Super Extreme sharpness experiments?

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manowar669

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Oct 1, 2002
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After reading a million threads by forumites about how extremely sharp their knives are, I was wondering if anyone has really gone "all out". Nothing practical, maybe a sub-20 degree edge, honed down to .3 micron, Blah, Blah...
How about 15 degrees? 10 degrees?
 
i have a knife thats under 20 with a mirror edge and its sick sharp. i made a kitchen knife for a membe and it was less than 15 with a mirror edge. you touch an arm hair and it jumps off.
 
Nothing I carry is as sharp as my straight razor, but my JYDII is close. Reground to almost a zero edge and convexed. Angle at the edge is under 20-degrees inclusive. It's finished the same as my straight, stropping with 100,000x diamond. It makes a great portable kitchen knife for when I cook away from home.
 
manowar669 said:
After reading a million threads by forumites about how extremely sharp their knives are, I was wondering if anyone has really gone "all out". Nothing practical, maybe a sub-20 degree edge, honed down to .3 micron, Blah, Blah...
How about 15 degrees? 10 degrees?
Click to expand...

There's a several folks over on the Maintenance Forum who go down to less than 10° per side. I've used 15° per side, but have settled in at 20 because I find it more useful for the way I use a knife.

BladeForums.com > General Knife Discussion Maintenance, Tinkering & Embellishment
http://www.bladeforums.com/forums/forumdisplay.php?f=794
 
What kind of experiments? I go down to 0.1 micron on my razors. It's cool because if you happen to cut yourself, you don't even realize it until you see the blood. Less tissue tear means less pain.
 
manowar669 said:
Nothing practical, maybe a sub-20 degree edge, honed down to .3 micron, Blah, Blah...
How about 15 degrees? 10 degrees?
Click to expand...
My Watanabe Honyaki Gyuto is 4-5 deg. per side. or 8-10 total. It is very practical knife and I use it a lot :) Finishing grit is 0.25...

Gunmike goes I think 0.10 or 0.05?

In general hard steel blades can be sharpened to much more acute angles and a lot of hard use knives can be easily thinned down to 15 or may be even less per side.
 
The lowest I go is 15 degrees per side and I can get them extremely sharp.

Polish the edges up to a 6,000 grit polishing tape on my Edge Pro, that is equal to 18,000 grit whetstone.

Popping hair is nothing when I get done. :thumbup:
 
Gator97 said:
My Watanabe Honyaki Gyuto is 4-5 deg. per side. or 8-10 total. It is very practical knife and I use it a lot :) Finishing grit is 0.25...

Gunmike goes I think 0.10 or 0.05?

In general hard steel blades can be sharpened to much more acute angles and a lot of hard use knives can be easily thinned down to 15 or may be even less per side.
Click to expand...

Wow... I never knew such thin angles were possible in normal use. Gorgeous knife. Plus, the knife doubles up as a vanity mirror. Double win. :thumbup:
 
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Have my Zing at 10. Polished on the wheel. Same as everyone else, pops w/o effort. Whittling is a little hard unless your real steady as it, well... pops the hair lol. Little difficult to shave as it grabs skin too quick as well. It is now my sharpest blade. It's what I consider "scary"
 
My Global kitchen knives are probably the sharpest ones I own, their thin, hard blades are absolutely hellacious slicers....when they come off the strop, they`re ready to give you a serious shave, or perform surgical duty....
 
What kind of experiments? I go down to 0.1 micron on my razors. It's cool because if you happen to cut yourself, you don't even realize it until you see the blood. Less tissue tear means less pain.
Click to expand...

I was just thinking about the math/physics behind this. .1 microns is 3.937x10^-6 inches. So if your edge is that thin, and you apply one pound of pressure, then you're applying ~3,937,000 pounds per square inch with the edge on whatever you're cutting. No wonder it cuts!

Oh yeah, I don't put less than 20 included degrees on any of my blades, but I can pop hair pretty well. Besides for proper shaving purposes, is there any marginal gain in utility going that thin/sharp?
 
Greenmachine said:
I was just thinking about the math/physics behind this. .1 microns is 3.937x10^-6 inches. So if your edge is that thin, and you apply one pound of pressure, then you're applying ~3,937,000 pounds per square inch with the edge on whatever you're cutting. No wonder it cuts!

Oh yeah, I don't put less than 20 included degrees on any of my blades, but I can pop hair pretty well. Besides for proper shaving purposes, is there any marginal gain in utility going that thin/sharp?
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Haha fun post. The 0.1 micron is the diamond compound I used for the final sharpening of my razor. The actual edge is more like 0.4 microns according to election microscope studies. Straight razors are between 14-18 degrees included, the thinner angles do make a noticeable difference when you shave your face. A 40 degree edge can shave arm hair, but is very uncomfortable if you try to shave your face. It would just grab on and pull each hair.
 
I once sharpened a knife so sharp that when I walked past Chuck Norris I was able to trim a couple of hairs of his beard...without him noticing.
 
Greenmachine said:
Oh yeah, I don't put less than 20 included degrees on any of my blades, but I can pop hair pretty well. Besides for proper shaving purposes, is there any marginal gain in utility going that thin/sharp?
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Yes!

Cutting is pushing one object into another to separate the latter. That's it. Common sense tells us the thinner the first object is, the more easily it will pass through the second object.

I too have knives that were taken to about 4-6 degrees per side, and while I don't take my choppers down that thin (They're 8-12) those knives sure do cut! You should see how a ZDP189 knife cuts with a full convex zero edge, or how a kitchen knife will fall through vegetables with little more than it's own weight.

For small utility knives and kitchen knives, using them the way I do, I can't think of any reason to go more obtuse than 8 or 10 degrees per side. Even that thin I never damage them. If you never receive edge damage on your blade, go thinner until you start to see some, then keep it just a hair thicker than that point. That's how you optimize a knife's cutting ability. You can keep it thicker, but it won't cut as well.
 
After seeing an Ontario machete perform with it's stock edge bevel of 10˚ inclusive, I can't for the life of me justify 20˚ per side on something like a pocketknife. I've found that almost universally, knives come with edge bevels that are simply more thick and obtuse than they need to be, and function better when modified with more acute edges. And if you really want to maximize performance, use a zero edge.
 
Most can handle surprisingly low angles without a decrease in resistance to edge deformation. 10-15 degrees seems to be a good comfort zone for about everything, I think the main advantage to having a thin edge is not only does it cut better and is sharper but when its dull it still cuts better because of its thin profile behind the cutting edge.





Sharp is when your knife will pass a hanging hair test.
 
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