problems with hemp rope cutting as a test of edge retention

[Jeff Clark]

Shane has some interesting points. To be scientific you need to provide enough information so that someone can replicate your experiments. That's being pedantic in our casual circles, but you at least want good enough control and record keeping to be able to replicate your own experiments after a significant interval. Using rope that is made to some well controlled spec would be nice (probably more expensive). Controling for moisture is likely another important point. Rather than working with frozen rope you might want to bake it a little or run it in a vacuum chanber (if you have access to one).

I have started to suspect that random lubrication can be a significant factor when measuring cutting performance in a medium with appreciable thickness. You may want to wipe down your blades, test materials, and fixtures with clean alcohol or acetone to prevent wax or oil influencing your results.

I have also been wondering about how you control the effect of your rope twisting or rolling as you run your tests. This would seem to add second order effects to your measurements. Maybe you could get more uniform results if you tested on something like canvas straps.

 

[Cliff Stamp]

Jeff, the hole would be the most stable, however there might be a problem due to the rope not being so stiff that it would readily cross the gap and go into the hole readily. Due to being bought in a roll, it tends to naturally kink very easily. It is an interesting suggestion though, the block is easily wide enough so that I can drill the hole on one side and still have the slot on the other.

I have started to suspect that random lubrication can be a significant factor when measuring cutting performance in a medium with appreciable thickness.

I looked at this a few years ago when cutting wood, I lubricated a few blades that all had similar binding in woods, and could not tell them apart in use. Maybe on a teflon coating or similar. I never looked at it in detail as someone else already did. Lots of testing in this area has been done on wood. The question was raised as to the benefit of polishing the whole face of a chisel as opposed to just the edge.

Tests ran saw no difference unless the wood was cut cross grain. I have looked at this on several occasions, and the magnitude of its effect is minor compared to the two major forces; what is necessary to cut the material, and what is necessary to push it apart. There are exceptions however, cheeze for example is *very* sticky.

However here you are looking mainly at the surface of the primary grind and not the edge, as the relative width ratio is very small. It depends however on the nature of the primary grind and overall extent of wedging as well. Deeply hollow grind blades only wedge at the edge for example.

... the effect of your rope twisting or rolling

The rope is pinched with the left hand during the cut, thus there is no movement during the draw. The rope is always positioned so that one strand of the cord is facing up directly perpendicular to the knife edge. It can also be positioned so two strands are spread out over the draw. The latter is better as it is harder to cut, but I started doing it the first way by chance, and didn't notice the effect it had until I had done a lot of cutting, and so kept doing it that way just to be consistent.

Shane :

[type of rope]

... there are a BUNCH of differetn kinds of MANILLA rope!

Manilla hemp is a specific type of cord as it specifies a type of plant, though I would imagine you could get different braids and get it weaved with other materials. As I have noted in the past, I buy it in plain rolls from KENTS, a local hardware store, no plastic internals or anything else. I have tried it from other stores it looks and cuts the same.

If anyone wants a sample so they know exactly what I am cutting, all they need to do is drop me an email with thier address and I'll pop a piece in the mail. This offer has been open for several years on the various threads and cord I use for reference cutting.

Did you include the humidity on the days you were making the cuts? Sometimes sweaty rope cuts different?

The rope cutting is (except for the early runs) taken as an average of at least three and as high as five runs each on a different roll. This cutting takes place over a period of a week or two so effects of humidity will in general be averaged out as will other small random factors like variances from one rope roll to another.

I have not noticed any systematic difference in the effects due to humidity, though it is in general *very* dry around here. It is an interesting point though, I could just soak the rope and see how it cuts when wet, as well as periodically as it dries out. This could have an effect on edge retention depending on how much the fibers would swell and possibly soften.

As for the cutting I have done, it rarely gets humid around here, and when it does, I don't do any rope cutting for fairly obvious reasons. Most of the stock testing like that I do in the winter. In the summer, when it does get slightly humid I am usually in the woods, so generally my knife work is focused on large bush blades and axes.

[backing board]

I figure it has an affect on the edge, and can be considered as part of the test.

Sure, my point wasn't that it wasn't an invalid test, as noted anything is informative as long as references are used. The point made was simply on how it is interpreted. Specifically it is very biased towards edge geometry so much so that this factor can mask the properties of the steel. Radically slim down the knife and it will not only cut much better, but stay sharp much longer for the reason described in the above.

Do you make knives?

No.

-Cliff

 

[shane justice]

Cliif,
As I suspected from your eply you are not a knife maker.

I havce read your review of the Camp Tramp and am amazed at the inconsistancy of your methods and comparisons.

What is light thread? What does it measure?
What is blazing sharp? Is that a scientific term?
You use the term "decent" alot...but for different analogies?
You compare the edges of a Tramontina Bolo to a Camp knife?
The Tramontina is made to be sharpened with a file for jungle use..the camp knife is a totally different tool?!? But because they are the same length you are comparing them? A machete sharpened to a 600 or better grit will dull in a heart beat! It was not made for such a fine edge! HELLO!

It became immediately apparent that you use no consistant mean of medium for testing. You mentioned light thread,3/8" hemp,phone books,hard wood dowels....and newspaper...where is the attention to detail here.

What exactly is a high polish?

I couldn't keep reading that "REVIEW"? ONce I read that you were comparing a Swiss Army knife to a Camp KNife to a Tramontina Bolo
I began to wretch. What's the idea?

Are you trying to prove that a very thin edge cuts better than a thicker one? Did I read that? Are you going to compare a filet knife to a chainsaw next?!?

Cliff, until you are ready to walk the walk...go home and be quiet.

Shane

 

[Cliff Stamp]

shane :

As I suspected from your eply you are not a knife maker.

Which is a public and well known fact, there isn't much of suspect.

What is light thread?

Espirit light baisting thread, stated in an earlier review and referenced in posts.

What does it measure?

Cutting it measures push cutting sharpness, influenced slightly by geometry.

What is blazing sharp?

The statement from the review :

"The NIB edge sharpness was a little less than optimal scoring 207 +/- 22 g on light thread. A blazing sharp finish can approach ~100 g."

Optimal would have been a more precise term. Most high end production blades like Spyderco and Cold Steel have this level performance. It is when the blade starts to be able to shave hair above the arm.

Colorful terms like blazing are used on occasion, mainly for illustration. Like "the knife parted the rope like water". This of course isn't an exact description, blazing sharp doesn't really meant the knife edge is actually on fire.

They are used mainly to give some context to the numbers and such, and to make the reviews a little less dry.

You use the term "decent" alot...but for different analogies?

It generally means average, performance which you would not rate a negative or a positive. Reviews generally contain very subjective elements along with the stock work. It is mainly for perspective and only useful in comparison.

The Camp Tramp for example works decent as a brush machete on woody vegetation, it doesn't have the length I find optimal for such work (12-14 inches), but isn't so short that you heavily suffer power or reach for limbing.

If you go any smaller, you start to have to bend far too much, and you can no longer chop off branches without requiring multiple hits a lot of the time. Yes a lot of this is vague and subjective. What is decent to one person is horrible to another.

Some of the early reviews didn't have any of this type of commentary in them, it was added on request. There are less subjective performance descriptions for those interested.

You compare the edges of a Tramontina Bolo to a Camp knife?

Yes, as the scope of work overlaps to some extent.

The Tramontina is made to be sharpened with a file for jungle use..

Many "jungle" natives do not use a file. Stones are common in Malyasia for example, and the blades finished honed on a fine stone, not sure of the grit of the stone, the maker didn't know it, just started that two grits were commonly used coarse and fine. It could be raised to a fine shaving finish with some stropping on leather, so I would assume something beyond 1200 DMT. The stropping was generally done just for cutting palm fruit, the parangs for general work were generally left with the fine stone finish (far beyond 600 DMT I showed the maker my hone) and would be sharpened once a week. If you want a sample of the stone I can give you the contact information for the maker.

A machete sharpened to a 600 or better grit will dull in a heart beat! It was not made for such a fine edge!

For the comparison referenced, the blades were chopping wood. For such work very coarse edges don't penetrate well (its just push cutting) and they degrade quickly and you lose a lot of metal as the microteeth break off. I initially used the Tramontina with a file and a butcher steel, this is noted in its review. But later I switched to various hones. The aggressive finishes however can be of benefit on some soft vegetation as you are doing slicing work.

It became immediately apparent that you use no consistant mean of medium for testing.

You use different things for different aspects of performance. You would look from one review to another to check for consistency in materials. If you do this you will note this is true to some extent, but the reviews are evolving. Some of the stock tests are only recent.

You mentioned light thread,3/8" hemp,phone books,hard wood dowels....and newspaper...where is the attention to detail here.

The specifics of each were given usually in the first review they were mentioned, which usually went into detail on method. I did intend to have a page on the specifics of the testing which would be linked to in the reviews, and a rough draft was written, however I never kept it updated. I am actually doing that now, but it will take some time before the reviews are all updated to reference it.

The hardwood dowel is a one inch round piece of basswood by the way. That test is quite problemative as it is very dependent on my strength, and I got significantly stronger as I did it often. I have to go back and update some of the older reviews as I recently retested some of the blades and the performance has changed significnatly for this reason.

What exactly is a high polish?

Generally above 600 DMT you start to lose slicing aggression quickly and the edge is more polished than aggressive. In the reviews it generally means very fine ceramic, which approachs the finish of CrO.

Once I read that you were comparing a Swiss Army knife to a Camp KNife to a Tramontina Bolo I began to wretch. What's the idea?

Guaging scope of work and relative performance in various areas.

Are you trying to prove that a very thin edge cuts better than a thicker one?

No Mike Swaim already did that on rec.knives many years ago, and also investigated the effect of various grit finishes. Joe Talmadge extended the work and made specific numerical comparisons before and after. This is referenced in several of the reviews, and many posts I have made in this area.

I have never claimed to originate commentary of these aspects. Neither did those two individuals, Mike however discovered the effects independently, though you can find older references. Alvin Johnson also talked a lot about the effect of edge geometry on cutting ability on rec.knives in the 90's in rec.knives.

Are you going to compare a filet knife to a chainsaw next?!?

Probably not, there isn't a lot of overlap there. Phil Wilson has chopped through a 2x4 with one of his fillet knives though (a test of toughness mainly), you could ask him if you are interested in how efficient it was compared to a chainsaw.

Back to the rope cutting :

I also forgot to mention, that besides being influenced by geometry, it also compounds the rate of blunting. Thus any difference in performance between two knives is elevated. As one knife starts to requrie more force, it then impacts the cutting board harder, as it does it now of course blunts faster (which makes it impact the board harder, which makes it blunt faster ...).

Thus the ratios for performance I have quoted in the past are artifically elevated, specifically if the blades were not used against backing materials, the performance advantage to the various blades (even of similar geometry) would not be as great. I am not sure of exactly how much of an effect this is, I should buy a couple of identical knives and try both methods to see.


-Cliff

 

[Jeff Clark]

Shane, Cliff is not simply comparing knives he is trying to quantify how basic design elements of knives effect performance in several different dimensions. He is taking advantage of existing knives which offer a vast range of materials and configurations as a source of experimental subjects. There would be many advantages if he had access to a full manufacturing facility, unlimited time and materials, and a materials science lab. Then he could make dozens of blade patterns, using dozens of alloys, sharpened dozens of ways, and run thousands of closely controlled tests. He does his best using dozens of existing models of knives, made from maybe a couple dozen alloys, sharpened a couple dozen different ways.

Many things he has explored are fairly familiar-- yes thinner blades slice more efficiently than thicker blades, but Cliff will try and quantify how much better and in what particular usage. He will tell you things that some of us are less familiar with--a thin machete will wedge into a thick log and will be harder to remove than a thicker tapered blade. In some areas he is really breaking new ground for common knife fanciers. For example there has been a common rationale that thicker edges are stronger and will remain sharp longer than thinner honed blades. Cliff has been quantitively measuring the opposite to be true. Not only do thinner edges out perform thicker edges when first put into service, they commonly maintain that advantage during use. This is provocative enough a revelation that he is double checking some of his methodology to insure that he is right and is not exagerating the effect.

Cliff is doing what engineers and scientists do. They try and breakdown complex systems into components and make measurements. Next you try and understand the interactions and synergies involved when you put the components together. Finally you publish your findings so that others can apply them to advance the state of the art or so that informed consumers can base their purchase choices based on relevant design features. If you are a potential custom knife buyer, reading Cliff's reports helps you to decide what you want to ask for when you go to your knifesmith. Cliff is trying to do his self-appointed job as knife researcher. I guess that like Ben Franklin with his kite, sometimes he's going to attract lightning. Some people find attracting lightning to be productive. Other's tell them that they are foolish. Some people are better with lightning than others.

 

[db]

First let me say I do find some of the things Cliff talks about very interesting. Cliff keep it up. But come on breaking new ground? Thicker edges are stronger, and thinner edges do cut better, but what one lasts longer depends on what is being cut. I don't think that is a new idea or ground breaking. Please don't and try and convince people that some home testing is science, and there is no bias in a test by a human. Or even a small sample of a knife can be very accurate.

 

[Jeff Clark]

db: Yes, absolutely, some home testing is science. It is not where you do your tests that makes it science, it is how you design your tests, perform, them and disseminate your results. What Cliff is doing isn't pure science, or theoretical science, it is experimental applied science. These tests would generally be considered engineering experiments. They are similar to tests that I was assigned to perform in the basement of the old Bridge Physics at Caltech. We were building submillimeter wavelength telescopes and we had to test components we were using and fabrication processes. We were not deriving physical constants to 10 digits of accuracy, but we needed to be sure we could keep our reflector RMS accuracy within spec when we hauled it out into the field. This was in the same building where Millikan first measured the charge of an electron with an oil-drop experiment that you could set up at home (if you used sufficient care). I believe that Cliff is a physics grad student and has a serious interest in doing useful experiments.

 

[brownshoe]

Right on db. It's not science. Often it's irrelevant testing Why cut carpet with a skinning knife? Why dress a hog with a SWAT knife? Clark, you may believe Cliff is a physics grad student, but what does that prove? Not much. Ever hear of cold fusion? Biggest science fraud of the late 20th century and a lot of very large brains were fooled by that one.

 

[db]

I am sorry , I didn't mean to imply you need 10 digits of accuracy, to be science. I stand by my last post. I'll even try to clear it up a little. I don't beleive Cliffs tests are anything even close to science. Are they usefull? Not my call, to some they may be, and to others they aren't. What do I really care? I still think thick edges are stronger, thin edges cut better, and it depends on what is cut as to what one holds an edge better. And I beleive that isn't ground breaking but fairly common thought.

 

[Jeff Clark]

db: The scientific method was designed to correct "common thought" (aka "common misconceptions") and to quantify how things work. Running tests can help you find how thick is "thick enough" for a blade used to chop or to pry. Or the tests could tell you how tough an alloy is required if you want a thin edge on your hunting knife, but need to be able to chop bone. Cliff runs many tests where he anticipates particular results and gets surprises. The surprises are where you really learn things.

brownshoe: It would be nice to have a year round supply of fresh elk carcasses for running durability tests on hunting knives, but few people have that luxury and the inclination to run the tests. Carpet is just a convenient material that offers high abrasion with moderate hardness. It has a slow enough blade wear effect that not all blades are wiped out on the first cut. It gives you wear that is slow enough that you can rank the edge durability of blades by how much material you have to cut before reaching a certain degree of dullness. On the other hand the wear is fast enough that you don't have to spend days cutting material before you get perceptable results. We call tests like this accelerated life tests. It is very common to run accelerated tests in engineering circles. Cliff has become concerned that his test is too accelerated and is looking at refining his methods. Thats the way that you do these things. If someone provided him with a gross of pig hides maybe he would switch. The tests aren't perfect, but he is constantly looking for ways to make them better.

 

[db]

Ummm, really? I didn't realize I needed someone elses test to tell me how thick or thin I should use for my edges. I wonder if just useing a knife could let me know? Is it posible that all users are the same? Could the same knife preform differently depending on who the user is? Maybe common thought is the wrong term maybe I mean to say common sence. I don't know. Like I said before if the info is useful for you then great. Just don't try and shove it's science or some new ground breaking idea to me.

 

[Zal]

Cavemen rubbing sticks/rocks/whatever together to make fire wasn't science, dag nabbit.

. . . but it did give us a nifty breakthrough. Whee!

 

[Jeff Clark]

Nobody wants to dictate how anybody builds or buys blades. The idea is to provide information that is sufficiently accurate to be useful when someone wants to try something new. You can find recommendations on the net for blades suitable for skinning an elk, but you might have to make some guesses if you wanted to field dress an American bison without stopping to resharpen in the middle of the process. You need to pick an alloy, blade length, blade thicknes and bevel grind, handle shape, etc. Cliff tries to tell you how the individual components perform so that you can select components when you go outside your area of personal experience. The idea is that you don't have to guess as much and don't have to try as many experiments of your own when you try something different. If he helps you to make a few choices before you start spending time and money his work has been useful. For example if he helps you to decide between A2, D2 or M2 for a particular application he leaves you more time to decide whether you want your blade flat ground, hollow ground, or convex ground.

 

[Cliff Stamp]

brownshoe :

Why cut carpet with a skinning knife?

The skin of some animals can be similar in grit composition due to dust and dirt.

However some knives are used for tasks which have no connection to their indended design. This is because the reviews are not intended to be solely for the purpose of grading a knife. Mainly they essentially are work I have done exploring various aspects of performance. At times I get specifically asked for a review, which I can do, but rarely limit the work to that.

For example the Deerhunter were supposed to be just used for destructive work as requested by A.G. Russell. I used them for lots of other work as it was a chance to work with near idential blades geometry wise in different steels.

Thus if I want to look at aspects of edge retention in high wear situations, I would use a fillet knife (or anything else) to cut carpet (or whatever) if it had a steel of interest, even though the fillet knife isn't going to experience anything similar to this in use. For the argument raised to have merit, the knives would have to be graded poorly because of performance in tests not in their scope of work.

Db :

I didn't realize I needed someone elses test to tell me how thick or thin I should use for my edges.

Obviously if you have the money and time to buy any knife you are interested in and do the work yourself to evaluate the performance this is the best method, and of course then don't need anyone elses opinion. However I read lots of reviews because I don't have the time, nor wish to waste money, on sub-par products, thus the reviews are used to tighten the scope of work I do, and it is therefore far more productive.

Jeff :

The idea is that you don't have to guess as much and don't have to try as many experiments of your own when you try something different.

Essentially. The main goal is just to allow more informed questions. For me, it was always a way to be specific with the maker. For example when interested in a custom bush knife I referenced the performance I had seen in the other blades I had used, those reviews could have easily been done by someone else and used in the same manner.

Back to the rope cutting :

Three trials were done on the Pronghorn, free cutting the hemp, no backing board in a box similar to what Jeff described. The edge retention was much longer than with the board as expected. Another blade was also used for two trials as a reference. Since the trials ran longer, this exausted the supply of hemp.

Today I am going to pick up another three rolls, and do another few runs with those blades and try a couple that should have very high performance (CPM-10V 62/63 HRC) and see what happens. I am also going to try a before and after run on a blade with extensive geometry modifications and see if the edge retention is consistent.

That would have been the logical thing to do first, however I was too curious about some other blades to wait. The only remaining geometry factor is the effect on the dynamics of the rope being cut, twisting of the edge on a small scale and similar. However, I would however be very surprised if that was such a major effect it could cross steel performance, if this is the case, then it makes a very strong statement about steel quality vs geometry.

The ironic thing is that due to past work, I actually don't have any knife on hand which can actually be reduced in edge thickness as I have ground down everything I own to minimal edges. I have to shop around at a second hand store and find some worn out knives with thick edges to see how any modificaton effects the edge retention.

The other factor I forgot to mention is a product of something I mentioned before, smaller angles produce greater depth of microserrations with a specific grit and are thus more aggressive and last longer. This can be a factor if you sharpen all knives to the same angle *IF* the relief angles are very different *AND* the secondary bevels are very slight, one to two passes per side.


However this difference seems to be removed if you hone the secondary bevel long enough to that it forms a distinct bevel on its own. This doesn't require much sharpening, 10 to 15 passes per side.

The other point I wondered about was that could thinner blades not actually be any sharper but simply score better on the the tests of sharpness I used. I checked this in several ways. First by measuring the initial sharpness (and they all scored the same), and second by testing the sharpness along the way periodically by various commonly used tests such as paper cutting and hair shaving. It doesn't seem to be a factor, and you would not think so based on the very reduced amount of the blade that the material "sees" in such cutting.

-Cliff

 

[Cliff Stamp]

In regards to Db comment about the results being biased because they are done by a human, there isn't a lot of scientific work today being done by robots, this doesn't mean it is all biased.

All measurements at some level are influenced by the people doing them. What is critical is to estimate the level of this influence and thus bound the performance. You look at how the work is being done and take steps to minimize the outside influence, and bound what can't be removed.

A fairly classic example, all measurements used to be taken on analog devices. All readings were subject to human judgement, this didn't mean all science was biased before the digital age. The solution was to estimate the sources of error (parallax mainly), and bound them in the recordings.

Many measurements are still being recorded on analog devices, and even the digital ones are often initially calibrated using analog machines.

-Cliff

 

[Gator97]

Originally posted by db

Ummm, really? I didn't realize I needed someone elses test to tell me how thick or thin I should use for my edges. I wonder if just useing a knife could let me know?
Does that mean just by looking at the knife or its picture you alredy know how it will perform at a given edge angle/type? Or you always buy and test? Former I really doubt, and the later is too expensive I think

 

[brownshoe]

Cliff, you are amazing. You claim that using a knife to cut something it wasn't designed for is a good test because (a) you say carpet > hide and (b) the knife didn't fail the test. By the way Clark, carcasses to cut can be found in many places, just go to your local animal control.

Cliff, your analog vs. digital analogy is off base. Analog devices, such as a dial, have some human estimation involved, but the person also realizes that the measurement is not exact. Just because you get 8 significant figures in a measument doesn't mean it is more accurate than the original 2 significant figure analog readout.

What is the quantitative definition of sharpness to be used in testing? If you can't answer that, all your tests are by nature subjective.

 

[OwenM]

Originally posted by Cliff Stamp
If the geometry difference was large enough, this effect would swamp out everything else and allow knives with softer steels which were of lower abrasion resistance to out cut knives which they should have no ability to do at all. Thus the obvious question was where is the performance coming from. Or was there a bias in the results.............However, on knives that don't cut as well, you don't have as much control on the end of the draw, when you approach the very bottom of the cut. Take a knife which you bare need to press on, ~8 lbs on a draw, and you can finish the cut with minimal contact on the resting surface. Take a knife which needs 40 lbs and at the end of the cut you are mashing the knife into the cutting board.

Ignoring the resting surface, I'm just looking at the force required to make the cut. More force necessary with a thicker geometry. That's more force, pressure, wear, etc. on the edge. Looking at 8lbs vs 40lbs on a cut, that's 5x the force, and 5x the wear on the edge. It makes perfect sense that a "lesser" steel could easily outlast one far superior when the edge is only seeing 1/5 the stress due to the difference in geometry.

 

[Cliff Stamp]

brownshoe :

You claim that using a knife to cut something it wasn't designed for is a good test because ...

The reviews are not intended to grade knives and thus many tests will be done to look at other aspects which can be found on other knives which are intended for such use, these can be steel or geometry issues. In fact tests can be chosen which a knife fails to do badly, just to understand why it fails. This is just as informative as seeing why it does well.

Cliff, your analog vs. digital analogy is off base. Analog devices, such as a dial, have some human estimation involved, but the person also realizes that the measurement is not exact.

Of course as are all measurements. What is important is being able to bound the results and present some estimation of the precision. The results I quote from time to time include such estimates and generally only use 2 significant digits, sometimes three. The older reviews contained more, as they were used to store some of the work for my use. A lot of that was trimmed down recently.

What is the quantitative definition of sharpness to be used in testing?

In push cutting, sharpness is due to alignment, thinness of the very edge and extent of contamination (weakened steel, abrasive grit, etc.) . Ideally you would do this under high magnification as Lee did, as any cutting brings in the influece of geometry and thus you are measuring cutting ability, of which sharpness is one factor. You can reduce the effect of geomery by reducing the size of the material being cut, and thus restricting the influence of the geometry.

In slicing, it is those same factors, but also now the depth of the microteeth, and their nature (teeth are also toothed on a finer scale). Sharpness in slicing is dependent on the applied pressure, as the more coarse the finish the more force is required to drive it into the material as well as pull it through. So the rougher finishes need a greater down push to reach their maximum efficiency on a given pull.

For example a 100 grit AO finish cuts most ropes very well, however it doesn't slice thin paper very well as it is too coarse and catches. A 1200 DMT finish slices fine paper very well, but skates over ropes. Generally though, most materials which slice very well with fine finishes tend to just push cut as easily. However I have in the past compared a range of finishes on various materials to show the kinds of perforamance that can be expected.

So if you wanted to measure it, the quanties are just force applied down for push cuts, and this and force on the draw for slicing. With a specific depth of cut, the lower the forces the sharper the blade. With slicing since there are two forces being used, total force applied could be used, or weight them by body mecahnices issues as it is easier to apply force straight down than on a pull.

-Cliff

 

[Daniel Koster]

All science is interpretation.

All results subjective.


Anybody who thinks that there is anything that is ultimately conclusive is naive.

Go on...show me something that is 100% objective and conclusive. Something that can never be improved upon, or studied further.



still waiting...