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Post by Sir Thorfinn on Jan 12, 2013 2:43:14 GMT
I looked for a bit, and can't really find a reference anyone has made to this.
How do you know when you've got the bevel right? I can't figure out how to test the geometry without going on a bottle slaughter rampage. It's simple enough for me to get a mirror polished razor edge, blend it into the bevel, and call the sword hair popping sharp. But I just don't know how to measure or quantify the edge to see if there is too much metal near the edge, or if it's thinned enough.
Anyone have some pointers?
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Post by willhart on Jan 12, 2013 5:50:20 GMT
Here's a good article about convex edges. forum.grtc.org/viewtopic.php?f=9&t=1001As for measuring it I'm not sure. I've been reprofiling some of my edges into convex and tring to do some zero grind edges on my euro blades using a belt sander and waterstones. Ricky from might be helpful. I've seen edges from , Tomk, and Razor. Ricky puts a great zero grind edge on the Katana I have from him. Using a Tomk's method of a 1x30 belt sander, it's hard to made a centered convex edge. You normally get a front heavy convex edge, which is normally just a little larger than a secondary beveled edge. The best thing I can think of is to use a light source to see how it deflects and if it deflects evenly. Another off the wall idea I have is to get a block of clay and mold it around half of the blade and then look at it from the side. Not sure if this would work.
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Post by lamebmx on Jan 12, 2013 14:58:59 GMT
You can also take a flat edge, say a credit card (dark colored card helps a lot) and basically roll it along the edge and note how its curved. For the second part, your are creating the geometry, so its basically what you want from it. I took a tenchi and reprofiled the niku to pretty flat then at the very edge it dipped down, creating only ha-niku or just a bit of appleseed right at the edge. Probably a lot less durable than it originally was, but it would draw lines through numerous hanging leaves and you could not see the leaves move as it cut them. Looking at a bunch of swords.
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Post by Sir Thorfinn on Jan 12, 2013 16:23:19 GMT
Wilhart, that's funny that you posted *that* particular article. I've posted it here a few times myself, it's a great article, and gives good visuals. Oh, and for reference, I'm working exclusively on Euros and a machete. So more to what I'm trying to measure... I agree that the belt sander method leaves a front heavy convex, I can make it very even down the blade, but to the eye, it seems like a pretty thick edge, irrespective of how sharp I get it. So if anyone has a high end Euro that they feel is scary sharp, maybe measure from the edge toward the blade spine, and let me know where the bevel starts towards the edge. I think the only real way to do that is Lamebmx's idea with a credit card. Flat on the primary bevel, and find the spots where it starts to dip towards the point. Maybe we can get a few samples and compare. I'm not sure why this is so important to me, maybe it's my inner OCD monkey screeching at me for perfection. I can make sharp edges, but I want *scary*. Once I can mentally quantify *scary-sharp* I'll know how much to back away from that for *practical*. And maybe we can all learn along the way
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Post by willhart on Jan 13, 2013 4:48:48 GMT
Well a belt sander will leave a front heavy bevel based on the angle you hold it to the belt sander and also the tension of the belt itself. I have a hack kinda for getting more tension on my harbor freight belt sander. I did this for my HT long sword when I used it to reprofile the whole blade. It did reprofile the whole thing and I'll try to take some pictures of it. The problem was that it could take all the scratches out of the central portion of the blade. I've posted about it here. forum.sword-buyers-guide.com/viewtopic.php?f=19&t=13671When reprofiling it I started with a 80 grit belt and it still took 4 hours to do, but I couldn't get the scratches off the center of the convex curve with it. I bought some waterstones to fix this problem. Also that guy is really helpful on the GRT site. **Edited. I tried to take pictures of it, but I can't take a picture that shows anything even with my DSLR camera. But I measured the secondary bevel with my HT Bastard which is unmodifed and the secondary bevel is 1/16th before it turns into the primary bevel. My HT Longsword which I tried to reprofile using the belt sander to make it a convex bevel is 1/4th of an inch before it turns into the primary bevel. Now I'm looking at my VA Arming Sword and it has a 0 grind convex edge it seems all the way to the fuller, just like how does it.
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Post by aussie-rabbit on Jan 18, 2013 2:25:38 GMT
I have a couple of swords that fits in the scary sharp bracket, I use a polishing stick (strop-stick, slick-stick) and 12,000 grit polish, then just add time. How to quantify is a big question
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