straightening an edge

[ARIES_RAM_OF_WAR]

I have a knife that while I was sharpening it the edge started going very one sided but its only near the tip its so bad that the edge is practically sideways any tips on how to fix this and what I might have done wrong? (i am an amateur but this is the only knife that this has happened)

 

[Obsessed with Edges]

Welcome to the forum.

A common trait of many knives is an asymmetrical blade grind from the factory. This basically means the steel is thicker on one side, relative to the centerline (if drawn from the center of the spine to the cutting edge's apex). If asymmetrical, you'll usually notice that the edge bevel on the thicker side will be wider (edge to shoulder) than the other, even if both sides are ground/sharpened at precisely the same angle. This is especially noticeable near the tip of the blade, because the steel is almost always thicker there anyway. If I were betting, I'd assume you're likely seeing at least some of this. Depending on the degree of asymmetry in the blade's grind, it's not always possible to get bevel widths on each side to match exactly, without altering the sharpening angle on each side. It's better to maintain the same angle on each side for the sake of cutting performance, and just accept that the bevel widths may not look identical.

The other possibility is just from too much grinding on one side during sharpening, or if the angle held is different on each side.

Some close-up pics of the tip of your blade would help in generating some more specific advice for this. Pics can be uploaded to a photo-hosting site like Photobucket, and then linked in your posts here.


David

 

[ARIES_RAM_OF_WAR]

http://imgur.com/o0wsakT hopefully this link works and thanks for the help I really appreciate it. Sorry I know its not the best picture where it starts getting fatter in the picture is where it starts going to the side I took it with my phone which is why its not focused properly

 

[Obsessed with Edges]

http://imgur.com/o0wsakT hopefully this link works and thanks for the help I really appreciate it. Sorry I know its not the best picture where it starts getting fatter in the picture is where it starts going to the side I took it with my phone which is why its not focused properly

I added the IMG qualifiers to the url for your pic, so it'll display in your quoted post above. I'm still betting you're seeing the effects of an asymmetrical grind, as I described earlier. With such an edge, I'd focus on maintaining a steady and equal angle on both sides of the edge, and not worry as much about the visual appearance of the bevel widths. Hard to tell from the pic, but it looks like the existing edge angle may be somewhat wide (obtuse); if so, narrowing/thinning the angle should at least improve cutting performance, maybe dramatically (especially at inclusive angles of 30° or lower, i.e. 15°/side or less). Maintaining equal angles on each side is what will make the most difference in cutting performance. If there's too much mis-match in angle from one side to the other (such as 15° on one side, and 20° on the other), the edge will tend to 'steer' the cutting toward the narrower side, and away from the wider side.


David

 

[ARIES_RAM_OF_WAR]

Ok ill try smaller angle and maybe picking up an angle guide to make sure I keep the same angle thanks for all your help

 

[Obsessed with Edges]

Ok ill try smaller angle and maybe picking up an angle guide to make sure I keep the same angle thanks for all your help

That thought crossed my mind, but I didn't want to push it on you, if you didn't want to; I'm glad you're considering it. It'll be especially helpful if you need to grind a lot of steel off your edge to thin it. That gets fatiguing anyway, and fatigue will destroy control. The guide will at least be helpful there. Beyond that, steady and patient will get it done. Focus on making sure you fully apex the edge, and don't worry as much if the bevel widths look a little different between sides. A crisp apex and symmetrical edge angle will make all the difference.


David

 

[Indianbladenoob]

It also strikes me that if the higher grind (whether hollow or flat) is asymmetrical, as in not completely matched on both sides one might have that problem with the final grind/edge itself.
David, I have seen this on almost all my production knives that are not FFG (All except the WRKTbackpacker). And its not visible to the naked eye on FFG's.
Even on my recently acquired ZT0566, the final bevel I am setting with my Lansky Diamond kit is wider close to the tip on the G10 side than the lock side. Plus Elmax being a PITA to sharpen makes it even more difficult. One hopes that speaks for its edge retention.

I have been (very) slowly grinding away the wider side with a few make up strokes on the opposite side. Based on an old suggestion of yours I am simply using a single rod on all the hones and marking the bevel with a sharpie before every hone. It makes the bevel so much more even. But I think one side will always be marginally wider on my 0566. I am satisfying myself with visually confirming that the edge is centered and apexed.

Hope that will do.