Edge Sharpness Tester

[HeavyHanded]

Seems like those sub 50 levels are quite the effort.

For me it takes a mental reset of sorts. Using a Washboard I can apply a fair amount of force and still get pretty darn good results, from 80s-50s on the BESS. I get a little lazy/used to sort of beating on stuff a bit compared to a lot of other sharpening media where you really should operate as light as humanly possible to get an edge of any worth. On my waterstones I automatically dial it back, on the WB requires a reminder.

Getting the EKA that bit sharper only took an extra couple minutes of work, 30-40 passes/side or so, but with a real light, edge accurate touch. The first test came back in the 40s and I thought "I bet if I just settle down, the same materials should be capable of a bit better, or the equipment will tell me right now." Helps that the EKA has RC in the 59-60 range while the rest are in the 56-58.

That's not to say I could repeat that with all of the samples, I bet if I rerun the test with a bit more finesse the numbers could drop 15 or so and maybe none would make it into the teens. Still, I'd love to see my Tram make it down to the low 30s upper 20s - even at 60s is pretty intimidating (at least to me). In the last five years I haven't cut myself once on a knife, but have caught myself twice wiping off machetes and once on a ditch bank knife.

Martin

 

[KennyB]

For me it takes a mental reset of sorts. Using a Washboard I can apply a fair amount of force and still get pretty darn good results, from 80s-50s on the BESS. I get a little lazy/used to sort of beating on stuff a bit compared to a lot of other sharpening media where you really should operate as light as humanly possible to get an edge of any worth. On my waterstones I automatically dial it back, on the WB requires a reminder.

Getting the EKA that bit sharper only took an extra couple minutes of work, 30-40 passes/side or so, but with a real light, edge accurate touch. The first test came back in the 40s and I thought "I bet if I just settle down, the same materials should be capable of a bit better, or the equipment will tell me right now." Helps that the EKA has RC in the 59-60 range while the rest are in the 56-58.

That's not to say I could repeat that with all of the samples, I bet if I rerun the test with a bit more finesse the numbers could drop 15 or so and maybe none would make it into the teens. Still, I'd love to see my Tram make it down to the low 30s upper 20s - even at 60s is pretty intimidating (at least to me). In the last five years I haven't cut myself once on a knife, but have caught myself twice wiping off machetes and once on a ditch bank knife.

Martin

I've come to the conclussion I have really thick skin because I've brushed my fingers against the edge of my knife while loading test media a few times and not been cut, despite it testing at 46

Yeah I'm thinking that's why I can get the Izula sharper. I have a lot more experience in "feathering" it on the hone surface and practice keeping the angle and contour of the edge in contact--I mean I've EDC'd one for like 3 years so it makes sense I can get it sharper than the Leek, which I just got a few weeks ago.

I'm a pretty unorthodox sharpener though honestly... I finish my bevel geometry on a benchstone, but when it comes to finishing I take a DMT credit card hone and actually stare down the surface right at the knife's edge to make sure the very apex is in contact. I kind of consider it a handicap because I can never even come close to getting the knife as sharp off the benchstone this way unless I also hold it up to my face and stare down its surface too

 

[Omega Leather Works]

Kenny, polished or relatively coarse? Maybe it was less likely to cut like a polished edge on a tomato?

 

[Brian77]

Just a word of appreciation for this thread and the information it is providing. And especially to the folks at Edge... I read the whole thread this evening, and I hope to use one of these units also.

 

[ToddS]

I'm curious to know how the measured "edge sharpness" correlates with deliberate dulling. I wonder if any of the testers would be willing to make a series of measurements, starting with a freshly sharpened blade and then draw the edge across a fine-grit hone with progressively more force, making measurements at each stage.

 

[KennyB]

I'm curious to know how the measured "edge sharpness" correlates with deliberate dulling. I wonder if any of the testers would be willing to make a series of measurements, starting with a freshly sharpened blade and then draw the edge across a fine-grit hone with progressively more force, making measurements at each stage.

There was another member here who did something similar with boxes full of sand. He'd put the blade in the sand and move it from one side of the box to the other. I think that would be more representative, because the stone surface and steel edge are so hard and the apex so small that even light amounts of pressure on the hone are going to be exponential downforces at the knife edge and something will have to give--either the stone grit or the edge. Not sure how representative of dulling in use this would be.

Oi, I forgot I reprofield this Leek to 20 inclusive and cut up some cardboard today with it. Gonna go test it later, if I'll have to look up the numbers I was getting for it before.

 

[REK Knives]

I'm curious to know how the measured "edge sharpness" correlates with deliberate dulling. I wonder if any of the testers would be willing to make a series of measurements, starting with a freshly sharpened blade and then draw the edge across a fine-grit hone with progressively more force, making measurements at each stage.

I will try to do this soon Todd...

 

[Omega Leather Works]

I will try to do this soon Todd...

I just realized that you and your youtube channel are the same person (that sounds dumb). I enjoyed the set-up video as well as others on the wep that I'd watched a while back. I'm really looking forward to more on this instrument. Do them soon! [emoji14]

 

[ToddS]

... because the stone surface and steel edge are so hard and the apex so small that even light amounts of pressure on the hone are going to be exponential downforces at the knife edge and something will have to give--either the stone grit or the edge. Not sure how representative of dulling in use this would be....

What I've seen is that this will square off the apex at about 1 micron width with light pressure and wider with increasing pressure. This should separate the influence of keenness (the last few microns of the apex) from the blade geometry over the diameter of the media (225microns).

 

[KennyB]

Interesting test today, I was trying to use the "ERU" to check the angle on my Leek and it just wasn't meshing with what I've measured with the calipers and stuff. Turns out I just didn't hold the bevel as flat as I thought I had. It was like 20 degrees at the shoulders but 30 degrees as it got closer to the apex, and the transition was nearly invisible.

I think Fred and others with the ERU might also find it interesting... I got it to a BESS score of 70 with the ERU.

 

[Lagrangian]

Has anyone tested an obsidian blade, broken glass, or a microtome of any type (steel, carbide, sapphire, diamond, or glass) in the Edge Sharpness Tester? I know some of us have done knapping to make sharp edges from obsidian.

 

[KennyB]

Has anyone tested an obsidian blade, broken glass, or a microtome of any type (steel, carbide, sapphire, diamond, or glass) in the Edge Sharpness Tester? I know some of us have done knapping to make sharp edges from obsidian.

No but that interests me. I have two pieces of shale rock on the car right now I picked up interesting in knapping them, but I've never done it before.

Might be interesting to see what kind of BESS score a novice could get knapping some shale rocks for their first time.


I haven't really had a lot of time to test edge retention stuff with the Leek, I've been messing around with Fred Rowe's ERU and testing how sharp that can get them--pretty surprising, I had an easier time getting sub 75 BESS scores with the ERU than with the hone. I mean I knew that the device worked getting knives sharp but I suppose I had my own like,internal bias where I assumed I couldn't get them as sharp on the ERU as on the hone--like the "renewal" part of the device being the key word, but I actually managed to get a 90-100 BESS score with my hone, cut up some cardboard, and then used the ERU to take it down to 69.

 

[bflying]

Well crap. I'm a little late to this party, but I see yet one more way for me to start obsessing over my blades. Back when my knife collection started to break the 100 mark, I decided to learn a little more about sharpening. Picked up a Sharpmaker, and soon realized that I could not keep the consistency that I needed to satisfy. Then on to an Edge Pro. Spent a ton of hours and learned a lot. Then added a KME. And when combined with what I learned on the EP, have been able to get some great results. But no matter what my end results need to be, OCD kicks in and drives me to my breaking point with each blade.

I'm almost to the point that when I open some mail with a knife, the edge goes straight to the strop. I could see an instrument like this sending me way over the breaking point of obsession. I don't need one, but now I really want one. Probably a good thing I can't afford it right now.

Other than my own collection now in the hundreds, I've only sharpened for a few friends and family. It would be fun to show someone a before and after test result of my sharpening, just not sure it could be cost justified. Maybe sometime in the future if I ever get to the point of actually accepting money for the work.

This has been an interesting read hearing the actual results of the pros experimenting and refining the test parameters. Thanks to all who have shared their thoughts and results. And good luck to the product designer (inventor?), wish you great success in the future.

 

[Mbrubacher]

KN100, Knife Edge Sharpness Tester
Hello and thank you from Edge On Up to Blade Forum and to all those who have followed this thread. A special thanks to Mr. Lucius, one of our first customers, for beginning this thread and the eight evaluators and KN100 owners who have contributed so much as well. It has been three weeks now since most of our evaluators received their instruments and while this point represents the close of our formal evaluation period I know that several are still currently working on projects related to edge retention, metal oxidation effects, wire edge detection etc. and we look forward to their findings.
The evaluators have definitely put the instrument through it's paces and, in some cases, caused the instrument to go places where the instrument has never gone before. This is both good and appreciated. Testing and pushing the limits is how we learn and improve. I will add one caution to this however for the general readership of this forum segment related to tensioning of test media. A number of our evaluators have experimented with tensioning the test media in an effort to smooth out the bumps in their readings. In this they have been remarkably successful as evidenced by the minimal deviation in their measurements. Correctly, their experiments have centered on what sharpening media produces what results with what blades and tensioning may afford some better detail in that regard. The issue with tensioning is that it skews BESS readings downward and if the casual reader with a sharpness testing instrument isn't aware of the exception to the measurement protocol he (or, of course, she) might become highly frustrated with their results relative to the pro's. The operating manual supplied with the KN100 describes in detail correct procedure for loading and tensioning (in effect, non-tensioning) test media. If we have fallen short somehow in this regard please let us know. I just want to encourage everyone to stay on the same page with the BESS. If we don't, we can't learn from each other's work.
Once again, thank you to Mr. Lucius, our evaluators and all who have contributed to this effort. If you have a question or comment please direct it to me at edgeonup@gmail.com if you would like a response.
Thanks to everyone - Mike

 

[ToddS]

I was very surprised that Josh measured the same "score" after both the 200 grit and the 0.25 micron diamond paste, so I asked him to send me the severed media to look at in the microscope.

...
200 grit stones, stropped on pant leg - would somewhat shave hair on arm
BESS: 65 average (0 gr spread: 65, 65, 65)
Fishing line: 155 gr average (50 gr spread: 180, 155, 130)
note: so above, for example, it took 180 gr on the fishing line and 65 gr on the BESS cord in the same spot, near the heel of the blade. these parallel each other throughout the progression.

.
Less than 100 passes on a balsa strop w/ .25 diamond paste - at this point passing HHT-4 all points of edge holding hair 3/4-1" from point of hold
BESS: 63 average (35 gr spread: 45, 85, 60)
Fishing line: 178 average (5 gr apread: 180, 175, 180)

So, needless to say, I'm still confused

 

[REK Knives]

I was very surprised that Josh measured the same "score" after both the 200 grit and the 0.25 micron diamond paste, so I asked him to send me the severed media to look at in the microscope.

Man... I love your photos =)

It does look like the highly polished one severed it more cleanly, but I still don't understand the averages being close to the same.

 

[HeavyHanded]

I was very surprised that Josh measured the same "score" after both the 200 grit and the 0.25 micron diamond paste, so I asked him to send me the severed media to look at in the microscope.

Can you determine direction of the cut based on the outside of the strand. There appears to be a "snap" zone that looks very similar in both pics. If that's what it is, there's quite a difference between entrance cuts. If that's where the cut initiated, the 200 seems to have a smaller zone depth.

 

[Twindog]

It looks like the 200 grit photo was cut from left to right, while the fine cut was from right to left in the photo.

The coarse cut seems to have started cleaner than the fine cut, maybe because the teeth formed points that made initiation of the cut easier. Once a cut was started, the blade would have little further resistance.

 

[ToddS]

The fishing line shows similar features; the lines get deeper as the cut progresses, presumably due to stretching of the material due to wedging of the blade.

 

[KennyB]

Can you guys make out that ring-like artifact that is formed just shy of the outer edge of the media? In some instances it disrupts the striations, interrupting the straightness of the lines, other times it is actually protruded, and others seems sunken beneath the surface. In fact in some of the instances it seems like it's almost been stretched out.