Lisa,

In terms of the specific question you have to answer for your knifemaker, a 30 degree primary bevel should give you good performance. That will allow you to sharpen and hone with about a 31 degree angle at the edge.

To put that in context, the edge on a really good sharp kitchen knife is about 40 degrees.

Lisa:

I am going to have to disagree a bit with Alastair. Really good Japanese knives are sometimes sharpened at a 20 degree, or even lower, angle. This is particularly true of single-bevel knives, such as those used for slicing fish for sushi, which may be as low as 10 degrees (10 degrees on the beveled side, 0 degrees --.i.e. flat -- on the back)

Double bevel Japanese knives are typically sharpened around 30 degrees, i.e. 15 degrees per side.

For skiving, I use a single-bevel (also called chisel ground) knife -- i.e. the blade is only ground on one side, with the other side remaining flat. For such a knife, you could definitely try something perhaps in the 20 degree range. The angle your knife can support is a function of the type of steel (alloy) used and the way it is hardened/tempered. The reason Japanese knives can be sharpened to such an acute angle is that the steel used is a different alloy from that used by the Europeans, and it is hardened to a substantially greater extent (Rockwell hardness of up to 62 or 63, vs the European knives being hardened more to the mid-50's). Also, the most acute Japanese blades are not meant to hit anything hard, such as bones. All things being equal, the more acute the angle, the lower the durability of the edge. But, you should be stropping very frequently, and even touching up the edge pretty often.

I will look at my favorite skiving knife in the next day or two and try to figure out the angle I have it sharpened at.

Lance

Lance,

You're right about the Japanese knives, I'll qualify my statement: the edge on a really good sharp western kitchen knife is about 40 degrees Sashimi knives are terrifying, and very high maintenance.

My experience so far with Japanese leatherworking knives having an iron back and a thin but very hard steel edge are that with the extremely shallow grind angles they chip if you look at them funny, but they are a lot more robust with a 30 degree (30 + 0 chisel grind) edge and still cut incredibly well.

I'm sure that's user error, and I need to find a Japanese expert to teach me how they use them and figure out what on earth they use as a cutting surface, because nothing I've tried stops the corners chipping.

Anyway, within reason you can grind the primary bevel as shallow as you like. In some ways a 20 degree primary bevel is better than a 30 degree one because your actual edge angle always has to be greater than the primary bevel angle.

That means if you go with a 20 degree primary bevel you've got the option of a 30 degree secondary bevel if you find a 21 degree edge chips or blunts too easily. It still won't be as robust as a 30 degree primary bevel though.

So, assuming a normal western type blade made of a chunk of tool or spring steel and hardened to around 58 rockwell, I'd still recommend a 30 degree primary bevel

Whenever I get a new knife (or a used one) that I intend to use, one of the first things I usually have to do is change the angle on them. Many people think that if it takes hair off one's arm, it doesn't need any sharpening, If it 'shaves', it's fine.

To start with, there is a big difference between taking hair off one's arm and shaving-sharp. Taking hair off one's arm is a good start, but shaving sharp requires very little pressure and the edge carries for the length of the blade.

I don't know what angle I use, my protractor is made by The Almighty and surgically planted in my head. It is fine for my purposes as well as many whose knives I've sharpened.

For regrinding knives, the best thing to remember is to keep a quench bucket close and use it every few seconds. If the edge gets hot, it will lose its temper and edge holding qualities. A rule of thumb I use is, if the metal gets too hot to touch, it's too hot. Quench sooner.

I also use and make single-edge 'chisel ground' skiving knives. Go to a junk shop and buy one-dollar kitchen knives that still have an edge. If you can reshape them without removing the temper (grind and quench often) you can come up with a pretty good set of knives.

Not an expert, but skiving knives are pretty delicate use, usually flat on one side. Would suggest 15 deg. or less for the primary grind (width about 4 or 5 times the blade thickness), then a tiny secondary bevel on the edge of about 30 deg. The secondary bevel will change as you use it and find what works best.
Chuck

Lisa:

I endeavored to measure my skiving knife (a Tina knife) -- I estimated an edge angle of about 17 degrees. I would say chuck's advice is worth following. If the edge is too weak, you can always gradually increase the angle of the secondary/micro bevel, and over time the primary angle will increase as you sharpen the knife.

Let us know how it works out.

Lance