More acute angle = Better wear resistanc?

K

KennyB

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Jan 19, 2010
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People seem to be mixed up about whether a more acute edge improves wear resistance, or reduces it? The idea is that if there's less pressure needed to make the cut, then less force is exerted on the apex and it lasts longer. On the other hand, the idea is that with the apex so thin, any force on it will be so much more than it will wear faster.

So which is the truth here?

Okay, put it within a more strict set of parameters to narrow the discussion down...

I do not have ONE knife that is under 30 degrees inclusive. In fact only one that's even under 34.

Now these are angles that I've "settled" on after becoming satisfied with the cutting performance, and satisfactory wear resistance.

So with that in mind, if I take my knives down to 30 degrees am I going to see an increase or decrease in wear resistance. Many of these knives I have had more acute in the past and I didn't find the performance increase of a more acute angle to do me much good, but maybe the wear resistance would be improved?
 
I'd ask 'edge retention?' instead, or maybe 'useful edge life?'. Wear resistance is a property of the steel itself, independent of the edge angle.

That being said, Buck Knives famously altered their edge grinds to a thinner profile after CATRA testing, which showed the edges cutting better, for longer, when at a thinner angle. Buck's spec for their new grind (called 'Edge2000') was 26-32° inclusive (13-16°/side). I think the underlying philosophy is that the thinner profile is a much more efficient cutter, requiring much less down-force against the edge, and therefore reducing the degradation of cutting performance as the steel wears at the edge. In other words, the steel still wears, but the underlying geometry keeps it working efficiently for a longer time than a wider and relatively inefficient cutting geometry, even when freshly sharp. Wide edge geometry gets really dull, really fast, when the apex goes away, because the underlying thick geometry becomes more of an obstacle to cutting efficiency.

I was happy in reading that Buck had seen & confirmed this, as I'd also thought a thinner, more acute edge lasted longer and worked better than most of us would've assumed, even in relatively 'soft' steels. :)


David
 
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Obsessed with Edges said:
I was happy in reading that Buck had seen & confirmed this, as I'd also thought a thinner, more acute edge lasted longer and worked better than most of us would've assumed, even in relatively 'soft' steels. :)


David
Click to expand...

Through experimentation I slowly moved to more acute edge angles. Among others, Murray Carter sums it up well by encouraging the most acute angle the tool will allow. Was surprised that even my camping choppers held up fine at 30 inclusive, maybe a couple degrees more broad due to stropping, but not by much. I don't normally sharpen anything above 30 and am generally about 26. Even "dull" they keep cutting well for a long time.
 
Too many knife makers believe a "thick" edge is the way to go. Thin is in, unless you are using your knife to chop heavy brush.
 
How thin is too thin? There's some guy who says AEB-L at sub 10° angles will outperform(as in hold the edge longer) the high carbide volume steels in cutting cardboard.
 
Cliff Stamp. I can see where he's coming from, theory wise, but when put up against Ankerson's real world tests, his theory seems to fall apart.

I think the simple answer to your question, how thin is too thin, is that it depends on the geometry and steel in any given knife. Some will fall apart at thin angles because they don't have enough metal behind the edge to sustain the angle, some will fall apart at thin angles because the steel can't support it.
 
MJF said:
Cliff Stamp. I can see where he's coming from, theory wise, but when put up against Ankerson's real world tests, his theory seems to fall apart.

I think the simple answer to your question, how thin is too thin, is that it depends on the geometry and steel in any given knife. Some will fall apart at thin angles because they don't have enough metal behind the edge to sustain the angle, some will fall apart at thin angles because the steel can't support it.
Click to expand...

Yes, it's Cliffy and his "science".
 
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