flat-ground VS. hollow ground ??????

[Cliff Stamp]

Jerry Hossom :

The exact same series of tests, run in parallel on flat ground blades of 5160, A2, and 1084/15N20 Damascus failed in the same tests (chipped edges and broken points).

And production flat ground blades of Carbon V, AUS-6 and 440A-class passed. In any case, edge chipping or lack thereof would be critical to the nature of the edge geometry specifically to the angle, the edge thickness would only be an influence if you were seeing gross edge rippling (the entire bevel is mashed out of place), which is the limit of the influence of the primary geometry to first order. For example, most ABS bowies have edges about half as obtuse as the edges on your blades, they would therefore be expected to suffer deformation *much* easier. This does not indicate a superior ability for your hollow grind to produce durable edges as opposed to their convex (or flat) primary grind, nor a difference in the steel, it simply reflects the huge difference in edge angle. It would be just the same if you did a bend test on a 1/4" hollow ground bowie, and one on a 1/8" convex bowie and claimed that this showed that hollow ground blades were stronger, well no, the stock thickness was the critical factor not the primary grind.


Same thing with the points, unless the cross sections are very similar, which is influenced by the point taper moreso than the primary grind, it will always be the deciding factor. Striders points for example are pretty much the most robust in existance, the WB I had for example had a tip tapered at ~22 degrees. This is the reason that it is so much stronger than something like the TAC-11 which tapers 3 times faster. The fact that the WB had a hollow grind and the TAC-11 flat is of no consequence to the relative tip strength (nor are the steels or the heat treatment) because the huge degree of difference in the speed of taper dwarfs out every other factor.

Joe, hollow grinds as a relief are found on many deep cutting blades such as felling axes and khukuris. The exact same geometry, scaled down would work very well for low stress deep cutting. However, the only person I can think off hand who makes blades in this manner is Alvin on rec.knives. I would assume though that any custom maker who was willing to do hollow grinds could easily make one up. It is possible to modify a finished flat ground blade in this way, which might be a good way to start since you would be very familiar with its performance.

Most hollow ground blades have the hollow grind as the primary profile with the grind running parallel to the edge at the start which then flairs out strongly at the top. These blades will perform just as you describe. The PAB from Strider for example was like this and would bind dead in wood and had to be knocked out with a mallet. A khukuri, also with a hollow grind, would not. You could notice the same type of behavior on deep cuts through various binding materials, deep meaning above the height of the hollow grind. However this property is caused by the nature of the grind, not the grind itself.

To be clear, yes there is a large class of hollow ground blades that bind strongly on deep cuts through resistive material however this is not the only way they can be ground, so in general it is not true that all hollow grinds have this behavior. There is also a way to use a hollow grind as just a relief, and this profile does not cause binding, in fact it prevents it, while at the same time offering many of the advantages of hollow grinds in general such as high strength to weight ratio, edge stability over long term sharpening etc. .

-Cliff

 

[Jerry Hossom]

Cliff, you either didn't understand what I was saying or chose to ignore it. To begin with I don't know what tests you're speaking of that were passed by Carbon V, AUS-6 and 440A steels. They were certainly not the tests I was speaking of. The tests I was speaking of measured not just abuse, but the capacity of the blade to cut through various materials. The abuse encountered is secondary to the cutting performance. I described the failure of the flat ground blades merely to be ilustrative of the fact that the grind does not necessary define better cutting nor the performance quality of the knife.

You keep referring to my edges as being extremely "obtuse". The only thing "obtuse" here is yourself at times. You simply can not measure the final edge bevel angle on a convex edges in any manner that is comparable to a flat beveled edge. My edges are shaped as they are for penetration, usually of flesh and bone. That they are also strong speaks to the nature of the convex edge, which should not be directly compared to anything else. Even within convex edges there are major differences.

In a fighter, tip strength is not easily achieved in a flat grind if the knife is to be balanced. Distal tapers, used to remove weight, may not preserve sufficient thickness at or immediately behind the tip to tolerate hard impacts. The actual bevel on the tip is irrelevant. A hollow grind more naturally preserves a stronger spine further out on the blade, and it is this spine that most often influences tip strength. At least that is the case in my knives. Does any of this make flat ground blades inferior as fighters? Not at all. In fact Rob Patton makes very large flat ground fighters that are the equal of any made today. But I promise, the issues he and I most often deal with are not quite as simple as flat versus hollow. The totality of the blade grind in all axes and dimensions must be dealt with, and then for each section of the blade according to its role in blade's overall performance.

BTW, Marbles makes an excellent example of the convex grind with an enlarged fuller to remove weight and reduce drag.

 

[Joe Talmadge]

> Joe, a 9" Hossom fighter just sucks on wood.

Jerry, I didn't think a fighter would be great on wood. I just wanted to see the effect that Cliff talked about -- the "hollow grind as relief". I see that you don't grind your hollow grinds that way, so it was a bad suggestion in any case. Well, not a bad suggestion -- I still want a 9" 3V fighter, but I can't use any goofy justifications about testing!



Joe

 

[Jerry Hossom]

Joe, if we all needed justification for wanting a knife, we wouldn't likely be here. At the moment I'm not taking new orders though, so you're safe.

 

[Joe Talmadge]

Originally posted by Jerry Hossom
Joe, if we all needed justification for wanting a knife, we wouldn't likely be here. At the moment I'm not taking new orders though, so you're safe.

Oddly enough, my accountant feels that that's the best news I've had all week

Joe

 

[Jerry Hossom]

Well then, I'm glad I could make your accountant happy at least.

 

[tom mayo]

 

[dogboye]

In a fighter, tip strength is not easily achieved in a flat grind if the knife is to be balanced. Distal tapers, used to remove weight, may not preserve sufficient thickness at or immediately behind the tip to tolerate hard impacts. The actual bevel on the tip is irrelevant. A hollow grind more naturally preserves a stronger spine further out on the blade, and it is this spine that most often influences tip strength.

After this part of the discussion, I'd be really interested in the opinions of the two main parties in this discussion, regarding the funky tip that is ground into/onto some of Bud Nealy's fighters/tacticals. I forget exactly what he calls them. {edit - It is called the Pesh Kabz} The blade is hollow ground, but the hollow grind goes away about a half inch from the tip, at which point the knife uses a flat, or possibly even convex, grind. It is supposed to be for tip strength, but it looks to me like it would place a massive stress riser at the point where the hollow edge grind stops.

 

[Jerry Hossom]

I THINK Bud does that by doing the hollow grind first and keeping it dead level as opposed angling it towards the point. Basically the grind remains level with the spine of the blade instead of the edge, so the hollow exits the front of the blade below the point. Once that is done, he puts a chisel grind on the front to shape the point using a fairly "obtuse" angle, for strength.

It should be strong and I really don't see why there would be any unusual stress risers from doing this. There aren't any spots where the edge or spine are sharply indented.

 

[Cliff Stamp]

Jerry :

To begin with I don't know what tests you're speaking of that were passed by Carbon V, AUS-6 and 440A steels.

Same tests, done by the same person, a few examples :

No edge or tip damage on a production AUS-6A blade :

http://www.bladeforums.com/forums/showthread.php?s=&threadid=89939

No edge or tip damage on a flat ground A2 blade, a production flat ground Carbon V and AUS-8 blades :

http://www.bladeforums.com/forums/showthread.php?s=&threadid=89631

No edge or tip damage on a flat ground 440A class blade, ~53 RC :

http://www.bladeforums.com/forums/showthread.php?s=&threadid=89829

In general as well consider that you know which tests are going to be performed on your knives and design specifically for them as they reflect how you think a "fighting" blade should perform. It is hardly surprising therefore that in general your knives will do better on those tests than blades picked from other makers/manufacturers as there is hardly uniform agreement on performance and thus they will gear their knives towards different performance spectra. In general you can extend this idea and look at all tests done by makers and manufacturers on their blades and they all do very well on their own tests, which you would expect. You can in fact extend this idea even further, pick any blade and you can design a set of tests which will showcase this knife over any other.

You keep referring to my edges as being extremely "obtuse".

This is based on the specifications you have listed for your blades as well as comments you have made about edge profiles in general and of course my perspective on the same issues. To be specific, your minimum requirements are pretty much where I would set the maximum geometry I would accept and therefore are obviously what I would call obtuse. Of course this could just indicate that I was very light on my blades, but ironically, I am not the one who judges the other as abusive. In any case, as it is obvious, obtuse is a relative term, the edges I put on my blades are obtuse compared to the edges that some of my friends use.

You simply can not measure the final edge bevel angle on a convex edges in any manner that is comparable to a flat beveled edge.

Of course you can, you can specify it completely if you want, its just not as trivial as on a flat ground edge. Here is an example of the full blade profile of a dual tapered convex ground blade :

http://www.physics.mun.ca/~sstamp/images/al_blade_profile.gif

and the edge up close :

http://www.physics.mun.ca/~sstamp/images/al_edge_profile.gif

This edge hits about 16-18 degrees at max, sweeps back quite quickly falling under 10 degrees at 0.075" thick, about 5 degrees at 0.175" thickness and then hits zero shortly after. It is at the limit of what I would want for a heavy use blade. It is not necessary to be this obtuse on wood work unless you want to be able to do uncontrolled heavy chopping on hard/frozen small diameter wood. Thus it only makes sense for a survival/emergency blade because it may be used in high stress situations when you are not really focused on correct technique, or might not even be able to because of injury, extreme cold etc. .

That they are also strong speaks to the nature of the convex edge

It simply indicates a large cross section, nothing more. You could easily grind a flat ground edge which is stronger. Now if you want to discuss a penetration / strength ratio, then that is different and more complicated. In general at the same level of cutting ability a convex edge will be more resistant to shallow damage as it can afford a final sweep which is above the edge angle on the flat edge profile, but the flat ground edge will be more resistant to deep damage because of the thicker shoulders. The latter advantage though is only seen if you actually exceed the capacity of the full edge which indicates a rather extreme case or a poor design. There are a few other issues like the smooth transition of the convex bevel, however this is a very small effect when compared to the extent of the sweep.

The actual bevel on the tip is irrelevant.

The angle I quoted above was not the bevel of the edge along the tip but rather the taper of the tip itself, which together with the stock thickness and primary bevel curvature specify the tip strength for a specific material.

In a fighter, tip strength is not easily achieved in a flat grind if the knife is to be balanced.

This well illustrates one of the primary advantages of the hollow grind. Strength is proportional to the square of the dimension opposing the distortion, so basically even a small amount of material left at full thickness can hugely effect overall strength. Thus just as you note, a hollow grind due to the large strength / mass ratio offers a lot to those that want neutral blades. However, this is only an advantage by your definition of "balanced", I can name off whole classes of fighting blades that are very blade heavy, the khukuris from HI for example. These are also "fighting" blades with a lot history, proven in combat. The exact same blades also do very well for utility, both heavy and light.

I don't make utility knives either, but I suppose one could use almost any grind on one and it would produce a useful knife.

Utility knives, quality ones, demand high performance, as they are used and judged simply by how they perform, nothing else. You can sell a tactical knife on name only such as "XXXX - official knife of the US Navy Seals", trying something like that with a utility knife doesn't have the same impact at all "ZZZZ - recommended by 9 out of 10 carpenters". The number of threads requesting info for knives used by the "Navy Seals" is far larger than those by tradesmen. Implying that geometry is less critical on utility knives is a pretty big slam on those makers who just produce "utility" knives and have spent quite some time devoted to making a better blade, using the optimum materials and profiles to produce a blade with the highest combination of cutting ability and durability, and I know quite a few of them.

In regards to cutting different materials. Materials effect a blade in three basic ways, a certain amount of pressure is needed to rupture the material (start the cut), a certain amount of force is needed to overcome the friction against the flats of the blades, and a certain amount of force is needed to wedge the material apart. Now while it is true that different materials have different abilities in these three classes, the cross over is huge and as well there is a "backwards cutting ability" factor. For example a blade that cuts well into a a hard material, with high internal friction, and strong internal bond obviously does even better on a soft material, with high internal friction, and strong internal bond. The latter is not necessarily true however.

rockspyder :

The blade is hollow ground, but the hollow grind goes away about a half inch from the tip, at which point the knife uses a flat, or possibly even convex, grind. It is supposed to be for tip strength, but it looks to me like it would place a massive stress riser at the point where the hollow edge grind stops.

Busse does the same thing, he uses a final convex grind. Yes, there would be a strong stress riser if the transition from hollow to convex is abrupt, however there is no need to leave this sharp, if the transition.

-Cliff

 

[Jerry Hossom]

Cliff, it's difficult for me to deal with partial truths. NONE of the knives you listed PASSED the same tests. NONE were able to cut through a leg of lamb as have ALL of my knives that have been tested. Several were only tested on some of the series of tests that Gaucho ran, so the comparison is incomplete at best. At least one sustained damage in the tests, and one was a retest after earlier damage. Unless the knife is capable of making the requisite cuts, it's edge durability is irrelevant. You could make the same literal comparison by testing a hammer against the same targets and say it "passed".

Further, in all test series that Gaucho has done with my knives, he has added tests to those he has previously done. It usually changes according to what he has on hand. In his last tests on one of my knives, he added a cocoanut to the target mix. In another he added dry bamboo. Another included 1 x 2" hard maple. Etc.

As for edges being obtuse. I gave you an approximate angle on one ATS-34 blade at some point in time, and might have said another was about the same (the latter though was a sword I think). That would hardly amount to "specifications you have listed for your blades". I don't have any specifications listed that I'm aware of. In fact each steel, every blade design, and the intended uses dictate which edge geometry is best. Regardless, my capacity to measure a parabolic curve is limited. And in any case, drawing one is a lot easier than making one, especially to said drawing...

And speaking of "said". enough said.

 

[dogboye]

Originally posted by Jerry Hossom
I THINK Bud does that by doing the hollow grind first and keeping it dead level as opposed angling it towards the point. Basically the grind remains level with the spine of the blade instead of the edge, so the hollow exits the front of the blade below the point. Once that is done, he puts a chisel grind on the front to shape the point using a fairly "obtuse" angle, for strength.

It should be strong and I really don't see why there would be any unusual stress risers from doing this. There aren't any spots where the edge or spine are sharply indented.

Hmmm... I guess you're right. It's hard to tell from this picture. It just seemed to look/feel pretty funky in he hand when I picked it up at the Chesapeake Show last Sunday. I thought the design was pretty neat, though.

 

[Jerry Hossom]

That's not the Nealy design I thought you were talking about. He has another along the lines I described. Still, I see no concern for stress risers on that blade in the pic.

 

[Cliff Stamp]

Jerry :

NONE were able to cut through a leg of lamb as have ALL of my knives that have been tested.

Do you really expect a small folder to cut through the same amount of tissue and bone as a large bowie, and further judge it as a failure because it doesn't? By the same reasoning, all of your bowies would "fail" if you tested against a full length sword. I don't recall the work done by Mario indicates for large bowies that the performance was so dominant in favor of your blades over all other customs he tested. I do recall the one A2 custom that didn't do well, nor its replacement from the maker. Some specific threads would be nice referencing the exact customs that he used which showed lower durability than your blades and had the same or lower level of cutting ability.

Based on some simple principles, it would seem to me that the optimal profile for flesh and bone would be a dual convex taper. That is commonly what is found on many parangs which serve both as weapons (flesh and bone part) plus as utility blades for both very thick and soft vegetation as well as very hard woods. I discussed this with a maker awhile back who had tested this on various large blades (up to 20+") and this was what he found. He had some very high demands for durability though which probably skewed his perspective away from hollow and flat grinds as one of the tests he had for large sword class blades was full heavy contact against other swords and he would test this by banging his blades off of an anvil.

I have however also heard the same thing from another maker who also claimed to have modeled it numerically as oblate curves, which is rather interesting. I have also seen such behavior on the few dual convex blades I have as opposed to the flat and hollow ground blades. They cut through very thick material in a very smooth flowing motion as opposed to the flat and hollow ground blades. There were other matters of geometry that were complicating the issue though as well as issues with handles and such, balance and mass etc. . Of course, we are speaking here of comparing optimal cases, it doesn't take much to be off for a blade to perform poorly and nothing is gained for free. For example even though the dual convex profile should cut smoother than a flat ground blade of similar stock, the flat ground one will be stronger, and everything has to be done right on the convex one as if the edge is a little too thick, or the handle a little off it will be swept away by the flat profiled blade.

There is a rather critical factor in regards to the weight issue as you noted. Neutral balance really favors hollow grinds because it allows a lot of cross section in the critical areas without a lot of mass and thus you can get really light and neutrally balanced blades that are still very strong. However as noted in the above this just reflects one perspective on what defines a quality fighting blade. There are many differing schools of thought on this matter as well as blade performance in general. For about the most extreme opinion of heavy use blades (utility + weapon) see the HI forum. One of the most telling statements I have read there was the reference to the Battle Mistress from Busse Combat as making a good karda, which is the smaller utility knife that accompanies the main khukuri blade. On any other forum the Battle Mistress gets regarded as pretty much an upper limit in heavy, blade balanced, blades, but it is very light and much more neutral balanced than say a 22" Ang Khola.

Flesh and bone though would be pretty optimal for a deep flaired hollow ground blade as flesh isn't binding thus it won't wedge on the blade and since the bone is under tension in the leg of lamb it will open up during the cut. The latter is also only critical when the thickness of the bone is more than the width of the blade. It would be interesting to see the leg was suspended horizontally and a cut made straight through the bone at a 90 degree angle, that is a worse case senario for a stationary target, for a moving one it gets worse. For the horizontal bone, the tension would tend to collapse the bone around the blade, the exact opposite behavior of when it was vertically suspended. This is why people get a lot of damage when cutting bone as that is how it is done on most game (horizontally).

In his last tests on one of my knives, he added a cocoanut to the target mix. In another he added dry bamboo. Another included 1 x 2" hard maple. Etc.

I thought cocoanut would be much harder on a blade than it was, seeing as how people have referred to it, maybe the ones I had were just soft, I did buy them from a few different places though at different times. I don't see how they could be bone class, and bamboo and maple certainly are not. In regards to the cutting ability demonstrated, you would have to compare it to other blades performance obviously to get a meaningful result.

My main point in the above though is twofold, first off, you could design a set of tests in which say a WWII khukuri (or whatever) would outperform one of your fighting bowies. This is only false if you think your blades outperform all others in every aspect of performance. What does this prove? Well simply that every profile and material is optimal at something. This is why I try to include work which illustrates where a blade is strongest, and where it is weakest. The reader can look over the entire spectrum of performance, see where the blade succeeds and fails and judge based on what they require if it is suitable as only they can make that judgement.

Secondly, in the past you have expressed pretty much the opposite opinion in that tests should only be done to showcase the "intended" useage of the blade. It is straightforward then on any blade that fails a test under such guidelines as defined by the maker, they can simply say the blade wasn't designed for that and void the results, and since there is not an accepted set of testing standards, that is a reasonable statement. Furthermore, you also can't judge a blade that fails (or passes) a set of tests as being suitable for a set of tasks (in general), as this only means they are suitable for someone who has the same viewpoint as the person who chose the tests as again opinions differ.

This is why I will do tests that others are curious of or showcase, even if they don't reflect what I am necessarily interested in or require of a blade, the wider the performance range the better. Mario's reviews for example have made me interested in hanging bone cuts, even though I don't really ever really have to do that, simply because he does it so easily and I am interested in figuring out how much is due to his skill and how much is due to the blade. Same thing for the ABS cutting competitions, I have spent a lot of time trying to duplicate the extreme performance they illustrate so easily, without a lot of success I might add, but hey if it was trivial it wouldn't be fun. Both offer a lot of valuable information.

I don't have any specifications listed that I'm aware of.

Off hand, three statements come to mind; one in which you described an edge as bullet shaped at ~22 degrees, another was were you noted you would not grind a "tactical" knife with an edge angle less than 15 degrees, and another where you noted a knife with an edge of 0.02" behind the bevel was very thin. My perspective is very different, for one, I would not have an edge of ~22 degrees on anything. The thickest I have now is on a 3/4 axe which is about 16-17 degrees per side right at the tip and flairs out quickly to under 10. Based on some abusive cutting I did with that last weekend, it is too thick as it didn't get damaged. Which is not surprising, as books on the subject when axe use was common will note about 25 degrees total being an upper limit, depends a lot on the user and type of wood of course.

For a large custom bowie, I would set 0.02" thickness behind the edge as a max, with a more acute angle than an axe obviously, as the impacts are far less energetic. For any cutting blade, 15 degrees is also about a maximum and that is a pretty harsh use knife. Currently the only blade that I have that is as obtuse as that is a small "survival" class knife which I have left that obtuse because I want it for emergency usage (splitting knotty wood etc.), cutting dirty materials etc., however the edge on that knife is about 0.005" thick behind the bevel. Of course if the edges on your knives are significantly more acute that the above would imply and more importantly are more acute than the other blades you refer to which got damaged, clarification would be in order.

All of the above of course assumes that the steel has been well chosen to suit the blade and heat treated accordingly.

drawing one is a lot easier than making one

The above are not drawings, they are drafted to scale off of measurements made along the profile. In regards to time, it is far faster (and easier) to grind a convex edge than measure it. The following profiles :

Edge :

http://www.physics.mun.ca/~sstamp/images/edge_profile_parrell.gif

Full blade :

http://www.physics.mun.ca/~sstamp/images/blade_profile_parrell.gif

required 30 measurements of both thickness and width, one going up and then another going back with an average to reduce parallax error. It took me longer to put the convex edge bevel on the blade. It came with a flat edge of about 22-24 degrees which I just blended into the primary bevel. The blade is 14" long, forged 5160. I would rather do such grinding any day than take the measurements as they are tediuus and require much more care as you can go by feel when grinding. I am just referring to edge grinding here, primary bevels are very different, much more difficult and obviously much more time consuming. In any case, I fail to see what the time has to do with anything anyway.

-Cliff

 

[Jerry Hossom]

In fact Cliff, one of my 8" fighters outcut most of the bowies tested, having transected the leg of lamb edge to edge with little difficulty. That particular knife weighed just 8 oz.

On the bolo/parang edge profile you show on your site, do I understand correctly that the blade expands in thickness from the edge to almost 0.4" in the distance of 0.5"? If so, and that began life as an angle of 22-24 degrees, you must have much bigger degrees there than we do here. Perhaps that is our problem...

 

[larry harley]

ther is no BEST

it depends on what u r goning to cut
straight razors r not cannel ground and machetties r not hollow ground
harley
www.lonesomepineknives.com

 

[dogboye]

Originally posted by Cliff Stamp
.....Flesh and bone though would be pretty optimal for a deep flaired hollow ground blade as flesh isn't binding thus it won't wedge on the blade and since the bone is under tension in the leg of lamb it will open up during the cut. .... It would be interesting to see the leg was suspended horizontally and a cut made straight through the bone at a 90 degree angle, that is a worse case senario for a stationary target, for a moving one it gets worse. For the horizontal bone, the tension would tend to collapse the bone around the blade, the exact opposite behavior of when it was vertically suspended. This is why people get a lot of damage when cutting bone as that is how it is done on most game (horizontally). ....
....Mario's reviews for example have made me interested in hanging bone cuts,... ...simply because he does it so easily and I am interested in figuring out how much is due to his skill and how much is due to the blade. Same thing for the ABS cutting competitions, I have spent a lot of time trying to duplicate the extreme performance they illustrate so easily, without a lot of success I might add, but hey if it was trivial it wouldn't be fun. Both offer a lot of valuable information.

Based on this information, wouldn't it be much more useful to the readers of your reviews to just do the horizontal, 90 degree bone cut instead of trying to duplicate Mario's tests, which you already say are quite possibly so successful due to his skill? Speaking for myself, I would much rather hear how a particular knife reacts to striking bone in a manner possible with dressing out game. While Mario's tests are neat to read, and very much showcase the power of a blade (and/or his skill), half the time I don't even know the cut he is executing. I enjoy reading them, but a lot of their content escapes me. Just a friendly comment...

 

[Jerry Hossom]

Harley is absolutely right! That was my original point (seems like years ago) that you just can't generalize about what is or isn't best. It depends...

 

[Samurai6]

Rockspyder:

Jerry's knives are fighting knives. Combat style cutting is the only appropriate way to determine their efficiency. It would make no sense at all to test them as a hunter or a bush knife. A pure fighter is a highly specialized design, like a boning knife or a skinner. As a person who studies martial bladecraft, I have no problem at all envisioning Mario's tests. I know exactly what he is describing.

Also, when the same tester tests multiple blades with the same technique and the same medium, any significant differences in the blade performance would most logically be attributable to differences in the blades. If two different guys using two different knives get different results, you don't know if it is the tester or the knife, but if one guy does the testing the same way twice, any large difference in results is going to be due to something besides the tester.

 

[dogboye]

Steve, I agree completely with everything you say, especially about Jerry's knives being fighting knives (I have one of them). Well, actually I can't agree with what you say about understanding exactly what Mario is doing, but I already said that.

Go back and read my previous post again. Maybe I left something out, but I intended to imply that Cliff attempting to duplicate Mario tests is useless to most of us, since Mario does them fine, and he already says a possibly more useful test for determining blade design/strength/execution is the horizontal bone/90 degree slash.{edit - Damn, can you say run-on sentence?! } I meant with different knives, not Jerry's, and not to test the fighting style of knives. More, different tests are more useful; not duplicate tests.