Knife Sharpness Scale

C

CharlieSoxx

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Apr 8, 2015
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Hello to all. I am starting this new thread as a result of a divergence in the subject matter from a previous thread (1095 Steel) that I began just a few weeks ago. I have received a couple of emails suggesting this move and since I am a forum neophyte I felt I better heed the advice of those more experienced. You may notice that my membership classification has changed mid-stream from "registered user" to "knife maker/craftsman/ service provider" and that was done once the tenor of the thread seemed certain to change. I may be none of those things but to make certain I wasn't stepping on forum rules I upgraded. With this preamble out of the way I'll get down to business. I am an appointed and uncompensated board member of BESS•U (BESS Universal - www.bessu.org). BESS•U serves as a non-profit organization whose sole purpose is to oversee the integrity and education in the proper use of the BESS. As a lifelong collector and practical user of things with sharpened edges I was immediately taken with the value of the BESS (Brubacher Edge Sharpness Scale) when first made aware of it two years ago. There is nothing to be sold here because use of the scale is free. That is why I serve on the BESS•U interim board with permanent board elections scheduled for this Fall. If you are not already familiar with BESS it is a sharpness scale based on the sharpness of a double edge razor blade. The scale runs from 0-2000 grams of pressure with the DE blade serving as it's zero point. The BESS is much more than a means of determining a numerical sharpness value of an edge however. It is, just as importantly, a means of communicating those sharpness values, one to another, in an unambiguous manner. While there is certainly an instrumentation element necessary to measure and collect initial sharpness data it is not necessary that one own an instrument in order to derive the benefits of the BESS. In fact, it is anticipated that when all is said and done only a small percentage of BESS beneficiaries will actually own sharpness testing instrumentation. The BESS has the same relevance to users as the Fahrenheit and Celsius temperature scales and just as we know that ice is cold "ice cold" DE blades are sharp "razor sharp". So the point of this thread is simply this - what do you think of and what suggestions or questions might you have regarding BESS? If you have test media or instrumentation questions I can probably help but only from a fairly experienced user point of view. Everyone's thoughts and input from expert to novice would be very much appreciated.
 
I'm an engineer and thus like standards ☺

However with knifes it seems to be super complex.
Sharp in one material doesn't translate to sharp in another one. Cutting tomatoes is different from paper or even wood.
Toothiness and many other things like the direction of the cut vs the direction of the grind, play into the thing we oversimplified call sharpness.

Would be cool to see a test which takes everything into account. Then it'll probably deliver a bunch of numbers and not just one?

Edit:
Just read up on it http://www.edgeonup.com/eou_web_pagelarge_013.htm
While it's not a complete test which I would like but will probably never exist in a quantifiable manner BESS has lots of other things going for it.
It seems cheap, easy and repeatable. ☺
 
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Well....since you asked....it all sounds like oversimplistic handwaving with only a passing resemblance to anything objectively scientific.

From the outset your "zero point" is a "double edged razor blade." Whose razor blade? How thick is it? What steel is it? Is there a "standard razor blade" that anyone can use to confirm/replicate your results? Do your razor blades always have exactly the same edge angle? Is the medium being cut by the razor blade always exactly the same? Are the conditions the cutting takes place under always exactly the same?

I applaud the effort, but it all sounds ambiguous from the very outset.
 
Jens Schuetz said:
Edit:
Just read up on it http://www.edgeonup.com/eou_web_pagelarge_013.htm
While it's not a complete test which I would like but will probably never exist in a quantifiable manner BESS has lots of other things going for it.
It seems cheap, easy and repeatable. ☺
Click to expand...

Precisely. "Sharp" not quantifiable property, making any testing method not much better than an arm hair test from a "scientific method" point of view.

Kinda like the "best" steel.

Again, I do appreciate the work that has gone into the method...but to me, not verifiable enough for all the effort involved. Everyone else's mileage my vary.
 
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Well gentlemen your comments and questions are exactly what I was hoping for but I have to wait until this evening before responding fully. Please keep'em coming.
In the words of Arnold - I'll be back!
 
Sounds like something that will just force knifemakers to grind their blades to get a higher BESS number, rather than grind their blades for how they are to be used. Kind of like the silly knife guild bending test.
 
Actually, the whole "measuring sharpness" topic is academic, since we all know that convex ground blades are the sharpest.

hide.gif
 
The proposed draft standard needs explanation. How is the test carried out? What is the test media? Is it a slice cut or a push cut? How deep is the cut? Does the scale factor in blade thickness at all?
 
I think we must now create the bladeforums sharpness levels and cutting ability scale. :)
 
if we could get any factory sharpened queen knife to even register on this scale that would be amazing........

looks interesting. got to do more reading on it before i make a judgement on way or the other. thanks for the heads up.
 
marcinek said:
The BF-SLACAS? We need something with a better acronym than that. :D
Click to expand...

yes. We definitely need to brainstorm a great acronym first. :)

But the Slacas score of my Carbon Opinel after stropping reached a good 7.2 yesterday.
 
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Can't you just look at the edge under magnification? Seems like that would tell a better story than some subjective cut tests...,
 
If you can somehow make the BESS scale take into account whether a knife is tactical, black, serrated, and was designed by someone who hangs out with SEALs than it will be adopted much quicker ;)
 
You know...I think that this test involves putting enough weight on one of the edges of a double edged razor until the other edge push cuts some so-far unnamed medium.

Now isn't putting weight on the non sharpened spine of a knife some kinda different distribution of force? Got any physicists or engineers out there? Dammit, I'm a mathematician, Jim, not a physicist.
 
And aren't the edges of a DE razor blade parallel? Doesn't seem like many knife blades have a parallel edge and spine.
 
Well, if they use an edge to push an edge into the test medium it would be plain wrong. And it would falsify the results. They would have to mount it.

Also, the test medium should not be cut further than the sharpening angle area is deep. Else they would need to factor in the primary grind shape and thickness, height and angles in degrees.

Of course this would be after factoring in the edge angle itself. A razor blade is always a chisel grind.

As I read it now they can reliably compare razor blades to razor blades, or razor blades to possible (limited valid results) utility knife blades.
 
How does jimping factor into the Slacas score of a blade? And slits/grooves? :D

I can remember in scouts arguing over who could get a blade sharper, but we never had a concrete way to test it, so I like this, its a neat concept. I don't know enough about it to know how accurate it is, but anything seems better to me than just saying "hair shaving sharp" and not being able to compare it past that.
 
I know you guys get a big kick out of this but, all I care about is....is the knife sharp enough for me and my needs. Frankly...I don't give a rip how sharp yours is, unless you're gonna drop by and cut rope, cardboard boxes and my meat and veggies for me . LOL ;)
 
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