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Post by Deleted on Oct 23, 2009 23:46:17 GMT
Sorry for the stupid question here guys but maybe some of you can chime in and help me understand how this works. I have a Cheness O-Kat that came extremely sharp to the touch. I have read many times that the edge geometry can make the blade feel deceivingly dull. I have cut nothing but plastic bottles (probably several hundred) and the edge seems to have lost its original, near razor sharp edge. In fact it ''feels'' almost dull..........however on a good cut it still passes through the target like it was not even there and it leaves a very crisp line where the two pieces seperated, no jagged edges at all. I will still have the occasional bad ''swipe'' where my form was off but it generally passes through the target like a laser. I could not love this blade more than I do and it really seems to fit me quite well {Im a 280 pound bodybuilder, so the sword feels like a feather in my hand.........anything less just doesnt feel quite beefy enough! In fact I told Paul that it feels like I could cut a car in two with this blade } Anyway guys..........Its just hard for me to get past this dull ''feel'' to the blade regardless of how well it performs. I just have that inherent feeling that the blade should have a razor edge to it. Thanks for your patience and maybe someone can ease this silly notion that it does not feel sharp. BTW............how often should I expect to touch up or even resharpen this blade? Thanks again for all the fantastic information you all provide here. Great site and great people to boot!
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Post by Deleted on Oct 23, 2009 23:58:30 GMT
Hm, I am not sure of a specific time frame you should be expecting to resharpen your sword, I suppose it depends on how much you use it and what you're cutting. Cutting plastic like that will, as far as I know, definitely dull the blade over time. Cutting anything will dull the blade, and it seems as though you've been cutting quite intensively . Knowing this, I am sure if you really want that sharp feeling back, you can either get professional sword sharpening (which costs a lot of money, and is not worth it for a lower tier Cheness), or you can just do it yourself. There are many good resources online regarding how to sharpen a sword, and I think it was a member on here (Ianflaer, perhaps) that set up some very very easy to follow sharpening tutorials on YouTube . You stated that you're a strong guy, so the repetitive motions and physical requirements to get a job like this done are obviously not of worry to you, so I think you will be fineee!^_^ Oh, and don't use an Accusharp .
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Post by Deleted on Oct 24, 2009 0:17:43 GMT
The geometry you speak of is called niku. It is the convex "apple seed" shape of the edge that allows a lot of steel to support the cutting edge. An edge that is flat, concave, or thin can feel sharper and in fact, it is sharper in that it is thinner. The best explanation I can offer is at: bugei.com/niku.htmlThe end result is that a convex surface actually causes the object being cut to be pushed away and peel from the blade surface as opposed to a concave edge that you must force the blade through the object being cut. The end result is a more efficient cut that travels with less resistance through the object being cut despite the edge being less sharp. No "razor" stays sharp without constant attention, honing, stropping, and sharpening as the edge is fragile. Niku solves the sharpness vs fragile issue very well. If your sword cuts, it is as sharp as a katana should be, not what you think it should be as the geometry should be unique compared to a kitchen knife. Edit - mixed up terms
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Post by Deleted on Oct 24, 2009 2:47:22 GMT
Thank you both for the comments. Oogway........great link my friend. That helps out tremendously!!!
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Post by Deleted on Oct 24, 2009 4:22:23 GMT
If your sword still cuts as well as it does the day you bought it, perhaps it hasn't become more dull.
When I was resharpening a sword with a file, I noticed that the edge felt sharper (and cut paper better) before I cleaned it up with sandpaper. I think that what I perceived as sharp was really the rough material on the edge acting like serrations and catching on my finger (and cutting the paper). I'm pretty sure I didn't make the blade more dull as I use the same technique to sharpen swords that have dulled.
Perhaps cutting bottles has smoothed out the edge material?
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Post by Deleted on Oct 24, 2009 8:06:28 GMT
Oh, and don't use an Accusharp . Yeah, not even if you get a euro sword. It creates uneven edges grrr... Federico
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Post by Deleted on Oct 24, 2009 13:50:06 GMT
My Cheness Kaze gets used a lot , and takes the best razor edge of any of my swords. I use a basic stropping technique whenever I feel it isn't quite scary-sharp enough. Here's my vid, all you need is a leather strap and some jewelers rouge ( available on ebay cheap , type 'tandy leathercraft jewelers rouge ' in the search bar).
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Post by Tom K. (ianflaer) on Oct 24, 2009 17:57:01 GMT
it is amazing how well a sword can cut when it isn't really all that sharp. I have seen people cut tatami with blunt swords. quite simply the sword generates a LOT of force and any sort of narrowing edge will further concentrate that force creating powerful shearing forces. obviously the sharper the blade is the more the force is concentrated and the better/easier it cuts but also the more fragile your edge will be. niku/edge geometry makes a big difference in edge strength but can limit sharpness. fortunately, you can get an edge with LOTS of niku pretty darn sharp if you do it right and it will still be tough because you'll have a lot of steel supporting the edge (this is what high niku does)
Randy's (morpheus) video above shows a very good technique and is probably all your sword would need to make it sharp enough to shave hairs off your arms and maybe even your face were you so inclined. I have some sharpening videos linked in my signature and I've been told by a lot of people that they have helped them so please take a look if you would like. my videos tend to assume you are starting with a very dull or blunt sword but it should be easy to pick out the parts that a sword like yours won't need and it's all good information too.
hope this helps.
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Post by Deleted on Oct 24, 2009 18:04:15 GMT
Thank you everyone for your replies. Yes Tom, it is amazing. When I slowly and oh so lightly run my thumb an inch or so down to blade I can almost feel the blade warning me to back off as if it is about to bite deeply into flesh..........almost a creepy feeling. Its like its saying ''You think Im dull??.......keep going.......just a few more millimeters, Im begging you.....''
Thanks again. Your a great group of people who jump at the chance to educate in a very mature fasion.
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Post by Deleted on Oct 24, 2009 18:05:10 GMT
I have a tenchi ko kat wich is the same steel and I had the same experience after half a year of cutting. So I drawfiled the edge and cleaned it up with sandpaper. Then I took a sharpening steel and ran it over the blade. After that I cleaned it up with sandpaper again. It felt sharper before it did that but like vyapada said, that was due to the smoothing of the edge. Now the sword is just as sharp as it was when it arrived.
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Post by Deleted on Oct 25, 2009 13:52:29 GMT
Hey guys, an odd thought.... I recently decided to switch to using a straight razor and have been looking for a 4000/8000 (the coarsest that will work, finer is better) barbers' hone. A buddy of mine stated he thought that using a barbers hone might be a great idea for working the edge of a sword to get a high level of sharpness. Any thoughts?
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Post by Matt993f.o.d on Oct 25, 2009 14:11:55 GMT
Don't bother sharpening it. The 'sharp' feeling was probably just edge burring left from polishing.
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Post by Deleted on Oct 25, 2009 14:41:22 GMT
Hey guys, an odd thought.... I recently decided to switch to using a straight razor and have been looking for a 4000/8000 (the coarsest that will work, finer is better) barbers' hone. A buddy of mine stated he thought that using a barbers hone might be a great idea for working the edge of a sword to get a high level of sharpness. Any thoughts? This would be overkill, as a true face shaving razor sharp edge is extremely fragile, and wouldn't last longer than a single cut on a sword. When someone says "razor sharp" this is misleading, as really straight razor face shaving sharp like i said is very fragile. Razor sharp as used in the sword and common knife world is usually sharp enough to shave arm or leg hair, which can easily be done with as low as 220 grit, and smoothly with as low as 400 grit. True face shaving razor sharp is not only a bit challenging to achieve, but isn't just a factor of the grit used to sharpen the steel with, it has alot to do with geometry of the edge itselfA burred edge will feel sharper than a smooth stropped edge, and most likely like Matt said it doesn't feel sharp is because the act of cutting removed the small burr from the edge, yet it still cuts because it is still just as sharp, it's just the edge is not as toothy as it was. With the stropped edge it has now, I can bet it will cut lighter targets better, such as a hollow rolled cigarette paper or free hanging sheets of printer paper. If you look at a standard pocket knife or kitchen knife under a microscope, and look at the edge, it will look like a hack saw or jagged broken glass along the edge. If you look at a straight razor under a microscope it will steel be jagged, but the teeth will be a thousand times finer, barely discernible except under much higher magnification. Because of this, if you catually tried to cut through say 1" hemp rope with a straight razor, it will take you much longer than if you used a regular knife with an "everyday" edge.
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Post by Deleted on Oct 25, 2009 15:34:51 GMT
Good to know. I am aware The geometry differences with knives, swords, and various tools. I was just wondering, what you might have thought about using a barbers' hone for a swords edge.
Ok, so that might be a little bit too fine, and it would be appropriate something a bit coarser for sword sharpening, such as my general duty whetstone that I use for my other knives and tools. Thank you for your opinion.
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Post by Deleted on Oct 25, 2009 19:40:24 GMT
A burred edge will feel sharper than a smooth stropped edge, and most likely like Matt said it doesn't feel sharp is because the act of cutting removed the small burr from the edge, yet it still cuts because it is still just as sharp, it's just the edge is not as toothy as it was. With the stropped edge it has now, I can bet it will cut lighter targets better, such as a hollow rolled cigarette paper or free hanging sheets of printer paper.You are absolutely correct. In fact just last night I realized that now that it ''feels'' dull...........its going through very light gauge small plastic bottles like a laser, leaving both peices with extremely crisp straight lines where the cut was made..........where before when it ''felt'' razor sharp, it was difficult to cut these same targets and when I did, the edges on the two peices where the bottle was cut, were jagged and uneven. Its almost as if, the duller it ''feels'', the cleaner it cuts. Very cool.
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