Also... did I mention that the angle slots on the Lansky are wrong? The real angles are a little different from what they say they are.
The clamp is approximately 3.5835" long from the tip to the point where the angle section sticks out. When the clamp is shut completely with nothing in it (with the clamp halves parallel), the angle guide holes are located 0.875", 1.171875", 1.5", and 1.828125" above where the center of the edge would be (for a double bevel knife) for the 17-degree, 20-degree, 25-degree, and 30-degree slots, respectively.
So let us say you place it so the tip of the edge is 0.5" in front of the tip of the clamp. That means the tip of the edge is located 4.0835" from the front of the angle selector part. Using the trigonometry I learned in high school (finally it has a use).... arc tan (h/4.0835) = x. X represents the real angle. Fill in h with the height of the angle selector (I stated it earlier). So... if I were to stick a knife with no thickness into the clamp (and have 1/2" stick out) and tighten it so the clamp halves remained parallel, and then put the hones (make sure the guide bars are same level as the hone's abrasive material) into the 30-degree slot, I would end up with a real angle of approximately 24.1174-degrees. Not exactly 30-degrees.
This however assumes that the knife has no thickness. If the knife has a thickness (all knives do), the letter h in my equation will be the height of the angle selector used PLUS half of the thickness in inches. This is for double bevel knives. If it is chisel ground, you will just add the height of the angle selector and the thickness (without halving it). Using this value of h, you will get the real angle. So when you put your CQC-7B into the clamp (1/8" thickness) with half an inch sticking out, your real angle when using the 30-degree selector is 25.5616-degrees. You'd be more than 4-degrees off the desired 30-degrees were you to do this. If you wanted a real 30-degrees, I would suggest using the very top of the clamp as the bottom of an angle guide. Close it in by duct taping chopsticks to the side or something. If you have the same setup with the CQC-7B, you should end up with 29.854-degrees using the top of the clamp instead of angle guide. This probably is very confusing.
Actually there is an easier way to do this... a protractor.
Anyways, I'm confusing myself now.... so if there is any confusion, just e-mail me, I'm programming my graphing calculator to do all this stuff. OK, sorry guys, I know it looks like nonsensical scrawl and nothing more, but it sure works for me.
Also, if you use this method of calculating angles, and you screw your knife up because I made a big typo... it isn't my fault.
I'll just say that my pocket torx kit typed all this and pretend I had nothing to do with it.
-Chang the Asian Janitorial Apparatus
