How sharp..is sharp?

Kniv1 said:
Just wondering what everyones take is on what is considered
a sharp knife? razor blade sharp? or more?

What does it take to get a store bought knife scary sharp?
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Really sharp = one molecule thick edge :D

What does it take to get that sharp? I dunno but if you find out let me know.:)
 
singularity35 said:
I thought hair whittling comes before tree topping. The sharpest knife I have is my FFG endura in ZDP. running a hair along the edge will cut the hair. I almost cried when this happened, you see, I'm sharpening challenged.
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In particular, I have two knives that I reprofiled with my Lansky system. One is a Buck 111 (420HC), the other is an A.G. Russell 'Brute' folder (ATS-34 w/micarta handles). With these two knives, I've been able to tree-top hairs from my forearm (pass the blade edge thru my arm hair, about 1/8" or so above the skin). I can see the clippings (not every hair, but a few) collect on the blade.

I also have a ZT-0350 (S30V) that I reprofiled with the Lansky, that once or twice has at least approached tree-topping (can feel the edge 'snag' on hairs as I pass it over my forearm).

All the above knives have been frequently & gently stropped on leather w/green compound, followed by stropping on bare leather. This was where I was able to get 'em to tree-topping.

I haven't been able, thus far, to 'prove' to myself that I can or can't whittle hair (it's tougher for my 48 year-old eyes to see such things). This is why I say I haven't achieved that yet. It may just be an issue of the fineness or coarseness of the hair itself, or just an issue of having hands not quite steady enough to whittle the hair without actually lopping it off. I'm not sure. I'd be interested in hearing from others here as to what they feel it takes to whittle hair.
 
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many formites can whittle & tree top hair, one of you guys can hang a hair tied by sewing thread & cut it in mid-air. i admire the expertise of this fine sharpening however it's way beyond my ability. i'm quite happy if my knives will slice the thin plastic sandwich bags with just sliding the edge over the bag.
 
Polished edge pictures, courtesy of knifenut1013:

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Raising the definition of "sharp" pretty high IMHO:thumbup:.

Spyderco Military with S30V blade -for those who are curious.
 
A question on the Lansky setup - I'm thinking about getting the diamond set up and am wondering if there are any limitations on knife size? All the videos I've seen on the net are under 4" blades. I'd want to be able to do my 6" and 7" kitchen knives and of course my Recon Scout.

Any problems using the Lansky on 7" blades?
 
HandofCod said:
A question on the Lansky setup - I'm thinking about getting the diamond set up and am wondering if there are any limitations on knife size? All the videos I've seen on the net are under 4" blades. I'd want to be able to do my 6" and 7" kitchen knives and of course my Recon Scout.

Any problems using the Lansky on 7" blades?
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If the clamp is mounted in the center (lengthwise) of the blade, it's not a problem. The hones will reach far enough on either side of the clamp to cover the full length of the cutting edge. I've done a couple of my longer kitchen knives (6" to 8") this way.

Another alternative would be to sharpen the forward half of the blade with the clamp at the center, then move the clamp back to the tang to do the rearward portion. The potential downside of moving the clamp, however, is the possibility of a mismatch or irregularity in edge angle at the overlap location between the forward and rearward halves of the blade. In general, I prefer NOT moving the clamp at all.
 
My small blades, an ESEE Izula and a buck 110, are shaving after sharpening. However the izula gets some nice outdoor use so it doesnt realy stay shaving sharp. When i get home and steeling the izzy its still close to shaving. And for outdoor use that is sufficient in my book.
My RTAK-2 isnt shaving but its a hard work knife and doesnt really need to be that sharp, as long as the edge is holding.
 
To me, sharp starts at shaving hair off my arm. However, as long as a knife still slices paper easily, it is still usable to me.
 
The sharpest that I have seen someone get a regular knife was a Buck 110 that would cut a lightweight single wide cigarette paper folded and standing upright on the table right in two with a fast swipe. That even beats the old trick of shaving off the glue strip.;) The guy who did that is from England and will be competing in the cutting comp at Blade again this year. Last year was his first time ever and he came in 5th using a standard (non-cleaver) shape knifemade from O-1 against guys who had full boat "race knives made from M4. His grandfather was a master cabinet maker who worked on, among other things, the Queen's private railroad car. This guy took the techniques that his grandfather used to sharpen his woodworking tools and adapted them to big blades and let me tell you, they work!!!! He tuned up a 13 1/2 inch Musso style bowie of mine at the show in Belgium and it would "treetop" when he was done. Bill Moran used to get his knives ridiculously sharp and I have heard that Tai Goo does his final stropping with typing paper and compound and the edge will split a coarse hair. You can get as crazy as you want as long as the steel has a fine grain structure. Most factory stainless knives that i see have a machine sharpened edge that looks like a washboard even if they come quite sharp like the old ATS 34 Benchmades did.
 
jdm61 said:
The sharpest that I have seen someone get a regular knife was a Buck 110 that would cut a lightweight single wide cigarette paper folded and standing upright on the table right in two with a fast swipe.
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I'm curious as to what vintage the Buck 110 was. In particular, I'm wondering if it was using the current steel (420HC), or one of the older variants (440C or 425M)? My Buck 111 (420HC) has taken the absolutely sharpest edge of any of the knives I've sharpened so far. I keep thinking it'd just keep getting sharper & sharper, IF my skill & technique could keep up with it.
 
All steels will get pretty close in sharpness with the finer grain steels becoming noticeable sharper as the scratch pattern is reduced.
 
jdm61 said:
The sharpest that I have seen someone get a regular knife was a Buck 110 that would cut a lightweight single wide cigarette paper folded and standing upright on the table right in two with a fast swipe.
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Not only can my own Buck 186 do the same trick with it's 30 degrees inclusive edge angle, my Strider SMF with it's 40 degrees inclusive edge angle can do the same.
I use the thinnest cigarettepaper (made from rice) that i could find.
While it's true your edge needs a certain sharpness to perform this trick, there is also quite a lot of technique involved.
 
I wish there were some tests that provided a higher 'resolution' on the differences in sharpness. Shaving arm hair without irritation can happen at double digit abrasive grit, or with a smooth cut file. Cleanly slicing newsprint with a relatively silent stroke at less than 500 grit. Whittling hair, the hht in the video jules posted, shaving the type from newsprint, etc can all be done at JIS 1000 grit. Face shaving without burn is pretty easy at JIS 4000.

But there are a lot of edges polished to 8000+, or stropped at 30,000+. I just don't know what can be done to differentiate those edges. I don't think we cut things with knives in hand precisely enough to demonstrate how these edges can act. At a certain point, our imprecise motions overwhelm the subtle difference the extra polish provides. This is also influenced by the alloy and condition of the steel.
 
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