Help needed with sharpening.

[scratchmasta]

Okay...

About a year ago, I bought one of the M2 RSKs. Great little knife. Wicked sharp. A few weeks ago I bought a TI-89 for my calculus class, and the clerk neglected to remove the security device for me. I tried to cut the seemingly plastic cord of the security device off of the calculator with my knife and discovered that the cord had a metal wire running through the middle of it that didn't want to be cut. The edge of my knife was practically destroyed.

So I just bought a sharpmaker to get my knife back into usuable condition, and surprise! I'm having trouble with it.

After a lot of work on the corners of the medium grit stones and finishing up with the corners and flats of the whites, I've managed to give it a usable edge again, but it's nowhere near as sharp as it used to be. I've watched the entire DVD that came with the sharpmaker, but I still have a lot of doubts about my technique.

1) The DVD says about 3 pounds, but I have no idea how much pressure that is. Should I use 3 pounds for everything? Just the medium grit? Just the white? I'm at a loss here.

2) The base of the blade has gotten a lot sharper than the tip, because of the curvature. I can push cut a piece of paper with the base, but the entirety of the curved tip will only tear, or at best roughly cut, a sheet of paper. I think this is because I'm having a really hard time keeping the blade's edge flush against the flat side of the stones while sharpening along the curve. What can I do to fix this? Should I use only the corners? Try to angle downward or outward?

3) Even the sharper base of the blade isn't that sharp. It'll push cut paper, but that's hardly as impressive as it used to be. Finer paper just tears or folds over, and hairs don't "pop" like they did when I first got it. Any advice for better sharpening would be much appreciated.

 

[James Muehlner]

Have you tried using the magic marker trick? Color the edge with a magic marker, and then see where the steel is removed. If, after a few passes on the sharpmaker, there is still marker on the very edge, then you are going to have to either reprofile it (keep removing metal until the marker is erased), or sharpen at a lower angle. I would want it to be at most 40 degrees inclusive, so if that's the case, and I were you, I would reprofile it. (This will be a lot of work; diamond stones are nice, but it can be done with the brown stones.)

If you are hitting the edge (marker removed all the way to the edge), make sure you are getting a burr if you do several strokes on one side. You can do this by dragging your thumbnail off the edge from the direction of the spine and feeling if it catches. If it does, you have a burr. Also make sure that the burr is removed by careful even pressure on both sides of the blade.

Overall, just make sure you are are getting the angles (same angle) and pressure (same, relatively light pressure) right on both sides. If not, you'll often get a rolled edge, which is like a super-burr. If I am not careful, that's a common problem for me. Such an edge is no good.

There is no need to press very hard on the stones. Use just light pressure (around 3 pounds I suppose) on all the stones. Pressing harder than that will not get you much but a rolled edge. Repetition and speed is what sharpens well.

I wouldn't worry about using the corners more; I almost never use them, and have mostly success at sharpening. Don't worry too much about angling the knife too much either, just make sure that the tip hits, but does not drag off, the stone. (another reason to use the flats) You will have to point the tip downwards as you finish the stroke. Every time you drag the tip off the stone, you will be blunting it a bit. Trust me. I know.

Practice will be the most important thing in keeping the blade at the right angle.

Also, even if you are hitting the edge, and sharpening properly, it may just be that the blade still has flat spots, or chips in the edge. It will take a lot of sharpening to get those out. Feel the edge with a fingernail or pad of the finger (carefully ) and see if any spots feel less "bitey", or uneven, slippery. If so, look and see if you can see light reflecting off the spots. That would most likely indicate a chip or dulled spot. You'll have to sharpen with the brown stones until the edge is nice and even again for that to go away.

I don't know how much of this you already knew, but hopefully something I've said will have been useful. Good luck! I know how maddening an edge that simply won't work is.

 

[dextersp1]

I'm new to the Sharpmaker and using it. A couple of thoughts from my experience:
1. I does take longer on the brown sticks than you might think
2. if the Sharpmaker is new the brown sticks need to be roughed up a bit to work properly
3. Clean the sticks often then get filled up with metal
4. Go lightly - you don't need that much pressure on the sticks

As far as the sharpness not being hair popping - I'm guessing that it is the 40 degrees angle. Your knife was probably set at something less than 40.

Finally, you might have a burr - does one side cut better than the other?

Other pros might let me know if I'm wrong.