Thu May 24, 2012 11:55 am
Traditional German (and their American cousin/knock offs) typically use a 20 to 22.5 angle right out of the box - and you can usually find it in their literature, online, etc. The bevel is usually ground 50/50.
Now, anyone who's ever tinkered with the angles on these knives (I have, many time) knows you can dramatically increase the sharpness by cutting the angle down to 15 or even 12 degrees. But you will be re-sharpening your knife almost every time due to the nature of the steel.
However - you can get much better performance from a German knife by re-grinding the edge to 17 - 18 degrees or so. The typical western factory edges, as most folks know, are simply not that sharp.
With Japanese knives, we have a much wider range of both sharpening angles and bevel distribution. You see bevel ratios ranging from "chisel" 100/0, to 70/30, 80/20, etc.
While I see lots of references to bevel ratios, I see almost no reference to bevel angles.
NOW - before everyone jumps on me - I do know how to put a knife on a stone and determine that knife's bevel angle simply by the look/feel from the stone.
But my point is the references I do see say something like 10 degrees, but every video (including your excellent ones, Mark) I look at the "real" angle appears to be much closer to 5 degrees than anything else. Sometimes even less.
I realize it may vary from knife to knife, and by maker, and/or manufacturer, but anyone have any insights?
Or is it simply something you "learn from the stone" - which is OK.
Thu May 24, 2012 1:06 pm
This is an excellent topic especially for beginning sharpeners. There is a lot of anxiety as to what angle to sharpen a knife and I quite frankly dodged the question when I did the videos because I thought that it would get in the way of getting someone up a running. Instead I taught that you should "copy" the edge and demonstrated how to listen and feel the steel grind and raise the knife until you hit the edge (you get a different sound and you can feel the knife stop slipping along). The problem with this method is you are copying an edge that you have no idea if it's ideal for the knife.
Most knives can take a 15 degree edge including most decent German knives. As a matter of fact, Wusthof now puts a 15 degree factory edge on all their knives. So in my DVD I'm planning on just telling new sharpeners to shoot for that angle until they get more experience and want to start experimenting with different angles. I'm going to either include a simple angle guide made out of a piece of cut plastic or show people how to make a quick one with a business card and a ruler and some scissors. It takes 2 minutes or less.
You're right when you say you lose edge retention as you steepen the angle on the knife especially with softer steel. It's a balancing act to get the right edge for your knife and your own preference. I tend to sharpen mine steeply since I like stropping and sharpening. I routinely sharpen my knives down around 10 degrees which is a little over the top for most knives.
Thu May 24, 2012 5:49 pm
THX for great remarks and excellent response time.
Completely agree with all of your comments regarding traditional knives. I cut plastic wedges on a chop saw to give to nieces/nephews who are serious about using good, sharp knives - so I know exactly what you're talking about.
But what about our Japanese knives?
Fri May 25, 2012 12:18 am
Most freehand sharpeners don't even know what angle they sharpen at
You would think they would but they don't. Part of the issue is that they aren't even holding a consistent angle anyhow and get a convex edge of varying degrees of convexity. To get real acute you do need some precision, with the exception being zero grind edges.
That said Euro knives shouldn't go much below 15 degrees - if that.
With Japanese knives this is very specific and steel dependent. Specific to the user's cutting style and the qualities of the knife. As you get more acute the odd properties of the steel make themselves known. I have sharpened knives as acute as 3.0 degrees per side to test limits and put a triple bevel on it at 5.0 degrees and 7.0 degrees eventually. I've done final bevels at 5.0 degrees to produce an exceptional edge. Delicate as hell - you bet! People who don't understand the delicacy of an edge like this can mistake it for a wire edge, but it is a true edge. It is rare to find a steel that will support a 5 degree bevel without spontaneous chipping, etc. This is a topic of endless experimentation to determine ideal angles and overall edge geometry configurations.
Fri May 25, 2012 3:38 pm
Great info. Thank you for sharing that - and it confirms what I thought - each type of knife and steel probably have their own unique characteristics.