Convex sharpening Sebenza?

L

luna

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Nov 9, 2007
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I took a very very dull and messed up Fallkniven F1 to hair-shaving sharp using mousepad-and-sandpaper followed by a leather strop with black and green compound. It was fun to do, and very satisfying to be able to do that myself to my own knife. So... I decided to reprofile my Sebenza and have had no luck at all. I have used 220-320-400-600-1500 grit followed by the strop and it just won't get sharp enough even to cut paper reliably. I'd almost think there was a burr, but the stropping ought have gotten rid of it (I'd think). Any advice? Am I missing something? I think my technique must be close to correct since it worked pretty well on the F1, and I am being very patient and working away at it. I guess it isn't though, eh?:jerkit:
 
My advice, stop with the convex sharpening nonsense. Convex sharpening requires you to be precise with both the angle and pressure. With stones pressure is of almost no significance. Sharpening on stones freehand will give you a certain degree of convexity due to the inherent imprecision of being human.
 
Convexing S30V is no easy task because of its high wear resistance, with a knife like the seb I wouldn't bother anyways because its already hollow ground and convexing would have no benificial effects. You will most likely wear out every piece of sandpaper you have getting a edge on it if you haven't already. If you want to continue to convex it then you will need to work each grit for a much longer period of time.
 
I have convexed blades with steels like VG-10, S30V, ZDP-189, INFI and a pile of carbon steels too, all with no problems.
The one thing that I can think of that might be tripping you up is the hollow grind on the Sebenza.
 
I don't believe the slight convex grind of the Sebbie is the problem - try running each side of the edge lightly over back of a fingernail - if it catches slightly then you still have a burr.
 
the F1 already has a convex edge so i'm supposing that all you were doing was touching it up.

you're trying to totally reprofile the Sebenza and that will take time. plus, that hollow grind is going to make convexing tough.
 
The hollow grind doesn't leave you enough steel for an F1 style convexing. On the other hand, the Sebenza comes from the factory with a convex secondary bevel. You could restore that, but I don't see where it's worth the trouble. CRK recommends the Sharpmaker at 40 degrees.

What's probably happening is that you're over-convexing the secondary bevel, rounding the edge like a Sharpmaker can round tips.
 
Vanadium carbides make sharpening a bit more difficult with abrasive paper. I just use a V grind with fine diamond.
 
I think the Sebenza may be too thin for that. I am probably wrong. I suck at sharpening.
 
i convexed a sebenza for jtr357 and it turned out extremely sharp. i worked up a burr on my belt sander and removed it with the paper buffing wheel. when i was done it would push cut newspaper easily.
 
I just recently convexed the S30V blade on my Bradley Mayhem with sandpaper and strop. It took a REEEEALY long time... I'm talking 20+ hours, it sucked but I was determined.

What finally worked was to start by placing 220 grit paper on a flat piece of plywood so that you can go ahead and USE SOME PRESSURE without rounding the edge. Once you form a small burr on both sides then go back to a mousepad, or leather backing and use a light touch while progressing through your finer grits. -this would have saved me ALOT of time, had I done this from the start-

If you use a good light sorce and magnifying glass you can actually see the edge being formed and should be able to tell if the two edges have come together correctly. And if all else fails you can touch it up by using a fine diamond stone with a light touch, followed by your strop.

Eventually I ended up with a satisfyingly hair-popping convex edge, but then I'm not sure how well this all works on a hollow ground blade, but good luck!!
 
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