Traditional knife (slipjoint) sharpening question

[btb01]

To preface: I've been sharpening by hand for a couple years now. I started out with Arkansas stones, but now I use two DMT Dia-Sharp continuous-surface stones (in Fine and Extra Fine). I carry a traditional slipjoints daily, mostly GEC, but occasionally Case, USA-made Schrade and some other older knives, so that's primarily what I'm sharpening (along with kitchen knives and a few modern folders).

I've had an issue that occurs every now and then, almost always on clip point blades, and I wanted to see if anyone else has experienced the same thing and could perhaps provide some advice or explanation of why this happens. What happens is I occasionally end up with a bevel that gets wider down near the tang, so that the transition from the main grind to the bevel looks like it slopes upwards as it gets closer to the tang.

This almost always happens on the mark side of the blade and not on the other side. It also seems to happen most often on older knives, but I've encountered it on new GEC knives as well, including the clip point blade on a new #81 Bull Moose I sharpened yesterday afternoon. (It's very slight on the #81, hardly noticeable, but it's there.)

I initially thought that this was a result of something I was doing -- perhaps using too much pressure with my right hand holding the handle, pushing that tang end of the blade down on the stone -- but as I've become more experienced, I'm very careful to use even, light pressure along the length of the edge, and it still seems to happen occasionally.

Here's a photo showing a few examples. The knife on the left is a stockman that belonged to my grandpa, and the knife on the right is a little Schrade USA jack knife.

Thankfully this doesn't affect the performance of the edge, but I do find it a bit annoying because it just looks bad, particularly compared to the nice even bevel along the entire edge that I get on most of the knives I sharpen. As I said, I'm not really sure what causes this, so any thoughts, ideas, theories or recommendations are welcome!

 

[Erik Norseman]

As far as I understand, that flaring out is usually due to an imperfect plunge grind. The plunge grind should reduce the stock thickness very quickly and not taper all too much distally, although a bit of thickening near the tip is pretty common. Because the knife is thicker near the tang (because the plunge grind is too gradual), the same sharpening angle produces a wider bevel. So although I am still a novice sharpener, I think that this is likely due to the grind on the knife, not what you are doing.
In fact, it is a result of your consistency! If you increased the angle slightly (more obtuse) near the tang, it should reduce that flare.

 

[Obsessed with Edges]

It's very common in production traditionals. I've seen it on a bunch of my knives (I carry traditionals, for the most part). My favorite pattern is a stockman; so, I've seen this a lot on the clip blades. The steel behind the edge in the heel is thicker; sometimes quite a lot thicker. Holding the blade to a fixed angle in sharpening will produce a bevel that's wider near the heel, and narrows (usually) in the portions forward of that, as the steel is a bit thinner forward of the heel. I've long since stopped worrying about the appearance of it, and instead have just focused on keeping the edge as sharp as I like it.

The asymmetry of it (noticing it more on one side) could be a lot of things. It may be a result of an aysmmetric factory grind, with the steel being thicker to one side of the blade's centerline (common). Or, it may be a small difference in held angle during sharpening, between the two sides. I did that quite a lot myself, in transitioning to freehand sharpening. I always noticed wider bevels on one side, than on the other. But it was just a difference in how I held the knife from each side, as well as due to differences in pressure I applied from each side; my 'weak side' hand is literally weaker, in that regard.


David

 

[Chris "Anagarika"]

These ^^
are what I think the cause.
Stop worrying and just use them.

 

[B.F.U]

I've noticed this as well. I think the previous answers explain it.

In my experience, after a good number of sharpenings it can start to even out.