Knife information you might want to know-very long read

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There's been a jump in recent years in the popularity of serrated edges, and there's often confusion as to when a serrated edge is advantageous, versus when a plain edge is advantageous. The question comes up often in rec.knives.

For our discussion, we'll need to talk about what we're doing with the knife. Think about what you can do with a knife you can shave, slice, slash, saw, hack, chop, etc. For our purposes, we'll divide all knife uses into two very broad categories.

Push cuts: The main cutting is done by pushing the edge through the thing-to-be-cut. For example, when you shave, you push the edge of the knife through your beard. When peeling an apple, you push the edge under the skin of the apple. When chopping wood, you try to push the edge into and through the wood.

Slicing cuts: The cutting action is substantially done by dragging the edge across the thing-to-be-cut. When you slice meat or a tomato, you drag the edge across the tomato as you cut through it. Slicing and sawing are examples of slicing cuts.

II. Plain vs. Serrated The Conventional View

In general, the plain edge is better than the serrated when the application involves push cuts. Also, the plain edge is superior when extreme control, accuracy, and clean cuts are necessary, regardless of whether or not the job is push cuts or slices.

In general, the serrated edge will work better than the plain edge for slicing cuts, especially through hard or tough surfaces, where the serrations tend to grab and cut the surface easily. Some of the cutting power of the serrated edge is due to its format alone; thus, even a dull serrated edge knife will often perform competently at slicing jobs.

The plain edge will work better for applications like shaving, skinning an apple, skinning a deer. All those applications involve either mostly push cuts, or the need for extreme control. Serrations work really well on things like tough rope or wood, where the serrations bite through quickly.

Generally, the more push cuts are used, the more necessary it is for the plain edge to have a "razor polished" edge. A knife edge becomes more polished when you move to higher and higher grit stones. Generally, 1200-grit is considered polished; a 6000+ grit Japanese water stone would polish the edge further.

One interesting case is cutting a tomato. In theory, you can just push a blade through a tomato, so a razor polished plain edge would work fine. However, the tomato is soft, and unless your plain edge knife is very sharp, the tomato will simply squish when you start pushing. You can (and many people do) use a slicing motion with your plain blade, but if it's even a little dull it won't cut well and it may not even break the skin. Use a sawing motion with a serrated knife (even a dull one), and your tomato will slice fine.
You will read about test after test where the above view is confirmed. That is, the plain edge excels in push cuts, and the serrated excels in slicing cuts.

III. Plain vs. Serrated Re-thought

Since actual tests confirm the truth of the conventional view, what more is there to be said? The problem is that the tests are often not as thorough as they need to be. That is, when testing plain vs. serrated performance, most tests are comparing a plain polished edge to a serrated edge. Given that, it is no surprise that the serrated blade easily outperforms the plain blade when cutting (for example) rope.

A polished edge is not the only choice with a plain blade. One can get the plain edge to perform much differently when sharpened with coarser stone. People who cut rope often use a plain edge sharpened on a file, to get an incredibly coarse, "micro-serrated" edge that performs wonderfully at slicing jobs. So the knife testers are testing with polished plain edges, whereas people experienced with cutting rope use coarsely-ground plain edges.

Whether or not serrated blades will out-slice coarse-ground plain blades seems to depend on the medium being cut. Harder materials (or materials under tension) do well for serrated blades. With softer materials, the serrations will sometimes catch and unwind the material rather than cut -- in this case, coarse-ground plain blades may easily out-slice serrated blades.

So the claim that serrated edges work better than plain edges for slicing needs to be re-examined. It appears that as materials get harder or put under more tension, the serrated edge may slice a bit better than a coarse-ground plain edge. As the material gets softer and looser, the coarse-ground plain edge may slice a bit better. And as we go towards push cuts, the polished plain edge comes into its own. The user may want to experiment on those materials that he often cuts, before choosing the edge format.

In addition, keep in mind that the coarse plain edge is much easier to sharpen than the serrated edge. Just grab your file or extra coarse stone, take a few swipes, and you're ready to go. With the serrated blade, you'll need to find a sharpening rig with the special serrated blade sharpener. Balancing this is the fact that serrated blades need to be sharpened less often.

IV. What Should I Carry?

Should you carry a serrated blade or plain blade for everyday utility carry? Unless you *know* that the majority of work you'll be doing heavily favors slicing or pushing (e.g., "I spend all my time whittling"), it may not matter much. My experience has been that general utility work is usually general enough that either format works just fine, though these days I tend to lean towards plain blades. Also keep in mind that by changing your sharpening strategy on the plain edge, you can significantly change its characteristics. If you do a lot of push cutting, you want to go with a razor polished plain edge. If you do a lot of slicing, you'll need to decide between a coarse-ground plain edge and a serrated edge. I don't mind sharpening, so I lean towards plain blades, strategically sharpened to the right grit (polished or coarse) for the jobs I happen do be doing.

Occasionally, people mention that the serrated edge looks intimidating to the masses. This could be good if you're using this knife primarily for self defense and want an intimidation factor. Or it could be bad, if you're carrying for utility work and don't want to scare people (especially the nice officer who pulled you over for speeding and asks to look at the knife in your sheath). Rumor has it that airport guards are particularly strict about serrated edges. Other than at airports, I don't think the menacing appearance of the serrated edge is important enough either way to affect what I carry.

V. Thoughts On The Partially-Serrated Blade

Another option is the combination plain/serrated edge. This format appears to have overtaken the all-serrated format. Typically, the 50%-60% of the blade nearest the tip is plain, while the back 40%-50% is serrated. There are mixed feelings on this format. Many people swear by this format, and feel that it is a good compromise, giving the user the choice of precise push cuts from the plain edge, and the advantage of the serrated edge for tougher materials. However, keep in mind that on a 3.25" blade, there's maybe 1.25" of serrations. The detractors of this format feel that 1.25" is too short a length for the serrations to be really be useful, and the length of the plain edge is being sacrificed for no good gain.

My own philosophy on partially-serrated blades at the moment is that since I have both edge formats in one knife, I try to let each one shine in their respective areas. So I'm razor polishing the plain edge part, often on a 1200 grit diamond stone or even 6000 grit Japanese water stone, and then stropping it. The plain edge is scary sharp for push cuts, and I use the serrations when I need to cut through hard or fibrous material.

Partially-serrated blades are often serrated at the "wrong" place. For example, for camp use, I might want the belly serrated for cutting my steak, and the part near the handle razor-polished for whittling and control-type usage. However, 99.9% of partially-serrated blades are ground exactly the opposite the ripping inaccurate serrations are at the control part of the blade, and the plain part is out at the slicing part.

In theory, one can use a plain blade to get similar performance to a partially-serrated blade. Just razor polish the plain blade, and then rough up one part of the edge on a file, to get a knife that will excel at push cuts at one point of the blade, and excel at slicing cuts at another.

KNIFE STEELS

One thing to keep in mind is that there's more to knife performance than the steel. The blade profile is also important (a tanto format isn't the best choice to skin a deer, for example). But perhaps most important is the heat treatment. A good solid heat treatment on a lesser steel will often result in a blade that outperforms a better steel with inferior heat treatment. Bad heat treatment can cause a stainless steel to lose some of its stainless properties, or cause a tough steel to become brittle, etc. Unfortunately, of the three most important properties (blade profile, steel type, heat treatment), heat treatment is the one that is impossible to assess by eye, and as a result excessive attention is sometimes paid to the other two.

Remember also to keep your particular application in mind. 440A is often scoffed at, but I'd rather have my salt water dive knife made of 440A than L-6. Properly heat treated 5160 is wonderfully tough, but if my application is skinning deer, I'm probably more interested in edge holding ala 52100. And on and on.

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Steel Alloys:

At its most simple, steel is iron with carbon in it. Other alloys are added to make the steel perform differently. Here are the important steel alloys in alphabetical order, and some sample steels that contain those alloys:

Carbon: Present in all steels, it is the most important hardening element. Also increases the strength of the steel. We usually want knife-grade steel to have >.5% carbon, which makes it "high-carbon" steel.

Chromium: Added for wear resistance, hardenability, and (most importantly) for corrosion resistance. A steel with at least 13% chromium is deemed "stainless" steel. Despite the name, all steel can rust if not maintained properly.

Manganese: An important element, manganese aids the grain structure, and contributes to hardenability. Also strength & wear resistance. Improves the steel (e.g., deoxidizes) during the steel's manufacturing (hot working and rolling). Present in most cutlery steel except for A-2, L-6, and CPM 420V.

Molybdenum: A carbide former, prevents brittleness & maintains the steel's strength at high temperatures. Present in many steels, and air-hardening steels (e.g., A-2, ATS-34) always have 1% or more molybdenum -- molybdenum is what gives those steels the ability to harden in air.

Nickel: Used for strength, corrosion resistance, and toughness. Present in L-6 and AUS-6 and AUS-8.

Silicon: Contributes to strength. Like manganese, it makes the steel more sound while it's being manufactured.

Tungsten: Increases wear resistance. When combined properly with chromium or molybdenum, tungsten will make the steel to be a high-speed steel. The high-speed steel M-2 has a high amount of tungsten.

Vanadium: Contributes to wear resistance and hardenability. A carbide former that helps produce fine-grained steel. A number of steels have vanadium, but M-2, Vascowear, and CPM T440V and 420V (in order of increasing amounts) have high amounts of vanadium. BG-42's biggest difference with ATS-34 is the addition of vanadium.

CARBON and alloy steels (non-stainless steels):

These steels are the steels most often forged. Stainless steels can be forged (guys like Sean McWilliams do forge stainless), but it is very difficult. In addition, carbon steels can be differentially tempered, to give a hard edge-holding edge and a tough springy back. Stainless steels are not differentially tempered. Of course, carbon steels will rust faster than stainless steels, to varying degrees. Carbon steels are also often a little bit less of a crap shoot than stainless steels -- I believe all the steels named below are fine performers when heat treated properly.

In the AISI steel designation system, 10xx is carbon steel, any other steels are alloy steels. For example, the 50xx series are chromium steels. In the SAE designation system, steels with letter designations (e.g., W-2, A-2) are tool steels.

There is an ASM classification system as well, but it isn't seen often in the discussion of cutlery steels, so I'll ignore it for now. Often, the last numbers in the name of a steel are fairly close to the steel's carbon content. So 1095 is ~.95% carbon. 52100 is ~1.0% carbon. 5160 is ~.60% carbon.

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O-1

This is a steel very popular with forgers, as it has the reputation for being "forgiving". It is an excellent steel, that takes and holds an edge superbly, and is very tough. It rusts easily, however. Randall Knives uses O-1, so does Mad Dog.

W-2

Reasonably tough and holds an edge well, due to its .2% vanadium content. Most files are made from W-1, which is the same as W-2 except for the vanadium content (W-1 has no vanadium).

The 10-series --

1095 (and 1084, 1070, 1060, 1050, etc.)
Many of the 10-series steels for cutlery, though 1095 is the most popular for knives. When you go in order from 1095-1050, you generally go from more carbon to less, from better edge holding to less edge holding, and tough to tougher to toughest. As such, you'll see 1060 and 1050, used often for swords. For knives, 1095 is sort of the "standard" carbon steel, not too expensive and performs well. It is reasonably tough and holds an edge very well. It rusts easily. This is a simple steel, which contains only two alloying elements: @.95% carbon and .4% manganese. The various kabars are usually 1095 with a black coating.

Carbon V

Carbon V is a trademarked term by Cold Steel, and as such is not necessarily one particular kind of steel; rather, it describes whatever steel Cold Steel happens to be using, and there is an indication they do change steels from time to time. Carbon V performs roughly between 1095-ish and O-1-ish, in my opinion, and rusts like O-1 as well. I've heard rumors that Carbon V is O-1 (which I now think is unlikely) or 1095. Numerous industry insiders insist it is 0170-6. Some spark tests done by a rec.knives reader seem to point the finger at 50100-B. Since 50100-B and 0170-6 are the same steel (see below), this is likely the current Carbon V.

0170-6 - 50100-B

These are different designations for the same steel: 0170-6 is the steel makers classification, 50100-B is the AISI designation. A good chrome-vanadium steel that is somewhat similar to O-1, but much less expensive. The now-defunct Blackjack made several knives from O170-6,
and Carbon V may be 0170-6. 50100 is basically 52100 with about 1/3 the chromium of 52100, and the B in 50100-B indicates that the steel has been modified with vanadium, making this a chrome-vanadium steel.

A-2

An excellent air-hardening tool steel, it is known for its great toughness and good edge holding. As an air-hardening steel, so don't expect it to be differentially tempered. Its outstanding toughness makes it a frequent choice for combat knives. Chris Reeve and Hartsfield both use A-2, and Blackjack made a few models from A-2.

L-6

A band saw steel that is very tough and holds an edge well, but rusts easily. It is, like O-1, a forgiving steel for the forger. If you're willing to put up with the maintenance, this may be one of the very best steels available for cutlery, especially where toughness is desired.

M-2

A "high-speed steel", it can hold its temper even at very high temperatures, and as such is used in industry for high-heat cutting jobs. It is an excellent edge holder. It is tough but not as tough as some of the toughest steels in this section; however, it will still be tougher than the stainless steels and hold an edge better. It rusts easily. Benchmade has started using M-2 in one of their AFCK variations.

5160

A steel popular with forgers, it is extremely popular now and a very high-end steel. It is essentially a simple spring steel with chromium added for hardenability. It has good edge holding, but is known especially for its outstanding toughness (like L-6). Often used for swords (hardened in the low 50s Rc) because of its toughness, and is also used for hard use knives (hardened up near the 60s Rc).

52100

A ball-bearing steel, and as such is only used by forgers. It is similar to 5160 (though it has around 1% carbon vs. 5160 ~.60%), but holds an edge better. It is less tough than 5160 however. It is used often for hunting knives and other knives where the user is willing to trade off a little of 5160's toughness for better edge holding.

D-2

D-2 is sometimes called a "semi-stainless". It has a fairly high chrome content (12%), but not high enough to classify it as stainless. It is more stain resistant than the carbon steels mentioned above, however. It has excellent edge holding, but may be a little less tough than some of the steels mentioned above. And it does not take a beautiful finish. Bob Dozier uses D-2.

Vascowear

A very hard-to-find steel, with a high vanadium content. It is extremely difficult to work and very wear-resistant. It is out of production.

"STAINLESS" Steels:

Remember that all steels can rust. But the following steels, by virtue of their > 13% chromium, have much more rust resistance than the above steels. I should point out that there doesn't appear to be consensus on what percent of chromium is needed for a steel to be considered stainless. In the cutlery industry, the de-facto standard is 13%, but the ASM Metals Handbooks says "greater than 10%", and other books cite other numbers. In addition, the alloying elements have a strong influence on the amount of chromium needed; lower chromium with the right alloying elements can still have "stainless" performance.

420

Lower carbon content (<.5%) than the 440 series makes this steel extremely soft, and it doesn't hold an edge well. It is used often for diving knives, as it is extremely stain resistant. Also used often for very inexpensive knives. Outside salt water use, it is too soft to be a good choice for a utility knife.

440 A - 440 B - 440C

The carbon content (and hardenability) of this stainless steel goes up in order from A (.75%) to B (.9%) to C (1.2%). 440C is an excellent, high-end stainless steel, usually hardened to around 56-58 Rc. All three resist rust well, with 440A being the most rust resistant, and 440C the least. The SOG Seal 2000 is 440A, and Randall uses 440B for their stainless knives. 440C is fairly ubiquitous, and is generally considered the penultimate general-use stainless (with ATS-34 being the ultimate). If your knife is marked with just "440", it is probably the less expensive 440A; if a manufacturer had used the more expensive 440C, he'd want to advertise that. The general feeling is that 440A (and similar steels, see below) is just good enough for everyday use, especially with a good heat treat (we've heard good reports on the heat treat of SOG's 440A blades, don't know who does the work for them). 440-B is a very solid performer and 440-C is excellent.

425M - 12C27

Both are very similar to 440A. 425M (.5% carbon) is used by Buck knives. 12C27 (.6% carbon) is a Scandanavian steel used often in Finish puukkos and Norwegian knives.

AUS-6 - AUS-8 - AUS-10 (aka 6A 8A 10A)

Japanese stainless steels, roughly comparable to 440A (AUS-6, .65% carbon) and 440B (AUS-8, .75% carbon) and 440C (AUS-10, 1.1% carbon). AUS-6 is used by Al Mar. Cold Steel's use of AUS-8 has made it pretty popular, as heat treated by CS it won't hold an edge like ATS-34, but is a bit softer and may be a bit tougher. AUS-10 has roughly the same carbon content as 440C but with slightly less chromium, so it should be a bit less rust resistant but perhaps a bit tougher than 440C. All 3 steels have some vanadium added (which the 440 series lacks), which will improve wear resistance.
GIN-1 aka G-2. A steel with slightly less carbon, slightly more chromium, and much less moly than ATS-34, it is used often by Spyderco. A very good stainless steel.

ATS-34 - 154-CM

The hottest high-end stainless right now. 154-CM is the original American version, but for a long time was not manufactured to the high quality standards knifemakers expect, and so is not used often anymore. Late-breaking news is that high-quality 154-CM may again be available. ATS-34 is a Hitachi product that is very, very similar to 154-CM, and is the premier high quality stainless. Normally hardened to around 60 Rc, it holds an edge very well and is tough enough even at that high hardness. Not quite as rust resistant as the 400 series above. Many custom makers use ATS-34, and Spyderco (in their high-end knives) and Benchmade are among the production companies that use it.

ATS-55

Similar to ATS-34, but with the moly removed and some other elements added. Not much is known about this steel yet, but it looks like the intent was to get ATS-34 edge-holding with increased toughness. Since moly is an expensive element useful for high-speed steels, and knife
blades do not need to be high speed, removing the moly hopefully drastically decreases the price of the steel while at least retaining ATS-34's performance. Spyderco is using this steel.

BG-42

Bob Loveless announced recently that he's switching from ATS-34 to this steel. Keep an eye out for it, it's bound to catch on. BG-42 is somewhat similar to ATS-34, with two major differences: It has twice as much manganese as ATS-34, and has 1.2% vanadium (ATS-34 has no vanadium), so look for even better edge-holding than ATS-34. Chris Reeves has switched from ATS-34 to BG-42 in his Sebenzas.

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CPM T440V - CPM T420V

Two steels that hold an edge superbly (better than ATS-34), but it's difficult to get the edge there in the first place. These steels are both high in vanadium. Spyderco offers at least one model in CPM T440V. Custom maker Sean McWilliams is a big fan of 440V, which he forges. Depending on heat treatment, expect to have to work a bit harder to sharpen these steels -- also, don't expect ATS-34 type toughness. 420V is CPM's follow-on to 440V, and with less chromium and almost double the vanadium, is more wear-resistant and may be tougher than 440V.

400 Series Stainless

Before Cold Steel switched to AUS-8, many of their stainless products were marketed as being of "400 Series Stainless". Other knife companies are beginning to use the same term. What exactly *is* 400 Series Stainless? I always imagined it was 440-A, but there's nothing to keep a company from using any 4xx steel, like 420 or 425M, and calling it 400 Series Stainless.

NON-STEELS USED BY KNIFEMAKERS

Cobalt - Stellite 6K
A flexible material with very good wear resistance, it is practically corrosion resistant. Stellite 6K, sometimes seen in knives, is a cobalt alloy. David Boye uses cobalt for his dive knives.

Titanium

Newer titanium alloys can be hardened near 50 Rc, and at that hardness seem to take something approaching a useful edge. It is extremely rust-resistant, and is non-magnetic. Popular as expensive dive knives these days, because the SEALs use it as their knife when working around magnetic-detonated mines. Mission knives uses titanium. Tygrys makes a knife with a steel edge sandwiched by titanium.

Ceramics

Numerous knives have been offered with ceramic blades. Usually, those blades are very very brittle, and cannot be sharpened by the user; however, they hold an edge well. Boker and Kyocera make knives from this type of ceramic. Kevin McClung recently came out with a ceramic composite knife blade that much tougher than the previous ceramics, tough enough to actually be useful as a knife blade for most jobs. It is also user-sharpenable, and holds an edge incredibly well.

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BLADE GRINDS

The Hollow Grind

The hollow grind is done by taking two concave scoops out of the side of the blade. Many production companies use this grind, because it's easier to design machines to do it. But many custom makers grind this way as well. Its great advantage is that the edge is extraordinarily thin, and thin edges slice better. The disadvantage is that the thinner the edge, the weaker it is. Hollow ground edges can chip or roll over in harder use. And the hollow ground edge can't penetrate too far for food-type chopping, because the edge gets non-linearly thicker as it nears the spine.

For designs where slicing is important, but the slice doesn't need to go too deep, this grind is an excellent choice. Many hunting knives are hollow ground, because field dressing is often best done with a knife that slices exceptionally well through soft tissues. Unfortunately, if you hit a bone, you can chip the edge, so the flat grind (see below) is also used often.
Another advantage of the hollow ground knife, at least at the beginning, is ease of sharpening. Most hollow grinds thicken slightly towards the edge. That means that as you sharpen (at least at first), the blade gets thinner and easier to sharpen. After this, however, the blade begins thickening non-linearly and sharpening will become more difficult. The ultimate push cutter, the straight razor, is usually hollow ground.

The Chisel Grind

The chisel grind is a knife which is not ground at all on one side. So it is completely flat on one side, and has a bevel on the other. It is simple to produce (the maker need only grind one side), and simple to sharpen (it is sharpened on one side only, then the burr is stropped off the other side). It is also typically very sharp, due to the single bevel design. Whereas a blade ground on both sides might be sharpened at 20 degrees per side, for a total of 40-degrees edge angle, a chisel ground blade is often ground at around 30 degrees, making for a thin (and thus sharp) edge. Accurate slices are very difficult with the chisel grind, due to the fact that the non-symmetrical design forces the knife to curve in the medium being cut.

The Sabre Grind

The sabre grind is a strong edge format. The bevel starts around the middle of the blade, and proceeds flatly towards the edge. This leaves a strong edge for chopping and other hard use. But it also means the edge will be fairly thick, so this design will not necessarily slice all that well. The sabre grind is found on many military classic designs such as the Randall #1 and the kabar.

The Flat Grind

The flat grind endeavors to provide an edge that is both thin and strong, and leaves a strong thick spine. The grind is completely flat, going from the spine to the edge. This grind is harder to make, because a lot of steel needs to be ground away. However, the edge ends up being fairly thin and so cutting very well. Because the bevels are flat, there is plenty of metal backing the edge, so it's much stronger than a hollow grind. It is not as strong as a sabre grind, but will outcut that grind.

The edge on this design also penetrates better for slicing and chopping. The hollow grind expands non-linearly as you go up the blade, the sabre grind expands linearly but very quickly. The flat grind expands linearly and slowly. Kitchen knives are usually flat ground, because when chopping/slicing food you need to push the blade all the way through the food. This grind is an outstanding compromise between strength and cutting ability, sacrificing little for either.

The Convex Grind

Also called the Moran grind, after Bill Moran. This grind is as you would expect, the grind arcs down in a convex curve down to the edge. This means the point can be very sharp, because there's no secondary bevels to create the edge itself, just two intersecting arcs. There is also a fair amount of steel behind the edge, because the convex arcs cause the edge to widen non-linearly. This is a strong-edge format, which won't penetrate like a flat grind but will be stronger. Knifemakers form this grind on a flat-belt grinder. A disadvantage of this grind is if you don't have a flat-belt grinder yourself, it is difficult to touch up the edge.

The Dual-Ground Reinforced Tanto

The Americanized tanto as executed by Cold Steel shows multiple grind types. Along the long flat, the knife is hollow ground, for a thin edge and incredible sharpness. However, along the front up to the point, the grind switches to a flat grind. This provides incredible tip strength. The result is a knife with a very keen bottom edge, but a strong profile towards the front where it pierces. Of course, the reinforced front edge is strong but doesn't pierce easily.

CUSTOM
VI. Putting It All Together

Okay, now we know the characteristics, grinds, and blade shapes, and what they are all good for. If you understand this, you can begin to see how to mix and match features to fine-tune a knife for the functions you want. For example, you may want a tanto, but are willing to sacrifice some of the point strength for control and piercing ability. Having read the FAQ, you know you can clip the point (controllability) and thin the edge via a false edge (piercing ability), which is exactly the approach Benchmade took with their Stryker. Or if you want your tanto to slice a bit better, you can make the straight edge slightly convex to simulate a belly -- the approach taken by Microtech on their SOCOM tanto. By mixing-n-matching, we can enhance a design's strengths or sacrifice a little to make up for a deficiency somewhere else.
With that in mind, let's briefly examine some popular knife designs, and see if we can figure out why the designers made the choices they did.

Combat/Utility Knives

The Marine Corps' kabar combat/utility knife is a classic. It's a clip point design, with a false edge that is sometimes sharpened. This makes the point very sharp, and easy to control in thrusts. As with most clip points, there is a nice belly for slicing. This makes it suitable for fighting and utility uses.
The grind chosen was a sabre grind. This makes the edge very strong, but sacrifices cutting ability (versus a flat grind). In theory, the sabre grind might have been chosen because of the very hard use and abuse this knife may go through, not just as a knife but as a pry bar or hole digger. At least as importantly, the sabre grind is faster and cheaper to produce than a flat grind, important when many knives have to be turned out.

The Mad Dog ATAK takes a different route, going with a thick spine and flat grind, but retaining the clip-point format. The flat grind means the edge will outcut the kabar, and the thick spine helps assure robustness for hard use (as does the differential heat treatment). A positive included angle (also discussed above) enhances chopping and slicing performance. Sort of a high-performance version of the standard combat/utility knife, more expensive to produce but outperforming the standard in just about every other category.

The Camp Knife

Camp knives are generally big, 8" or more. They're almost always flat ground, for good edge performance. The job of this kind of knife is to do camp chores, from chopping limbs to splitting kindling to food prep to anything else. The flat grind provides great performance, and the usual clip- or drop-point format provides point control when needed. Size and weight is needed for chopping effectiveness.

Three Folders

The tactical folder craze has spawned many folders with sabre grinds, and that emphasizes strength over cutting ability. But there are a few folders that consistently do very well in cutting tests.

The Sebenza had a straight clipped point, for excellent control, and plenty of belly. A very high hollow grind provides a thin edge, for great push-cutting and slicing.

The AFCK has a sabre grind, but still performs wonderfully. The blade is relatively thin, so even with the sabre grind the edge remains fairly thin and performs well. In addition, the blade is at an angle to the handle, providing even better slicing and slashing performance. The straight-clipped point is very sharp and controllable.

These two folder makers have made different design decisions, but both have achieved excellent results. The main objectives -- a working point, a belly, and a thin edge -- are achieved through different designs.

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The Microtech SOCOM tanto is another design worth examining. It is ostensibly an Americanized tanto. However, the designers have made a large number of interesting tweaks to enhance the design. First, for point control, the point is clipped slightly and the blade meets the handle at an angle -- both of these things bring the point in-line for control. To make the point a better piercer, the front bevel is at a much smaller angle to the point than is normally seen. The normally straight edge is slightly curved, and combined with the low-angle front edge, the secondary point ends up not very sharp. So this is a tanto with a bit of a belly, and combined with the blade/handle angle, functions well as a slasher/slicer. Lastly, Microtech ground in false edge bevels on the spine, which disappear near the point. This leaves the point full width for strength, but removes some weight (and adds good looks) along the spine.

A Hunter

A.G. Russell's Deerhunter is a drop-point format, and is flat ground like many hunters, to provide a thin edge that cuts exceptionally well. To improve the geometry even more, the spine is <.125", making the entire package extraordinarily thin. As a result, the knife wouldn't be a great choice for prying, but for slicing and push-cutting it is outstanding.

A Custom-Made Folder

To show the kind of tweaking that can be done, I will describe a custom folder I had made for me by Allen Elishewitz. The blade has the dual-grind of a tanto. That is, flat grind up front near the point, hollow grind along the straight edge. However, this knife is not a tanto, it is a drop point. So this knife has the tip strength of a tanto, but the useful belly of a drop point, and a dropped point for better control. In addition, the point has false edge bevels ground in, which makes it penetrate a bit better. In short, we took the massive point strength of a tanto, but ground it on the more useful utility shape like a drop point, then ground in bevels to make piercing ability a bit better. Tweak and tune!

LINERLOCK TESTS

Liner Lock Tests, by A.T. Barr and Joe Talmadge

A well-made liner lock is a beautiful thing. The action is smooth, the lock is very strong, and it can be opened and closed one-handed. However, it is easy for the knifemaker to make a mistake on a liner lock. Many common mistakes can result in the lock accidently unlocking, and this is a serious threat to fingers. Below are some of the tests we recommend a potential buyer try on a liner lock. Keep in mind that many of the factory knives easily pass all the tests below, while many knives from custom makers -- including those lauded in the knife rags -- often don't pass. Test your knives, don't assume the more expensive knife has the more secure lock-up!

One caveat is that the second of A.T.'s suggestions, the "palm-on-spine" and "whack-the-spine" tests, are a bit controversial. We both feel that a blade should never close due to palm pressure, and a moderate whack on the spine shouldn't make a blade fold up either. Some makes say that a knife in normal use does not ever get whacked on the spine, so this test is not real-world. You can decide for yourself how secure you think the lock should be.

A.T. Barr's tests

You don't want your blade to open except when you want it to. Always check for a good detent ball to blade tang contact. Open your liner lock normally and then close it very slowly. The blade *should* snap closed the last 1/16" or so.

Open your knife blade very slowly, until the lock engages. Do not snap it open. You want the tension of the liner lock to just snap to the tang of the knife. Then do two things. First turn the knife over, and using the palm of your hand try to close the blade. It should not close. Then strike the blade spine on the table. Not real hard, but it needs some pressure. It should not close.

Snap the blade open REAL FAST, then close it. If it takes a lot of pressure to unlock the blade, walk away from that knife. Open the knife blade real slow, and check for any movement. Sideways or up & down.

Great tip

Also, if your liner lock has a sloppy lock-up, sometimes you can help it by snapping the blade open and then half-way hard striking the blade (try to close it) on it's tang. That will help seat the Titanium liner to the tang of the blade. If that does not work, send it back to the maker. Be careful when you do this. If the blade does disengage, the blade will hit your knuckle. A number of rec.knife readers have reported good results using this tip.