Understanding Blade Angles

Let's first dispel some rumors: 

Claim #1 - Your knife MUST be sharpened with a specific gadget. FALSE - Refer back to our first post regarding how to sharpen without a sharpener. In short, you just need something abrasive enough to move metal. 

Claim #2 - Your angle must be precisely what that particular "expert" says. FALSE - Your angle must be consistent - not exact.

Claim #3 - You must make "X" number of passes to arrive at sharp. FALSE - success will be dependent on lots of factors like the type of steel, type of abrasive, pressure, and how dull it was, to begin with, but there is no specific number of passes that equals success. 

Why are these claims all false? Because sharp is the condition of two angles meeting in a congruent form. Until the APEX is reached, you will still have a dull knife - no matter if the angles are perfect at 20 degrees if you are using some $400 sharpening system that has a really cool name, and no matter if you've made 30 passes on the fine grit. If you didn't reach a new apex, you didn't arrive. 

So what do we mean when we say, "angles are less important than apex"? If I gave you a knife that was precisely sharpened at 20 degrees but did not reach an apex versus a knife that was sharpened somewhat irregularly (maybe 18 degrees at the tip and changing to 22 degrees at the point where it reaches the tang, you will say every time that the knife with the irregular angle is sharper - every time.

Why? Because it IS.

Here is the point; when sharpening by hand, your stroke may not hold the exact degree from one end of the knife to the other. This may not look beautiful on your Sebenza in the display case, but we are talking about practical applications. What is important here is YOUR STROKE. It matters less that your stroke is perfect and much more than your stroke is consistent. Making the exact same stroke will dramatically improve your results. Don't get too hung up on being at an exact degree.

Sure, degrees do matter. Hatchets may be ground at 25 degrees or more. Japanese chef knives are usually about 16 degrees. Twenty degrees is right in the middle of the spectrum, so we advise people to practice that one and stick with it until comfortable and good results are achieved. But a consistent stroke is the KEY!

Bottom line – APEX, APEX, APEX. Here is a picture of what that looks like under magnification. 

The bent-over part is the burr. This burr happens when you reach the apex. You can see it and feel it. The burr can be broken off by further refinement on smoother abrasives. When achieved, the edge will look something like this:

Practice and patience will get you there. Once you have mastered roughly 20 degrees, you can begin to experiment with more acute and obtuse angles. Practice on a basic carbon steel knife like an Old Hickory kitchen knife instead of your Spyderco in M4 steel. And most importantly, enjoy the process! 

Stay Tuned for the next Knife Skill: Supersteel versus Traditional Carbon?

Knife Skills is a collection of important techniques that all people should know. These valuable life-skills will significantly improve your experience with knives and produce better results with all knife tasks. Published in partnership with Georgia Bushcraft.

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