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Post by Iridionprime on Feb 2, 2013 16:27:40 GMT
I'm looking for something like an accusharp, but word is that accusharp leaves a secondary bevel which is unsuitable for cutting well? Are there any other handy devices out there that will give the proper edge to say a kris cutlery viking sword (which I dulled regrettably).
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Post by willhart on Feb 2, 2013 17:55:40 GMT
The only thing that would be almost as fast would be powered. There is hand held power mini belt sander sharpener that has a guide that if you want easy but it's not cheap.
There is nothing that is like an accusharp that will work for swords normally as most swords have different angles and thickness. It may make it sharp, but it wiill not be a strong edge that will take any abuse or last long.
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Post by MOK on Feb 3, 2013 1:46:49 GMT
An accusharp also doesn't work on a blade with varying thickness and/or edge angle, or too obtuse main bevels, or any number of other little things. I have used them to start an edge on a couple of unsharpened Windlass pieces, but I stopped doing even that because cleaning up after the accusharp was actually more work than just using files, stones and sandpaper right from the start. For restoring a dulled edge, shaving off strips of metal with an accusharp is complete overkill, anyway. My favorite sharpening tool right now is my new Dianova lapstone (I might want to get the Cook model at some point, the longer diamond surface should make it handier for large blades). Rough and fine sides (30 and 60 micron) and a steel body that doubles as a steel for removing the burr. Much better than any accusharp, and almost as fast unless you're actually creating an entirely new edge where there was none before. And it fits in my pocket, too.
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Post by Iridionprime on Feb 3, 2013 7:23:27 GMT
And as for technique, should I be grinding at a 30 degree angle? Is there any trick to make sure that I don't screw up the angle im at while sharpening?
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Post by aussie-rabbit on Feb 3, 2013 12:26:44 GMT
30 degrees is fairly coarse, try to follow the original angle, if it's not too bad go for the rubber sanding block and 400 grit wet-or-dry paper.
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Post by aussie-rabbit on Feb 5, 2013 13:21:54 GMT
Katana blade angles average around 19 degrees +/- 3 degrees or so, please do not run a stone down the edge at 45 degrees Viking/Euro "knightly" type swords tend to be 25 to 30 degrees, there are plenty of other angles, sabres go down to as little as 9 degrees. Here is a youtube vid from the old pro-boards site.
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Post by MOK on Feb 5, 2013 19:28:03 GMT
Of course, one thing to note is that if you want an edge angle of 40 degrees, you have to sharpen each side holding your tool at an angle of 20 degrees. That is, the angle between the two bevels is twice as large as the angle between the plane of the blade and either individual bevel; the problem is that either one can be referred to as the edge angle, which causes no end of confusion. (Personally, I prefer to use the angle between the bevels. It just feels more intuitive.) Regarding parabolas... technically, a parabola can be anything between a semicircle and a triangle, exclusive (ie. never quite a perfect semicircle, nor ever quite a perfect triangle, but anything in between), so having your bevels follow a parabola doesn't actually say anything other than that they grow more steeply convex as they approach the edge. A parabola is also flat at the peak, so a literally parabolic cross-section would result in blunt, round edges; what you actually want is two parabolas, each defining one bevel and intersecting at the edge to form the sharp cutting angle. And the reason you want the bevels to follow a parabola is simply that a parabola is a perfectly, mathematically smooth curve (much like a spiral).
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Post by lamebmx on Feb 6, 2013 1:14:47 GMT
19*2=38 and that looks about right for the ha, funny thing is, up by the shinogi-ji the blade angles (combined) looks as though it might be close to 19 degrees. Yes, 2 intersecting parabola's would better describe the edge as produced. something like;
for X<0, AX^2 +B & for X>0, AX^2 -B where A is a constant defining the amount of niku or meatyness to the appleseed geometry. The smaller the value of A the meatier the edge. B is a constant to define the entry angle as defined X approaching 0. The greater the value of B the smaller the entry angle.
While I do not have a patent, if you use the above to CNC a stock removal blade, you owe me a free sword!
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Post by MOK on Feb 6, 2013 9:12:41 GMT
Alternately, instead of mucking about with parabolas you can just use ellipsoids. They're geometrically identical for our purposes and much simpler to work with.
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Post by aussie-rabbit on Feb 9, 2013 4:10:49 GMT
Alternately, instead of mucking about with parabolas you can just use ellipsoids. They're geometrically identical for our purposes and much simpler to work with. [/quote] And if you look at some appleseeds there are fat ones and thin ones
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Post by MOK on Feb 9, 2013 9:14:32 GMT
Indeed - just like swords! So you see, it all... makes... um...
Wait, what were we talking about?
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