Asymmetrical Edge (Sharpening)

[Rider675]

All of my knives seem to have a "longer" edge bevel on the right side. They bite into the finger nail with much less angle needed, when going away from the hand. This problem has been around sense I started sharpening, and now remains a problem on hair popping edges, hair popping on one side that is . I have experimented with more passes on one side, pressure, different angles, and im just getting confused.
btw this is on the Sharpmaker, on 40 degrees (is it me, or is it a LOT easier to get consistent angles on 40 vs 30?).

 

[molecular]

I know this seems to be more of an observation on your part as opposed to a question, so i'll bite the bullet for you and ask, if I have a knife with a very asymmetrical bevel between the two sides, how would I fix this (I have an edge pro)? Do I just set a desired angle and go to town on both sides until the magic marker trick confirms I have the right angle? I think somewhere on these forums someone said to sharpen more on the thinner bevel side as well to "even" things out.

 

[unit]

It is a simple, yet complex problem.

Assuming that the blade (primary bevel) is symmetrically ground, the edge bevels should be the same size IF they are also symmetrically ground. Meaning that they are the same angle and ground equally. If you have an angle disparity, it can cause asymmetry. If you grind one side more that the other, it can also cause asymmetry.

If (and this is a wild one) you have different grind angles and different amounts of grinding on each side, the bevels can actually appear to be the same "size".

If you are actually using the blade, I suggest trying it out. You might be surprised at how overstated the "use issues" seem to be with uneven bevels in general use. For very precise applications (such as wood carving) the differences can be noticeable, and some of us actually grind the bevels on these specialized knives asymmetrically on purpose.

 

[richard j]

try out the knife like unit said. have you ever tried a convex edge?

 

[Rider675]

If (and this is a wild one) you have different grind angles and different amounts of grinding on each side, the bevels can actually appear to be the same "size".

^^ I know what you mean there, Im just looking to increase performance via geometry, rather than make it look even. As long as an uneven grind isn't going to hold me back from getting a much better edge, im not worried about it. Though I suppose all my knives could have been ground more on the right from the factory. I know my Resilience was ground more on the left side, and I can get it to a different level of sharp than both of my Delicas.
I have had someone put a convex edge on my Rajah that was even, but wasn't really sharp. It had a severely uneven grind from the factory (unlike my Spydercos!), I thought that new edge would make it easier to maintain an even bevel. They blunted the tip, and the grind is uneven again after use and sharpening.

 

[molecular]

So first off, thanks for helping a new guy out. I appreciate it.

I'm super new to knife sharpening so I picked up a Buck Vantage Pro to practice on. Didn't have any of the blade centering issues that people have mentioned but the grind is super asymmetrical. As in, when i look at the tip from the top, it literally looks like a chisel. I'd say one bevel is consistently 1.5 times bigger than the other side. At the tip it's even more pronounced. As this is not a super expensive knife but a good steel, I nominated it as my edge pro "learnin" knife. I'm betting it probably cuts just fine like people here have suggested, but i figure its a good opportunity to learn some tricks and techniques.

So in order to center the edge, would it make sense to sharpen on the shorter bevel exclusively until it seems more or less balanced out, then sharpen both sides as normal? I think other places in the forum says that's the way to do it though it takes a long time (depending on the steel) and wastes a fair amount of blade material.

 

[Obsessed with Edges]

When I see an asymmetrical bevel on a blade (usually a factory edge), I generally focus on the 'narrow' side first, in order to get the bevel width where I prefer it to be. I don't spend much time at all on the 'wide' bevel, until the narrow side has been widened to my preference. The goal is to get the edge angle on this one side down close to where I expect it to be, relative to the centerline of the blade. To me, a narrow bevel on one side always tells me the edge angle is too 'thick' (obtuse) on that side, and that is what I focus on fixing first.

Focus on removing metal from the shoulder of the bevel only. This will have the effect of pushing the bevel's shoulder higher up on the blade, and minimize taking metal from the very edge itself. Minimizing metal removal from the edge itself will reduce the chance of unintentionally narrowing the bevel on the 'wider' (opposite) side, while you're trying to fix the narrow side. Eventually, the new bevel will widen until it reaches the edge. Keep working in this manner until a burr can be felt or seen 'leaning toward' the opposite side of the blade, towards the pre-existing 'wide' bevel. When you reach that point, then some work can be done on the opposite side, as needed, to clean up the burr.

The above advice runs counter to the standard directions for using the Sharpmaker, which recommend an equal number of passes on each side. That only works well on bevels that are already balanced up. Asymmetrical bevels require asymmetrical work to fix. If that means expending almost all effort on one side only, then so be it.

 

[Rider675]

^^ Ill give this a shot. Though when the factory grind is really off like my Rajah, it needs a primary bevel regrind it seems. Like unit mentioned, trying to achieve symmetry on the secondary bevel, with a primary that's off = a crooked edge that's even.

 

[Obsessed with Edges]

^^ Ill give this a shot. Though when the factory grind is really off like my Rajah, it needs a primary bevel regrind it seems. Like unit mentioned, trying to achieve symmetry on the secondary bevel, with a primary that's off = a crooked edge that's even.

The closer I look at each blade, the more convinced I am that a perfectly symmetrically ground blade is a very rare thing. It's more noticeable on bigger, thicker blades especially. There'll almost always be more steel on one side, relative to the centerline, than on the other. It always affects bevel width, to some degree. That's why I tend to focus more on establishing a satisfactory bevel width and edge angle on the narrow side, and if the 'wide' side isn't a perfect match to it, I don't worry too much. It'll still cut much better than the (usually) horridly mis-matched bevels will.

 

[molecular]

Would you say this is considered typical factory edge/typical offset grind. I guess to me this looks really bad. Especially when you look at the tip from top down.

 

[Obsessed with Edges]

Would you say this is considered typical factory edge/typical offset grind. I guess to me this looks really bad. Especially when you look at the tip from top down.

That does look pretty bad at the tip. The tip is where it's almost always more noticeable. Having said that, sad truth is, it's more typical than it should be.

 

[molecular]

Yeah, i'll try your advice of using the edge pro on the shorter bevel side and go for it.

 

[confucius37]

I just got a buck vantage pro also and my edge is exactly the same. I'm not too upset though because it is quite literally hair whittling sharp. Sharpest edge I've ever seen on a new knife.

 

[molecular]

Yeah the edge is actually pretty nice. This is more of a learning exercise to see how I would go about evening out the edge. Confucius, was your lockup pretty late. Mine is way over, just don't care that much.

 

[confucius37]

Ya lock up is pretty late, but its not a big deal for me, I just flip it open anyway. I'm just happy that the blade is not hitting the backspacer. I previously ordered one that had the blade hitting the backspacer every time you closed it and the blade came with a big fat dent in the middle of the cutting edge.