INFI edge info

[t1mpani]

Hey guys, quick question:
Having had the opportunity to play with my Active Duty a bit, I've come to a very strange conclusion...it slices well, but it's not really sharp. The edge profile is good and thin, and I can whisk off strips of paper with ease, but I have better hair shavers and I can also run my finger along the edge and not get cut--and while I'm not bearing down when I do this, I am pushing hard enough to squish my finger pad out of shape.

My other INFI (especially my custom fighter) would have split my finger down the middle if I'd performed the above action, with edge bevels nowhere near as narrow, so what's up? Is the edge too polished, maybe? I don't want to mess with profiling if a switch from 1000 grit paper to 400 would do the trick. Truth be told, I am more familiar with the behavior of SR-101, so I figured I'd ask the experts here.

 

[Cliff Stamp]

Edge which are highly polished will lose slicing aggression, but not to that extent. The edge could have been rounded slightly in stropping or just very worn. Cutting paper isn't as demanding a test of sharpness as shaving, unless of course the paper is very fine, which is why one can be seen but not the other.

This isn't significantly influenced by edge angle, it is just a matter of quality of finish. I would suggest a complete sharpening of the edge. Starting with a medium grit like 600 DMT, 1000 waterstone, or similar. The edge when fully sharpened at this grit should shave but be scratchy and may require a bit of a slice to shave. It should cut into the skin with very little draw and light force.

As the polish is refined you will lose some slicing aggression on hard materials like synthetic ropes, but shaving ability should be refined and push cutting in general should see a large increase.

-Cliff

 

[t1mpani]

Thanks Cliff, I guess it's time to pull out the sandpaper and leather, and start stropping. Up to this point I'd only tried a few passes on a Spyderco so-smooth-it's-like-glass ceramic sharpener, and wondered if I might be going in the wrong direction. Guess I have to mess up that pretty satin finish sometime.
Warren

 

[Josh Muller]

if you tape the knife up in painters tape before sharpening it, you shouldnt mess up the satin finish. basically cover everthing on the blade portion except for the cutting edge that will be sharpened. i found out the hard way with my bandicoot about how bad it can mess up the finish trying to sharpen it without any protection.

 

[t1mpani]

Already fixed! I guess I was just going too fine. That cermaic block I have is supposed to be like 8000 grit. I stopped stropping at 600 grit, skipped the 1000 and 2000 and went straight to steeling on one of my HI chakmas. This knife will now cut already-hanging paper strips into smaller strips, and I have to be careful shaving because it just starts skinning my arm. I guess the ulra-fine ceramic just won't see any use with my INFI. Actually, that's fine with me, as it lets me make use of all this other sharpening stuff I have lying around. Thanks for the idea with the taping, Seth, and for your help as always Cliff.