Sharpening Calculator

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(Please note, this is not a primer on knife sharpening. It is only an assist for setting an accurate angle on a stone.)

The Problem:

A real key to a nice knife edge is an appropriate and consistent angle on the edge bevel. That's easy to say, but hard to do. There's 2 problems you must overcome:

Finding the right angle for your purpose.
Creating that angle on the sharpening stone.

Finding the right angle takes some planning, but it's not rocket science. It depends on how hard the steel is and what it is used for. Here's a general guide:

15 to 17 degrees
	This is the extreme. Razor blades and fillet knives fall into this group. Also high quality knives with high-performance steel can take this thin of an edge and hold it for a long time.
17 to 20 degrees
	Angles in this range are fantastic for a number of cutting and slicing chores. But it still requires a high quality steel to hold an edge at that angle.
20 to 23 degrees
	Most any knife can perform well in this range. Many commercial kitchen knives are factory set at around 22 degrees. If you are not sure about which angle to use, start with 20.
25 and up
	A cleaver would do well at 25 degrees. It places more steel near the edge to add strength. But you certainly won't be shaving paper. Unless your name is Dan. Very fat-beveled cleaver

While choosing the angle is important, it is not nearly as important as actually making it!

It's that second part that this calculator is all about. You might plan on creating a 20 degree angle on that edge. But how in the world can you do that? The difference between 20 and 25 in cutting ability is huge. However, in an average knife that's only one tenth of an inch lift in the spine!! And one pass at the wrong angle and all your hard work is gone.

......

So, now you're going to sharpen your knife on a stone. You place the edge on there and then wait! What angle am I sharpening at? How high to I lift the spine of the blade? What's going to happen?

Say you can find the height, but how do you set for each pass? A stack of coins is handy, but how many coins?

The Solution:

Many people use jigs and guides to help set the angle. But if you are a freehand kinda sharpener then this calculator just might help. It will tell you exactly how big that gap is supposed to be between the spine and the stone. It will also tell you what combination of coins will give you the perfect angle!

Find your perfect stack of coins here.

Simply fill in the first 3 fields and press "Calculate Now!".

The width is measured from the edge to the spine, right where the edge starts closest to the handle. The thickness is the thickness of the spine at that same point.

Width of the blade:
Thickness of the blade:		(1/8" = .125, 3/16" = .1875, 1/4" = .25)
The edge bevel angle:		(15 for razors, 17 for very sharp, 20 for general use, 25 for choppers)

The gap should be		inches.
		millimeters
Your US stack of coins is:
Dimes
Pennies
Quarters
Nickels
Your Australian stack of coins is:		I'm still working on the international stuff, please bear with me....
5c
10c
20c
50c

How to use:

You sharpen the knife on the stone as you normally would. The difference is using the stack of coins to get you started.

Place the stack of coins near where you start your stroke. Place the spine of the knife on the stack of coins. This will get you going at the perfect angle. Now sharpen as normal. On each stroke begin with the spine at the same point on the same stack of coins. Besure to use the same stack with each of your stones, from course to fine.

If you like to removing the burr by increasing the angle, add a dime on the top of the stack for those last 2 strokes - and stay light.

A helpful hint from YAM on BladeForums:

After you've set the knife on the coins, cozy your thumb up behind the spine. This will do 2 things: It will help 'train' your thumb at setting the gap automatically and it will help maintain the angle during the stroke (but don't follow with your thumb too often --- rubbing skin on a stone will cut it. I know.)