Question regarding single bevel and handed-ness

[Colin]

I’ve been trying to figure this out, but cannot found a clear answer.

I finally have a fair set of stones (50-1600 and 5,3.5 strops, along with a better angle cube) and have been playing with grinds and bevel and I had the idea to do a single bevel on one of my opinel carbon knives. It’s closer to a 90/10 with a 14 degree main edge and  19 degree back that was only barely used to knock down the burr, so it’s nearly invisible. It’s very sharp and feels nice to use, but I am wondering if I put the correct side of bevel for a right handed person. When holding the knife in my right hand facing forward, the main bevel is facing towards my left hand. That feels correct for me, but is it?

 

 

[Mark76]

Just try it. Japanese single bevel knives have a lot of “steering”. With those knives you’ll notice it clearly, sice they have very wide bevels (> 1 cm).. I’ve never put a single bevel on a small knife or a folder. I’m curious what your experiences are.

Molecule Polishing: my blog about sharpening with the Wicked Edge

[tcmeyer]

I’ve played with this a little recently.  Generally, moving the apex to the left or the right can make a big difference in slicing materials which are fairly solid, like salami or radishes.  If you have a wide bevel on the side toward the stock (opposite your hand) the blade will tend to slide off toward the side of your knife hand.  In an experiment, I thinned a blade to about 0.025″ (about 0.6mm) with the edge biased toward the left side when viewed looking down on the spine of the knife in your right hand.  When cutting radishes to less than 2mm thickness, the blade would cut beautifully.  When cutting the same with my left hand, the blade would fall off to the left side, making thin slices almost impossible.

This is most obvious when testing a chisel-edge.  The bevel side will slide off of the face of the stock being cut, making thin slices very difficult.

When sharpening chef’s knives for friends, I ask if they use one hand exclusively to hold the knife in, then sharpen the edge accordingly.  Everybody seems very happy with the results.

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Gib Curry, Alan, wickededge, CliffCurry, Mark76

[wickededge]

Tom, that’s a great explanation and I really appreciate your real world testing.

Maybe for purposes of being clear about which side of the knife we’re referring to, we can say that the knife is held by the handle, spine up and tip directly away from the user. So a right hand dominant person would hold an asymmetrically ground blade in their right hand and the small bevel would be on the left of the blade, toward the center of their body and the the large bevel would be on the right, facing away from the center of their body. We would assume that they would hold their work piece in their left hand and remove the material towards their right. Does that seem like a reasonable approach?

-Clay

[tcmeyer]

Clay:  Your description matches what I’m trying to convey exactly, but I think a set of simple diagrams would be more helpful for others to understand.

As part of my experiment, I bought a Chicago Cutlery cleaver (about $15) and ground one side down to create a chisel edge.  One side has no bevel and the other side is all bevel.  Thin slicing on the no-bevel side is wonderful.  Thin slicing – even medium slicing – on the bevel side is impossible.  The blade guides itself right off to the side with least resistance.

By the way, if you give this a try (I used a $10 chef’s knife), you’ll find that almost everything you cut thin tastes better.  I’m guessing that you are exposing a higher percentage of the content to your taste buds.   Did you ever notice that a Rueben sandwich with thin-sliced corned beef tastes better than one with thick-sliced corned beef?

 

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Alan

[wickededge]

As a matter of fact, I have noticed that! And carpaccio too. I’ll see what I can do about diagrams.

-Clay

[Mark76]

Your descriptions make it clearer, gentlemen. I’ve used a yanagiba (single-beveled Japanese slicer with a wide bevel – wide means over 10 mm here) a long time ago and indeed recall that with the bevel on the one side it worked and on the other side it didn’t.  I’ve also got a number of Japanese chef knives with a-symmetrical bevels – say 70/30 or even 80/20. Those are normal bevels, not wide bevels. To be honest I don’t experience any steering with those knives. So I guess it mainly depends on the width of the bevel (next to how a-symmetrical a bevel is).

I wonder, Tom, I imagine what they call steering (rotation of the knife) when cutting radishes. Did you? When holding the knife in your left hand while cutting radishes, the blade would fall off to the left, as you describe it. Did you try to make the cuts on the left side or the right side of the radishes?

And when holding the knife in your right hand, you are able to make straight cuts, Tom. Again, did you then try to make the cuts on the left side or the right side of the radishes? It would be logical to assume you’d expect rotation the other way around, i.e. the knife was trying to force itself deeper into the food. Did you? And did you have to use force to prevent it from doing that? (If not, was that because radishes are very hard? How does it work with, say, a soft salami.)

Some diagrams would be great, Clay, to illustrate what happens exactly.

Molecule Polishing: my blog about sharpening with the Wicked Edge

[tcmeyer]

Mark:

Yes I tried cutting  both ways.  I’m left-handed, so I’ve sharpened my knife with the wide bevel on the left.  I hold the radish with my right hand, so I’m always cutting the left end of the radish.  If I change hands, the wide bevel will tend to push the blade off to the right, making thin cuts more difficult, and if the bevel is wide enough, making it almost impossible.

I can’t hold the knife in one hand and then cut from the opposite end of the radish.  I’d have to cross my arms.  I can, however, switch hands and that’s when I see the difference.

Certainly, if the thickness of the blade is thin enough, or if the bevel angle is acute enough, there is less of such a tendency.  In any case, the edge will try to take the path of least resistance and if the bevels are offset to one side the path will be skewed on thicker cuts.

An exaggerated version of this is with the cleaver I reground to a chisel grind.  It cuts wonderfully thin on the flat side, but not at all on the bevel side.  It just slides off the radish, following the bevel angle.

The main thing to take from this experience is that offsetting the bevel can be to your advantage in terms of making very thin slices.  It has the same effect as making the edge thinner.

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Alan

[Colin]

That clears it up. I was fairly confident that I had the right grind, but that confirms it.  For handed-ness grinds, we would want to cut the bevel down on the inside edge of the blade (holding knife point directly away, spine side up, with the bevel facing our other hand) My opinel no 12 carbon is relatively enormous as far as pocket knives go (4.75 inch blade, nearly a foot long including the handle) so I was most curious about a chisel grind on that knife for ease of sharpening as it’s more of a field knife used for cutting seatbelts and hacking through plastics in mangled cars as well as a camp knife. I keep a 20 degree double bevel spyderco kiwi for cutting oranges and other food stuff while on shift.  I can say with confidence that I think I’m going to try to knock down that tiny secondary bevel I put on it and only use 1200+ stones for taking off that burr. Changing the bevel like that took off a substantial amount of metal, so I’d only suggest it be done when you’re absolutely confident you want a chisel grind. Opinels are kind of a “do what you want, it’s your knife, we just stuck a good piece of steel in a chunk of wood” and are dirt cheap, so overall I’m very happy with my change, but my other four are staying double bevel. I have five opinel folders in my house, I really should cut down!

[Mark76]

Tom, if you – being left-handed – hold the knife in your right handle and the food in your left, the wide bevel will push off the blade towards the right.

What I wonder is how you are able to make straight cuts then with your left hand and the food in your right. I would imagine that in this case the knife would have a tendency to rotate the other way, i.e. cut itself deeper into the food. Does it? Do you have to use some force to prevent it from doing so? And if not, do you have any idea how come?

Molecule Polishing: my blog about sharpening with the Wicked Edge

[tcmeyer]

Mark: I wish I could show you a diagram, but alas, one needs to have an account on the internet.

Imagine a knife with a chisel edge cutting a radish.  The beveled side is quite thick, say 3mm.

The vertical side will cut nicely, provided that there is no resistance from the beveled side, which is the case when the beveled side is directed away from the radish.

When reversed, the bevel will feel resistance from the bulk of the radish and will tend to slide away from it.  Since there is little or no resistance on the vertical side, the knife will be pushed away from the radish.

The principle of this is simple mechanics.  Imagine a very large scale model of the knife edge trying to push through a firm substrate.  The bevel will slide off to one side, just as a cam follower moves with the displacement of the cam.

If you have a knife with an offset bevel on a rather thin edge, this action will be much less pronounced and perhaps undetectable unless you attempt to cut very, very thin slices.  The knives I have worked with are abut 0.6mm or more thick at the shoulders of the bevels.

[Mark76]

Thanks, Tom, luckily Clay is a master at graphics (or is that your advertising agency, Clay? ). Nevertheless, slowly but surely it is entering my brain.

I understand why the knife slips off (i.e. steers the wrong way) when the bevel is at the wrong side. The chisel comparison makes sense. But what happens when you try to cut a compressible material, say a soft sausage, when holding the knife the right way? Does it dig itself deeper into the sausage (i.e. steer the other way) or doesn’t it?

I’m inclined to try it right away, but unfortunately I don’t have an appropriate knife right now of which I can screw up the edge, let alone a yanagiba.

I guess (my brain is still processing and it sounds like a philosophical question, but it isn’t) the essential question is: why does a chisel have a chisel grind and not a double bevel?

Molecule Polishing: my blog about sharpening with the Wicked Edge

[tcmeyer]

Maybe if I put it in the context of a wood chisel.  The side of the chisel without a bevel is used to cut straight down into the wood, as when forming a mortise.  If the chisel had bevels on both sides, it would allow the edge to follow changes in density in the wood grain, thereby hindering a perfectly straight cut.  A straight (non-beveled) face will track perfectly straight (vertical).  The vertical face of the wood you’ve cut will prevent the edge from drifting to that side, while the wood on the beveled side will tend to drive it toward the vertical face.  (The side with the bevel actually helps to keep the chisel face cutting straight by driving it to that side.)  This principle is key to making cross-grain cuts in wood.

You need to find a thick, cheap knife and move the bevel completely off to one side.  Then go out and find a willing radish.

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Mark76

[Mark76]

Tom, I’ve still got a question. Your chisel analogy made a lot of sense. Basically my question would be: why does a chisel have a chisel grind (single grind) and not a double grind? Is that the precision you can get by putting the edge exactly in the place where you want the cut to be in the case of cuts perpendicular to the wood? (But you could do that too with a double-grinded chisel? Or would that be more difficult?)

The question that lies behind that is of course why somebody would get a knife with a chisel grind. On kitchen knife forums the opinio communis is that for 95% of the tasks a double-beveled knife works much better, because it has no steering. And of the remaining 5%, 3% is for those cases where you want to make very long and thin slices of particular vegetables. (Analogous to using a chisel to chip out parts of wood by keeping the chisel blade almost parallel to the wood.) But what about the remaining 2%? Does a knife with a chisel grind allow you to make more precise thin slices?

Molecule Polishing: my blog about sharpening with the Wicked Edge

[tcmeyer]

Mark:  Sorry for not seeing this earlier.  I believe all of your observations are correct.  Certainly, I have no personal knowledge about what professional chefs prefer, but the test I did with the cleaver (converted to a chisel grind) did indeed allow me to make very precise cuts on vegetables and sausages.  On pepperoni, for instance, it was very easy to cut perfect 1-2 mm thick slices.  Of course, a chisel grind only works when used in the correct hand.  Unlike a double-bevel knife, it has a very strong tendency to “steer” away from the bevel, especially when used to cut thin slices in the opposite hand.  I haven’t yet tried it for general use such as thicker slices or for raw meats.  My interest was solely for producing thin slices.  It should also be understood that my test is with a very, very thick blade, but the bevel width is quite normal.

With the wood chisel analogy, I was referring to the instance where the chisel is used to clean out deep mortises (pockets) perpendicular to the wood.  I had not even thought about making thin slices parallel to the length of a vegetable.  What particular veggies are you referring to?

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