Any advice for trying to help a neighbor sharpen KNASA knives?

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bdaabat

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Jul 2, 2025
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More adventures from the neighborhood. This time, a neighbor brought two KNASA knives.
I hadn't heard of these before. Here's what I found:

So....some special super hard metal (the website says Rockwell of >70) bonded with stainless steel. Sharpened at an angle of 12.5 degrees.

Seems like mostly a marketing thing. Whatever, the neighbor bought them.

I'm still learning and don't believe I've had the opportunity to attempt to sharpen knives with that high a hardness rating.

I've definitely never sharpened anything (at least, not intentionally) at an angle of 12.5 degrees. Nor do I believe I have the tools to be able to do so (Work Sharp KO mk2; Edge Pro Apex; my own eyeball-arm isn't calibrated well enough to do that freehand).

Suggestions for how to approach this challenge would be appreciated!

Thanks!
Bruce
 
According the ad copy puffery "Another benefit of this nano-serration is the self-sharpening aspect of the microscopic teeth. As the knife is used, these tiny teeth are exposed and essentially sharpen themselves – and this is part of what allows the Habitat KNASA Chef Knife to retain its ultimate edge far longer than other knives." So, does it really need sharpening? If it does, you will need diamond stones if the edge is really at 70 rockwell. A guided system as well if you don't think you can hold a 12.5 degree angle. Myself, I wouldn't touch them.
 
Checked with the owner. Said the knives have previously been sharpened by her husband using a whetstone. So...I'd expect the 12.5 degree angle to no longer be the current angle.

Bruce
 
The HRC scale only appears to go up to 68, which is about 940 Vickers hardness, and aluminum oxide is 1200-2000 Vickers. Common synthetic stones should be fine. That being said, hardness is not necessarily the same thing as abrasion resistance and we use it with knives mostly because of its rough correlation with the percentage of martensite, which is more wear resistant than pearlite and the higher presence of the martensite phase correspondingly increases the wear resistance, but the presence of carbides of various kinds in the microstructure greatly impacts it, of course.

All that said, it really sounds like a bunch of marketing hooey to me.
 
FortyTwoBlades said:
All that said, it really sounds like a bunch of marketing hooey to me.
Click to expand...

Copied from the kickstarter page:

"The patented metal alloy edge possesses a natural nano-serration at the molecular level. This serration is like microscopic, ultra-hard “teeth” that are what make the effortless and breathtaking cutting power of the Habitat KNASA Chef Knife possible. Another benefit of this nano-serration is the self-sharpening aspect of the microscopic teeth. As the knife is used, these tiny teeth are exposed and essentially sharpen themselves – and this is part of what allows the Habitat KNASA Chef Knife to retain its ultimate edge far longer than other knives."

I can't say I've ever seen a knife manufacturer badly explain what a burr is and try to pass it off as a feature that helps the edge sharpen itself. Also, if the steel is super hard then:
(1) how would the edge wear away easily enough to expose new tiny teeth; and
(2) how would those tiny teeth not be obliterated just as easily?

I would be delighted to eat my words if these claims are true, but I won't abstain breathing just yet.

Regardless, diamond plates should be able to cut through whatever steel is actually used in the KNASA. Mark the edge with a sharpie and take your time.
 
While you've got the Sharpie out, it may also be helpful to write on the blade, "YOU'VE BEEN HAD" and "AVOID KICKSTARTER" to serve as friendly reminders. I'd have wondered how many "nano serrations" self sharpened themselves into my food.
 
“NASA and Caltech's patented metal alloy reinvents the Chef Knife. It is the first knife-making innovation in over 200 years!”

Good grief. At least they out themselves as charlatans or fools on the very first page.
 
Umkay. Just got done my first attempt at sharpening these knives.

The bottom line? As expected, the marketing claims were just that. The metal IS harder than the usual Victorinox type knives that I've been seeing. But regular belt abrasives worked just fine.

I had a hard time with the chefs knife solely because I'm a noob. The edge is sharp....except for a section around an inch from the tip. There's a spot that just isn't very sharp. That's just me not being consistent with technique with a relatively long knife with a curve. I've asked the owner for a bit more time to get it sorted.

Bruce
 
bdaabat said:
Umkay. Just got done my first attempt at sharpening these knives.

The bottom line? As expected, the marketing claims were just that. The metal IS harder than the usual Victorinox type knives that I've been seeing. But regular belt abrasives worked just fine.

I had a hard time with the chefs knife solely because I'm a noob. The edge is sharp....except for a section around an inch from the tip. There's a spot that just isn't very sharp. That's just me not being consistent with technique with a relatively long knife with a curve. I've asked the owner for a bit more time to get it sorted.

Bruce
Click to expand...
Glad to know the blade is at least harder than most. If you continue using belts, please be sure to make quick passes and frequently dip the blade into cool water in order to avoid overheating the blade and damaging the temper. I've done it before several times with a stone grinding wheel and on a Worksharp and was shocked how quickly it can happen. Since then I leave powered grinding tools to the professionals.
 
Quick passes, with light pressure. If you do it right you will never build enough heat to need a dip.
 
Heat is the enemy. Move the blade across the belt at a decent pace. I believe Vadim from Australian Knife Grinders stated 5cm a second will keep things cool. The other part of grinding heat comes from the pressure. Let the abrasive do it's thing. Pressure will really heat that apex quickly.
Lastly, I use Formax, an abrasive coolant. Pretty much grease I think. Does a nice job of helping mitigate the heat.

Oh... buy a Tormek (or knockoff) and use controlled angle sharpening. No more guessing on the angle.
 
Thanks all for the comments!

I was able to get the chefs knife sorted using the knife sharpening part of the KO elite mk2. I'd previously been using the blade grinding attachment for the other knife to get a ~13 degree angle (what the marketing said was the original angle) and was able to get a nice edge on the santoku style knife. Bah! Frustrating to not be able to get the chefs knife truly sharp throughout the entire blade using the blade grinder. But, that's part of the process...figuring things out. And, what this tells me is that I need more practice. And, that's useful info for me!

@ Gottagofishn: My wife would not be happy if I purchased another sharpening system! At least, not this week. :cool:

I do see a Tormek (or two) in my future. But, that will have to wait until we move.

Bruce
 
bdaabat said:
The edge is sharp....except for a section around an inch from the tip.
Click to expand...

bdaabat said:
Frustrating to not be able to get the chefs knife truly sharp throughout the entire blade using the blade grinder
Click to expand...

Sounds like the shoulders needed to be knocked down on that section of the blade to thin it out behind the edge. Does the edge bevel look narrower from the heel and main portion of the blade, and wider toward the tip? If so the the tip portion of the knife will not pass through material as easily as the thinner part of the blade, even if it comes to an apex at the edge. And knife will eventually present the same sharpening challenges again unless you thin out the steel behind the edge around the tip as well.

You could do that on the blade grinder, but it would be a pain since removing shoulder material with it would go slower than apex grinding, and the temptation to increase pressure to remove material faster would be strong.... however that could lead to a more pronounced convex that runs counter to the goal of making it thinner. Personally, I would want to "cheat" and use my grinder, but I've also done it on diamond bench "stones".

Following original angles without regrinding behind the edge always eventually leads to thicker and thicker edge geometry.
 
Thanks David. I have no doubt that you are correct. I can't check now because the knife got returned to it's owner.

In this case, I know I'm new to all of this. I don't trust my ability to get to a specific angle using diamond stones. So, I used a "guided" process that would (theoretically) allow me to grind at the marketing stated angle. That guided process is probably more aptly considered some different description (supported?, strongly suggested?)...there's plenty of leeway for a relative noob to alter their angles as they proceed down the edge and get toward the tip. I believe I just wasn't consistent with my technique. When I switched to the more rigidly enforced "guided" process, things turned out fine.

Just means more practice for me!

The challenge for me know: I need to find some more and different knives to practice on.

Bruce
 
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