties given the label difficult to sharpen? I've never understood this.
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I think the problem is people who are not using a coarse-enough stone, or just simply have not had enough practice sharpening. After I got a DMT X-coarse and got enough freehand practice rebeveling, I found that ZDP-189 actually wasn't that hard to sharpen. Using a low grit like DMT XX-coarse works great and once you have a good primary bevel, adding a microbevel is easy, even on a wear-resistant steel.

I recently found out what a hard to sharpen steel really is: I was sharpening a paring knife of 440A. The burr just flops back and forth and is hard to remove because the steel is softer (I think).
 
nphelps4130 said:
I recently found out what a hard to sharpen steel really is: I was sharpening a paring knife of 440A. The burr just flops back and forth and is hard to remove because the steel is softer (I think).
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That is the issue.

Time I have and is rarely frustrating. Dealing with a Franken-burr is hard, annoying, and frustrating as I go through my reportiore of techniques.
 
The floppy burr can be difficult indeed. It seems to be the case when the steel at the edge is hopelessly fatigued. At that point, it's easier to just run the knife perpendicular to your stone, as if you're trying to slice it into two. The idea is to grind off the bad steel. It only takes a few light passes, you don't really need to saw into it. Once the bad steel is gone, and you're down to good steel, you can re-hone a good edge. Try to avoid forming a large burr again. I avoid making a burr at all, so that if they do form, they're exceedingly small and easy to grind off because they haven't been pushed back and forth.
 
Somewhere there is a major disconnect between our methods if you find it hard to sharpen AUS8. That has to be about the easiest steel in the world to sharpen and I never have an issue with a burr. So I wonder what you are doing that I am not doing or vice versa.

If I am reprofiling I expect to create a burr no matter what method I use to grind the blade. When you remove a lot of steel there is always some left over that is not fully removed. I knock that off with a little light honing at an elevated angle using edge-first strokes. Subsequently I do all of my real honing using light edge-first honing strokes. If I am going for an ultimate edge I finish by some stropping on a smooth stiff material coated with sub micron diamond grit. Maybe my technique just fundamentally takes care of burring problems, but I never note any special issue with AUS8. The resulting edge is always extremely fine compared to most other alloys.

One alloy that really does give me extreme problems with burrs is with badly hardened L6. That takes extreme deburring measures to get a crisp edge.
 
You usually don't buy nice and thinly profiled blades from the factory. Starting from an obtuse and possibly dull factory edge you have to remove so much material on your first sharpening that you are virtually reprofiling the blade. When that is the case S30V, D2, ZDP189, S60V, CPMD2 are hard to "sharpen". If you consider reprofiling as a fundamental part of your sharpening process then S30V, D2, ZDP189, S60V, CPMD2 are hard to "sharpen". If you do not use diamond abrasives it is hard to cut the carbides in S30V, D2, ZDP189, S60V, CPMD2 so they are hard to "sharpen". All things are possible with diamond abrasives.
 
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