Originally posted by greyeyezz: The issue I've had with a clamping system involves longer blades, the heel and tip angles change ever so slightly relative to the center. Also for maintaining an edge unless you clamp in exactly the same spot(basically impossible) your going to change the angle slightly.
It's been my experience: The Clamp should be at the center of the BLADE with longer knives.
Originally posted by maladat: There are a lot of details that go into putting a really nice edge on a knife. It isn't easy.
However, putting an OK edge that will cut pretty well on a knife IS easy. A coarse stone, used sloppily with way too much of an angle, will produce an ugly edge, but it'll produce an edge that will cut just fine.
The two small flat surfaces on either side of the blade that intersect to produce the edge of the blade are the bevels.
When a knife gets dull, what happens is that the intersection of the bevels gets rounded over.
When you sharpen a knife, you're basically grinding the bevels farther into the body of the blade so that you remove the rounded off part and get a nice, crisp intersection again.
If you don't remove enough metal from the knife, or if you use too shallow an angle, so that the metal you remove comes from where the bevels meet the sides of the blade, rather than from where the bevels intersect, you'll never get the knife sharp because you aren't actually touching the edge.
That's pretty much the bottom line. If your knives aren't coming out at least pretty sharp, you aren't sharpening to the edge of the blade.
If you have good eyes, you can see this with the naked eye under bright light. A magnifying glass makes it easier. The best way to look at the edge and see where you are removing metal is with an inexpensive loupe.
You can also do it by feel. When you sharpen right to the edge of the knife like you're supposed to, you produce a wire edge on the opposite side from the one that you are sharpening.
This is a very good video. You can skip the information about how to sharpen on a whetstone, but he gives a great explanation (with good diagrams) on what actually happens to the edge of a knife as you sharpen it and about the wire edge and how to feel it.
He's also interested in sharpening kitchen knives - you may want to use a different sharpening angle if you're sharpening pocket knives or something.