Chisel Edge Blades

[Knife Fumbler]

Originally posted by dragon2
Does anyone have a fully ground chisel blade (no secondary edge bevel) that they use frequently? If so, how does it work. I read that a chisel ground blade made in that manner doesnt really have a tendency to curve to one side during cutting. I havent tried one myself.

Hey dragon,
A fully ground chisel blade?
Wouldn't a fully ground chisel blade be the same as a full flat ground blade with a crooked spine?
Hehe...I think we talked about this one night on the hall and I admit, you're right, a fully ground chisel blade would cut straight because the differences in the area of the "flat" side and that of the "ground" side are minimal and would not produce a large difference in friction (which is what causes the tendency to track off sides).

 

[hwc]

High end traditional Japanese knives are all chisel ground. Typically they have a thin layer of Hitachi White or Blue high-carbon steel hardedend to Rockwell 61 or 62 for the cutting edge. This is forged to a thick layer of soft steel (or salvaged wrought iron in the super expensive stuff) to provide the bending strength the hard steel lacks.

The "flat" side of the knife is actually a little concave. Thus, when you hone the back of the knife, you are only honing a small strip along the circumference of the blade.

The front of the knife has a single broad bevel (often an inch wide) that extends all the way to the cutting edge. Depending on the style of knife, this bevel can be as little as 8 or 9 degrees. (Think about how sharp a total included angle of 8 or 9 degrees can be compared to the total angle of 36 to 40 degrees on a typical German kitchen knife).

The knives I bought came with a microscopically thin "micro-bevel" at a steeper angle to give the edge some strength. This could only be seen under magnification or as a white reflective line under the right lighting.

The chisel grind on a Japanese knife is almost always on the right side of the blade for right handed use. Left handed knives are available as custom orders, but the standard up-charge is 50%.

These knives have some practical limitations: the edges are brittle and chip easily. They rust if you look at them wrong and they will discolor in the time it takes to slice an onion. But, they are in a completely different universe of sharpness compared to standard Western style knives.

The chisel ground edge takes a little getting used to because it behaves differently than a double-edged blade. The thing you have to keep in mind is that the effective "cutting edge" is the flat side of the knife. Whatever direction that plane is aiming is the plane the knife will cut on. What I found is that with Western knives, I subconsiously aimed the cut inwards a little bit (when thin slicing a carrot, for example) in order to keep the knife from cutting out the end of the piece. Once I figured out that I didn't need to do this with the Japanese knives, they work great. The accuracy and controlability is remarkable. You can cut paper thin slices and the knife stays right on plane and never slides out the end of the piece. You get incredibly consistent thickness on the slices.

One other thing you have to watch for. The cutting edge is RIGHT at your fingers - not back from the blade by the thickness of the bevel as on a double-edged knife. You better be darn sure that your fingers and fingernails are curled back out of the way. These knives are so sharp, they will easily slice through the nail (and your fingertip).

For the right cutting chores (delicate precision cutting with zero effort), I would take one of these chisel-ground Japanese blades over a standard Western knife any day.

 

[hwc]

Originally posted by Knife Fumbler
From my experience, when you're talking about cutting food,
the blade on a chisel grind will not track either way because you're usually slicing and the material is soft.
In hard materials with push cuts, the chisel grinds do tend to track towards the flat side.
I don't know if this is true, it;s just my guess, but you would want a correctly ground chisel blade for delicate cutting (like fish) so you could see and more easily place the edge where you wanted it.
It's easier to place a cutting plane than it is to place a curved side...I don't know if you understand what i'm saying...kinda difficult to describe.

With one exception (the Deba style knife), you would never use a high-end Japanese chisel ground knife for a push cut on a hard material. The typical Usuba (veggie knife) and Yanagiba (sashimi slicer) are pure slicers. For one thing, the spine is too thick for a push cut in a hard material. More importantly, the cutting edge is too fragile for whacking into a pumpkin. You are talking about a 9 degree total included angle at the bevel and super hard brittle high-carbon steel. You'll chip 'em every time if you whack a hard rind or a cutting board. The edges are too brittle to do "rocking style" chopping like you'd do with a chef's knife. For any kind of slicing, even of relatively hard stuff like carrots, they are incredible. They track straight and true.

The exception is the Deba. These are made the same way and have the same chisel grind. But, they are massively thick and heavy with a spine that is more than 3/8 inch wide on a 7 inch knife. The bevel is more robust (20 degrees or so). These knives are intended for boning fish -- whacking the heads off, etc. -- and are often used as choppers like a cleaver. They are sort of a cross between a meat cleaver and an ultra-sharp chef's knife.

I just got one - a 7 incher that weights over half a pound. I've only used it for a few things so far, like carving up a rack of baby back ribs. It is totally unlike any knife I've ever used. The weight of the knife combined with a sharp cutting edge does all the work.

 

[hwc]

Originally posted by dragon2
Does anyone have a fully ground chisel blade (no secondary edge bevel) that they use frequently? If so, how does it work. I read that a chisel ground blade made in that manner doesnt really have a tendency to curve to one side during cutting.

Yes. The Japanese knives are effectively fully ground chisel blades. The single bevel starts right at the cutting edge and extends as much as an inch back from the edge (where it joins a thick flat spine). These knives track incredibly straight and accurate on the same plane as the flat back of the knife (which is really the cutting edge).

As a practical matter, I don't think these knives taper straight to the cutting edge. For one thing, they are traditionally sharpened on waterstones. You can't really hone a 1 inch wide bevel completely flat in the real world. So I think what typically happens is that you lift the blade just slightly to focus the honing at the cutting edge -actually more applying a twisting pressure on blade to get the cutting edge to bite the stone rather than physically lifting the blade. I suspect this forms a slightly convex bevel at the cutting edge. It's not something you can really see, but from my experience with these knives on a stone, it's the only way I can see to really sharpen the edge.

Also, as a practical matter, I think most people put a tiny microbevel on the knife by doing a few strokes on a 6000 grit stone with the knife lifted 5 to 10 degrees higher to finish the knife. I know the knives I bought had this microbevel (visible only under magnification) and most of the comprehensive sharpening instructions I've seen for these knives recommend that.

I know why. I sharpened one on an Edge Pro at 12 degrees (remember, it's chisel ground, so that's the total angle) and did not put the microbevel on the knife. It cut like butter with no pressure at all -- just a light grip, start the knife slicing forward, and it just fell to the cutting board. Problem was that at the end of the every slice, the darn thing embedded in the cutting board and I had to pull it to get it back up! I went back and put on a tiny microbevel at 22 degrees with five or six passes with 3000 grit polishing tape -- just a tiny reflective line under a strong light. It solved the embedding problem and didn't hurt the cutting performance at all.

 

[dragon2]

Hey Cliff,
Please look on my profile and send me your email address. I'm having trouble getting the (*&(*) email portion of your post to work, so I guess I'll have to do it the hard way.

 

[DJ _Wolf]

Originally posted by Bugs3x
Are Cold Steel folding tantos blessed with a chisel edge, or not? Have they always been one way or the other? Isn't it generally regarded that CS popularized both tantos and chisel grinds? Am I imagining that?

I have owned three cold steel folding tantos. the 3in. and 4in. blade voyagers, and the 5in.blade Gunsight.

The blades are ground on both sides in the traditional 'V' grind.

When CS refers to them as "chisel grind" I believe they are refering to the shape of the angle on the end of the blade.

They did an artical in one of their past catalogs, saying why they thought the one-sided grind was inferrior to the two-sided grind.

Hope this answers your question Bugs.

 

[dragon2]

Hey Cliff,
Nevermind. I looked on your web page and got the email. Now I just have to figure out why I couldnt email you from your post.

 

[RJ Martin]

Bud: An interesting, and, correct observation. Having ground more "pure" chisel grinds than probably anyone here, I can offer the following comments to your post:
1) For a right handed user, the grind should be on the Right hand side of the blade. This is based on the fact that most cutting is done away from the user, holding the item being cut in the left hand. For food preparation, a chisel grind done on the right hand side is ideal, because the flat side of the blade goes up against the fingertips of the left hand, and the slices of food being cut are pushed off to the right.
2) The tendency of a chisel grind to "wander" during cutting is increased as the stock thickness increases, and as the grind angle increases. Also, harder materials produce more twisting. More on this in a bit.
3) A "zero thickness" chisel grind is an extremely difficilt grind to execute, as the entire edge must come to "zero" at precisely the same point-otherwise, the edge will either be wavy or parts won't be fully sharpened.
4) The chisel grind with a secondary bevel requires virtually NO SKILL to execute-there are no symmetry issues, as only one side is ground, and, the edge thickness can vary all over the place, since the sharpening process produces a bevel which starts at the flat side and ends on the bevel side. You can easily check for thickness variation by looking at the top edge of the bevel-if the width of the sharpening bevel changes, of the top edge is wavy, then the grind isn't even.
5) If you have a wide blade that is not too thick, with a full chisel grind, it is basically equivalent to a double grind blade and will cut the same, if the blade is twisted slightly during use so that the edge is "centered" under the knife.
6) Several years ago, I made a chisel ground chef's knife for CHEFGET, a Forum member. Within a week, he was cutting straight and true through all the food he serves at his excellent restaurant. The hand/eye/brain coordination occurs almost automatically, assuming you're paying attention to cutting straight.

So, personal opinions aside (which I respect), the "zero thickness" chisel grind offers the opportunity for EXTREME sharpness, if executed properly. It also offers great cutting performance in softer materials (clothing, flesh, vegetables), and great strength.
The main drawback is aesthetics-some people just don't like them, or can't get used to them, which is fine. You can always get a double flat grind with a "zero thickness" edge, and it will cut just the same.

Hope this helps,

 

[rdangerer]

Originally posted by Architect
For general utility tho, I have found them very annoying. Got rid of both my chisel ground tanto blades.

That's pretty much where I ended up also ... as most of what I own is for utility of some sort, and defense is from carrying a good solid folder and something that launches fast lead pills, where I can.

 

[rdangerer]

Originally posted by Cliff Stamp
You can get full dual flat ground knives as well, Ed Schott makes them for example, puukos etc., the absence of a secondary edge bevel is not restricted to chisel ground knives.

Full convex blades fall into this category, and on a slack belt or via other methods, can be very sharp also (Moran, ABS type)

...The main advantage of a chisel grind ... because it is flat on one side you can make very thin slices with it because there is little deformation of the material being cut because the wedging action only takes place on the side of which the material is falling away as it is being cut. This is why it is found on chisels as otherwise you would have to raise the chisel at an angle above the edge bevel or it would just skate across the surface of the wood.

This makes a lot of sense. It explains why a chef's knife w/ chisel grind would be nice to have in the kitchen arsenal, if it were ground on the correct side for your dominant hand, and 90%+ of the world is right-handed. That is why grinding chisel on the left side of the blade, ala Emerson, is wrong-headed. Yeah Yeah...it's a defense weapon. Even soldiers and commando-types use their knives 99.x% as tools, not often as weapons.

There is also the issue of a lower drag profile vs a dual flat ground blade, but I think that while this is true, it would be a very small effect and that even minor improvements to the dual flat ground blade would mask that effect completly.-Cliff

Yup. Such a minor effect that, for me anyway, it is 99% moot & obviated by the hassle-in-use in having the grind on the wrong side for righthanders.

(By the way, when RJ is moved to "talk", I find myself copying and pasting into a Word file for storage.)

 

[rdangerer]

edited to include zero content.

 

[Gary W. Graley]

ONE of my favourite edge grinds, as my email name will attest.

Sharp? No question as to the sharpness...

Strength? Depending on how thick behind the grind
determines lasting edge...

Ease of Sharpening? Not always, but I've found the
chiseledge to take an exceptional edge, cutting
standing hair tests will show this edge off pretty easy.

Wavy or uneven cutting? As RJ Martin stated it's a
matter of control, lack of control will make it too
easy to start wandering when cutting and thicker
stock even more so.

Chisel Edges:
Serrated knives are a bunch of small
curved chiseledge faces...

Sicssors, always chiseledge...

Razors, as in the kind you shave with, not straight razors...

Paper cutters, both rotary and arm rocking type are
chiseledge, for precise cuts...

Chisels...well...of course...

I have several knives with a chiseledge and
I find that when you attempt to cut into hard
plastic the chiseledge will grab faster
and not slip when cutting as opposed to dual ground knives.

My next favourite blade edge has to be the convex grind,
almost as sharp and almost cuts with equal ease as the
chiseledges do.

One test I show people at work is to take a thick
paperback book and just press the chiseledge knife
down against it....slices through so easy and cleanly!
It is amazing! I was cutting some leather last night
and as usual I had several knives on the table, one my
Jimmy Fikes chiseledge and sliced down through 6 pieces
of leather effortlessly. I took my David Boye Basic #3
and did the same and there was a little more resistance,
not a lot more but a difference non the less.

I made a chiseledged Tanto of A2 steel, 3/16" stock removal,
making it zero edge bevel and actually took that to cutting
several limbs off of some offending trees that were in my
path to the mailbox, sweet! and it didn't hurt the edge at
all...Chefget now has that knife...Blade is 11 1/2" long
with cord wrap over red sting ray, thanks to RJ Martin as
I had to redo the epoxy, went overboard and RJ was kind
enough to let me have a small section of sting ray...

Here is a pic of that knife, been thinking about making a
short sword from the same stock but haven't gotten the urge to grind lately...

 

[qwertyname]

Actually, scissors and paper cutters work on a shearing principle and don't "cut" at all. Some paper cutters just have 90 degree angle on both sides.

One thing to note is that if you are cutting something that doesn't have give on the side being cut (for example going through a branch as compared to slicing a piece of paper) can actually be more difficult because only one side of the cutting media is being compressed to form the wedge. Even if doing as RJ suggested and centering the edge, you would end up with a slightly angled cut and exactly the same effect.

 

[Gary W. Graley]

Originally posted by qwertyname
Actually, scissors and paper cutters work on a shearing principle and don't "cut" at all. Some paper cutters just have 90 degree angle on both sides....

Very true Qwerty, just wanted to bring up the point that not all things that cut or shear need to be ground on both sides. Some of the scissors and paper cutters I've seen have pretty sharp edges all by their lonesome, but are agreeably more useful against the designed opposite edge or anvil.

G2

 

[Jeff Clark]

For utility and combat uses I think it is significant to know that a chisel edge is WEAKER than a symmetrical grind. I did some tests involving chopping beef rib bones. A chisel edge folds over to the flat side where it has less support. It does this significantly faster than a symmetrical edge. Once it starts to roll over it is more exposed to folding stresses and rolls more. If you want a strong edge go with a symmetrical grind.

 

[Knife Fumbler]

Originally posted by Jeff Clark
For utility and combat uses I think it is significant to know that a chisel edge is WEAKER than a symmetrical grind. I did some tests involving chopping beef rib bones. A chisel edge folds over to the flat side where it has less support. It does this significantly faster than a symmetrical edge. Once it starts to roll over it is more exposed to folding stresses and rolls more. If you want a strong edge go with a symmetrical grind.

I've had experience with the edge rolling onto the flat side on a chisel grind too.
I can't say it's weaker, there are too many factors that go into the properties of an edge.

 

[Scott Dog]

I don't like chisel grinds either and I'm left handed.

 

[Cliff Stamp]

Jeff :

a chisel edge is WEAKER than a symmetrical grind

Note a full chisel grind and a full dual flat grind have the exact same edge profile. The only difference is the orientation of the blade. Draw a chisel ground blade profile. Now rotate the paper until the edge is inline with the center of the two sides. This is the same edge profile as a fully flat ground blade.

The difference in cutting ability (skew) and durabilty is due to the orientation of the edge in relation to how the force is being applied on the handle. You can rotate a fully flat ground blade and can get it to behave as a fully chisel ground blade and vice versa as R.J. said. The only thing is now the handle is not well suited to the cutting.

In regards to cutting ability (in general), and issues like strength this is far more dependent on the extent of the grinds rather than an issue of chisel vs dual full flat. People who use chisel grinds that are obtuse and shallow tend to group chisel knives as sharpened prybars. People who use knives like R.J.'s tend to group them as very high performance cutters. But again this is simply because of the extend of the grind.

You can get full dual flat ground blades that are weaker than chisel grinds and cut better and those that are stronger and cut worse, depending on how far up the grinds are on each blades as well as factors like the blade stock used, distal taper, as well as to a lesser extent, the steel used and heat treatment.

Hwc, makes a good point about the hollow grinding on Japanese blades, this makes sharpening much easier. From a cutting point of view it is an advantage as well.

In regards to the difference in area for a given edge angle, this is very small for most cutlery (like 1%). But more importantly, physical properties depend on the tangent of the angle not the angle itself. From that point of view both grinds (full chisel and ful dual flat) are identical in profile - they have the same edge thickness at a given height, same cross sectional area etc. .

-Cliff

 

[Jeff Clark]

Cliff, I still say that in any heavy use the chisel grind will be weaker. Anytime I use a blade hard, either my grip or the material that I am cutting through will make the force of the cut be in the plane of the blade. This applies whether I am chopping or doing a hard push or pull. If I try and apply hard pressure with the blade slightly twisted to allign the edge force central to the apex of a chisel edge I am highly likely to uncontrollably twist the blade and hurt it worse than if I simply followed the flat of the blade. I believe that the chisel blade is only as strong as an equivalent thinly ground symetrical blade under light usage (where strength isn't much of an issue).

 

[Cliff Stamp]

Yes, to clarify, I was not in disagreement that the chisel grind will be of lower durability, but just pointing out that is is not because of the edge geometry but simply the way it is orientated with respect to the centerline of the thrust / impact.

-Cliff