Why can't I get knives "really sharp?"

[kershawguy13]

Usually when I get a new knife I use it for a bit and then go to sharpen it. I usually reprofile on the Lansky at the lowest setting which is usually around 15-17 dps, then add a microbevel on the Sharpmaker at 20 dps. For some reason my knives are not getting as sharp as I remember they were a while ago using this setup. They will shave and cut paper, but feel really rough cutting paper, and compared to a few knives I had professionally sharpened I can tell a difference. I think i may have a problem with a wire edge that I cannot get rid of. I also noticed the Lansky hones are not flat any more, they are a bit concave. Could this be causing an issue? Does anyone have any advice/recommendations? Thanks.

 

[115Italian]

If your lansky stones are not flat that could be a problem. I have the diamond stones extra course to fine and they never lost their flat surface but the extra course did smooth out. I had to replace it.

 

[bucketstove]

Usually when I get a new knife I use it for a bit and then go to sharpen it. I usually reprofile on the Lansky at the lowest setting which is usually around 15-17 dps, then add a microbevel on the Sharpmaker at 20 dps. For some reason my knives are not getting as sharp as I remember they were a while ago using this setup. They will shave and cut paper, but feel really rough cutting paper, and compared to a few knives I had professionally sharpened I can tell a difference. I think i may have a problem with a wire edge that I cannot get rid of. I also noticed the Lansky hones are not flat any more, they are a bit concave. Could this be causing an issue? Does anyone have any advice/recommendations? Thanks.

Hi,
yup, you've got burr,
and yes, concavity will contribute because it changes the angle,
so you're shooting for
so 15-17 and you're actually getting 17-20 (or whatever),
so when you go to sharpmaker,
its not a ~5 degree difference anymore,
meaning its not enough to cut off the burr

simplest way to remove burr, freehand a double angle on the sharpmaker all the way to 40, do 2 passes per side max,
that should take care of the burr, then go back to 20 degree setting and do 10 alternating passes per side


For more detailed/advanced sharpmaker steps see Sharpening Curriculum / Trouble sharpening super blue - Spyderco Forums


Eventually you'll want to flatten and condition that hone ... see How To straighten/flatten out a lansky stone ??

 

[kelbro]

Sounds like you might have been bearing down too hard on the Lanskys.

 

[Ratman79]

I agree with making sure you cut the burr off before testing the edge. Also, I don't know which stones you use but if they are dished, lap them true with an xx coarse dmt or atoma 140 or even SiC powder 60 grit on glass.

 

[Obsessed with Edges]

Usually when I get a new knife I use it for a bit and then go to sharpen it. I usually reprofile on the Lansky at the lowest setting which is usually around 15-17 dps, then add a microbevel on the Sharpmaker at 20 dps. For some reason my knives are not getting as sharp as I remember they were a while ago using this setup. They will shave and cut paper, but feel really rough cutting paper, and compared to a few knives I had professionally sharpened I can tell a difference. I think i may have a problem with a wire edge that I cannot get rid of. I also noticed the Lansky hones are not flat any more, they are a bit concave. Could this be causing an issue? Does anyone have any advice/recommendations? Thanks.

Focus on attaining a sharp-as-possible edge with only ONE hone (the first one), and NO microbevel yet. No matter how coarse it is, if you work to make it cleanly slice paper with the very first stage, any degradation in cutting performance that turns up in following stages will immediately highlight where the real problems are. Make sure to FREQUENTLY test paper-cutting every few passes and in all stages, to see if it gets better, or to reveal exactly where it turns for the worse. Problems might include new burrs forming with the finishing stones (when they should only be removing burrs), inconsistent angle control, too much pressure with finer hones (often causes burring and other issues like clogging); or, weaknesses with the hones themselves might be revealed, like lack of aggressiveness (clogging, glazing), inadequate abrasive to the steel type, etc. But, more often than not, if you have it cleanly cutting after the first hone, the subsequent work becomes much, much easier in refining the edge, so long as it's not overdone and thereby taking aggressiveness out of the edge or introducing other errors due to fatigue or lapses in concentration/focus.


David