VG 10 Edge Question

[Mr.Wizard]

@Ourorboros Dr. Kraichuk's report agrees that the X50/4116 edge holding is poor. It seems however that even with this steel a more acute edge angle may be advantageous. It has been known that a more acute edge has a longer wear life, but community wisdom has been that mainstream German steel does not have sufficient rolling resistance to make use of acute angles. The report provides evidence that this wisdom might be wrong. (I presume the edge rolls but still performs due to superior geometry?) I'll certainly be experimenting with lower angles on this class of knives.

 

[Obsessed with Edges]

@Ourorboros Dr. Kraichuk's report agrees that the X50/4116 edge holding is poor. It seems however that even with this steel a more acute edge angle may be advantageous. It has been known that a more acute edge has a longer wear life, but community wisdom has been that mainstream German steel does not have sufficient rolling resistance to make use of acute angles. The report provides evidence that this wisdom might be wrong. (I presume the edge rolls but still performs due to superior geometry?) I'll certainly be experimenting with lower angles on this class of knives.

This is exactly what I've noticed with such 'softer' stainless steels. Even in very inexpensive knives I've purchased for kitchen use, they always do better when the edge geometry is thinner than factory defaults, even down to 25-30° inclusive, which is the optimal 'sweet spot' for virtually all knives I use every day. So, I've recalibrated my strategy when I'm seeing seeing edge retention issues on new knives in such steels. If I'm noticing edge-retention issues on them when new, my first instinct is always 'go thinner'.

I look at it this way: the steel will deform and/or wear at the same rate anyway, due to it's built-in limitations on hardness and wear resistance. If the edge angle is wider and the geometry behind it thicker, almost all cutting success will be entirely dependent on the keenness of the apex itself. So when the apex degrades quickly away by rolling, denting or abrasion, cutting performance then suffers immediately, because the wide-angled, thick geometry behind the dulled apex just doesn't lend itself to good cutting at all. On the other hand, if the edge and steel behind it are thinner, the edge can still cut relatively well, even if the apex has rolled or worn somewhat. I notice this with every single blade I thin out, no matter the steel. There are limits as to how thin you can go, obviously; once thinned to something below 25° inclusive, some of these 'softer' steels will become a little too unstable at the edge for their own good. But otherwise, the 'conventional wisdom' that soft steels can only function well at wider edge angles (40° inclusive or more) doesn't really hold true, most of the time. Such wide, thick geometry becomes more a handicap than a help, even on it's best and sharpest day.

A side benefit of a thinner edge on soft steels like this is, they're that much easier to tune up with a minimum of metal removal, using such means as steeling to realign the edge, or by stropping to accomplish essentially the same thing, but maybe with some additional refinement (polish, etc). So the thinner edges are that much easier to maintain over the longer run.

 

[UncleBoots]

The only thing that I have that is above 19 degrees is my cleaver. I set it at 25 degrees.
I do my lawnmower blades at 30 degrees.
I do hunting knives at 19 degrees.
All my good kitchen knives are 15 degrees or less.
I do have some cheap knives that wont hold an edge that I do on 19 degrees also.

Do this, take the global paring knife and reprofile it at either 13 or 15 then see how you like that. Keep in mind if the steel is cheap that it might roll after some use, that's when you just touch it up a little.

I also have a Hapstone R-1, it was my 1st guided sharpener.

I have been thinking about your post a lot. I now think that I have a whole lot of knives whose angles are too high, and I'm thinking I've liked them a lot less than I should. I think I might be able to guess the reason. Your basic normal person, not a knife geek, judges a knife by two things: (1) Is it sharp? Not by our standards, but how normal people mean that. (2) How long does it stay sharp? This, I am guessing, is the part that leads to knife makers going for really large angles.

I've been sharpening for decades, but I've never reprofiled a knife. Now I'm excited to do that. My weekend plan is an orgy of reprofiling on the Hapstone.

To prepare, I decided to reprofile a little modest Gerber folder I've never had more than a little affection for, and to do it by hand. Worse, I decided to do it only with my Spyderco ceramic Med-Fine-ExtraFine stone set (and some strops). The Medium actually seems like quite a fine grit; it's not a shaping stone by any stretch. I like to sharpen, I like it a lot, but I won't be doing that again. I'd guess that it took 4,000 strokes on the medium stone, though a big part of that was getting the point to the same bevel as the rest, because why not. The reason I subjected myself to that ordeal was to get the hand-skill down, and also to play with some techniques I read about in John Juranitch's book. The result was not pretty, at least to anyone but me, but I am much much happier with this knife now.

Can't wait to make the same transformation happen to several designated kitchen knives this weekend.

 

[UncleBoots]

OK, yeah. I reprofiled that Japanese VG-10 utility knife, the one that came at ~37 degrees, to 15 degrees, and it's suddenly awesome. I was making paper-thin slices of a cauliflower stem with little effort. I was vaguely dissatisfied with that knife before, now I love it.

I reprofiled the Global paring knife -- I don't know to what angle. My Hapstone R-1 definitely can't go that low for a knife with such short distance between spine and blade, so I did it by hand. I haven't owner a protractor since high school, so no measurements here, but 13 degrees would be a reasonable guess. It seems seriously sharp in a way it never has before. Global's steel is designed to be friendly to sharpen, so maybe 57 hardness? Not hard steel, not crap steel, but it took a nice edge here at the shallow angle.

I even reprofiled my wife's goes-in-the-dishwasher 35 degree crap steel knife to 19 degrees, and it's as sharp as it has been in its miserable life. I'm actually looking forward to seeing how it dulls, and what it takes to get it back to where it is now.

Thanks for the great advice.

 

[K80Shooter]

That's the same problem I had with the Hapstone R-1, I just couldn't get the angles that I wanted/need for filet knives and such. I asked about if there were plans for longer clamps to be able to attain the degrees needed for narrow knives and that's when I was told about the table attachment that was in the works to be released shortly. That's not what I wanted so I got me a TSPROF KO3 at close out price.

If you find that the edges roll too easily on the Global paring knife you might need to up the angle a couple of degrees at a time until you find what works best for it. Not knowing the steel type it will be trial and error till you find it's sweet spot.