The ultimate "sharp" when it comes to polished edges? With WEPS...

[REK Knives]

read this the other day when looking at Tom's blog at Jende Industries. Apparently the straight was finished on the WEPS with a .125 micron cubic boride nitride spray. The claims made in this review are astounding! I'll put a few of them in quotes below... what do you guys think? Anyone here ever had success getting an edge this "sharp"? and when I speak of "sharp" in this thread, I'm speaking of a polished sharp, not a toothy sharp (which I actually like more for EDC). Thanks!

for those that don't know, HHT = hanging hair test. google it.

"HHT with my wife's (I'm bald myself ) "normal" brunette hair was a good first measure. It fell silent from touching the edge, holding the hair well over 2 inches from the blade."

" I upped the ante & went for my 2-year old's flimsy blond hair. Same results... I even came up with a new test. 'The falling flimsy blond hair test' It consists of dropping 1 flimsy blond hair from 2 inches above the edge. 2 out of 3 times the razor severed the hair cleanly.."

pretty impressive... anyone had this success with the EP?

 

[Ben Dover]

Now that I have convinced my hunting companion (whose knives I maintain) to assist in defraying the cost of the WEPS, I have ordered the machine, and after an intitial familiarization period, I will attempt to answer your question by sharpening a knife to extreme levels with it. :thumbup::thumbup:

 

[REK Knives]

Yeah, I just ordered one to... Lol, i couldn't resist any longer! Clay answered all my questions and concerns... So I didn't have any reason not to anymore! Hehe. So what progression are you going with? I'm going to stick with all diamonds until I get to the extreme levels Cuz I wanna be able to sharpen ceramic knives.

 

[Komitadjie]

Welcome to the waiting-for-a-WEPS club. Hopefully mine's supposed to ship on or before the 9th of next month, after those parts shortages they ran into... I've got my fingers crossed!

Being able to sharpen ceramics is a large part of the reason I picked one up, that's a fairly uncommon capability, and the EP only sorta seems to address it, with only two stones. The Atoma plates are something that might help there, but the WEPS looks to be kind of the king as far as ceramics go. Clay is sure willing to answer any question you've got, I sure know I spent a while bugging him before I ordered.

 

[pwet]

two stones and a tape. the 3K tapes are diamond and specifically sold for ceramic knives like the two diamond plates. take care when sharpening ceramic knives it's a whole different world. no burr at all and it will chip if you apply more than 2grams pressure

 

[REK Knives]

Huh thats weird... I have both the diamond stones and tape and found that it is not high enough of a Polish to put a very sharp edge on a ceramic knife. Ben Dale will even tell you that it wont get an edge sharp enough to shave arm hair with, just "kitchen working sharp". Maybe I was putting too much pressure on it, but I don't think so.

 

[Medic1210]

So the guy claims a flimsy thin hair dropped freely onto his blade severed from only its weight on the blade? I gotta say I'd have to see that with my own two eyes to believe it.

 

[Noctis3880]

So the guy claims a flimsy thin hair dropped freely onto his blade severed from only its weight on the blade? I gotta say I'd have to see that with my own two eyes to believe it.

Well, you never know. If the angle was low enough, say 5 degrees per side on a hollow ground blade, it could be possible. Though I suspect such an edge would dull from cutting hair alone. I swear I dulled the edge on my Para2 from cutting hair. Or maybe it just wasn't sharp enough to begin with.

I might try testing out such a low angle edge when I get my Mora Flex in.

 

[Ben Dover]

Yeah, I just ordered one to... Lol, i couldn't resist any longer! Clay answered all my questions and concerns... So I didn't have any reason not to anymore! Hehe. So what progression are you going with? I'm going to stick with all diamonds until I get to the extreme levels Cuz I wanna be able to sharpen ceramic knives.

Initially, I plan to sharpen with the higher end diamonds, then take the blade to the EP for 5,8, and 12K, Shaptons. I've ordered two sets of leather stropping paddles for polishing to .5, .25, .125 and .050 micron diamond spray.

If the initial experiments are satisfactory, I will, of course, order paddles with the Shapton stones at least in 5,8, and 15K for use before stropping.

Eventually, of course, I intend to order blank paddles to mount balsa to since I've had such excellent results with the balsa and sprays on the EP.

Progress and advancement of any acvtivity should be considered a journey, and not a fixed destination.

 

[Jason B.]

A few things.... Razors are not knives and trying to pass the same test with a knife is much harder and much different. You can make a knife as sharp as you like even using .050 micron compounds but you reach the point of diminishing returns at 1-3 microns.


Good luck sharpening ceramic knives without power tools.

 

[Noctis3880]

A few things.... Razors are not knives and trying to pass the same test with a knife is much harder and much different. You can make a knife as sharp as you like even using .050 micron compounds but you reach the point of diminishing returns at 1-3 microns.


Good luck sharpening ceramic knives without power tools.

True, razors are thin behind the edge. Like Phil Wilson kind of thin, but with a hollow grind. Not even in the same league.

However, while edges below 1 micron are just novelty and would be destroyed in EDC use, I feel sub-micron edges are nice to have in the kitchen. Though again, I could swear I dull a 0.25 micron edge just by cutting some leg hairs. And cutting some leaves and grass definitely messed up the edge.

I'm experimenting with using sub micron abrasives on worn out belts for the Worksharp, because it might be worth it if you can put such an edge on with just a few swipes per side rather than carefully stropping the edge for over 15 minutes. Though I suspect the abrasive doesn't sit as well on the cloth belt as it does on a leather strop.

 

[ofelas]

I'm far from being an expert, but it's relatively easy for my razors to pass the "HHT" using minimal hand held methods, though I've never tried the "falling hair" test.

I use a yellow Belgian coticule to set the bevel as well as hone & finish the edge; I then strop on a vintage shell horsehide strop. That's all that's required to pass that Hanging Hair Test, which isn't a great indicator of how effective a razor is.

Sharpness in a straight razor isn't everything; the real test of how well it performs is the way it shaves - after all, the purpose is to push cut hair, without slicing skin.

I find the heavy English wedge grinds (they're essentially a true Scandi blade) work the best for me, due to the softer steel used & their extreme smoothness, even though the full hollow grinds come out a bit sharper.

 

[unit]

Well, you never know. If the angle was low enough, say 5 degrees per side on a hollow ground blade, it could be possible. Though I suspect such an edge would dull from cutting hair alone. I swear I dulled the edge on my Para2 from cutting hair. Or maybe it just wasn't sharp enough to begin with.

I might try testing out such a low angle edge when I get my Mora Flex in.

I am not going to claim to be the greatest in the world, but I have a ZDP-189 blade I reground to about 3.5 degrees per side and it will pass every test I have heard of, but it will NOT sever a hair dropped onto the blade.

I hate to be a skeptic, but I would need to see that.

 

[REK Knives]

Well, you never know. If the angle was low enough, say 5 degrees per side on a hollow ground blade, it could be possible. Though I suspect such an edge would dull from cutting hair alone. I swear I dulled the edge on my Para2 from cutting hair. Or maybe it just wasn't sharp enough to begin with.

I might try testing out such a low angle edge when I get my Mora Flex in.

well, while you are right about "the lower the degree the weaker the edge," i think it would depend on the steel greatly as to how much it would dull cutting hair. i get about 10-14 shaves on my straight before i have to re-hone it on the EP. however, the edge i put on that is around 19-20 degree per side (has an extremely thick spine ). but i don't think this guy's straight was that low of an angle, for the simple reason that it was sharpened on a WEPS, which can only go 12 degrees per side minimum (without modifications, which Tom may have had).

True, razors are thin behind the edge. Like Phil Wilson kind of thin, but with a hollow grind. Not even in the same league.

However, while edges below 1 micron are just novelty and would be destroyed in EDC use, I feel sub-micron edges are nice to have in the kitchen. Though again, I could swear I dull a 0.25 micron edge just by cutting some leg hairs. And cutting some leaves and grass definitely messed up the edge.

I'm experimenting with using sub micron abrasives on worn out belts for the Worksharp, because it might be worth it if you can put such an edge on with just a few swipes per side rather than carefully stropping the edge for over 15 minutes. Though I suspect the abrasive doesn't sit as well on the cloth belt as it does on a leather strop.

Yeah, straights are hollow ground and yes that makes a huge difference. I have sharpened a knife the same way to the same polish but it won't sever a hanging hair the way a straight will. Which is weird to think about, because in theory, it should since the very point of the edge is the same polish.... maybe it was due to different steels . worksharp idea is good! i've heard it takes forever to wear those belts out though lol. oh, and there is a lot of controversy out there about polished vs. toothy edge for EDC, which is better.

I have a theory, tell me what you think. The background to the theory: For EDC I tend to like toothy edges. That is because of my experiences with pocket knives honed at 21-22 degree angles per side. On the same pocket knife I have found that toothy works much better for EDC than a highly polished edge. BUT this is at 21 degrees/side, remember! Since I got my para 2 (in cts-20cp) and honed it to 15 degrees/side with a 1 micron polish, I have found that it also performs extremely well for EDC. The difference between the two being the angle (and the steel I guess). My theory: The more narrow the spine and angle, the higher polish you can use and still see extremely good performance... even surpassing that of the typical toothy edge when the spine is thicker and edge angle is thicker. In other words, the steeper the edge angle, the more toothy you must make your edge to see the same performance. I will try to do a youtube video comparing this at some point. It is very interesting.

I'm far from being an expert, but it's relatively easy for my razors to pass the "HHT" using minimal hand held methods, though I've never tried the "falling hair" test.

Well, I wouldn't qualify it as "easy" for the typical knife sharpener, but for those on this forum who eat, think, and sleep about knife sharpening, yes it would be easy BUT you must have the settup to put the highly polished edge required of a straight razor, and you must be able to maintain very consistent angles throughout the honing process.

I am not going to claim to be the greatest in the world, but I have a ZDP-189 blade I reground to about 3.5 degrees per side and it will pass every test I have heard of, but it will NOT sever a hair dropped onto the blade.

I hate to be a skeptic, but I would need to see that.

I am right there with you buddy... I tend to be skeptical of this as I have never seen this in person. Hopefully Ben Dover will be able to weigh in on it after he get's his settup now you'll just have to get a straight ben, to play around on! lol. Be careful of your jugulars!

so unit, let me ask you... have you found to be true what i stated in my theory? how does 3.5 degrees/side perform for EDC? that is awfully narrow, how does it hold an edge?

thanks for the weigh-in guys!

 

[unit]

It depends on what tasks are involved for "EDC". Generally speaking it would be a very bad idea for most to carry and use an edge that acute.

I use that knife for s very narrow work scope... And grinding it was really more about exploring limits, extremes, and learning something in the process. Suffice to say it is very fun to use, but it is delicate.

 

[Ankerson]

I dunno, that does seem pretty unrealistic.

 

[Lagrangian]

Against my better judgement, I'm going to post here. :foot: Keep in mind I've only been a knife-enthusiast for about 3 months; my experience and expertise is quite limited. Take stuff with salt, etc.

If a knife gets thinner and thinner, then at some point these bending forces get too big to sustain a sharp edge. So, there is probably an optimal of angle for cutting a single strand of hair once (given a particular steel and heat-treatment). (See page 3 of Prof. John D. Verhoeven's tech report:"The width of the blade at the edge and just behind it is extremely thin. Hence the force against the edge from the abrasive media will result in large stresses, force per area, at the edge, which can lead to plastic flow (bending) of the edge region." http://www.bushcraftuk.com/downloads/pdf/knifeshexps.pdf. He includes a few electron-micros-scope pictures which suggest bending.)

Toughness is the energy required to break a material. For example, the energy required to rip a sheet of paper in two. Now, cutting in the paper into two with a sharp knife uses less energy. How much less? I don't know.

But the energy required must have a lower limit, namely, the energy to separate molecules in the hair. (I mean things like van Der Waals force, and other chemical forces which attract molecules together. I don't mean chemical bonds within a molecule like covalent bonds; normally cutting does no chemistry.) So I don't know how to find it, but there is a lower limit to how much energy is required to cut a hair in two. Let's call this the minimum-split-energy for hair. It is a lower-bound on the amount of energy needed to break one strand of hair into two. Notice that it is a lower bound, so it could be an under-estimate.

Next, the falling hair reaches terminal velocity before it his the knife edge. So it has kinetic energy. This total kinetic energy is a reasonable upper-limit on how much energy is available for cutting the hair. If this total kinetic energy is smaller than the minimum-split-energy then it is theoretically impossible.

The the kinetic energy of falling hair seems easy to estimate to me. The hard part is how to estimate the minimum-split-energy for a strand of hair. If someone has a back-of-the-envelope way of estimating the minimum-split-energy for a human hair, then please chime in. I won't throw you to the sharks even if it is way off base!

Doing good estimations is hard. It is both a skill and an art, and arguably, it is what separates great engineers from good ones. Not to mention, it shows up in homework.

And if someone can cut free-falling-hairs, please post a video and tell us how you sharpened it.

Okay, that's it for now.
Did I just make a fool of myself? :foot:

Sincerely,
--Lagrangian

P.S. This argument is only goes one way:
If the total kinetic energy is less than the minimum-split-energy, then it is theoretically impossible.
If the total kinetic energy is bigger than the minimum-split-energy, then we known nothing. (We don't know if all the kinetic energy can be used in cutting the hair. The minimum-split-energy is a lower-bound on how much energy splits a hair; the actual energy required by a knife could be much bigger.)

 

[Lagrangian]

So much for theory. Now for a post about experiment:

The sharpest knives I know are either a diamond microtome knife, or fractured obsidian. These edges are _literally_ a hundred times sharper than a commercial razor. If you are an excellent flint-knapper, please make the sharpest-flattest shard you can. Then see if it can pass the falling hair test.

(Ditto, if you work in a biology lab with a high-end microtome, or if you are a medical student who does work on cornea surgery or micro-surgery.)

btw, given my (limited) experience with broken glass, I have never seen it cut free-falling hairs. So I am skeptical.

Here are examples of extreme sharpness:

According to Prof. Verhoeven, a modern sharp razor has an edge of 0.4 microns.
http://mse.iastate.edu/fileadmin/www...nifeShExps.pdf

Diamond coated razors can have an edge of 0.05 microns.
http://www.technologyreview.com/computing/25988/

Diamond microtome knife has an edge of 0.005 microns. This is 30 carbon atoms wide.
http://www.tedpella.com/diamond_html/diamondk.htm

Concoidally fractured obsidian has an edge of 0.003 microns.
http://en.wikipedia.org/wiki/Obsidian

Tips for atomic-force-microscopes and scanning-tunneling-electron-microscopes can be sharp as a single atom.

Sincerely,
--Lagrangian

----------------------------------------------------
"What grit sharpens the mind?"--Zen Sharpening Koan

P.S. For reference a human red-blood-cell is about 7 microns.
http://en.wikipedia.org/wiki/1_E-6_m

 

[230grains]

I am not going to claim to be the greatest in the world, but I have a ZDP-189 blade I reground to about 3.5 degrees per side and it will pass every test I have heard of, but it will NOT sever a hair dropped onto the blade.

I hate to be a skeptic, but I would need to see that.

Same, I took an m4 blade down to about 8 degrees per side, finishing it on bare horsehide. It is by far the sharpest i've gotten a knife, and I'm no slouch in terms of sharpening. It could take news print in any direction push cutting. It could whittle free hanging hair with zero issues, over and over. It could do any sharpness test i've ever seen but a free hanging hair dropped onto the blade would not cut. I'd have to see it to believe it.

 

[Jason B.]

It's not going to happen, hair does not have enough mass by itself. The hair would need to be long (like 12in) to make its weight greater than the cutting force.