Can a knife be too sharp?

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tautisg1
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Can a knife be too sharp?

Postby tautisg1 » Sat Aug 18, 2012 5:29 am

Hey everyone.
So, I just finished sharpening my edc as the knives were getting dull ( standard Manix 2 with convex edge and Kabar Dozier with convex edge). I finished them with 2000 grit sandpaper and they can both shave hair easily. That is the sharpness level I like my knives at. Now, while sharpening I had this really strange thought pop in my head. If you kept sharpening a knife for a REALLY long time on really high grit stones/sand paper (6000 grit plus), and then stropped it for like 5 hours, could a knife be so sharp that it wouldnt cut? You would have eliminated the vast majority of the micro serrations, so in theory, how would the knife cut? I am no expert on this, and would love to hear people's opinions on this :)

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The Deacon
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Postby The Deacon » Sat Aug 18, 2012 5:55 am

A knife can never be "too sharp", but it can be too sharp for a given use. There's a point at which a knife will be too sharp to cut certain materials effectively, and a point at which it might be too sharp to cut them safely. I doubt there's such a thing as too sharp to slice garlic paper thin, but I find a blade with a slightly "toothy" edge cuts through the skin of a ripe tomato more effectively than one with a highly polished edge. Cutting a sandwich in half for your kids while it's sitting on a paper plate balanced on your lap is going to be considerably safer with a relatively dull blade. Same with slicing up a sheet cake on a Tupperware tray, especially if the Tupperware belongs to someone else.
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tautisg1
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Postby tautisg1 » Sat Aug 18, 2012 6:34 am

I definately agree with what you said. For example, a really polished, sharp edge will not cut cut rope as effectively as a knife sharpened at 600 grit.

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Dr. Snubnose
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Postby Dr. Snubnose » Sat Aug 18, 2012 7:34 am

I favor a semi-polished edge, finished to 6,000 grit.....some times after sharpening I will make one or two passes on the Spyderco white stones, just to give it a slight toothy finish....Doc :)
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Postby .357 mag » Sat Aug 18, 2012 7:35 am

Depending on the tasks, I would say yes. I've found that I like my EDC knives to be more toothy somewhere in the 1000-1200 grit. Hunting knives I like polished for gutting but I steel the edge when I go skin and process. Camping knives where I baton and shave wood, a mirror polish edge is what I want for push cutting. Kitchen knives I sharpen to 600 grit.

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Postby Evil D » Sat Aug 18, 2012 9:20 am

As Deacon said it depends in the intended use. Some medium requires a toothy edge to get bite or that sharp edge will slide along the surface. Also at some point you have to start thinking about edge thickness because that plays a major role in how sharp the edge actually is, and thin edges aren't good for harder uses. Beyond all that you'll come tobacco point where the grain of the steel can't be refined any smoother or more acute than it is or it'll just chip out carbides. At least that's how I imagine it.
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Each Edge type has It's own job

Postby JD Spydo » Sat Aug 18, 2012 9:39 am

tautisg1 wrote:I definately agree with what you said. For example, a really polished, sharp edge will not cut cut rope as effectively as a knife sharpened at 600 grit.
Great Point "tautsig" :) That's why I've been preaching Spyderedged blades for cutting fibrous material like rope, twine, jute or just about any other type of cordage. Every type of edge has it's own specialty you might say.

Not all serrations are created equal. Most people have been exposed to Rip-Mart type serrated blades and thus draw the conclusion that they are all bargain basement trash. But Spyderco's patented Spyderedge is truly heaven sent for cutting chores involving fibrous material.

Yeah you can get an edge to refined to be efficient at a lot of cutting jobs. Sometimes I do my tune ups on the medium grit Spyderco 302 Benchstone and have fabulous results.
Long Live the SPYDEREDGE Spyderco Hawkbills RULE!!

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Postby dialex » Sun Aug 19, 2012 12:35 am

Dr. Snubnose wrote:I favor a semi-polished edge, finished to 6,000 grit.....some times after sharpening I will make one or two passes on the Spyderco white stones, just to give it a slight toothy finish....Doc :)
Same here. I merely preffer an utility edge rather than a mirror polished one.
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Postby dbcad » Sun Aug 19, 2012 5:22 am

Here's a pic of my Super Blue Mule edge. The backbevel is semi polished, the edge bevel a bit more toothy. Took the picture thru a 15X loupe, then cropped to actual pixels to zoom in.

Sharp is good :D :D
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super blue edge small.jpg
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Postby Eee » Sun Aug 19, 2012 9:04 am

Evil D wrote:As Deacon said it depends in the intended use. Some medium requires a toothy edge to get bite or that sharp edge will slide along the surface. Also at some point you have to start thinking about edge thickness because that plays a major role in how sharp the edge actually is, and thin edges aren't good for harder uses. Beyond all that you'll come tobacco point where the grain of the steel can't be refined any smoother or more acute than it is or it'll just chip out carbides. At least that's how I imagine it.
I couldn't agree more, I vary the edge according to to the grind, useage and steel (for example 12c27 seems to love to be polished). A good half of my knives have a toothy utility edge. The almost universal popularity of the Ackerman Serrata amongst owners says how effective a toothy edge can be. Lets hope the rumours of a Spydie version are true.

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Postby Blerv » Sun Aug 19, 2012 9:45 am

Thinness leads to the upper echelon of sharpness. Some steels, users, and tasks are best served by thicker edges that are technically less sharp.

Other factors such as technique and finishing are closer to universally beneficial. At least on the basis the edge won't potentially see the same level of failure.
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Postby jorgea » Mon Aug 20, 2012 8:27 pm

That is a great question. No knife can be too sharp. Thanks for sharing your knife sharpening experiment here at http://www.spyderco.com

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Postby Stuart Ackerman » Mon Aug 20, 2012 8:38 pm

Eee wrote:I couldn't agree more, I vary the edge according to to the grind, useage and steel (for example 12c27 seems to love to be polished). A good half of my knives have a toothy utility edge. The almost universal popularity of the Ackerman Serrata amongst owners says how effective a toothy edge can be. Lets hope the rumours of a Spydie version are true.
The Spyderco Serrata is a fact...just have patience...Sal and Crew are juggling a gazillion balls and trying not to drop any...

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Postby Evil D » Mon Aug 20, 2012 9:53 pm

If you sharpen two knives, one to 400 grit and one to 3k grit, both at the same angle...which is sharper? Technically, the higher polish has the potential to yield a sharper edge, IF the steel has a fine enough grain structure to allow it, otherwise you're just making the teeth at the edge shiny when you polish it, though i'd say it's still more refined than the 400 grit version and likely "sharper". The real question is, which is going to cut better, given a particular medium? If you're using both to cut corrugated, i'll take the 400 grit over the polished grit. If you're looking to push cut newsprint, then the polished edge wins. Some steels are going to allow the edge to be refined down to a much thinner apex, but it's going to be very delicate at that level of sharpness and regardless of the steel it's going to degrade fast. Of course some steels will hold it better than others, the but reality is a thinner edge is a sharper edge is a more delicate edge. It just depends on what you're cutting.
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Postby syphen » Tue Aug 21, 2012 7:44 am

JD Spydo wrote:Great Point "tautsig" :) That's why I've been preaching Spyderedged blades for cutting fibrous material like rope, twine, jute or just about any other type of cordage. Every type of edge has it's own specialty you might say.

Not all serrations are created equal. Most people have been exposed to Rip-Mart type serrated blades and thus draw the conclusion that they are all bargain basement trash. But Spyderco's patented Spyderedge is truly heaven sent for cutting chores involving fibrous material.

Yeah you can get an edge to refined to be efficient at a lot of cutting jobs. Sometimes I do my tune ups on the medium grit Spyderco 302 Benchstone and have fabulous results.


Spyderco's Spyderedge (H1 Salt I SE) does not cut 3/8" novalite (spectra based) rope very well. I was sailing a long distance endurance race and needed to get a line cut quickly. The Spyderedge Salt I just jammed the teeth in the rope and did not cut. I changed up to a PE knife (non spydie) for later on during the race as it was cutting better. I think there is a certain point where the serrations maybe become TOO aggressive and can bind on some high end synthetic rope types.
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Postby Eee » Tue Aug 21, 2012 3:47 pm

zackerty wrote:The Spyderco Serrata is a fact...just have patience...Sal and Crew are juggling a gazillion balls and trying not to drop any...
Hi Zack,

I didn't mean to imply any sort of reproach. I haven't been following the progress closely; I'm just excited that it is on the cards. It'll be great for more people to experience how well they work. I love using mine :D

Ian

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Postby phillipsted » Tue Aug 21, 2012 4:22 pm

I remember reading a Science Fiction book a few years ago ("Snowcrash" by Neal Stephenson). In the book, they had these swords that were made of synthetic diamond - and their edges were supposed to be only one molecule wide. These were the weapon of choice in the book because they were so sharp they could cut through any material - including the owner of the sword. :eek:

I got to thinking that 1.) these edges are "too sharp" - they were described as being so sharp that you could cut your finger off even before you realized you'd come into contact with the blade; 2.) A blade with this fine of an edge would be impossibly fragile and would not be able to cut through much steel or masonry, and 3.) I wonder what that blade would look like with a Spydie Hole in it!

These blades were so fine and so sharp that many people who chose to use them were seriously injured by their own weapons. That's "too sharp".

Sci Fi can require a suspension of disbelief...

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Postby Evil D » Tue Aug 21, 2012 5:43 pm

Technically, you can only get as sharp as one single atom at the very edge, which has been done already http://news.softpedia.com/news/The-Shar ... 9607.shtml


So, until Spyderco comes up with a steel that will hold a one atom wide edge, then we can't say an edge is too sharp. Once that steel comes along, we're all doomed because there's bound to be some steel snob out there who'll try to hone it down finer than that and end up splitting the atom of the edge and blow us all to pieces.
SHARPEN IT LIKE YOU LOVE IT, USE IT LIKE YOU HATE IT
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Postby chuck_roxas45 » Tue Aug 21, 2012 6:39 pm

Evil D wrote:Technically, you can only get as sharp as one single atom at the very edge, which has been done already http://news.softpedia.com/news/The-Shar ... 9607.shtml


So, until Spyderco comes up with a steel that will hold a one atom wide edge, then we can't say an edge is too sharp. Once that steel comes along, we're all doomed because there's bound to be some steel snob out there who'll try to hone it down finer than that and end up splitting the atom of the edge and blow us all to pieces.

Then the search would start for a smaller atom. :D

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Postby tautisg1 » Wed Aug 22, 2012 11:17 am

Wow, it's really interesting to hear all the awesome responses from everyone. Thanks a lot for sharing your opinion :)


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