Edge taking, as opposed to edge retention

B

BruceMack

Joined
May 20, 2015
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106
I am new to knives but have sharpened woodworking plane irons and chisels for years. I have an Opinel #7 in carbon steel and a newly acquired Kershaw Leek with Sandvik 14C28N. The Opinel sharpens easily freehand but wanting to get the best out of the knives, I bought a Spyderco Sharpmaker which I like a lot. The Opinel became really sharp, but the Leek has resisted my efforts to achieve comparable sharpness. It does slice paper easily but not with the absolute ease of the Opinel. The blades are both thin so I don't think blade geometry is an issue. I have prepped the Leek with coarse, medium and fine diamond plates, raising a burr (wire edge) with each. I followed with Spyderco coarse and fine stones (all acquired in my years as a woodworker hobbyist) and then used the Sharpmaker to make a 15° micro bevel on each side. Maybe I'm daft but the edge, while very sharp to touch, does not seem to slice as easily as the Opinel.
Do some steels simply take a better edge (as Japanese laminated blades in woodworking) or am I failing to get the best out of the Leek? Thanks.
 
In this case, Geometry.

Opinels are thin AF.

Check yourself with a micrometer how thick it is Behind the edge.

If you want you leek to cut like an opinel then you need a regrind, not a sharpening.

Yes some steels take a better edge but it's not always the steel but a mix of heat treatment and Geometry.
 
Simple alloys will take a sharper edge. The higher the carbide volume, the harder it is to put a true razor edge on it (the PM technology helps somewhat because the grain size is smaller). Plain carbon steel, like what your Opinel has, are good for this. Sandvik steels like 14C28N, are usually very fine grained and will take a pretty sharp edge, too.

Are your Opinel and Leek brought to the same level of sharpness? Do they both do the same thing to arm hairs? Once you start cutting other materials, like paper, a little difference in edge geometry can make a big difference. Opinels are well known for very thin edge bevels and pretty thin blades, too, and cut much better than other knives of the same edge sharpness. I would be very surprised if your Leek has an edge geometry anything like the Opinel.
 
Whats the sharpening angle for the leek? I would sharpen it around 17 degrees per side and if you want to micro bevel do it at 20-22 degrees per side.
 
Do you strop your blades after sharpening? In order to get the wire edge off of some steels, using a strop completes the sharpening process.
For me, stripping fine grained steels like 14C28N, VG10 and AEB-L really gets them scary sharp
 
I agree with Ajack60 that some steels such as 12C27N, 14C28N, VG10, etc take a much keener edge (and much faster) than I can achieve with steels such as S30V, D2, etc. I honestly prefer to work with a finer grained steels to see how sharp I can get them. Sometimes I will sharper through my progression to .25 micron (scary sharp and amazing polish)
 
I used to sharpen: 320, 600 diamond, then 1000 and 5000 water stones on all my knives.
Now I go five passes on each side on a 600 diamond if just a bit dull until sharp (cleanly cuts copy paper, won't slip off my thumbnail). Consciously making some passes a little lower to "knock the shoulder off" and "back the edge up" and making others a little higher angle to give a bit of micro bevel and true the apex of the edge up.
I've only seen benefit of 5000+ grit when slicing meat and 1000 grit when slicing veggies.
Up to 600 grit for utility, and maybe a few passes on a ceramic stick if the edge is real burry. I only ever use 320 or lower for edge repair. I let my natural human flaws convex the edge over time:p
 
I have trouble with Spyderco's VG-10 and Real Steel's Sandvik 14C28N. I use the flashlight test and I can never get a fully invisible edge with these steels. Always some light reflections here and there. They will get shaving sharp but not newspaper push-cutting sharp. No issues with Cold Steel's CTS-XHP, Benchmade's 154CM, Spyderco's 8Cr13MoV, Kershaw and Leatherman's 420HC, Real Steel's D2, Ka-Bar's 1095 Cro-Van, Opinel's Sandvik 12C27Mod and Ontario's AUS-8. In short, most of my knives.

I do have some troubles with Real Steel and Kershaw's 8Cr14MoV and the 420HC on my Gerber Strongarm, but those are due to soft steel. 420HC on my Gerber L.S.T. takes a shaving edge but will never push-cut newspaper no matter what I do. Holds that shaving edge quite well, though. Edge-taking is a phenomenon I will probably never really understand...
 
BruceMack said:
It does slice paper easily but not with the absolute ease of the Opinel. The blades are both thin so I don't think blade geometry is an issue. I have prepped the Leek with coarse, medium and fine diamond plates, raising a burr (wire edge) with each.
Click to expand...
You don't necessarily need to raise a burr. It's arguably even detrimental, since you'll just have to remove that and likely some weakened steel at the apex that it leaves behind.
Do some steels simply take a better edge (as Japanese laminated blades in woodworking) or am I failing to get the best out of the Leek? Thanks.
Click to expand...
Any material can be formed to have a razor's edge, if it can be shaped to that fine a degree. If there isn't sufficient strength, the edge will collapse rapidly. Any hardened steel with a properly formed edge should be able to do a paper cutting test without issue.

In that test geometry at the edge matters much more than the overall cross section, unless it's extreme. So like someone noted, you might want to thin out the blade behind the cutting edge if there is a large difference between the knives. If you can look at the edges under high magnification, you might be able to see what's going on outright.

Have you noticed a difference with other cutting tasks? Does one dull much more rapidly in use than the other? Do you use very light pressure with the final sharpening steps? (especially with a sharpmaker) Use the same faces on the sharpmaker rods consistently, without switching their places, since the rods may not be dead straight.
 
Thanks for the replies and good tips. I haven't yet calipered them, but the spine of the Leek is visually slightly thicker below the pivot while the Leek is thinner for the last half inch before the tip. The Opinel has no shoulder behind the edge, while the Leek does have a small shoulder followed by a distinct hollow grind. I do strop and have noticed the improvement in edge sharpness. I haven't put the knives to use since sharpening but will try both when I next cut cardboard for recycling.
 
BruceMack said:
Thanks for the replies and good tips. I haven't yet calipered them, but the spine of the Leek is visually slightly thicker below the pivot while the Leek is thinner for the last half inch before the tip. The Opinel has no shoulder behind the edge, while the Leek does have a small shoulder followed by a distinct hollow grind. I do strop and have noticed the improvement in edge sharpness. I haven't put the knives to use since sharpening but will try both when I next cut cardboard for recycling.
Click to expand...

Makes a HUGE difference.

Less resistance when cutting, less material to remove when sharpening. Easier to sharpen since it's more forgiving to angle inconsistency.

I DON'T EVEN like Opinels.

Hell, the steel is Wayyy better on the leek.

But just goes to show,

Geometry is what cuts.

The hollow grind doesn't automatically mean it's thin. People get way too fixated on the grind itself without looking at the acutal size and thicknesses of the different areas.
There's a formula to it and it all depends on what the knife is used for.
Ya can't laser grind a knife used as a cold chisel and ya can't use a sledge hammer to make sushi.
 
IMO Kershaw doesn't do the best HT with their steels. Their 13C26, which is AEB L, is poorly done. I have some AEB L knives with a good HT and they perform fantastically! I suspect that may be the same situation with your 14C28N steel you have from them. I have some 14C28N blades that I actually like more than AEB L. Real Steel is a company that does a decent HT on 14C28N, for a budget knife company. I love my point man fixed blade from them, and their Sea Eagle folder. Both knives perform very well!
Steels that sharpen well. AEB L, CPM 154, 14C28N, Nitro V, most carbon steels, XHP, 420HC, Z-Finit/ LC 200N, A8MOD. Steels that get sharp but are more wear resistant. IMO easy to sharpen, but NOT to reprofile. More speedy usually. M4, Elmax, M390, CPM 3V, Cru-Wear/PD#1, Spectrumwear.
 
BruceMack said:
Do some steels simply take a better edge (as Japanese laminated blades in woodworking) or am I failing to get the best out of the Leek? Thanks.
Click to expand...

Heyyyyyyy ! A fellow Woodworker . . . Greetings !
To answer your question . . .
. . . . well before I do I want to say I am not saying you shouldn’t use the Sharpmaker. Enjoy it; it’s good stuff.

. . . there . . . now onward !
I find that if I use a great sharpening jig that anything I put in that sucker turns out equally super / still blows me away SHARP. How sharp ? Well the locals here are just sick of hearing me say it but :
Picture a single hair on your arm firmly rooted and happy.
Picture taking the freshly sharpened edge off the last stone ( NO STROPS ) and carving little curls off the same hair repeatedly. I use a jeweler's visor to view this.
I realize there are sharper things on the planet but . . . heck . . . that’s good enough for this bozo.

What does that edge look like ? See photo below. That’s off a Varitas jig and Shapton Pro water stones (an A2 Steel alloy) but with diamond plates the same thing happens on the high vanadium alloys such as S110V, S90V etc. I find it easier to photograph the polish on the flat planes of the plane blade than my knives and the polished area on the knives is way, way smaller; often just a half millimeter or so right at the edge still . . . same goes for the knives (I like a precision bevel and polished to 8,000 Shapton Pro or 4,000 Shapton Glass or 8,000 diamond stone (on the Edge Pro).

For knives I use an Edge Pro Apex.

As far as what comes up nice after use and a free hand touch up and what I use for the freehand touch up . . .

the most surprising experience I have had so far (and the blade was already sharpened on the Edge Pro and then used) . . . the edge was near shave sharp sorta and I wanted to get it back to at least shave sharp.

The blade was Spyderco M4 alloy and the stone I used to touch it up free hand (no holder) was the Spyderco Ultra Fine triangle rod for the Sharpmaker. That blade became tree topping sharp; I noticed it as I started to try to shave and it was cutting the tops of the hair before I could get it down on my skin.

In short : Me Likey !

Still though anything I were to put on the Edge Pro for a few passes would have come up about the same in about the same amount of time. I just lucked out that the M4 liked the ceramic sharpening rod and that the edge wasn't too far gone to respond.

And lastly for steel that I just like with out too much logical thought put into it . . . that just feels great to me in use and sharpening, that would be Hitachi White Paper steel. Probably what is in some of your laminated Japanese chisels. Those are superior aren't they . . . mostly I dare say . . . due to the much better heat treat and temper compared to the western BS they pass off as woodworking tools these days.

WARNING : too many photos ahead >>>>

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Heck now I have to make another post to clarify :
The test of cutting curls off a hair ignores edge geometry. I can do it with 54° inclusive as well as 24° inclusive. It's an indication of edge sharpness and can test the edge at points all along the edge to verify consistency in the level of sharpness.

I will say though that if there is too much round over from stropping then the hair curl test can get to be less easy to do. I suppose that is geometry.

The paper cutting and my comment to Deadbox is also true though; once you get all that blade wedged into something firm (cardboard = firm . . . meat ≠ firm) then blade thickness, thickness behind the edge, and edge bevel angles (geometry ) is HUGE !
Like yeh :
IMG_3727_4.JPG
 
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Wowbagger said:
Heyyyyyyy ! A fellow Woodworker . . . Greetings !
To answer your question . . .
. . . . well before I do I want to say I am not saying you shouldn’t use the Sharpmaker. Enjoy it; it’s good stuff.

. . . there . . . now onward !
I find that if I use a great sharpening jig that anything I put in that sucker turns out equally super / still blows me away SHARP. How sharp ? Well the locals here are just sick of hearing me say it but :
Picture a single hair on your arm firmly rooted and happy.
Picture taking the freshly sharpened edge off the last stone ( NO STROPS ) and carving little curls off the same hair repeatedly. I use a jeweler's visor to view this.
I realize there are sharper things on the planet but . . . heck . . . that’s good enough for this bozo.

What does that edge look like ? See photo below. That’s off a Varitas jig and Shapton Pro water stones (an A2 Steel alloy) but with diamond plates the same thing happens on the high vanadium alloys such as S110V, S90V etc. I find it easier to photograph the polish on the flat planes of the plane blade than my knives and the polished area on the knives is way, way smaller; often just a half millimeter or so right at the edge still . . . same goes for the knives (I like a precision bevel and polished to 8,000 Shapton Pro or 4,000 Shapton Glass or 8,000 diamond stone (on the Edge Pro).

For knives I use an Edge Pro Apex.

As far as what comes up nice after use and a free hand touch up and what I use for the freehand touch up . . .

the most surprising experience I have had so far (and the blade was already sharpened on the Edge Pro and then used) . . . the edge was near shave sharp sorta and I wanted to get it back to at least shave sharp.

The blade was Spyderco M4 alloy and the stone I used to touch it up free hand (no holder) was the Spyderco Ultra Fine triangle rod for the Sharpmaker. That blade became tree topping sharp; I noticed it as I started to try to shave and it was cutting the tops of the hair before I could get it down on my skin.

In short : Me Likey !

Still though anything I were to put on the Edge Pro for a few passes would have come up about the same in about the same amount of time. I just lucked out that the M4 liked the ceramic sharpening rod and that the edge wasn't too far gone to respond.

And lastly for steel that I just like with out too much logical thought put into it . . . that just feels great to me in use and sharpening, that would be Hitachi White Paper steel. Probably what is in some of your laminated Japanese chisels. Those are superior aren't they . . . mostly I dare say . . . due to the much better heat treat and temper compared to the western BS they pass off as woodworking tools these days.

WARNING : too many photos ahead >>>>

View attachment 843781
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View attachment 843789


View attachment 843802
View attachment 843803
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Click to expand...
Wow, that's great work there.
I wouldn't even know what to do with a knife that sharp.
 
Wowbagger said:
The paper cutting and my comment to Deadbox is also true though; once you get all that blade wedged into something firm (cardboard = firm . . . meat ≠ firm) then blade thickness, thickness behind the edge, and edge bevel angles (geometry ) is HUGE !
Like yeh :
View attachment 843850
Click to expand...

Great pic to illustrate you post.

For me, I don't sharpen my blades to the point where the thin foil edge is easily damaged. I might be cutting plugs out of yellow pine, carving off a knot in a piece of trim, or cutting insulation for a wall. None of those tasks appreciate a mirrored edge like you might think. And if it is ultra thin on the edge to boot, it can easily be damaged with MY routine tasks. I stop sharpening at 1200gr for my work knives, and at go a bit higher for my pocket knives.

Over the years I have not only learned that geometry of the blade is about the most important thing to consider when you want a real slicer. But I also learned how fragile some edges can be. Top that off with the steel of choice, and you have some options to consider. Personally, I have found that some steels seem to perform better than others with a toothy edge, and likewise some better with a near polished edge.

With that in mind, all my knives are sharpened to the edge bevel and grit that makes them perform the best for me. I appreciate the skill and the investment in equipment that some folks have put into their sharpening efforts, but I don't need to read the newspaper (literally) from the cutting edge of my knife.
Pretty, no doubt but not practical for me.

Robert
 
Hickory n steel said:
Wow, that's great work there.
I wouldn't even know what to do with a knife that sharp.
Click to expand...

Ha,ha,ha, "pay no attention to the man behind the curtain".
No talent or effort on my part. All I did in both cases ( wood tool jig and knife jig ) was follow the instructions and then mindlessly go through the motions.
That's what I love about precision sharpening guides; takes all the fun out of it.
It's fun to have fun . . . to . . .but some times one just likes to geeter done.

Hah and as most every one here will tell you that hair curl sharpness lasts about one good pass down the plank of wood or cardboard box slice . . .still . . . it is, as I said, a good way to tell that you have done all you can and at every point along the usable portion of the edge.

OK . . .it's dumb and fun at the same time.
I like dumb if it's fun.
 
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