So what is the measure of sharpness to go by?

Sharp is relative.
For some its how well the knife will slice tomatoes for others its cutting cardboard or chopping tree branches
and then there are those that it's whiting wood & slicing toilet paper.;)


What is the task at hand?
 
Slicing tomatoes is a good test for a kitchen knife.
If you stay out of the kitchen, then a push-cut through 2-mil Yellow Pages is fine. There is truth that a toothy edge works just fine with some steels, some materials. That's usually around 600 grit. I prefer to go to 1000 grit at least.
 
If I can cut my finger off without chopping or sawing, I know the knife is sharp. People may question the reliability of this approach, and wimps might whine about the pain, the blood, the cost of reattaching a severed digit, blah blah blah. All that crap is meaningless when you know you've got a truly sharp knife.
 
Sharp is bringing two sides of a knife to one point. From there it is just refinement.

I split my thumb on a machete edge that was sharpened with a basterd file. Same machete is used to skin and butcher animals on the farm. It would not shave but it is sharp enough to do the job......and then some.
 
Yeah it depends what your needs are.

My work knives, being a sushi chef need to very sharp and polished, so that I cut fish as cleanly and smoothly as possible. Being called razor sharp would be an insult at this point.

My work duty knife (various sebenzas) mainly cut cardboard boxes, some of them triple wax walled (heavy produce boxes come in wax cardboard, super tough), plastic bags, plastic yellow wrap (think giant ziptie), and even frozen boxes.
So my bevel must be widened, convexed, and polished so that it just flies though all of that without me having to jiggle or seesaw to get the blade through, just 1 quick swipe.

It's funny when people touch my edge and say it feels dull, and show me their toothy edge, and say 'this is sharp' yet they couldn't slice through paper to save their life, and my 'dull' polished blade will carve circles in any paper.

I guess some are more obsessed than others.

My kukri is dull, but seems to work better that way.
 
marcinek said:
Oh man, there's a low-hanging joke here, and I am NOT going to make it. Even on a Friday afternoon.
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Laugh all you want, but after a sharpening session, out of boredom I shaved a patch on my leg where my sock goes, as I thought, "Who's going to see that?". Well, later that week I fell and broke my leg and had to have surgery. Wonder if it was noticed....
 
actually this is measurable. if you have the right tools you can guage this.

the steel can be measured width wise in centimeters, millimeters, micrometers, nanometers, picometers. as you go up the scale the sharper the blade becomes.

of course you would have to go to a university laboratory and use million dollar equipment. :cool:
 
doug5551 said:
When I tested the edge of my Microtech Scarab with my finger, it took off a layer of skin!
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Yeah, someone at microtech is a master at getting a good edge on their knives. They arent always the straightest edges but you cant say they arent sharp.
 
proton said:
actually this is measurable. if you have the right tools you can guage this.

the steel can be measured width wise in centimeters, millimeters, micrometers, nanometers, picometers. as you go up the scale the sharper the blade becomes.

of course you would have to go to a university laboratory and use million dollar equipment. :cool:
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That is grossly inaccurate statement.
 
proton said:
not even. depending on your precision requirements this can and does get achieved.
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I would think (I could be wrong) but 'sharp' is a relative idea, meaning that it's not definitive but needs to be compared to something.

There is a new tool that measures sharpness, I know Josh (Razor's Edge Knives) is testing it, but the tool measures sharpness relative to a razor blade.

Personally, once I can slice phone book paper with ease, I am good.
 
JR88FAN said:
I would think (I could be wrong) but 'sharp' is a relative idea, meaning that it's not definitive but needs to be compared to something.

There is a new tool that measures sharpness, I know Josh (Razor's Edge Knives) is testing it, but the tool measures sharpness relative to a razor blade.

Personally, once I can slice phone book paper with ease, I am good.
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of course. in my example, sharpness was compared relative to a one meter slab of cold steel.
 
proton said:
actually this is measurable. if you have the right tools you can guage this.

the steel can be measured width wise in centimeters, millimeters, micrometers, nanometers, picometers. as you go up the scale the sharper the blade becomes.

of course you would have to go to a university laboratory and use million dollar equipment. :cool:
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Do you know what you're talking about ?
If you think you do, please explain :p
 
Lots of good info here: https://scienceofsharp.wordpress.com

He distinguishes between sharpness and keenness, and then measures both with electronic microscopy while moving up through the stones and stropping. Pretty neat if you actually want to quantify sharp.
 
Eliteone2383 said:
Im reading alot that factory sharp is in fact not sharp. I thought my Benchmades were very sharp but I am mistaken lol. What is "sharp"?
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Eliteone2383 said:
I cut alot of rope, plastic wrap and band ties at work.
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For those type of cutting chores I sharpen no finer than 320 grit. This will give you a slightly toothy edge , I then buff/polish the wire/burr off of the edge.
This is done on a slack belt so the edge is con vexed and is very strong as well..

Your mileage may vary!:)
 
Ken44 said:
Do you know what you're talking about ?
If you think you do, please explain :p
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it is very simple. a 1 millimeter width blade is sharper than a centimeter width blade. a 1 micrometer blade is sharper than a 1 millimeter blade, a 1 nanometer width blade sharper than a 1 micrometer blade, a 1 picometer wide blade sharper than a 1 nanometer width blade, and so on.
 
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