noob mistake - how do i undo my shaving sharp edge safely?

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Mar 23, 2011
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i've been reading some of the recent posts that say "shaving sharp is too sharp". so how can i safely "unsharpen" my khuk without risking chipping? i could chop some wood, but to be honest, i don't know a hard wood from a soft one. and i'll be the first to admit that my chopping technique is horrible. i could run the edge on a sharpening stone a little (one of those cheap two sided aluminum oxide bars).

i guess that leads to the follow up question - once it's dulled a bit, how sharp is sharp enough? now, i live in the city, so i don't have an axe in my garage to compare with and the only other knives in the house are kitchen knives. should my khuk be able to cut through paper easily?

btw, this is for a bonecutter, so the edge is too sharp for chopping duty.

thanks everyone!
 
You could slice through some heavy cardboard for a while. That will take the razor edge down a bit without removing any metal.
 
What were you planning on using it for?

If your Kukri is a showpiece that doesn't use use by all means leave is sharp. If you're going to go out and chop some seasoned hardwood run your stone down the edge and a higher angle to round it a bit.

Do you have any pictures of it?
 
I grew up being taught that a sharp knife is a safe one, it can cut through things easier(less pressure that could accidentally slip and cut something you don't want it to.) Also sharper knives make cleaner and more accurate cuts. I may be wrong, but I am a firm believer that the sharper you can get a knife, the safer it is.
 
What everyone needs to bear in mind is that a chopping tool is best sharpened at a more obtuse angle such as an axe has..not to compare it with an axe....and when you shaving sharp an edge it is a finer less obtuse edge, and thats where problems can occur. The more mass behind the cutting edge the sturdier it is.
I guess if i were doing it, i'd use the stone to carefully dull the edge and the put the edge back on until you feel it's just gotten sharp. A chopping edge should sort of cut paper, but mostly tear and should not be able to push cut.


Lijap said:
I grew up being taught that a sharp knife is a safe one, it can cut through things easier(less pressure that could accidentally slip and cut something you don't want it to.) Also sharper knives make cleaner and more accurate cuts. I may be wrong, but I am a firm believer that the sharper you can get a knife, the safer it is.

That is true for knives used for slicing. On a wood chopper absolute sharpness can be detrimental and cause failure.
 
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What everyone needs to bear in mind is that a chopping tool is best sharpend at a more obtuse angle such as an axe has..not to compare it with an axe....and when you shaving sharp an edge it is a finer less obtuse edge, and thats where problem can occur.




That is true for knives used for slicing. On a wood chopperabsolute sharpness can be detrimental and cause failure.

Thanks for clearing that up, I don't have much experience using blades solely for chopping. Good to know!
 
Have you got an abrasive rod? Diamond or ceramic? If so, give the blade a couple dozen strokes on each side at a reasonably obtuse angle and that will leave it nice and sharp, only just more obstusely so. Sharp is kind of a peculiar state. Most simply put, sharp is achieved when the two sides of an edge meet at a very straight narrow juntions or apex, with as little width as possible. That edge, maybe just a few fractional microns across could be at the edge of a very acute 15 degree inclusive edge or at the edge of a very obtuse 45 or 50 degree edge. Anybody whose ever fallen against a "sharp" counter top made of granite or even Formica knows how "sharp" a 90 degree inclusive edge could be.

But to shave hair, no matter how narrow...how sharp...that edge really is, it's going to have to be pretty acute and that's what's bad for chopping.

What I recommended is what I do with my Khukuri to maintain it. I tilt the blade pretty far up off the rod and run repeated strokes. Not sure what angle I have going as it's kind of hard to compute with a complex shape like a Khukuri edge. I am going to say my edges, at the very edge, are probably in the 40 - 50 degreee inclusive range at the minimum. Let me also assure that the blade is in fact very sharp.
 
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I'd do the cardboard thing. Nothing seems to evenly dull a knife like a few swipes through good ol' thick corrugated cardy-board.
 
Strange. I keep my kuk's and all my other knives hair pushing sharp. Including my M43 and I've used it to build cabins. That said I use a convex edge, and have had absolutely 0 problems. The edge needs to be as sharp as you can make it. The edge geometry just has to be supportive enough to handle chopping tasks.
 
If you'd like, I could sharpen it for you.

I can make ANYTHING duller than it was when I started.

:)

justsayin'
 
Strange. I keep my kuk's and all my other knives hair pushing sharp. Including my M43 and I've used it to build cabins. That said I use a convex edge, and have had absolutely 0 problems. The edge needs to be as sharp as you can make it. The edge geometry just has to be supportive enough to handle chopping tasks.

Yes. .
 
Ive never chipped out a shaving sharp khuk w/ a high angle--being it will shave holding almost vertical to limb being shaved...I just usually strop the edges after a workout w/ a diamond steel and compounded leather, and clean up after use. These knives are not as difficult 2 keep flinging sharp, and still use in almost any role...I mean if you dont use anything below 40 degrees and strop u should be just fine.
 
I am no expert but just because its shaving sharp doesnt mean it has to be a thin edge. So if your edge is supported/sturdy/obtuse/strong, whatever term you want to use, and still shaving sharp go have fun with it. I just got a chopper this past weekend that came shaving sharp and cut down a small tree and de-limbed it with no edge damage just some dulling. I have also gotten folders to shave hair but couldnt even use the sharpmaker to touch them up because the angle was too great.
 
btw, this is for a bonecutter, so the edge is too sharp for chopping duty.
I created an ICU scene once trying to sharpen a BC. It sure took a good chunk off my thumb.

Back to OP, i would try to slide it across grade 1000-1500 sandpaper the convex way. That way you create an apple seed that maintains much of the "flesh" but blunts the edge a bit.
How thin is your primary edge and the angle?1-2mm would be alright.
BC has a very high 2ndary bevel and i do doubt like many mentioned up there shaving sharp for finer work and high bevel to take care of the monsters.
 
Take a ceramic rod or stone and run it against the blade (like when you cut your steak on a plate.) Dulls it quickly, evenly and safely. Then sharpen at your new angle.
 
There are two things people mean by "sharp". The first is an acute angle - more acute angles are "more sharp", but have less metal behind and edge, and are weaker (as several people above point out).

It is also possible to get an edge to shave by making it SMOOTHER at a given angle, ie going progressively to very fine stones or sand paper. This makes the edge less "toothy", so it won't slice fibrous things as well, but it does make it better at push cutting (which is what shaving is). This should NOT make the edge any weaker, as long as you are polishing the existing geometry. You can get a hatchet to shave hair if you work at it, without changing the angle and making it weaker.

Karda has far more kukri experience than I do, so I will hope he corrects me if I am wrong... but shouldn't it be possible to achieve a polished shaving edge, while leaving the original angles in place, and thus not compromise strength?

In any case, making the knife duller by going through cardboard would not seem to also make it stronger, or do people disagree on that point?
 
There are two things people mean by "sharp". The first is an acute angle - more acute angles are "more sharp", but have less metal behind and edge, and are weaker (as several people above point out).

It is also possible to get an edge to shave by making it SMOOTHER at a given angle, ie going progressively to very fine stones or sand paper. This makes the edge less "toothy", so it won't slice fibrous things as well, but it does make it better at push cutting (which is what shaving is). This should NOT make the edge any weaker, as long as you are polishing the existing geometry. You can get a hatchet to shave hair if you work at it, without changing the angle and making it weaker.

Karda has far more kukri experience than I do, so I will hope he corrects me if I am wrong... but shouldn't it be possible to achieve a polished shaving edge, while leaving the original angles in place, and thus not compromise strength?

In any case, making the knife duller by going through cardboard would not seem to also make it stronger, or do people disagree on that point?

No correction needed from me, BD, as you're pretty much correct in your thinking.
You can get them very sharp and still leave enough mass to support the edge, but you must take the time to do it carefully. But as i've stated before a polished shaving sharp edge does not equate to being any better chopper than a field sharp edge.
It is why i always advocate hand sharpening instead of the usage of belt sanders and the like. With power tools it is too easy to take too much off and compromise the edge. Proper routine care and maintenance should negate their usage anyways.
 
Edge profile is the critical factor. I may have led people astray by talking about shaving sharp when a better phrasing would be acute edge profile. An acute edge profile is not easily corrected by dulling a knife.
 
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