Does uneven sharpening affect sharpness and longevity of the edge?

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ukknifer

Joined
Jan 30, 2010
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Does uneven sharpening affect sharpness and longevity of the edge?

Hi
I found out that I sharpen one side of the blade deeper than the other. The other side has a shallower angle on it.
I sharpen free hand and no matter what, I cant do both sides the same angle.
It seems that because one side is sharpened by dragging the blade towards me and the other side away from me, the pressure and angle changes.

Any way. Does it affect the longevity of my edge?

I could use some experiences from you.
Thanks
 
I try to get as even as possible but at times I don't. I asked a pro here on the forums and he says it doesn't matter much. Then he brought up chisel grinds and how they are not even. So I felt better about it.
 
Some factory grinds are deliberately asymmetrical (chisel grinds, etc), so asymmetry doesn't necessarily degrade longevity. The overall inclusive angle and the steel & heat treat have greater effect on that. More often than not, an accidentally asymmetrical edge is usually thicker (more obtuse) anyway. BUT, it may affect how useful the working edge is for you, depending on how you plan to use it. Symmetry in the edge makes maintenance/sharpening easier (usually), and also contributes to the straightness and ease of making cuts. Asymmetric edge grinds will often try to 'steer' or turn the blade's edge away from the wider (more obtuse) side of the bevel, and toward the shallower (acute) side. Making straight cuts can be more difficult when this happens. Some chef's/cook's knives are deliberately ground this way (bevelled only on one side), so fish/meat/other foods will be 'pushed away' (falls away) from the bevelled side, while the flat side remains oriented vertically for straight slicing. Again, depends on what the uses of the knife will be.


David
 
ukknifer said:
It seems that because one side is sharpened by dragging the blade towards me and the other side away from me, the pressure and angle changes.
Click to expand...

I've noticed something similar several times, but I could never tell if it was me, or if the knife started that way. I think I had something to do with it in most cases. So now I sharpen differently. First I now use the Japanese Stroke instead of the Western stroke. This alone makes an incredible difference in consistency and results. Using two hands on the blade is so far superior to using one, I'm amazed I wasn't taught it earlier.

Second, I now sharpen both sides of a blade with the spine facing me. This means when sharpening the right side of the blade, the handle is in my right hand, and my left hand is on the blade, guiding it and controlling the pressure right at the edge. When I switch to sharpening the left side of the blade, the handle is in my left hand and my right does the guiding and pressure control.

This gives me a consistent view of the blade, so holding the spine the same height off of the stone is easier for both sides. In practice I'm usually trying to follow the bevel that's already on the knife though. I do that mostly by feel, which is another place where the two handed technique comes in. If you haven't tried the Japanese two handed way, you really should. It's a revelation, at least for me.

Brian.
 
If you have any sense of craftsanship, you sharpen both sides evenlt unless you're doing a Japanese kitchen knife.
 
My japanese knives are all 60/40.

These are a few of the sharpest knives around.

but no it doesnt affect sharpness or longevity.
 
Nice even, uniform, symmetrical bevels look very professional.

Depending on how the blade is actually intended to be used, there may be rationale to go asymmetrical...but we are really talking about some very fine details of performance here. I would suggest that for many users, it won't matter. If you are pleased with the sharpness you have achieved, enjoy it. If you would prefer the appearance of symmetrical bevels, practice and work toward that as a goal...but do not lose sleep over it in the mean time;)
 
I don't think it makes a strong effect on performance if we're just talking about the slight differences from hand-sharpening. If you try to keep each bevel as flat and the same angle as the other, I don't find performance changes from a knife sharpened like so by hand and one sharpened by a jig--so in other words exactly flat and precisely the same angle.

I don't think it makes a difference until it becomes more exagerated, like a 40/60 bevel or a chisel grind. Basically, the amount of inconsistencies that will be produced by hand-sharpening are still consistent-enough that it won't matter, in my opinion.
 
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