Sharpening Angle: How Much Deviation is Significant?

PeteCress

PeteCress

Joined
Jan 2, 2023
Messages
16
On my Ruxin Pro 008, I can adjust the sharpening angle to exactly 17⁰.

But when I flip the knife over, the angle may change to 16.8⁰.

"May" because if I lay the weight of my hand on the stone the angle may change to something like 17.1⁰ and sometimes even stay there after the hand is removed.

Even moving the stone from the center of the blade to near the tip can change the angle by a few tenths of a degree.

I have watched the YouTube vid about changing the angle diff by adding layers of tape under the clamp jaws.

But I keep coming back to wondering:
  • How much angle variation is significant - especially given the typical .1⁰ accuracy of most digital angle indicators.
  • Whether more expensive sharpening jigs with independent clamps have similar variations when the knife is flipped 180⁰.
 
Most angle cubes are only accurate to plus or minus .2 degrees some are better. Even if it reads to .01 degrees it may only have an accuracy of .1 or .05 degrees. So, it depends on the accuracy of your measuring devise. With accuracy and precision, you are always chasing your tail. Does it matter for a pocket knife? Probably not too much.
 
I use the Wicked Edge and the only thing I do is try the keep the angles within 0.5° for each side based on the measurement from an angle cube. Emerson knives obviously excluded from this. Although as others have mentioned, it won't affect cutting performance, just your OCD meter.
 
Find yourself a chisel ground knife, sharpen it up, and see if it’ll cut stuff. When you take up your old knives again, even a couple degrees won’t be a big deal.

Parker
 
The guided systems give only that much accuracy. When you flip the knife, there might be a very slight difference in the angle, but it's not something to get upset about (the Lansky being somehow flexible, very simple and easily portable, is not the most accurate. There are more precise radial devices but they are quite the size and the price). More disturbing (to me, anyway) is that the selected angle cannot be consistent (on a long blade) from heel to tip. On a radial sharpening device, the angle will get narrower towards the tip and somewhat narrower towards the heel (less...). Not by that much, but hey, geometry, it can't stay the same. Not a big deal either, for sure, but it ended up bothering me all the same. The solution is a belt sharpener, like the WorkSharp, on which the blade runs paralell to the abrasive. I get very clean, consistent and reliable results with this device. It's also noticeably quicker, even compared to diamond stones on the Lansky. If you are the patient type, you can also enter the learning curve of manually sharpening. It's quite fascinating, it works just great (and could be more precise) after you have acquired the muscular memory required, but, in my experience, the varying levels of wear of the different stones can be quite a hassle (and expensive). I hollowed my "very coarse" stone with attempting to reprofile a Serbian Chef knife which was too thick behind the edge for my liking. New "very coarse" stone incoming...
 
I have never measured angles since I have always sharpened freehand. I can most times tell that the angle is little bit different on the other side but I think it just adds cool little flavor of hand crafted.. and also I can’t give arse! :D
 
Others have covered this but its not that significant. Even in an imaginary world were you are able to control for every imaginable variable including flex in the sharpener, grind imperfections from the factory, differing pressure in your hand, stone imperfections, and all the rest......at the end of the day you are probably talking about no difference in perceived sharpness and likely one that wouldn't even show up on a BESS test.

Even more important to keep in mind: even if that BESS test was a few points better in your imaginary world... the minute you put that edge to anything it will be moot. Super steels are awesome but even those at the very apex are going to degrade from peak sharpness almost immediately down to an (admittedly amazing) working edge.

Whatever small improvements a perfect angle on either side would yield would have no practical real world benefits once the cutting begins. Focus on the important parts of sharpening which is apexing your bevel, and deburring after.
 
herisson said:
The guided systems give only that much accuracy. When you flip the knife, there might be a very slight difference in the angle, but it's not something to get upset about (the Lansky being somehow flexible, very simple and easily portable, is not the most accurate. There are more precise radial devices but they are quite the size and the price). More disturbing (to me, anyway) is that the selected angle cannot be consistent (on a long blade) from heel to tip. On a radial sharpening device, the angle will get narrower towards the tip and somewhat narrower towards the heel (less...). Not by that much, but hey, geometry, it can't stay the same. Not a big deal either, for sure, but it ended up bothering me all the same. The solution is a belt sharpener, like the WorkSharp, on which the blade runs paralell to the abrasive. I get very clean, consistent and reliable results with this device. It's also noticeably quicker, even compared to diamond stones on the Lansky. If you are the patient type, you can also enter the learning curve of manually sharpening. It's quite fascinating, it works just great (and could be more precise) after you have acquired the muscular memory required, but, in my experience, the varying levels of wear of the different stones can be quite a hassle (and expensive). I hollowed my "very coarse" stone with attempting to reprofile a Serbian Chef knife which was too thick behind the edge for my liking. New "very coarse" stone incoming...
Click to expand...
I guess you’re talking about things like Wicked Edge or other clamp and guided rod systems? If so, as long as the blade is straight the angle is the same. It does matter when you get to the curved portion at the point. Many try to clamp just at the beginning of the belly or curve to keep this consistent.
 
I sharpen sometimes with a knife in one hand and the stone in the other. There is no way I’m keeping the angle consistent less than a couple degrees. It still gets sharp though. Tree topping sharp if I’m careful.
 
I guess your talking ( possibly ) about the angle changing during sharpening ?
It is what it is and as long as the knife is sharp . To minimize deflection , lighten the pressure as you go ( knife is sharp ) and you are minimizing / removing the bur .
Getting a 100% perfect edge ? Wet stone grinder ( knife sharpener ) with a 1000 grit wheel possibly , might get you close !
 
I freehand also. I do keep an analog angle finder in my tool kit, the one that Harbor Freight sells. But by now I can guess within 1 degree the angle I am applying without assistance. I have tested this by reference to the angle finder. With freehand, you develop very accurate habits over time, and you no longer need to spaz out over the details. You can also feel when your angle is off by the feedback you get off the stone. My major adjustment occurs when I switch from folding knives to my kitchen knives, with their flatter angles. Still no big deal. 15 to 17 degrees is just fine with those. They cut like nobody's business and that makes me happy.
 
King of the Cheese said:
More an issue for people with OCD, not an actual “issue”. Tenths of a degree aren’t anything to be worried about.
Click to expand...

Just coming in to say exactly this. Folks who have a Spyderco Sharpmaker or other guided device know easily a few fractions of a degree can be (and usually are) introduced into a sharpening session. As long as the knife cuts afterward, you're good.
 
I'm comfortable in simply knowing all of my freehand edges are within acceptable limits for how I want them to cut. This basically means everything is at or below 30° inclusive, and sometimes closer to 25° inclusive, give or take a little. I realized a few years ago, my most comfortable freehand hold on the knife always keeps the edge angles within that range, which suits my preference perfectly. In that range below 30° inclusive, there's an obvious, perceptable improvement in ease of cutting as compared to edge geometry that's wider. And after sharpening my knives this way for a few years now, it's easy for me to recognize in cutting tests when it's 'in the zone' or when it isn't.

There's also value in recognizing if there's too much asymmetry in an edge, from side-to-side. If the sharpening angle is much different on one side than on the other, you might start noticing some 'steering' effect of cutting through materials. The cut will try to steer in the direction of the side with the lower (more acute) geometry, and away from the side with more obtuse-angled geometry. So after sharpening, the symmetry can be tested with a quick slice through some paper. If the path of the cut isn't dead-straight through the paper, and instead tends to arc consistently one way or the other, that's the cue the edge angles aren't balanced very well, from side-to-side. And as mentioned, it's usually sufficient just to compare the bevel widths from side-to-side, to see how they match up visually.

Also important to know that the thickness of the steel behind the edge will vary along the edge's length, in most knives. So, even if the angle is perfectly maintained throughout, you'll still see the bevel widths vary along the edge's length, due to the changing thickness of the steel near the edge. Conversely, even if the bevel widths look completely uniform along the full length of the edge, it's still possible and even likely the edge angle is varying somewhat to compensate for changes in thickness near the edge. It's common for factory-ground edges to look very uniform in width of the bevels, for the sake of aesthetics - but they do that by changing the sharpening angle as the edge is ground from heel to tip. The factory edge angle is usually more obtuse near the tip in blades with tips sweeping up toward the spine, when the thicker still is.
 
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