On many knives, especially folders, the truth is that the factory edge angle *raises* as you approach the tip. Why? Because on these blades I'm talking about (not all of them) the blade stock is very thick at the spine, and as you near the tip, the edge sweeps back to be closer and closer to the spine. Which means that the blade stock at the tip is THICKER than in the rest of the edge. At a constant edge angle (like 20 degrees for example) a thicker stock produces a wider edge. So, if you keep a constant edge angle, your edge width at the tip (in thicker stock) will be wider than in the rest of the blade. This "looks funny", so factory knife sharpeners raise the edge angle as they near the tip, in order to keep a CONSTANT EDGE WIDTH through the entire blade edge.
If instead, you actually *do* maintain a constant angle as you resharpen these blades, you'll notice that you are widening the tip significantly. It looks a little weird. But it will cut better too.
As I said, not all blades do this. Many blades have distal taper, which means that the spine thickness decreases as we approach the tip. Which mostly keeps the edge thickness constant, negating these effects.
So, your first job is to use Secret #4, Observation, to know the geometry of your blade before you begin sharpening. Examine the tip. Examine the spine and see if it changes. Look closely at the existing edge and see if it varies as it goes to the tip. Use a loupe! If you do, you will likely find that many factory edges either don't get all the way to the tip, or they grind over it. Both result in blunt tips. Other manufacturers do a great job and ship blades with sharp tips. But they are the exception in my experience.
After you learn the geometry, form a plan for what to do. Will you maintain a constant edge angle to the tip? Or will you emulate the factory grind? Either way you should use secrets #1, 2, and 5. Nearly all of the 7 secrets apply to powered sharpening as well as hand sharpening on stones or plates.
You would be surprised how much you can use #1 and #2 at the tip of the blade by pressing your fingers right at the edge near the tip and feeling how it touches the belt.
Good luck!
Brian.
