Sharpness levels defined

[stitchawl]

Using non-standard, non-reliable, and strictly subjective testing, I find an old style Gillette thin double-edged razor blade to be 'sharper' than a newer style single edged Gillette razor blade. I'd like to think that the Gillette company sharpens both to the same level of sharpness using their expensive plasma sharpeners, but I can easily see different results with my tests.

Is it because of the thickness of the blade? That's my guess. Edge geometry.
And the same reason why my fillet knife is so thin and flexible and takes such a wicked edge compared with my Chinese cleaver.

I know how to sharpen. I have the tools to do it. But I see different results with different knives. All are sharp. All do exactly what I need them to do. But all won't carve a hair into a statue of Venus. My Randall Model 15 with the 6" blade won't fillet a fish easily but it will do just about anything else, including tree top the hair off my arm. It too won't carve hair into fine art but it will still shave hair after dressing two deer, a few rabbits, and clean a mess of fish.

We really do need to figure out some sort of standardization for sharpness...

Stitchawl

 

[NotSoSharpBob]

Z-

Good thread and I'm intrigued by all the variables people smarter than me have come up with.

I got the edge tester from Razor Edge and from how I understand to use it I can consistently get the so called 100 points but I'm not even sure I'm doing it right. Although the arm hair test gives me the willys because of my wimpness I think I saw a good scale in Singularity's thread earlier:

Hair scraping sharp
Hair popping edge
Hair splitting edge
Hair whittling

I fully appreciate the differences in hair and the fact that many of us sharpen more than we can grow hair back but most of us have relatives .

Now maybe someone can tell me with 48 year old eyes how exactly I go about splitting or whittlin hair.

 

[stitchawl]

Z-

Good thread and I'm intrigued by all the variables people smarter than me have come up with.

Bob, I've been trying to reach you via e-mail about the pocket sheath.

I got the edge tester from Razor Edge and from how I understand to use it I can consistently get the so called 100 points but I'm not even sure I'm doing it right. Although the arm hair test gives me the willys because of my wimpness I think I saw a good scale in Singularity's thread earlier:

Hair scraping sharp
Hair popping edge
Hair splitting edge
Hair whittling

But... but... but... everybody has different hair!! Blond hair is MUCH thinner than black hair. Young folks hair is often finer than us old guys. Facial hair is different from arm hair, etc., etc., etc.! It's the reason I buy razor blades to shave my neck instead of using my EDC which is sharp enough to whittle hair! (I haven't shaved my 'face' since the day I got discharged from the Military... 41 years ago!)

Now maybe someone can tell me with 48 year old eyes how exactly I go about splitting or whittlin hair.

Argue with my wife?


Stitchawl

 

[unit]

I will suggest that in order to begin a discussion of defining sharpness a person must first define what and how they want to cut...not the other way around.

First off, isn't "sharpness" really a descriptive term used to discuss how well a knife cuts? If not, then what is "sharpness" and what is it good for?

Failure to preface this discussion without placing some statement regarding edge geometry is questionable also.

If you are cutting thick heavy media I will suggest that edge geometry plays a much larger role in how much effort is needed to make the cut than differences between "sharpness" level 1 and 4 on the list you have so far.

 

[Sparljo]

Only two levels really.

Sharp enough
Not sharp enough.

The rest is just gravy.

 

[Any Cal.]

I will suggest that in order to begin a discussion of defining sharpness a person must first define what and how they want to cut...not the other way around.

First off, isn't "sharpness" really a descriptive term used to discuss how well a knife cuts? If not, then what is "sharpness" and what is it good for?

Failure to preface this discussion without placing some statement regarding edge geometry is questionable also.

If you are cutting thick heavy media I will suggest that edge geometry plays a much larger role in how much effort is needed to make the cut than differences between "sharpness" level 1 and 4 on the list you have so far.

+1

I was going to mention something similiar, but on the other side of the coin. If there is a standardized sharpness test, it would still only tell how 'sharp' a knife was, not how well it cut, how long it cut, or what type of cutting it did.

While there are at times a need to know the sharpness of a knife, it is usually best for comparing similiar knives, or wear on the edge, or ability of the sharpener/sharpening media to get a knife sharp. A good sharpness test would be much like knowing the RC hardness of a blade. It would tell us something about it, and we might know what the blade would NOT be suitable for, but it doesn't paint a complete picture.

That having been said, I really wished I hadn't misplaced my "super duper thread holding sharpness tester" yesterday after I finished sharpening and polishing my knife, because I REALLY wanted to know if it was my sharpest edge yet. From the way it cut, I am betting it was within striking distance of decent DE razor blades, but with no way to test???

 

[Any Cal.]

Only two levels really.

Sharp enough
Not sharp enough.

The rest is just gravy.

Too sharp.

Plenty sharp.

Sharp enough.

Not quite sharp enough.

Not sharp.

Been not sharp for a while, now it's really not sharp.



Dang son, don't they teach you anything in school anymore?:grumpy:

 

[unit]

Only two levels really.

1. Sharp enough
2. Not sharp enough.

The rest is just gravy.

I respectfully and wholeheartedly disagree. Level one does not exist

 

[Sparljo]

I respectfully and wholeheartedly disagree. Level one does not exist

Yep... the gravy is tasty thats for sure.

Go and check the paring knives your wife uses to prepare dinner. Its pretty likely they are sharp enough.... or you wouldn't be eating.

 

[zyhano]

Guys, thanks for all the answers and the discussion. I'm kind of typing on my ipad this week so I'm not posting or participating that much, but thanks all of you for the info and explanations.
:thumbup:
I kind of expected this thread to go where it is now when I started this thread. It seems we have a hard time in finding common ground to tread on.

While I agree that things like edge geometry have a role in a discussion about sharpness, I also feel that that just makes for a harder discussion with more variables, less conclusions and more confusio. Because then we should also talk about steel type, carbides, edge shape, angles, heat treat, edge retention, how much/ how long etc.

The question is a simple one.

While defining clouds it was found that with a few basic definitions, a whole lot of combinations could be found describing exactly what a cloud shape was.http://en.wikipedia.org/wiki/List_of_cloud_types

Without going into the underlying mechanics and tools of getting a sharp edge, would it be possible to just define a lot of levels of sharpness used in common conversations by us?

A lot of good ones have been mentioned, for all i care someone comes up with nose hair whittling sharp... As long as we can classify and order it, it would be a good contribution imo.

Yes , we can discuss humidity, temperature and other environmental factors we can not control, but this would be a theoretical issue, i'd like to make it practical, use your everyday references: wood, hair, tomatoes, sandwiches, paper, cardboard etc

A term or word would say something about sharpness in a context, which is meaningful for that context. We can derive from or combine these terms to come up with other combos like: air bleeding hair whittling tomato sawing yellow page push cutting wormhole generating finger poppin sharp (or something like that) and then everybody would know exactly how sharp it is in THaT context. Furthermore, you can then explain how you achieve those results with certain mechanics, tools, steels and other varaibles explained.

It's as simple as trying to come up with a sensible 'sharpness alphabet', that must be something we can achieve right? Or do we accept the situation as is? And speak in terms we all have different associations with?

I'd like to give it a try, see where we end up. Saying we can't do this or too many variables involved, talk about context and standardization are all valid, but they might just kill this idea....

 

[singularity35]

Guys, thanks for all the answers and the discussion. I'm kind of typing on my ipad this week so I'm not posting or participating that much, but thanks all of you for the info and explanations.
:thumbup:
I kind of expected this thread to go where it is now when I started this thread. It seems we have a hard time in finding common ground to tread on.

While I agree that things like edge geometry have a role in a discussion about sharpness, I also feel that that just makes for a harder discussion with more variables, less conclusions and more confusio. Because then we should also talk about steel type, carbides, edge shape, angles, heat treat, edge retention, how much/ how long etc.

The question is a simple one.

While defining clouds it was found that with a few basic definitions, a whole lot of combinations could be found describing exactly what a cloud shape was.http://en.wikipedia.org/wiki/List_of_cloud_types

Without going into the underlying mechanics and tools of getting a sharp edge, would it be possible to just define a lot of levels of sharpness used in common conversations by us?

A lot of good ones have been mentioned, for all i care someone comes up with nose hair whittling sharp... As long as we can classify and order it, it would be a good contribution imo.

Yes , we can discuss humidity, temperature and other environmental factors we can not control, but this would be a theoretical issue, i'd like to make it practical, use your everyday references: wood, hair, tomatoes, sandwiches, paper, cardboard etc

A term or word would say something about sharpness in a context, which is meaningful for that context. We can derive from or combine these terms to come up with other combos like: air bleeding hair whittling tomato sawing yellow page push cutting wormhole generating finger poppin sharp (or something like that) and then everybody would know exactly how sharp it is in THaT context. Furthermore, you can then explain how you achieve those results with certain mechanics, tools, steels and other varaibles explained.

It's as simple as trying to come up with a sensible 'sharpness alphabet', that must be something we can achieve right? Or do we accept the situation as is? And speak in terms we all have different associations with?

I'd like to give it a try, see where we end up. Saying we can't do this or too many variables involved, talk about context and standardization are all valid, but they might just kill this idea....

Agree, but we're also at this point at present. We can't be precise about sharpness levels but I do understand what it entails when somebody says his knife is treetopping sharp or hair scraping sharp. It may not be precisely the same treetopping(I wish) edge mine is but the approximation is good enough to make a meaningful discussion possible.

 

[Any Cal.]

Well worded zyhano.

If I get your drift, you are asking everyone to explain what THEY think of when terms are mentioned. If so:

paper slicing-can make a clean cut through paper with proper technique. Doesn't have to be amazing.

hair scraping-can scrape hair off the skin, even if not well. Will typically scrape bits of skin and then a couple hairs. Will cut paper a bit smoother.

shaving sharp-will get 'sticky' and edge will bite at hair at skin. I don't worry about actually shaving because there are so many variables. Will whisper through paper at this point.

Hair whittling-will whittle a skinny, healthy, blonde hair being held at one end. Obviously, there are a million variables here, just like everywhere else, as a thick hair can be whittled at a lower level of sharpness. Regardless, it is what it is. At this point, the knife will usually pushcut the white pages, copy paper, or cardstock.

Tree topping-this is a bit nebulous to me, I consider it to be when the knife will easily cut hair above the skin. However, direction of the cut, thickness of hair, etc. all make a big difference. I don't think there are many that could make a knife sharp enough for a fair skinned 16 year old kid to consider it tree-topping.

Anyone is more than welcome to tear my definitions apart, agree, or disagree with them...I think that is what zyhano had in mind.

 

[Jason B.]

Putting a general lable on a complex issue is what has made so many missinformed sharpeners. Its why many judge sharpness by the factory edge, its why many slap a steel and think it re-aligns "teeth".

Bad information through the standardized teachings of average Joe has resulted in a world of dull knives. Though having a standard would be nice it only hides you from the truth and complexities of the subject.

 

[KennyB]

Well, the problem is that we're trying to convey relative meaning with things that happen to be very specific. My facial hair is brown and on average .003" - .005" thick, and very curly. Then, if I can shave this hair with no stubble remaining with it being "reasonably comfortable" I consider it shaving sharp. So it's not so much all the variables involved, but more about the fact that there's too much that's subject. Again, hair width and type are variables, but then so is something like pain tolerance, and worse yet it can't really be that well defined and you enter into a tangent of circular logic where you're trying to define the different levels of pain while shaving in order to explain the different levels of sharpness of shaving.

To get right down to something that's very communicable and manageable in regards to hair I would say "hair manipulation". I don't care if you tree top it, whittle it, scrape some of the material off of it, shave, if you can actually cut something as small and hard as hair that's a great edge. However, to put it on the highest echelon may be flawed, because while hair is as hard as copper of the same diameter, if you're shaving against a .005" thick hair how does that really compare to cutting through .002" thick phonebook paper? Because of the variability, the sharpness itself isn't consistent; a blade that can shave your face might not slice up phonebook paper, and on the other hand paper is much softer than hair so an edge that cuts phonebook paper may not cut hair.

I think the scope is much broader than placing the levels of sharpness as "hair splitting" or "hair popping" or even differentiating between slicing very thin paper and hair, because at those scales the variables just matter too much and peoples' ideas of it change too drastically.

To answer your question from before though, I would order it as so in regards to my own hair, but would still just put it all under "hair manipulating"

Hair popping arm or leg hair
Shaving arm or leg hair
Whittling taut facial hair
Shaving facial hair
Hair whittling sharp

In general though an edge that can do anything to hair is usually so sharp I don't really notice any performance difference in most other tasks except when it comes down to blade geometry. I mean, I don't want to debate the theoretical aspect of that, it just makes sense that a box cutter I can't shave with would be better at cutting boxes than some hunting knife I can shave with because it's so much thinner. It seems the smaller the material the edge can effectively cut the "sharper" I consider it for pretty much every other type of task, and once you're comparing between how well it cuts paper or how well it shaves, you're testing on a scope that is so narrow you really won't see a huge difference no matter what because of the variables involved. So in respect to that idea, I see it as this...

Firm material cutting for things like plastics, woods, cardboard, styrofoam etc. benefit a somewhat keener edge to make a cleaner cut and do so without too much force, but can usually be cut with rather dull edges.

Soft material cutting for things like fabrics, ropes, food, and animal products need an edge that is keen but not necessarily highly polished or finished to keep things cutting clean instead of just "tearing" through.

Small material cutting for things like hair, thin materials like phonebook/newsprint/tracing/paper or film, sewing thread, etc require an edge that's refined to a much smaller scale, and at this point this type of edge can achieve all of the tasks from the other categories as well and so to me is the most desirable.

Given those categories, I think most can figure out where phonebook paper versus a tomato would be based on my perception of things, but as far as this "thin material" realm of things goes, I've only really been able to "compare" many edges using paper and hair and as I said earlier when at this level it's just too close to really tell, but I personally changing hair more impressive because of its hardness, how thin it is, and then it's shape in general. Trying to debate how well an edge performs in regard to if it can whittle free-standing hair or taut hair is scrutinizing and edge that won't show any noticeable difference in pretty much all of the other tasks you might use a cutting edge for and I think are used more for bragging rights than trying to convey a real level of sharpness.

 

[zyhano]

Well worded zyhano.

If I get your drift, you are asking everyone to explain what THEY think of when terms are mentioned. If so:

paper slicing-can make a clean cut through paper with proper technique. Doesn't have to be amazing.

hair scraping-can scrape hair off the skin, even if not well. Will typically scrape bits of skin and then a couple hairs. Will cut paper a bit smoother.

shaving sharp-will get 'sticky' and edge will bite at hair at skin. I don't worry about actually shaving because there are so many variables. Will whisper through paper at this point.

Hair whittling-will whittle a skinny, healthy, blonde hair being held at one end. Obviously, there are a million variables here, just like everywhere else, as a thick hair can be whittled at a lower level of sharpness. Regardless, it is what it is. At this point, the knife will usually pushcut the white pages, copy paper, or cardstock.

Tree topping-this is a bit nebulous to me, I consider it to be when the knife will easily cut hair above the skin. However, direction of the cut, thickness of hair, etc. all make a big difference. I don't think there are many that could make a knife sharp enough for a fair skinned 16 year old kid to consider it tree-topping.

Anyone is more than welcome to tear my definitions apart, agree, or disagree with them...I think that is what zyhano had in mind.

Thanks, that is exactly what I meant. Tree topping is above the skin, with the grain. So what would it be called when going against the grain.

Putting a general lable on a complex issue is what has made so many missinformed sharpeners. Its why many judge sharpness by the factory edge, its why many slap a steel and think it re-aligns "teeth".

Bad information through the standardized teachings of average Joe has resulted in a world of dull knives. Though having a standard would be nice it only hides you from the truth and complexities of the subject.

Judging from what you say you make a leap too far and it seems you have a low perception of the intelligence of people. This thread will not make knives duller nor will it misinform people. People know sharpening is complex, when you want to go to the extreme details.

Otoh, the principle of sharpening can be stated in a simple single sentence, as you have often done yourself. That is called defining or modelling, we can do the same here.

You're not willing to participate in a constructive way imo since you cannot agree with some simple definitions. How then, are you ever going to explain how you get good edges and what a good edge constitutes and does? By showing a picture? We've seen those. How sharp are your knives anyway?

If you are able to tell multiple shades of sharpness, you can sense them. If you can sense them, directly by your senses or indirectly through feedback of cutting tasks, you can describe them by describing how you know.

Youre talking about the truth about sharpening, what is it? Stop talking in vague terms please, explaining would be better

For me, at this moment, you're not helping here...

Well, the problem is that we're trying to convey relative meaning with things that happen to be very specific. My facial hair is brown and on average .003" - .005" thick, and very curly. Then, if I can shave this hair with no stubble remaining with it being "reasonably comfortable" I consider it shaving sharp. So it's not so much all the variables involved, but more about the fact that there's too much that's subject. Again, hair width and type are variables, but then so is something like pain tolerance, and worse yet it can't really be that well defined and you enter into a tangent of circular logic where you're trying to define the different levels of pain while shaving in order to explain the different levels of sharpness of shaving.

To get right down to something that's very communicable and manageable in regards to hair I would say "hair manipulation". I don't care if you tree top it, whittle it, scrape some of the material off of it, shave, if you can actually cut something as small and hard as hair that's a great edge. However, to put it on the highest echelon may be flawed, because while hair is as hard as copper of the same diameter, if you're shaving against a .005" thick hair how does that really compare to cutting through .002" thick phonebook paper? Because of the variability, the sharpness itself isn't consistent; a blade that can shave your face might not slice up phonebook paper, and on the other hand paper is much softer than hair so an edge that cuts phonebook paper may not cut hair.

I think the scope is much broader than placing the levels of sharpness as "hair splitting" or "hair popping" or even differentiating between slicing very thin paper and hair, because at those scales the variables just matter too much and peoples' ideas of it change too drastically.

To answer your question from before though, I would order it as so in regards to my own hair, but would still just put it all under "hair manipulating"

Hair popping arm or leg hair
Shaving arm or leg hair
Whittling taut facial hair
Shaving facial hair
Hair whittling sharp

In general though an edge that can do anything to hair is usually so sharp I don't really notice any performance difference in most other tasks except when it comes down to blade geometry. I mean, I don't want to debate the theoretical aspect of that, it just makes sense that a box cutter I can't shave with would be better at cutting boxes than some hunting knife I can shave with because it's so much thinner. It seems the smaller the material the edge can effectively cut the "sharper" I consider it for pretty much every other type of task, and once you're comparing between how well it cuts paper or how well it shaves, you're testing on a scope that is so narrow you really won't see a huge difference no matter what because of the variables involved. So in respect to that idea, I see it as this...

Firm material cutting for things like plastics, woods, cardboard, styrofoam etc. benefit a somewhat keener edge to make a cleaner cut and do so without too much force, but can usually be cut with rather dull edges.

Soft material cutting for things like fabrics, ropes, food, and animal products need an edge that is keen but not necessarily highly polished or finished to keep things cutting clean instead of just "tearing" through.

Small material cutting for things like hair, thin materials like phonebook/newsprint/tracing/paper or film, sewing thread, etc require an edge that's refined to a much smaller scale, and at this point this type of edge can achieve all of the tasks from the other categories as well and so to me is the most desirable.

Given those categories, I think most can figure out where phonebook paper versus a tomato would be based on my perception of things, but as far as this "thin material" realm of things goes, I've only really been able to "compare" many edges using paper and hair and as I said earlier when at this level it's just too close to really tell, but I personally changing hair more impressive because of its hardness, how thin it is, and then it's shape in general. Trying to debate how well an edge performs in regard to if it can whittle free-standing hair or taut hair is scrutinizing and edge that won't show any noticeable difference in pretty much all of the other tasks you might use a cutting edge for and I think are used more for bragging rights than trying to convey a real level of sharpness.

Very well put, thanks.
Will be an interesting thread "sharpness defined for different materials"

Bragging rights, yeah probably, but that is what happens if you want to go the extra mile in sharpness.

I appreciate your story about 'feel'. Same with straight razor shaving. I can sharpen two razors the same way, they look the same at the edge, but they stiil feel different. Subjective terms like smooth, scraping, raspy, gliding, flow, buttery etc all come into play and they are probably telling me something about geometry, edge refinement, steel, heat treat but I dont know how to translate it to those properties (yet).

But, they are all ShAVinG SHaRP!
So we can have consensus about that

 

[Jason B.]

I don't mean to seem that way but so many factors go into defining one stage of sharpness that I just don't see how it can be done. For example: S30V from BM, kershaw, and spyderco all sharpen and polish different because of HT and reach slightly but noticable differences in sharpnesses on the same grit stone. Though slight in feel you can't tell the difference in testing. Also if the steel is of a premium HT like CRK S30V, M4 of the GB, 154cm of Coye knives, they will all reach sharper levels at lower grits with cleaner edges than the same steel with a factory HT.

So to generalize sharpness IMO is far more complex than simply slapping a name on it. But just for you I will do my best.

For my example it will all relate to diamond products, I will also try and generalize sharpness regardless of steel.

The range will be from 120-100,00 with the compounds being used on balsa wood. Note: changing strop media will change effect of compound. ie. leather, hardwood, MDF...

120: Saw tooth like edge, shaving/hair ripping at best, rough cutting.

220: Shaving/hair pulling, rough feel with a bit of bite sharpness to the finger tips.

320: factory like sharpness, beginning of a refined and clean edge, clean shaving with slight pull, good slicing ability but force and sawing action will be needed to start cut.

600: Hair popping, splitting possible with thicker hair, refined toothy feel with aggressive cutting ability, reduced force and sawing action needed to start cut.

1200: fine toothy feel, clean shaving light drag, hair popping, single hair split possible, best described sharpness; unpolished utility razor.

6 micron paste: haze polish, utility razor sharpness, minimal drag shaving/ hair popping, will start to take curls of hair easier.

8000: Smooth polished feel that's a bit sticky, high degree of razor sharpness, easily makes up to 3 curls of hair, hair popping, minimal to no feel of hair being cut.

3 micron: Slight advance from 8k stone, more sticky feel, better ability to split hair, smoother shave, tree topping.

1 micron: mirror polish, minimal to zero visable scratch, sticky/toothy feel, tree topping, hair popping, multi hair splits with a average of 5, Ideal finish for knives.

0.5 micron: Bright and deep mirror polish, sticky smooth feel, bites the meat of your finger with almost no pressure, clean no feel shave, good for facial shaving.

0.25 micron: deep nearly black mirror finish, smooth as glass edge, nearly instant bite into skin, sharpness almost un-feelable, shaves with no effort, facial shave on par with disposable razor, cutting paper and other soft objects requires nearly no effort.

Hope this is more what your looking for. Please realize much of this can change due to uncontroled factors like HT, blade grind, thickness, and bevel angle.

Standard size of test hair .001

 

[zyhano]

thanks knifenut, now that is a big help :thumbup: Much appreciated.

Very informative and we can establish the grit sizes and the results you get as a benchmark, taking into consideration that there are variables beyond our control and differences in sharpness depending on those variables.

I'm doing some work at the moment, but will try to gather all we have so far in this thread and make a summary/list (unless someone else does this in the meantime) that is of course very open to alterations suggestions and additions, as anycal has also stated.
:thumbup:

 

[Jason B.]

I'm sure I missed out on a few small descriptions and will edit later. I probably need to do a complete sharpening so I can alter descriptions as I progress.

I still like Any Cal's description best

 

[stitchawl]

I really believe that if we're going to define 'sharpness,' it must be based upon a standardized test. Hair is too variable a testing tool. Steels are too variable in that the carbide sizes will affect sharpness. Blade thickness needs to be somehow taken out of the equation too. Juranich shaved his face with an ax. Would you try that with a survival knife? I wouldn't, and I know I can sharpen to a 'shaving edge.'

What device can be used for all edges, that will measure the cutting power of just the apex of the edge? Someone mentioned sewing thread and a postal scale. As thread can be purchased in different materials and strengths, we need a common denominator. The brand "Coats & Clark" is sold all over the world, and the cottone thread comes most commonly in 30, 40, 50 ply twists although there is an 8 thread that is also sold. Cost? About a buck for enough to last a few years.

And perhaps we need something even more delicate than a postal scale. Something closer to a gold scale. There are enough cocaine scales being sold in every major city to make that an effective common measuring device. I've seen them being sold for about $25.

Stretch a 40 ply cotton thread 12" between two pencils and you have a perfect testing surface. Rig the scale to measure the pressure needed to part the thread and we have a uniform way to discuss how sharp a blade really is. Someone in Sweden, someone in South Africa, someone in the US, someone in the UK... we can ALL use the same testing tool... a spool of Coats & Clark 40 ply white cotton thread.


Stitchawl

 

[Any Cal.]

stitchawl, I had mentioned the thread cutting. I do it at times for my own reasons. The difficulties I see with it are

1)when knives get REALLY sharp, it is hard to read a scale with enough precision to have a meaningful estimate. My postal scale, which is fairly easy to use, is graduated at 1/2oz, which means that I could give a reliable estimate down to 1/4oz. The problem is that once you get down to 1oz, the changes in sharpness are going to be small, so a reliable .1 oz measurement would be much better, but at the same time, being able to have technique consistent enough not to vary the results by .1oz would be extremely difficult.

I do have a scale that reads to less than 1/4000th of an oz (.1 grain), but since it uses a beam, even though the measurement would be extremely accurate, the measuring process would be an extremely tedious series of pass or fail tests. I guess that if a proper test was rigged though, it would eliminate the need for multiple passes of the same test. Edit-I guess you would probably get to where you could get the answer in 3 or 4 trys, which wouldn't be all that bad.

2)When two knives of different edge geometries, finishes, or thickness are being compared. Is a DE razor blade that cuts thread at .75oz sharper than an EDC knife that cuts thread at 1oz? Or are the differences in cutting geometry masking the sharpness? What if the EDC knife cut thread at 1.25oz... would it then be duller than the razor?

3)When technique of two operators differ. What if one tends to hold the knife canted sideways 5*? What if one holds the edge completely horizontal, while the next holds it 10* from horizontal, so it tends to shear more efficiently? What if one has had too much coffee, and is shaking slightly, like I am rrrighttt noowwww?/

4)When setup of the test is different. How much difference does it make if the string is loaded and taught with the edge making a large angle in the string vs. the edge making a small angle in the string due to much less slack? I haven't tested this one yet, but I *think* that this is one area where the test will stack variables badly as you get away from the sweet spot of the test (dull knife would possibly show much more pressure required to cut very slack string than that required to cut a slightly slack string, and obtuse edge angles and rough finishes could aggravate the issue as well.)

I don't mean for any of these to be reasons not to proceed, just mentioning the difficulties that I could think of the other night. It wouldn't surprise me if someone came up with a very simple way to eliminate several of these variables, or to come up with a decent reason to show that they wouldn't matter. It may be that none of it matters for a bunch of knifenuts talking about who got their blade sharper on the EF stone.

stitchawl, your idea of having 12" between points of support for the thread could remove a lot of the variability of angle/slack in the string before cutting, especially if the support was close to the testing fixture.