Tutorial Video

How it Works

Thank you for purchasing your Anystone Sharpener! Sharpening is easy. Let me show you the basics! See the video above for a full sharpening session with Anystone. if you want to know the nitty gritty, keep reading!

Fundamentals: 

The Anystone Sharpener operates on the same basic principal as most guided sharpeners. Your edge angle depends on 3 variables: 

  1. The width of your blade (W)
  2. The height of your stone (H)
  3. The length of the sharpener (L)

These three variables form  a triangle that defines your sharpening angle, θ. Because your blade width and stone height are set values, all that's left to change is the length of the sharpener. This is easily done by twisting the ball at each end of the sharpener to lengthen it. The longer the sharpener, the larger the angle. For your convenience, I've done the math for you. 

φ+θ = arctan (B/A), your sharpening angle is simply θ = arctan (B/A) -φ. 

φ = arcsin(D/C) and C is of course sqrt(A^2+B^2). Thus, you can easily determine θ by measuring L,W,H (in inches) and inputting them into the equation below. 

θ = arctan((2.5+L)/(W+4.625) - arcsin(H/sqrt(((2.5+L)^2)+((W+4.625)^2)))

Of course, this will be an iterative process of adjusting L and re-solving until you reach the desired angle. 

You may be thinking: that is way too much work. I’m not doing that! And I wouldn’t blame you. Fortunately, you can easily solve this equation for the required L value given your desired sharpening angle using common numerical solutions like Newton-Raphson!

IMPORTANT

Jokes aside, you do need to be aware of two important results of the geometry above. The height of your stone and the distance between your edge and the jaws of the sharpener affect your edge angle. This means that switching stones will change your angle if they are different heights. It also means that the position of your blade in the jaws will change the angle. You don't need to worry about either much as long as you always double check the angle indicator before sharpening!

Angle Indicator

Of course, if you don’t mind a couple of percent error, you can just turn the screw thing until this dangly arrow points to the angle you want.

 

Once it’s on the right angle, turn the red set knob until its snug against the body of the guide to lock it in. Repeat on the opposite end and you’re ready to sharpen!