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Post by Deleted on Dec 16, 2008 4:44:12 GMT
I was wondering your opinions on ways of testing sharpness of a katana. I don't think paper cutting tests are very accurate, I can grab the dullest knife from the kitchen and can easily slice paper with it. Now I know this is not the right way of doing it, but I usually just to the thumb test. I have a tenchi, it feels very dull, but I know that has to do with niku. But still I find it strange that I can apply a significant amount of pressure and drag my thumb across the sharp edge without getting cut.
Is there a definitive way to test sharpness? Or do you have your own way?
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Post by salvatore on Dec 16, 2008 4:53:28 GMT
I was wondering your opinions on ways of testing sharpness of a katana. I don't think paper cutting tests are very accurate, I can grab the dullest knife from the kitchen and can easily slice paper with it. Now I know this is not the right way of doing it, but I usually just to the thumb test. I have a tenchi, it feels very dull, but I know that has to do with niku. But still I find it strange that I can apply a significant amount of pressure and drag my thumb across the sharp edge without getting cut. Is there a definitive way to test sharpness? Or do you have your own way? Paper cutting tests with katana are a good judge of sharpness. You have all that beef in the blade, all that weight and with such a heavy blade, can still cut paper, it is a pretty good judge. With a kitchen knife, it is thin and light, cutting paper with a lightweight, slender and flat ground blade is easy. With a katana, you have all that geometry for the paper to get past, if it can cut it, your probably the proud owner of a sharp sword. You can also use your nails, if it can shave bits of your nail it is a good judge of sharpness, not the best, but hell it works. As compared to a kitchen knife, a katana blade is very bulky so if it can cut paper, it is sharp IMO. The appleseed bevel can also mask the sharpness, it will feel dull, but will "Cut like a laser". It happens. I'm sure there will be more input, and you can get some more sharpness test ideas. Sal
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Post by Tom K. (ianflaer) on Dec 16, 2008 4:57:21 GMT
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Post by Deleted on Dec 16, 2008 5:09:40 GMT
Yea I have seen that nihonzashi page, but that mostly tells you how it gets dull, not ways of testing the sharpness. For paper cutting, my tenchi does cut paper, but only if I get the intial bite into the sheet just right and then pull the tenchi back. If I apply pressure directly downward w/o a slicing motion it won't cut paper.
I guess where I get confused is when I think of sharp I think of cutting sharp, as in you apply pressure and cuts into your skin. But that's not the base with my tenchi. With my paul chen XL blade, if I applied the same pressure and dragged my thumb I know for sure I would be CUT. But not with the tenchi, i can drag my thumb across the blade all day (yea yea I know I'm not supposed to).
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Post by Deleted on Dec 16, 2008 5:26:41 GMT
Try taking it to your leg, then see if you bleed to death.
If you're still alive, you should get back to sharpening and repeat. If you're dead, you can die happy knowing someone, somewhere, will have a hella sharp sword!
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Post by Deleted on Dec 16, 2008 10:40:13 GMT
In my opinion, the nail test and the paper cutting test isn't enough to see if something is sharp, possibly that it's not sadly unsharp.... My way is to draw my fingers after the edge extremely lightly, if they feel like getting stuck, or there is a drag, the edge is sick sharp, if they slide on top of it it's not sharp enough for me.... When I do this, I use absolutely NO pressure! I just lay my fingers on the edge and slowly lightly feel along it. And yes, it may give some small cuts in the fingertips, but nothing that goes through the skin! And ok, nothing needs to be that sharp, but why shouldn't it
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Post by Deleted on Dec 16, 2008 10:42:40 GMT
do this with it; if it does that then you know it is sharp.
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Post by Tom K. (ianflaer) on Dec 16, 2008 10:52:21 GMT
yup, that's it BW! you've got THE definitive test there. oh by the way, WOW!
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Post by Deleted on Dec 16, 2008 11:07:02 GMT
Yeah shiva ki, the man is a legend and one day I would love to own one of his knives, not to mention the guy himself is an inspiration.
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Post by Deleted on Dec 16, 2008 16:36:28 GMT
Well BW beat me to it... sorta. I was going to say go out and cut something with it. If its not sharp it won't cut. Plain and simple. If it slices through water bottles, tatami, deer carcasses you found on the side of the road... etc its sharp. If you don't have any readily available targets you can always roam the streets looking for stray bums...
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Post by Deleted on Dec 17, 2008 0:41:00 GMT
Here is an answer to the original question from the guy who made the tenchi.
Dragging your thumb across is not a good measure and there is no benchmark that I can use to tell you if it is properly sharpened or not... since I don't use that method to measure sharpness myself, and it is not a good indicator. Additionally, the only section of the sword that should be sharp would be the monouchi.... ("cutting portion" which is the section just below the tip and extends for about 1 foot from the tip). I can tell you that it is not intended to break skin just from touching the edge, but I cannot say specifically what the case is in your situation. Best Regards, Paul Chen
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Post by Deleted on Dec 17, 2008 1:41:22 GMT
good old paul cheness, lol
i hope he has a brainwave soon, and makes kaze with hi...
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Post by Deleted on Dec 17, 2008 1:42:18 GMT
in response the the op
the best test of sharpness would be to go cut a mat or some bottles.
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Post by Deleted on Dec 17, 2008 8:49:06 GMT
in response the the op the best test of sharpness would be to go cut a mat or some bottles. Hmm why didn't the old japanese do this? Because human bodies are better of course Including thumbs ;D
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Post by Deleted on Dec 17, 2008 15:26:55 GMT
well ... you could always put it in shirasaya then try fast drawing it till ya mess up .....i learned real quick how sharp my shirasaya was by doing this.... ouch lol bad idea...
try cutting suspended papper , that should be extreamly hard to do =/ if it can do it ... wow .... if it cant.. dont feel bad not every sword can i guess lol xD i doubt my shirasaya could do it ...but then again it got my thumb really really good =/ ... oh well swords are made to cut flesh and bone , not paper .... hmm sry i'm not helping much lol
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Post by Deleted on Dec 17, 2008 20:51:47 GMT
Yea, swords like the tenchi are weird. It doesn't feel sharp at all and can't cut you unless you really tried hard, but it cuts bottles and paper w/o a problem.
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