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Post by miyamoto05 on Sept 11, 2015 22:18:35 GMT
Hello,
How can I sharpen my Katana the best way?
With which grit should I start?
Is 3000 grit sufficient for making a Katana very sharp?
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Post by DigsFossils-n-Knives on Sept 11, 2015 22:40:40 GMT
Here is a vid from our very own asoundlikesilence
Green buffing compound which is 1800 grit is enough, higher is better but you don't really need it.
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Post by greatsaiyaman on Sept 12, 2015 6:09:19 GMT
I personally wouldnt do it this way as you are removing lots of metal and destroying the geometry just to turn it into a flat grind. Each blade is different and this way wouldnt do anything but reduce the belly on blades with correct geometry and niku. It will also grind away and flatten the shinogi ji causing you to then having to reprofile the shinogi.
The better way to do it is instead, polish the blade horizontal just behind the edge rather than lengthwise in small areas working up the blade. This way you are removing the shoulder caused by beveling done on the blade by a belt sander and creating a burr. Keep your angle consitent throughout as you grind with a very slight rocking motion to blend the edge in with the rest of the blade.
Once it is all shaped nicely (which can be very time consuming) get some 400 grit sandpaper laid flat and run the blade up and down to remove profiling scratches and polish it up.
Polishing stage is hard to explain in words so I will leave that out, but the higher you go working the blade, the edge will get more and more polished and sharper and sharper.
I finish off with a leather strop green and white compound to create a microscopic bevel that will refine the edge super scary sharp and it will not chip or roll after 100's of cuts on light or medium targets.
Edit - this way is done starting with a coarse 120 waterstone then working on to sandpaper at 400, 600, 800, 1000, 1200, 1500. Sorry i can't explain this process well enough so I should make a video lol
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Post by DigsFossils-n-Knives on Sept 12, 2015 12:26:24 GMT
The process asoundlikesilence uses is absolutely fine. If you are concerned about removing too much of the niku you can put a soft sheet of material like a thin mouse pad, or very thin felt material to get more of a convex geometry. By doing this you, and giving the blade a slight angle as you grind/polish, the lower part of the shinogi-ji is ground out to a sharp edge. But then you are adding niku. After a few sharping sessions your niku will become too thick so you'll need to do it as asoundlikesilence shows.
Here is a vid where a master sharpener/polisher is doing it very much like asoundlikesilence (forward to 5:38)
The only time I would not follow this process is when the blade has a bend or bends. You need to straighten the blade first.
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Post by miyamoto05 on Sept 12, 2015 12:58:05 GMT
Here is a vid from our very own asoundlikesilence Green buffing compound which is 1800 grit is enough, higher is better but you don't really need it. Can I start with 1000 grit and continue with 3000? |
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Post by DigsFossils-n-Knives on Sept 12, 2015 13:17:34 GMT
Can I start with 1000 grit and continue with 3000? Depends.... If you are "honing or stropping the edge" then yes start with 1000, but I wouldn't do it as asoundlikesilence shows. asoundlikesilence is showing how to sharpen a blade from "very dull or dull". I would do it more as greatsaiyaman is suggesting because you are going to work the "busy part" of the katana. If you need to sharpen a dull blade then I'd say start with 220 if the blade is very dull or maybe 400-600 range if the blade needs a little sharpening. If your blade has no edge at all then you might have to start a little more aggressive and use 80-120. Expect to cut a lot of steel with 80-120. And to state the obvious if your blade has a poor heat treat then you will never get it very sharp. Keep in mind that 1000 grit barely cuts any steel so you are not sharpening but polishing with >1000 grit. |
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Post by miyamoto05 on Sept 12, 2015 14:45:14 GMT
Can I start with 1000 grit and continue with 3000? Depends.... If you are "honing or stropping the edge" then yes start with 1000, but I wouldn't do it as asoundlikesilence shows. asoundlikesilence is showing how to sharpen a blade from "very dull or dull". I would do it more as greatsaiyaman is suggesting because you are going to work the "busy part" of the katana. If you need to sharpen a dull blade then I'd say start with 220 if the blade is very dull or maybe 400-600 range if the blade needs a little sharpening. If your blade has no edge at all then you might have to start a little more aggressive and use 80-120. Expect to cut a lot of steel with 80-120. And to state the obvious if your blade has a poor heat treat then you will never get it very sharp. Keep in mind that 1000 grit barely cuts any steel so you are not sharpening but polishing with >1000 grit. The katana I have can't cut through paper... With force, it cuts trough bottles. With which grit should I start? 400? Where can I get those cheaply? |
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Post by DigsFossils-n-Knives on Sept 12, 2015 15:51:34 GMT
The katana I have can't cut through paper... With force, it cuts trough bottles. With which grit should I start? 400? Where can I get those cheaply? I buy my sandpaper from www.trugrit.com/ and www.supergrit.com/Sometimes from Home Depot and Amazon. I always look for the low price. |
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Post by greatsaiyaman on Sept 13, 2015 3:50:03 GMT
I second using a thin mousepad underneath the sandpaper. Makes conserving geometry a whole lot easier.
I only do lengthwise strokes for the final 2-3 polishing grits though to smooth out the reprofiling. Doing it to early changes the geometry and removes the convex surface you have created.
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Post by miyamoto05 on Sept 13, 2015 17:14:25 GMT
I second using a thin mousepad underneath the sandpaper. Makes conserving geometry a whole lot easier. I only do lengthwise strokes for the final 2-3 polishing grits though to smooth out the reprofiling. Doing it to early changes the geometry and removes the convex surface you have created. Which grit are you using? I want to say that it isn't dull, half sharp, so to say... |
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Post by DigsFossils-n-Knives on Sept 13, 2015 17:38:21 GMT
I second using a thin mousepad underneath the sandpaper. Makes conserving geometry a whole lot easier. I only do lengthwise strokes for the final 2-3 polishing grits though to smooth out the reprofiling. Doing it to early changes the geometry and removes the convex surface you have created. Which grit are you using? I want to say that it isn't dull, half sharp, so to say... We can't answer this via forum posts without the blade in hand. Start with 600 and if you're not making progress fast enough then drop to 220 or 400 grit. It's really your call. |
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Mikeeman
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Post by Mikeeman on Sept 14, 2015 15:00:26 GMT
The only problem I have with a mousepad, or other foamy surface, is that it can easily wrap around the ha and start dulling it. I've had it happen, before.  Instead, I would use a rubber sanding pad. Or some other material that may have a little bit of give, but not enough that it could ruin all of your progress. |
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Post by Billybob on Sept 14, 2015 17:37:40 GMT
An inexpensive marble or granite block works the best. The kind one finds in woodworking supply stores. I purchased one for about $40 USD and it works great. They are used for sharpening chisels and other woodworking tools. Anything that has give to it (that isn't stone, metal or ceramic) will dull as it sharpens by wrapping around the ha. Anything that is irregular will not remove metal consistently and your edge won't be even. Your edge geometry has more to do with the proper sharpening method than anything else and a granite block may not be the proper way to sharpen a blade with lots of niku.
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Post by twalker32 on Sept 15, 2015 13:33:23 GMT
The only problem I have with a mousepad, or other foamy surface, is that it can easily wrap around the ha and start dulling it. I've had it happen, before. Instead, I would use a rubber sanding pad. Or some other material that may have a little bit of give, but not enough that it could ruin all of your progress. This is what I did, I used a mousepad initially, but it was obviously dulling it. I found a hard rubber sanding block in the automobile section of Walmart, made by 3mm. Has just enough give to follow the convex shape of my Oni Forge Kiyomaro very well. Course I wasn't just sharpening, I was polishing. Took it up through 3000 grit plus metal glo, made a world of difference. |
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