Is this sharp or what?

[MVF]

I just got a William Henry B15 Attache, the old version with the DLC coated ZDP 189 laminate blade. I don't get it- it will shave my arm very well, not "hair poppin", but smooth and easy- no pulling, but the edge is so smooth I can run my finger along it all day without it cutting- it actually feels dull. Do I just need to rough up the edge to give it some teeth, or does it need to be sharpened? The edge seems very thin already.

Thanks for any help,
Mike

 

[matt321]

This is a common complaint. A freshly applied edge that feels polished but dull when felt with the thumb pad. ( I worked on a folder last night and ended up with the same thing!)

I presume there is a bur issue here. The edge is not cleanly formed. If the knife shaves better from one side than the other this would support the bur theory. Also, if you test the edge on the back of your thumb nail and it grabs better from one side than the other.

Oddly, the smoother and more polished edges sometimes feel the dullest when tested on the thumb pad. Here is the theory on that as I understand it:

A coarse edge has an aggressive bite that acts like micro serrations or saw teeth. Even if the edge is not perfectly formed, the coarse micro serrations are individually sharp and will cut aggressively

A polished edge is less forgiving and must be more perfectly formed (clean intersection of the bevels with limited bur). The micro serrations have been polished out, so any bur-like flaws along the edge are less crisp and only serve to widen or round the edge making it less effective.

OK..somebody else throw in their 2-cents.

 

[ashtxsniper]

It will feel dull till it catches then it will slice ya to the bone. When it comes to this it is a matter of what type of edge you prefer.

 

[sog]

Try using a steel or strop.

 

[Cliff Stamp]

... does it need to be sharpened?

It would depends on how you use it. Try to do some cutting and see what happens. If you find that it is slipping then it needs to be resharpened as the edge is overbuffed.

-Cliff

 

[pbubsy]

I'd suggest trying the push cut with news print. If it slices clean through with no drag......you've got nothing to worry about. If it slices rough or tears the paper rather than cuts it, just do about 20 strokes (each side) on fine with the spyderco sharpmaker to clean the edge up. Then it should be nice. I've got knives that are pretty much as sharp as you could possibly get them, but they don't shave my arm hair very well as I've got thick, tough hair. The shaving test isn't the most accurate one. The push cut through the paper always works, slicing a thin piece of skin off your thumbtip works (if you've got calluses), and seeing if the blade shaves a little of your thumbnail off also works.

 

[MVF]

It would depends on how you use it. Try to do some cutting and see what happens. If you find that it is slipping then it needs to be resharpened as the edge is overbuffed.

-Cliff

Bingo! (I think) I found no bur, either side would shave, it would only push cut paper within about 1/2" of my fingers, and would only slice paper if started at a good angle and speed. Once a cut or slice was started, it was fine. I imagine if I had put enough pressure on the blade, it would definitely slice me to the bone, but I could apply a pretty ridiculous amount of pressure and run my finger up and down the blade without it biting. "Overbuffed" sure seems to fit what I'm seeing. Thanks all!

 

[matt321]

Well, there are highly buffed and polished edges out there that will tree-top shave and pushcut newsprint. So what is overbuffed?

 

[Cliff Stamp]

... I could apply a pretty ridiculous amount of pressure and run my finger up and down the blade without it biting.

That is a problem and a common one as are the other issues you raised regarding paper cutting. While a coarse edge will have more slicing aggression a very highly polished edge when properly sharpened would not be something you would want to drag across your finger, even under the weight of a light knife. It is unfortunate that a lot of knives are like you describe initially as it gives many people the impression you can oversharpen a knife and make it dull. Makers/manufacturers would often seriously benefit from having someone like Ben Dale give a lecture/demonstration to the people sharpening their knives. If production knives were constantly sold that sharp you could likely sell the line on that basis alone to a lot of people.

So what is overbuffed?

The edge was rounded, usually by too much pressure. I would assume it happens on production knives where the knives are pressed hard against the buffer to limit the number of passes.

-Cliff

 

[Terry M.]

This was a very informative thread as I was having the same issue earlier today sharpening my Benchmade.

 

[Jeff Clark]

A buffer wheel does not create a precise edge bevel like a hard hone or a grinding wheel will. The cloth wheel is soft and compliant and will tend to make rounded surfaces. If you do a really good job of honing an edge and touch it just lightly with a buffer you may improve an edge somewhat. If you press hard or buff for a long time you will round off the edge.

There are rigid paper buffing disks that would do a better job, but cloth ones have to be used very carefully. Often they are used by manufacturers to remove burrs and make the edge look pretty. That gives you a second rate edge.

If you have a Sharpmaker I would try honing with the flats of the white rods in the 30-degree (15 degrees per side) honing slots. This will restore a fine edge and provide just the slightest bit of roughness for better slicing. If you don't have a Sharpmaker try visiting a knife store and ask to try a Sharpmaker. Most stores have a demo unit.

 

[gunmike1]

I highly polished the edge (ultrafine spyderco's then stropped) on the modified (very thin) Falkniven U2 Cliff lent me and it sure bit your finger like a champ when you did a thumbpad test. You would have a terrible cut if you tried to push your finger into the edge and drag it down the edge in a slicing motion. It could tree top arm hairs easily and push cut the San Francisco Chronicle 4" from the point of hold. It cuts through cardboard with no resistance, and even went through thick plastic packaging for headphones and an electric shaver with next to no resistance. My factory sharpened Byrd Cara Cara (push cuts newsprint 2" from point of hold) took much more effort to go through those packages, basically having to be manhandled to start the cut and continue straight through. The other extremely sharp polished edge I dealt with was when Ben Dale sharpened my Spyderco R2. It literally shocked me how sharp it was. It was similar in sharpness to the U2 (before I had used that knife), but at 3 times the angle and 3 times the edge thickness. It tree tops hairs, pushcut newsprint at 4", and just plain cut rediculously well. And boy did it bite your thumb on a thumbpad test. It would cut you if you even thought about running your thumb along the edge in a slicing motion.