shaving one way, dull the other

hardheart

hardheart

Joined
Sep 19, 2001
Messages
8,968
I have this problem with my M2 Rittergrip. After dozens of strokes on a 600 DMT, a medium Spyderco, and even a fine, the knife will shave on one side, but not the other. The shaving side will switch, and I can even it up with enough sharpening, but I don't see why this happens in the first place, and why getting it shaving both ways on one grit can still leave me with a lopsided edge after the next. I'm not using much pressure, extremely little, actually, and I'm moving the blade edge leading. I don't feel a wire, but there has to be a very small one. I could notice something with the little Radio Shack magnifier, but it just wasn't much. M2 shouldn't be flopping around, should it? It doesn't seem to be dead soft, but it doesn't sharpen cleanly. I ran the edge straight into the DMT to remove it first thing, so there shouldn't have been fatigued metal at the edge.
 
Sounds like a wire to me. How hard do they run the M2 in that knife? Any chance something went wrong with the blade? M2 at full hard doesn't form a wire all that easily in my experience.

Anyhow, what I normally do in such cases is this: I do about five light strokes with edge trailing on one side to get the wire all "lined up". I use my normal sharpening angle for those strokes. I then switch sides and do *one* or two very light strokes on the other side, this time with edge leading, and at an angle about twice as big as my normal sharpening angle.

I find this helps a lot with thin wires.

Hans
 
I've heard that described as something you will see sometimes with a wire edge but have never experienced it myself. I'm surprised to hear this reported with M2 using diamond abrasive, sure doesn't sound like a recipe for a stubborn wire edge to me.

FWIW I've had just excellent results with Jeff Clark's method of removing a wire edge: making 2-3 very, very light passes per side on fine Sharpmaker at an elevated angle of about 40 deg/side. Under magnification (40x or so) the edge should look exceptionally smooth and even after this. I then proceed to microbevel on the fine white Sharpmaker with extremely light pressure until sharp.
 
Well, the last couple times I've sharpened I've had to use a really high angle for the microbevel. I had tried some edge trailing strokes with no noticeable improvement. It finally came down to fifty or so strokes each side with the medium ceramic at even more pressure. The steel is supposed to be 60-62, IIRC.
 
That has only happened to me with burrs, and is actually one test I used to check for burrs before I got my lighted microscope.

Mike
 
hardheart said:
Well, the last couple times I've sharpened I've had to use a really high angle for the microbevel. I had tried some edge trailing strokes with no noticeable improvement. It finally came down to fifty or so strokes each side with the medium ceramic at even more pressure. The steel is supposed to be 60-62, IIRC.
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Hmmm ... not the behavior you'd expect. Before I knew any better I sort of grew up with little M2 blades my brother used to make, all left very hard, and burring just wasn't something you even thought about; wasn't until I started spending good money on soft, commercially made stainless blades that I discovered real sharpening grief. :(

I've read enough of your posts, hardheart, to know that you know your stuff. If you're looking for a second opinion that it sounds like a problem with the steel/heat treat ... well, that would be my guess.
 
I'd cut the edge off and start again. Sounds like there's a lot of fatigued steel at the edge. Five or six perpendicular strokes into the 600 grit diamond should take away enough worn steel. If that doesn't work, curse a lot and then call the Aeromedix folks.
 
If you are sharpening at more than 10 passes then something is wrong. Once the edge is shaped it should take very little work to finish it. Anything else is just pushing metal around as noted.

-Cliff
 
I like Thom's idea. If there is a wire burr, it will bend from side to side and be difficult to remove. Once the deformation is created it will reform with each sharpening session. (I used to get this with 420HC routinely.)

Cut the old edge off and start with a fresh, undamaged base. Use light strokes and good quality ( & clean) abrasives to avoid new deformation.

Let us know if you ever figure this one out.
 
Hardheart, if this is the knife blade I sent you I’ve had no burr problem like this at all with the knife I made with the other half of the piece of hacksaw blade it is from.
 
db said:
Hardheart, if this is the knife blade I sent you I’ve had no burr problem like this at all with the knife I made with the other half of the piece of hacksaw blade it is from.
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Can't believe you kept the better half for yourself ... it is a Ritter Grip, after all!
 
OOPS I missed that part, never mind. I should really lern to read before posting. But yeah, I do keep the better half of the blades for myself. :)
 
I used to have this problem for a long time with all my knives until I started cutting straight into the stone before sharpening. Most of the time I'll cut straight into the stone, form the edge, cut into the stone a few more times, then finish the edge lightly so that a new burr doesn't form. I'll microbevel after that at around 3-5 degrees higher than the main bevel. Another thing I've noticed about wire edge formation especially at higher grits, is that it tends to happen much more often when the stones are not completely clean. I use one of those Mr. Clean magic erasers to clean my Spyderco ceramics and I don't have much trouble with wire edges anymore.
 
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